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Attorneys' Textbook of Medicine (Third Edition)
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CHAPTER 177 TREATMENT OF PAIN
excerpt
AUTHOR: David Cramer, MD
P 177.00 INTRODUCTION
More than any other reason, people consult their physicians seeking relief of pain.
Ideally the underlying cause of pain, whether disease or injury, will be identified and
corrected, thereby relieving the pain. When, however, the cause of pain remains
obscure or is not treatable, some means of alleviating the pain itself must be sought.
Despite major advances in understanding how and why pain can develop and persist,
and the advent of many sophisticated medical and surgical treatments, physicians
are by no means always able to substantially relieve their patients' pain.
[177.01] Complex Nature of Pain
Pain is far from the simple matter it may sometimes seem to be. The same injury or
disease may produce trivial distress in one individual and intolerable pain in another.
Furthermore, seemingly severe pain may continue for years after an injury has
healed or disease is cured.
The damage sustained by a body part or organ is only one determinant of the
severity and quality of pain. Past episodes of pain, cultural influences, and whether a
patient understands the origin of the pain and feels in some degree of control, all
contribute to the pain experience. Prophetically, Plato asserted that pain arises not
only from peripheral stimulation, but also from an emotional experience in what he
called the soul (Caillet, 1993). It is becoming increasingly clear that the ''subjective''
aspects of pain may actually influence the nerve signals that convey painful feelings
from the affected part of the body to the brain.
1
Successful pain management requires an appreciation of how physical, psychological
and sociocultural factors interact to produce pain. The complex nature of pain,
particularly when chronic, often dictates a multidisciplinary approach to its
treatment. Flexibility is the key: management must be continually modified
according to the severity and extent of whatever is causing the pain, previous
treatment and the response to it and the patient's personal preferences (NCI, 1996).
[177.02] Definition of Pain
Pain is commonly thought of as a warning signal that something is wrong. As such, it
may be viewed as adaptive if it leads to the discovery of what is causing pain and to
its abolition. An operational definition of pain (Feuerstein, 1994) takes into account:
the patient's actual experience as described;
''pain behavior''-- observable expressions and actions that suggest a patient is
suffering;
how pain affects the patient's functioning at home and at work;
how emotional factors alter the perception and expression of pain; and
a cognitive component involving how sensitive the patient is to pain, and how
much attention is paid to bodily discomfort.
P 177.10 TYPES OF PAIN
Pain may be classified, first, by its time course: whether it is acute, subacute or
chronic. A second way of classifying pain is to specify the particular sensory
mechanism involved. In addition, there are a number of clinical pain syndromes
associated with particular injuries or diseases.
[177.11] Acute Pain
Acute pain develops instantly (as after an injury such as a laceration), or over a
period of hours to a few days. Migraine headache, appendicitis and dental abscess
are examples. It is this type of pain which typically serves as a warning that
something has gone wrong in the body. Subacute pain is similar but develops over a
few weeks, rather than hours or days.
[177.12] Chronic Pain
Pain that continues longer than three months generally is termed chronic, though it
need not be constantly present. Typically this type of pain is less well localized than
acute pain. It also differs in quality, tending to be described as ''nagging,'' ''deep,'' or
''boring,'' rather than ''sharp'' or ''cutting'' - terms often used to describe acute pain.
Chronic pain often goes on well past the point where it is a useful warning sign. It
may even continue after a lesion has healed or a disease is seemingly cured. When
this is the case, chronic pain is liable to affect the patient's psychological and social
status, and compromise his or her ability to function.
2
[177.13] Physiological Distinctions
Pain often is classified according to how it is produced (its mechanism). There may
be overlap between different physiological (functional) categories of pain. And a
patient may have more than one type of pain at the same time.
The skin and other tissues and organs of the body have free nerve endings called
nociceptors, which are sensitive to mechanical, thermal or chemical stimuli. When
exposed to such stimuli, the nociceptors activate their nerves and send pain signals
to the brain. Nociceptive pain may feel sharp and intense (touching a hot object),
aching (low back pain) or deep and severe (invasion by cancer). This type of pain
very often can be relieved by narcotic or other analgesics, alternative medical
measures or surgery.
Neuropathic pain occurs when nerves are damaged mechanically, by a virus (herpes
zoster), by a toxic substance such as mercury, or by any number of other causes. A
localized growth of a nerve (neuroma) may cause this type of pain.
When nerves in the brain and spinal cord or ''outside'' (peripheral) nerves are
damaged to the point where nerve signals are actually interrupted, the result is
deafferentation pain. The term refers to dysfunction of afferent nerves, those
bringing information (such as pain) from the outside world to the brain. This type of
pain (also called causalgia) may be very severe. It often has a burning quality. Or, it
may be described not as pain itself but as an unpleasant sensation in part of the
body that otherwise has lost feeling (anesthesia). Some patients report being
exquisitely sensitive to painful stimuli (hyperalgesia), or as having an exaggerated
reaction to what should be a minor stimulus (hyperpathia). This form of pain tends
not to respond to drugs or surgery (although antidepressant drugs hold some
promise).
So-called psychogenic pain is seen in patients with psychological or psychiatric
disorders. It is diagnosed only after all bodily (somatic) causes of pain have been
ruled out. (Nashold, Jr. et al., 1994; Wilson and Lamer, 1992).
[177.14] Clinical Pain Syndromes
Pain syndromes may be defined by the part of the body they affect. Examples are
the combination of headache with facial pain, pain in the face and mouth (orofacial
pain), low back pain and pain affecting the neck and upper extremity. Other
syndromes are associated with particular disease states or conditions. They include
obstetrical pain, postoperative pain, pain resulting from sports injuries, and pain
caused by cancer or AIDS.1
Certain types of nerve damage or disease also may produce recognizable clinical
syndromes. Neuralgia is a form of pain caused by infection or disease that injures
peripheral nerves. A special case is postherpetic neuralgia complicating infection by
herpes virus. Patients requiring amputation of a limb may experience severe and
persistent pain (phantom pain) as if the extremity were still present (Raj, 1992).2
FOOTNOTES:
Footnote 1. See also ch. 176.
Footnote 2. See also ch. 2A.
3
177.20 PHYSIOLOGY OF PAIN
An understanding of what actually happens in the body to produce the experience of
pain will help explain how various treatments work, and why all attempts at treating
pain sometimes fail. Most often pain occurs when signals are sent along certain
neural pathways. In other instances, mechanisms that ordinarily inhibit pain are
suppressed, permitting feelings of pain to emerge.
Mechanisms of pain production are discussed briefly in this section.176. for a more
detailed discussion of the mechanisms of pain.
[177.21] Peripheral Nervous System
Stimuli cause pain by activating receptors, the end-branches of sensory nerves lying
just below the surface of the skin. The nociceptors are those receptors that are
especially sensitive to pain-causing stimuli. The nerve ending converts the stimulus
into a train of electrical impulses, the nerve signal, that passes along the peripheral
nerve to the spinal cord. The strength of a stimulus may determine whether or not it
will be painful. Light pressure, for instance, is not felt as painful, but increased
pressure eventually will cause pain (Hall, 1994).
[177.22] Spinal Cord
In cross-section the spinal cord is seen to have a central butterfly-shaped area of
gray matter, consisting of the bodies of nerve cells. The long extensions of these
nerve cell bodies form the axons that transmit nerve signals to and from the brain.
Each axon is protected by a covering sheath of a substance called myelin.
The afferent peripheral nerves, which bring messages from the body surface to the
brain, enter the posterior (dorsal) part of the spinal cord through nerve roots. Their
cell bodies lie together in small masses called ganglia which are just outside the
spinal cord itself. Each of their axons has two branches, one passing from the outside
of the body to the ganglion, and the other from the ganglion along the dorsal root
into the spinal cord. Nerve cells are connected to one another by tiny spaces called
synapses, which serve as relay points. At the many points where nerve cells meet,
pain signals may be either strengthened or weakened (inhibited).
Pain signals pass from the dorsal part of the spinal cord to the brain in nerve bundles
called tracts. A very important one is the spinothalamic tract, which sends nerve
fibers to the thalamus, a central brain structure. From this point signals proceed to
the outer layer of the brain, the cortex. Many other tracts send nerve signals to the
reticular system in the lower part of the brain. Messages also go to the limbic
system, a part of the cortex that controls behavior and emotion, as well as directly to
the cortex itself. The fact that nerves carrying pain signals run together in tracts
makes it possible to relieve pain by surgically cutting the right tract (Melzack and
Wall, 1988).
[177.23] Brain
In contrast to what was formerly thought, there is no single ''pain center'' in the
cerebral cortex. All sensory signals including pain messages are received in the
cortex and relayed to other parts of the brain. In effect, the entire brain contributes
4
to the pain experience. At the same time, the brain is able to suppress pain through
descending (efferent) nerve tracts that inhibit sensory nerve signals.
Exactly how nerve signals produce pain remains uncertain, but a number of
chemicals may play a role. ''Substance P'' is a brain protein that apparently transmits
incoming pain impulses. Other chemical mediators of pain may include prostaglandin
E, inflammatory substances called leukotrienes and histamine. All these chemicals
act at the site where pain is felt. They may directly activate pain receptors, or cause
changes such as tissue swelling and inflammation which have the same effect
(Cailliet, 1993).
[177.24] Inhibition of Pain
The existence of neural mechanisms that can inhibit nerve signals both peripherally
and in the brain can help explain many observations: that injury and pain are not
always related in a consistent manner, that non-painful stimuli may produce pain
and that pain often continues after an injury has healed. Inhibitory nerve cells in the
spinal cord help determine which incoming signals will reach the brain. At the same
time, inhibitory nerve fibers from the brain connect with nerve cells in the spinal cord
and suppress them.
[1] Gate-Control Theory An ingenious theory was proposed by Melzack and Wall in
1965 that helps explain some of these puzzling observations. They proposed that
special cells in the reticular formation of the brain and an area called the substantia
gelatinosa can control the flow of pain signals and determine which, if any, will reach
the brain. Pain is felt when this ''gate'' is open, but is diminished or absent when it is
closed. It now is recognized that, while the gate-control theory may be right, it is not
the whole story. At least three other neural systems exist which can influence the
transmission of pain signals (Hoffert, 1992).
[2] Enkephalins An important element in pain relief is the enkephalins, a type of
built-in (endogenous) narcotic produced by cells in the dorsal horn of the spinal cord.
The enkephalins act at synapses between nerve cells to suppress incoming nerve
signals (Wilson and Lamer, 1992). When released by nerve cells, enkephalins inhibit
the release of substance P. In this way they are able to stop incoming pain signals
from reaching the brain. It is as if the body produced its own pain-killer, which in
structure closely resembles the opiates so often used to treat pain.
[177.25] Mechanism of Pain Following Nerve Injury
When a peripheral nerve is injured, the normal input from outside stimuli is cut off.
Instead, signals that normally would be suppressed by inhibitory mechanisms pour
in. Nerve injury also keeps the usual chemicals vital for normal nerve cell function
from passing along the nerves. The net result is that nerve cells in the brain and
spinal cord become highly excitable. They start responding to stimuli from parts of
the body with which they have no direct connection.
This condition is called denervation hypersensitivity. It may well explain the pain that
often continues long after a nerve injury has healed. It also can explain the
''phantom limb'' phenomenon. Cells, for instance, that used to serve an amputated
foot now respond to stimulation of the knee, making the patient feel as if the foot
was still there (Melzack and Wall, 1988).
5
P 177.30 EVALUATION AND DIAGNOSIS
Pain is a symptom, and as such is a private experience that is not objectively
measurable. Although the physician can find clues in how the patient looks and
behaves, the patient's own description of pain is of paramount importance. There
are, however, ways of codifying what the patient has to say, and thereby gaining
some idea of how intense the pain is and how much it changes over time. In certain
cases, imaging the site of pain can be helpful.
[177.31] History
How the patient describes pain will sometimes suggest a specific condition. Back pain
that is made worse when the patient sits or walks, for instance, is good evidence of
degenerative disease of a spinal disc. When back pain gets worse in bed, however, a
spinal tumor may be responsible. The exact words the patient uses when describing
the pain are often quite helpful in distinguishing between various pain syndromes.
What makes the pain worse, and what tends to ease it?
The patient should be asked about past instances of pain and whether any particular
methods have proved helpful in controlling pain. How the patient feels about using
opioids and other types of medication should be established; have substances been
abused? Whether the patient also has suffered anxiety or depression may be a key
factor. Of importance as well is what the patient knows about pain treatment, what
is expected, and any preferences the patient may have for (or against) a given type
of treatment (PHS, 1992). The physician should know how the patient's pain has
altered sleep or eating habits, and how much it has interfered with activities at work,
home or play.
The McGill Pain Questionnaire was developed by Melzack to help the patient describe
the pain experience in detail. The most commonly used psychological measure used
in patients with chronic pain is the Minnesota Multiphasic Personality Inventory.
Older patients may have to be prompted frequently when asked about symptoms.
Observing how an elderly person responds to pain medication may be revealing.
When evaluating children, repeated assessments and careful observation will help
clarify the picture (Hinnant, 1994).
[177.32] Physical Examination
The part of the body where the patient feels pain is carefully examined. Redness and
swelling may suggest inflammation. The examiner should probe for tender points,
and monitor pain as nearby joints are moved through their full range. Stretching an
arm or leg may worsen pain if a major nerve or group of nerves (plexus) is inflamed
or compressed by some other structure.
A neurological examination may reveal signs that nerves are not functioning
properly, marked by muscle weakness, loss of sensation or abnormal reflexes. The
physician should know that pain sometimes is referred to a site other than where it
arises. Disease of an internal organ may make a particular area of skin
hypersensitive to painful stimuli.
[177.33] Laboratory and Radiographic Studies
The electromyogram (EMG), by recording electrical activity from muscles, can show
6
that a nerve which controls a particular muscle or group of muscles is not working.
Nerve conduction studies determine how well nerves transmit their signals. Together
these studies may show whether the cause of pain resides in the spinal cord, nerve
root, or the nerve itself. Another way of assessing nerve function is through evoked
potentials, whereby electrical nerve responses to applied stimuli are recorded
(Waldman, 1996).
Pain in a bone or joint may be pinpointed by plain x-rays, computed tomographic
(CT) scanning, or magnetic resonance imaging (MRI).3 Bone scans made with a
radionuclide contrast medium are often very helpful in locating the source of pain,
and sometimes its cause as well. These scans can disclose a hidden or tiny fracture,
demonstrate the spread of cancer and diagnose joint disease. Ultrasound is a safe
and often revealing study. In special cases it may help to inject a contrast material
into a joint, the spinal column (myelography), or a major blood vessel (Abrams, et
al., 1996).
FOOTNOTES:
Footnote 3. See also ch. 70.
P 177.40 GENERAL PRINCIPLES OF TREATMENT
As for centuries past, there remain three fundamental ways of relieving pain.
Analgesic drugs (pain-killers) are a mainstay of treatment. The choices available and
the means of delivering them are both widening. Furthermore, drugs are being
increasingly used in combination with what are called sensory-modulation
techniques. These range from anesthetic methods (nerve blocks) and sophisticated
surgical procedures to a broad range of physical methods. Finally, recognizing the
importance of the psychological aspect of pain have prompted attempts to allow
patients to use their own resources to cope with chronic pain (Wurm, 1992).
Relaxation techniques, biofeedback, hypnosis, behavioral methods, and cognitive
approaches all fall into this category.4
[177.41] Therapeutic Approach
Whenever possible the specific condition producing pain will be the object of
treatment. But this often is not possible in patients with chronic pain, and for some
types of pain there may be no specific treatment. In these cases the goal must be to
help patients carry on with their lives and their work as well as possible while
controlling pain to some degree, hopefully without long- term narcotics (Wurm,
1992).
An accepted guideline is to first try a relatively noninvasive procedure such as a local
nerve block with anesthetic or electrical nerve stimulation before resorting to a more
drastic approach, such as destroying a nerve. Increasingly today, multiple measures
are given concurrently rather than sequentially in the hope that they will augment
one another. For instance, a narcotic and a nonnarcotic drug will control pain better
when used together than when each is used separately. A patient with chronic pain
may benefit when, in addition to analgesics, a relaxation technique is taught and
appropriate physical therapy is carried out.
Prevention always is better than treatment. Caregivers should encourage their
patients to ask for relief before pain becomes severe (when it will be more difficult to
control). Relaxation exercises can help control postoperative pain (PHS, 1992).
7
Chronic pain is best managed using a team approach: the patient, the family, and all
health care providers involved. The patient should be an active, not a passive
member of the team. Patients and their relatives should know that numerous
effective and safe ways of relieving pain are available, and they need not be
reluctant to ask for relief (NCI, 1996).
[177.42] Use of Drugs
The issue of whether, and when people suffering chronic pain should receive narcotic
drugs remains as controversial as ever. Most experts agree that fear of addiction
(psychological dependence) should not cause these effective analgesics to be
withheld from a patient with end- stage cancer who is not expected to live much
longer. On the other hand, caution is appropriate for those with a longer life
expectancy or patients with benign disease that is causing severe pain. They may
require ever larger doses to keep the pain under control (tolerance), or they may
become physically dependent and develop withdrawal symptoms if the dose is
lowered or the drug dropped altogether (Freidberg, 1992).
Patients with cancer should not, however, be confused with street addicts. They seek
pain relief, not euphoria. When patients using narcotics gain relief from a
neurosurgical procedure, the drugs often can be rapidly withdrawn with no signs of
dependency (Melzack and Wall, 1988). Furthermore, many patients who are allowed
to give themselves narcotics actually use less than if placed on a conventional dose
schedule. Their dosage tends to stabilize (assuming disease does not progress), and
they do not become addicted.
[177.43] Placebo Effect
A placebo is a substance that does not have any effect on the body, but nevertheless
relieves pain. The so-called placebo effect is an element of pain control that must not
be ignored. In some respects a placebo does act like a ''real'' drug. In headache
patients, a larger amount of placebo will be more effective.
The physician must take care not to lose the patient's trust when trying a placebo.
When a placebo does relieve pain, it does not mean that there really was no pain. In
general, placebos are about half as effective as whatever drug they are compared
with. They tend to work better when pain is severe and in a patient who is anxious.
The down side is that, over time, a placebo becomes less effective (Melzack and
Wall, 1988).
[177.44] Psychological Factors
When psychological factors are an important part of the pain experience - not an
uncommon circumstance - invasive treatment may make the situation worse. But
pain must not be assumed to be purely psychological unless physical illness has been
carefully ruled out.
The physical and psychological aspects of pain often interact in complex ways.
Among the many factors that may have to be taken into account are the patient's
expectation of the final outcome, past experience with pain, ethnic or cultural
attitudes toward pain and its treatment and ''secondary gain'' - effects of pain (such
as not working or receiving attention) that the patient may welcome (Aronoff, 1992).
8
[177.45] Treating Pain in Children
It often is assumed that a child's pain is, in a direct way, proportional to the nature
of disease or injury and how much tissue damage has taken place. This view is
incorrect, however. Pain in children seems to be even more plastic than in adults.
How often pain is adequately relieved in children is far from clear. Opioids should not
automatically be forbidden to children. Issues of safety are, however, paramount. It
is helpful to design treatment programs aimed at specific conditions afflicting
children, such as cystic fibrosis, sickle cell disease and cancer (Waldman and Winnie,
1996).
[177.46] Treating Pain in the Elderly
To assess how older persons are responding to treatment for pain, it may be
necessary to use simpler measures and to repeat assessments at frequent intervals.
This is especially important for those who are cognitively impaired, and for all elderly
patients who undergo major surgery. Pain management should be re-evaluated when
an elderly patient is discharged home or goes to a nursing home.
Older patients very often are taking many drugs, and so are at risk of adverse drug
interactions. Nonsteroidal anti-inflammatory drugs (NSAIDs), though effective, are
especially likely to cause physical or mental side-effects in the elderly. Older persons
tend to be sensitive to the pain-relieving effect of opioids, and so may require lower
doses. In general, treatment should start with a low dose and be carefully adjusted
to the clinical response (NCI, 1996).
FOOTNOTES:
Footnote 4. See also ch. 178 for a detailed discussion of the psychiatric aspects of
pain.
P 177.50 DRUG TREATMENT
The three basic groups of drugs used to relieve pain include, firstly, nonnarcotic
analgesics such as aspirin and acetaminophen. Aspirin is one of a large number of
nonsteroidal anti- inflammatory drugs (NSAIDs), which effectively relieve pain that is
not too severe. Secondly, there are the more potent narcotic drugs used to treat
severe pain such as that caused by cancer. The opiates include morphine and drugs
derived from morphine. The opioids are man-made drugs that resemble morphine in
their chemical structure, and have similar effects. Thirdly, a wide range of drugs
including antidepressants and muscle relaxants, do relieve some types of pain
although they are not used primarily for this purpose. Finally, many attempts have
been made to relieve pain by smoking marijuana or taking a drug that contains its
active substance.
[177.51] Nonnarcotic Analgesics
Aspirin and acetaminophen are by far the most widely used of this class of painrelieving drugs. Probably more than twenty other nonnarcotic analgesics are widely
prescribed. Some of the more familiar ones include ibuprofen, indomethacin,
naproxen, diclofenac and phenylbutazone (Melzack and Wall, 1988).
[1] Aspirin and Other NSAIDs
9
Aspirin, which chemically is acetylsalicylic acid, was developed along with many other
drugs of this type in the late 1800s. Besides relieving pain, aspirin combats fever and
suppresses inflammatory responses. The various NSAIDs differ in their ability to
exert each of these effects. Which is prescribed may depend on the particular clinical
circumstances.
[a] Mode of Action NSAIDs relieve pain by their effects on the injured tissue itself,
not the peripheral or central nerves. Relief of pain, fever and inflammation all are
related to suppression of a substance called prostaglandin, which is released into
injured tissues. It is these prostaglandins that sensitize the nerve endings to trigger
pain messages. They also produce swelling, redness and other signs of inflammation.
The NSAIDs not only inhibit the production and release of prostaglandins, but also
counter the effect of bradykinin, another pain- producing chemical. NSAIDs also
dilate peripheral blood vessels, which may lower the body temperature (Denson and
Katz, 1992).
[b] Uses Many clinical trials have shown that all NSAIDs are about equally effective.
Most of them relieve pain about as well as a low dose of aspirin, 1 to 2 grams per
day (Denson and Katz, 1992). Typical conditions treated by NSAIDs include arthritis,
common headache, bone injury and sore muscles. They also are used after tooth
extraction and some other minor operative procedures.
Aspirin and other NSAIDs are generally given by mouth. Aspirin has a ceiling effect
of about 1 gram (1,000 milligrams). That is, higher doses will not make them more
effective (Aronoff and Evans, 1992).
[c] Side Effects Because they are so widely used, aspirin and other NSAIDs are the
major cause of serious drug side-effects. The commonest is irritation of the lining of
the stomach and bowel. Aspirin also slows clotting of the blood. Together, these
effects can cause serious gastrointestinal bleeding, especially in patients with an
ulcer. Heavy drinkers who take aspirin to cure a hangover are especially at risk.
Despite warnings and the availability of coated aspirin that slows its release into the
bowel, many patients take too much of these drugs and suffer side-effects as a
result. In fact, physicians today commonly advise their middle-aged male patients to
take a low dose of aspirin on a regular basis to help prevent heart attacks (Denson
and Katz, 1992).5
Clues that a person is overdosing with aspirin are trouble breathing easily, an
irregular heartbeat, sudden trouble hearing clearly, a ringing in the ears (tinnitus),
and nausea or vomiting. Tinnitus is a particularly reliable sign of toxicity from aspirin.
Persons who have disorders of the gastrointestinal tract, liver or kidneys should
avoid aspirin and other NSAIDs. The same applies to asthmatics. These drugs also
should be kept from pregnant women and those with any type of bleeding disorder
(Melzack and Wall, 1988).
[2] Acetaminophen When aspirin and other NSAIDs are not tolerated for any
reason, acetaminophen (also called paracetamol) is an option. Acetaminophen does
no harm to persons who have an ulcer of the stomach or duodenum. It relieves pain
as efficiently as aspirin, but lacks its anti-inflammatory effect and so does not help
those with arthritis. Like aspirin, high doses of acetaminophen may seriously damage
the liver (Aronoff and Evans, 1992).
10
[177.52] Narcotic Analgesics
Nerve cells, both peripherally and in the brain and spinal cord, possess receptors for
opiates on their surfaces. Ordinarily these receptors are occupied by enkephalins and
endorphins, the body's own opiate-like substances. Narcotic agonists like morphine
relieve pain by binding chemically to these opiate receptors. Narcotic antagonists
bind to the same receptors and prevent agonists, either endogenous (in the body) or
administered, from relieving pain. There also is a group of mixed agonist-antagonist
drugs which have opposed effects on pain.
Opioids are the major type of drug used to relieve moderate to severe pain. They are
effective when used properly, and the proper dose can readily be determined.
Unfortunately, many patients do not receive the benefits of narcotic therapy because
physicians confuse the predictable effects of long-term treatment - tolerance and
physical dependence - with the much feared psychological dependence, or addiction
(NCI, 1996). The key in any case is to balance a given drug's ability to control pain
against its potential adverse effects.
[1] Agonists
Most agonist-type narcotics are opiates, so-called because they derive from opium,
an extract of the poppy plant. Both morphine and codeine are extracted from opium,
and further changes in their chemical structure have yielded hydromorphone
(Dilaudid (R)), oxycodone and heroin. Synthetic narcotics such as meperidine
(Demerol (R)), fentanyl, and methadone and propoxyphene (Darvon (R)) are
attempts to separate the pain-relieving effect of narcotics from their often serious
side-effects.
Among the many myths surrounding opioids are that there is a maximal safe dose,
that addiction is inevitable and that all users eventually require larger doses. Further,
it should be recognized that not all types of pain respond to opioid treatment, and
that opioids do not always depress respiration (Caillet, 1993).
[a] Site of Action In the midbrain, opiates activate descending inhibitory nerve
paths that keep the spinal cord form transmitting pain messages. In the spinal cord,
the same drugs prevent pain messages from passing from incoming nerve paths to
the brain cells that perceive pain.
Apart from their direct effects on transmission of pain signals, opiates produce
euphoria, a feeling of profound well-being, and they reduce tension and fear. These
effects can be very helpful to ill or injured patients who need to rest. But they may
be gained at the cost of excessive drowsiness and difficulty thinking clearly.
Narcotics also can promote blood flow by paralyzing the muscle tissue in vessel walls
that keep the vessel constricted. This can increase blood flow to the heart after a
heart attack, or to the brain after a stroke.
[b] Clinical Use Opiates are called on most often when severe pain develops
suddenly, as after severe injury or a heart attack. They also are used to control
chronic pain from cancer and other serious illnesses, severe labor pain and
postoperative pain. The stronger narcotics such as morphine and Dilaudid (R) are
used only when nothing less will suffice. Moderate pain may respond to a weaker
11
narcotic such as codeine or oxycodone.
Opiates may be given by mouth or by injection into a muscle or vein. Injection is the
norm in any emergency situation. Because individuals may differ widely in how they
respond to the same dose of narcotic, it is essential to individualize treatment. A
regular dose schedule will prevent pain from recurring and avoid the need to have to
overcome it each time. As a rule, doses are altered by one-fourth to one-half of the
previous dose. If changing from oral treatment to injection, a lower dose will be
needed. When and if pain resolves, opiate treatment should be gradually withdrawn
to avoid withdrawal symptoms (NCI, 1996).
[2] Antagonists and Mixed Agonist-Antagonists The best example of a narcotic
antagonist is naloxone, which totally blocks the action of morphine. As such, it is
used to treat morphine overdose.
The so-called mixed agonist-antagonist drugs, such as nalorphine and pentazocine
(Talwin (R)), activate some opioid receptors while blocking (or not affecting) others.
These agents are used mainly to relieve postoperative pain. They are avoided in
patients with long-lasting pain because they may produce psychotic changes, and
can trigger withdrawal symptoms in patients who are dependent on another narcotic.
[3] Recent Narcotics Research Current research has attempted to produce
chemicals resembling enkephalins, the body's own narcotics, so as to relieve pain
while avoiding side-effects. One form of enkephalin has been used in lieu of
morphine (Melzack and Wall, 1988). Current work in this area also focuses on better
ways of managing narcotic withdrawal symptoms and new approaches to helping
those who have survived serious illness but become psychologically dependent
(addicted). Work also is being done on refining narcotic delivery systems for use in
particular circumstances.
[4] Side Effects of Narcotics Opiate receptors are found throughout the body, not
merely in neural tissues. This explains the wide range of side-effects that can occur.
Tolerance, if viewed as a side-effect, occurs when the period of relief shortens
progressively and increasing doses of narcotic are needed. Either other drugs may be
substituted, or a different approach such as a nerve block or neurosurgery may be
tried.
Respiratory depression is the most feared side-effect of narcotics, and the
commonest cause of death from an overdose of morphine. The opiate antagonist
naloxone is an effective treatment for depressed breathing.
Some narcotics may produce nausea or vomiting, but patients often are relieved by
changing to a different drug. Constipation also can result from narcotic treatment.
Cathartics and stool softeners may help, as well as the right type of diet.
Patients given narcotics may become drowsy and mentally confused. The answer
often is to give smaller, more frequent doses or to give a shorter-acting narcotic.
Alternatively, the narcotic may be combined with an amphetamine for its stimulating
effects.
Miscellaneous narcotic side-effects include dizziness, suppression of the cough reflex
and muscle spasms (especially from Demerol (R)).
12
The mixed agonist-antagonist narcotics may cause serious psychiatric symptoms
such as depression and hallucinations. Patients may have nightmares and experience
a sense of unreality. When occurring postoperatively (when these drugs tend to be
used), these symptoms may be relieved by naloxone.
[177.53] Adjuvant Drugs
Apart from NSAIDs and narcotics, a variety of other (adjuvant) drugs may help
relieve pain even if this is not their prime clinical use. Adjuvants include drugs with
psychiatric effects (psychotropic drugs), See also ch. 106. anticonvulsants (used to
treat seizures), steroid drugs, muscle relaxants and a miscellaneous group including
antihistamines and amphetamines.
[1] Psychotropic Drugs The major tranquilizers such as phenothiazine drugs are
able to relieve both superficial and internal (visceral) pain in patients who have
become tolerant to narcotics. (Minor tranquilizers such as the benzodiazepines
Valium (R) and Librium (R) are not effective painkillers; they may even make pain
worse).
Persons who are depressed are less tolerant of pain and, with any condition causing
pain, they require higher doses of analgesic drugs. A vicious cycle of pain, depression
and insomnia may be very difficult to break. Tricyclic antidepressant drugs such as
imipramine may be helpful in this situation. They can relieve pain independently of
any improvement in the depression itself (Aronoff and Evans, 1992). Antidepressants
also can help relieve pain from arthritis, migraine and the neuralgia that follows
herpes infection.
[2] Anticonvulsants When pain arises directly from diseased or injured nerves, as
in trigeminal neuralgia (a severe type of facial pain), it may be relieved by drugs
used to treat convulsions. They include carbamazepine (Tegretol (R)), phenytoin
(Dilantin (R)) and valproic acid.
[3] Steroids Steroid drugs such as prednisone and dexamethasone have antiinflammatory effects, and can relieve pain caused by acute inflammation. Steroids
also can relieve pain from tumors in bone or nerve tissue. Chronic back pain may be
eliminated by injecting a steroid into the epidural space between the spinal cord itself
and its covering membrane. This is the case when pain results from inflamed nerve
roots. Steroids also relieve neuralgic pain following herpes infection. A side benefit is
that they counter the nausea and vomiting so often seen in patients given narcotics.
[4] Muscle Relaxants Many pain states are accompanied by muscle spasm. Both
injury and inflammatory diseases can cause abnormal muscle contractions which
may be very painful. Muscle relaxants such as baclofen may relieve pain by altering
how it is perceived in the brain. These drugs are generally well tolerated, and cause
few side-effects (Gallagher, 1994).
[5] Other Adjuvants Amphetamines, which stimulate the central nervous system,
can increase pain relief when used along with narcotics. They also are used to reduce
the dose of narcotic and thereby its sedative effect. Antihistamines such as
hydroxyzine also are used in conjunction with narcotics. They augment pain relief,
lessen anxiety, and also have antiemetic (prevent nausea) effects. Sedatives,
hypnotics, and anti-anxiety drugs occasionally are noted to relieve pain, but the
effect is not striking and it is hard to separate this effect from the other clinical
13
actions of these drugs (Haddux, 1992).
[177.54] Marijuana (Cannabis)
Marijuana is the leaf of an easily cultivated plant, Cannabis sativa. Recreational users
nearly always smoke marijuana (''pot'' and ''grass'' being common colloquial terms)
in the form of a cigarette, or ''reefer.'' Rarely, though, it is chewed and eaten. The
active chemicals derived from cannabis leaves are known as cannabinoids. The one
used most often both for experimental purposes and in the clinical setting is known
chemically as delta-9-tetrahydrocannabinol (THC). THC is taken orally as tablets of
dronabinol (Marinol (R)).
[1] Background Painful states always have been featured on the long list of
conditions that putatively benefit from smoking cannabis. The use of cannabis for
pain relief has been documented since ancient times.
In the 19th century hemp was officially welcomed into the pharmaceutical repertoire
both in Europe and America. It was marketed by major pharmaceutical companies in
numerous forms available over-the-counter as well as by prescription (Robinson,
1996). A century ago, cannabis was second only to the opiates as a means of
controlling chronic pain. Its mood-elevating properties were welcomed, as they
seemed to enhance the relief of pain. Specific conditions for which cannabis products
were used included migraine headache, a very severe form of facial pain called tic
douloureux and other neuralgic disorders. Cannabis also was widely used as a topical
anesthetic and to lessen the pain of childbirth (Mikuriya, 1994).
Cannabinoids were censored from the U. S. Pharmacopoeia in 1942. In 1950 the
Merck Index, a comprehensive list of accepted pharmaceutical agents, deleted its
listing of cannabis.
[2] Mode of Action When rats were given a synthetic cannabinoid, and at the same
time pressure was applied to the hind paw to a degree that usually caused a painful
response, the nerves in the spinal cord that convey pain signals stopped firing. This
is direct evidence that cannabinoids can inhibit pain transmission in the spinal cord
(Hohmann, et al., 1995).
Another study identified specific receptor sites by which cannabinoids can attach
themselves to nerve cells. In this way they might be able to mimic natural body
compounds that regulate nerve signaling for mood, memory, movement and pain
perception (Mackie and Hille, 1992).
Finally, when pregnant rats received THC, it had the effect of altering pain sensitivity
in their offspring. This probably resulted from the cannabinoid interacting with
opioids naturally present in the brain (Vela, et al., 1995).
[3] Clinical Use
Studies and observations of how cannabinoids affect pain in humans entail certain
problems not encountered with most other types of drugs. Firstly, how they are
given seems to make a considerable difference. Those who habitually smoke
marijuana often claim greater pain relief than when given tablets of THC. In contrast,
some clinical studies suggest just the opposite, but these subjects often are thought
to be ''naive,'' lacking past experience with the drug.
14
A second problem is that clinical studies of pain rely on participants reporting the
point at which pain begins during stimulation, or ends when a painful stimulus is
removed, an entity known as the threshold. The double-blind study design, in which
neither the experimenter nor the subject knows whether active drug or a placebo has
been given, is supposed to assure objectivity. But the psychoactive effects of
cannabis (euphoria, clouded consciousness, a ''fuzzy'' or distanced feeling) may allow
subjects to ''peek through the double-blind,'' rendering their responses unreliable
(Clark, et al., 1984).
[a] Indications for Use Today cannabis is probably used most widely to relieve
chronic pain from cancer, and in patients with AIDS who may suffer from a number
of painful conditions. In addition, cannabinoids are sometimes used to lessen pain
from very severe arthritis, combat migraine headache and relieve intolerable itching
in patients with inflammatory skin disorders (Robinson, 1991). When 57 San
Franciscans, most of them HIV-positive, were interviewed at a cannabis buyers' club
and asked their reasons for using cannabis, 22 mentioned arthritis and other forms
of pain, and 11 cited migraine or vascular headache.
Several of the aforementioned purchasers mentioned that they smoked marijuana as
a substitute for drinking or for using opiates or sedatives. A study from the early
1940s found that patients attempting to stop using an opiate did better when they
replaced it with a cannabis derivative than when they simply tried withdrawing,
either suddenly or gradually. They reportedly experienced less marked withdrawal
symptoms, felt much better, and were able to return sooner to their work
(Grinspoon, 1994).
[b] Effectiveness Results from a series of studies conducted in the 1970s run the
gamut from an impressive rise in pain tolerance to an actual increase in sensitivity to
painful stimuli. Marijuana smoking did augment pain tolerance in one double-blind
investigation. In another study, a series of cancer patients gained relief from orally
administered THC, but a competing trial failed to confirm this finding. Two
independent studies found that both THC and smoked marijuana made normal
subjects more sensitive to pain when their fingers were stimulated electrically. (This
should not be unexpected, as marijuana smokers often report that they feel all
manner of stimuli more acutely, a form of ''heightened consciousness.'') The overall
conclusion from these studies is that any analgesic effect of THC is not consistent
enough to recommend its clinical use (Nahas, 1984).
Another series of studies from the same period were well-controlled trials comparing
cannabinoids with analgesics. Good pain relief was the rule but, as in many of the
previously cited studies, it often was accompanied by euphoric feelings and a wide
range of side-effects. Again, the overall conclusion was that cannabinoids cannot be
routinely recommended explicitly for treating cancer pain (Raj, 1992).
[c] Side-Effects Although euphoria and other aspects of ''getting high'' may be
purposefully sought by recreational users of cannabis, from a clinical standpoint they
must be viewed as side-effects. Apart from these so-called psychoactive actions,
marijuana users (and subjects in experimental studies who receive THC) frequently
become drowsy and develop a slow heartbeat and low blood pressure.
How and whether cannabis affects the brain is perhaps the greatest concern. A
recent survey, covering both volunteer subjects given known amounts of cannabis
15
and habitually heavy users, showed that there are in fact residual effects on shortterm memory, attention, and the ability to perform tasks requiring clear thinking and
coordination. These effects generally last from 12 to 24 hours after exposure.
Whether some users may have more persistent changes remains uncertain (Pope, Jr.
et al., 1995). An extensive review of the literature suggests that using cannabis
heavily on a regular basis may impair the ability to process information. There is,
however, no firm evidence that the brain is irreversibly damaged (Castel and Ames,
1996).
The U.S. Pharmacopeia warns against giving THC to pregnant women (because
studies suggest the fetus is at risk), or to lactating women (as cannabis passes into
the breast milk). It also cautions against using THC along with agents (including
alcohol) that depress the central nervous system, or with the tricyclic antidepressant
drugs used to treat depression. Finally, THC can worsen the symptoms of heart
disease, and may aggravate schizophrenia or manic-depressive illness (U.S.
Pharmacopeia, 1994).
[4] Prospects The National Institute on Drug Abuse has convened a panel of 8
experts to recommend studies that will clarify the clinical uses of marijuana. Their
proposals will be subject to approval by the director of the National Institutes of
Health. The panel is expected to recommend that controlled studies should in fact be
carried out. The panel asserted that among the medical uses of cannabis to be
considered is alleviating the suffering of patients with severe pain. Whether to study
the effects of smoked marijuana or THC remains an open question.
The present position of the Food & Drug Administration (FDA) is that no drug has to
be demonstrably better than existing agents - or even as good - in order to be
approved (New York Times, 1997).
[177.55] Drug Combinations
It is very often possible to afford the patient greater relief from a combination of
drugs than is possible with a single type of drug. For instance, an analgesic acting
locally to stop the release of prostaglandin (such as an NSAID) may be combined
with one (possibly an opioid drug) that inhibits pain perception in the central nervous
system. When ongoing narcotic treatment is supplemented by a nonnarcotic drug,
the patient benefits without having to raise the dose of narcotic. Another advantage
of using drugs that work differently is that the risk of side-effects is reduced.
Drug combinations that have proved helpful include codeine plus aspirin, and adding
a small dose of desipramine, an antidepressant, to morphine. Using
dextroamphetamine (''speed'') along with morphine is a very effective means of
relieving pain from cancer, despite their reputation as ''street drugs.'' A three-drug
regimen for resistant cancer pain could include the opiate methadone, the
antidepressant amitriptyline and a nonnarcotic analgesic (Melzack and Wall, 1988).
Combining a potent codeine derivative such as hydrocodone or oxycodone with
acetaminophen helps control postpartum and postoperative pain. Propoxyphene, a
relatively weak narcotic, works much better when combined with aspirin or
acetaminophen. There currently is interest in adding a weak opioid to NSAID
treatment when this by itself does not adequately relieve pain (Beaver, 1992).
[177.56] Delivery Systems
16
Customarily, pain-relieving drugs have either been taken by mouth or injected into a
muscle. New ways of administering analgesics can make them more effective while
at the same time limiting their adverse effects. Patients may be spared the
discomfort of repeated injections - a considerable boon for those who need long-term
or indefinite treatment. Patients who vomit easily can receive drugs rectally. Some
drugs, such as fentanyl, may be given transdermally (through the skin), although it
is difficult to find the proper dose (NCI, 1996).
[1] Slow Release Preparations Morphine may now be given in the form of an
implanted pellet whose coating releases the active drug over a period of 8-12 hours.
This allows patients to sleep through the night.
[2] Continuous Infusion When a patient cannot take a narcotic by mouth for any
reason and refuses (or cannot tolerate) repeated intramuscular injections, the drug
may be given continuously (infused) either intravenously or beneath the skin surface
(subcutaneously). If a patient needs long-term treatment, a pouch may be easily
implanted under the skin. A timer mechanism releases the drug at the desired rate
into a tube leading to the spinal cord or the brain itself. The pouch can be refilled by
simply injecting drug through the skin.
[3] Spinal Administration of Morphine Giving an opioid directly into the spinal
canal is an effective means of controlling postoperative pain as well as severe
cancer-related pain. The drug may be injected or infused into the space separating
the membranes covering the spinal cord and the cord itself. The great advantage of
this approach is that motor and sensory functions are unaffected. The patient is able
to walk without the danger of sudden low blood pressure - a risk when a local
anesthetic is used. Spinal opioid therapy is especially useful in elderly patients, those
who are very obese, and those whose heart and lung function is compromised
(Rawal, 1996). In addition, little narcotic reaches the brain, so that patients are not
excessively sedated or confused.
Morphine has a stronger effect when given spinally rather than intravenously, and its
effects last longer. There is, however, always a risk of injuring the spinal cord,
suggesting that this method be used only when it has very definite advantages.
[4] Patient-Controlled Analgesia-Postoperative patients who wish to avoid
repeated injections to control pain can take partial control of their own treatment.
With patient-controlled analgesia (PCA), the patient is able to deliver small amounts
of morphine or another analgesic, up to a limit and at specified intervals. The
injection itself can be subcutaneous or into a muscle or vein, although the
intravenous route is most convenient. When the patient is able to take oral
analgesia, the physician can learn how well it is working by noting how much PCA
the patient is using (PHS, 1992).
FOOTNOTES:
Footnote 5. See also ch. 30.
P 177.60 NERVE BLOCKS
When the cause of pain cannot be corrected and drugs fail to control it, other
approaches are possible. One of them is the nerve block, which generally uses a drug
such as a local anesthetic to stop the transmission of pain signals along those nerves
17
responsible for the pain. A more drastic type of nerve block is to use a neurotoxic
substance to permanently destroy a nerve (neurolysis). A nerve block may also help
when a patient does respond to drugs, but requires doses so large that they
seriously interfere with the patient's activity or mental function.6
Another use of the nerve block technique is for diagnosis: to determine the exact
origin of pain in a particular patient. This is done by surrounding (infiltrating) the
suspect nerve with a local anesthetic to see whether pain ceases. The effect is
intended to be a temporary one. A nerve block also may be used prognostically, to
predict the outcome were a nerve to be destroyed. Finally, when a procedure is
planned that may lead to some painful state such as causalgia, a nerve block may be
given ahead of time to forestall pain (NCI, 1996).
[177.61] Indications and Selection of Patients
A nerve block, whether temporary or permanent, should be viewed as part of a
range of treatments that can help a patient cope with pain. Any physical measure
such as a nerve block must not ignore the behavioral and psychosocial aspects of the
patient's condition and how they relate to the pain that is experienced. The success
of neural blockade will depend on the patients ability to estimate the severity of pain
and how it is changing during the procedure. A diagnostic nerve block can help
distinguish between pain of somatic and psychogenic origin. (Wurm, 1992).
A nerve block can effectively control either acute or chronic pain. In patients with
acutely painful conditions, the block will temporarily cut off the source of pain from
where it is consciously perceived. A bone fracture and dental surgery are good
applications. Although nerve blocks may be less dramatically effective in relieving
chronic pain, they still may have considerable diagnostic and even therapeutic value.
If neurosurgery is being considered to permanently ablate the source of pain, a
temporary block will inform the patient of what may be expected and help in making
the decision of whether to operate (Raj, 1992).
Nerve blocks are avoided in patients who have a bleeding problem or are on
anticoagulants, and also in those with infection in the region. Poorly localized pain
seldom responds to neural blockade. Patients dependent on narcotics are not good
candidates. A nerve block may not be feasible if the patient cannot tolerate the pain
of the procedure itself without receiving an analgesic. If a patient clearly has
psychogenic pain, a nerve block will not be helpful (Wurm, 1992).
[177.62] Mechanism of Action
Neural blockade is intended to halt the transmission of pain messages to the brain. A
small area of localized pain may be abolished by blocking the peripheral nerve
serving the area. More diffuse pain requires a block closer to the spine - the site
where all peripheral nerves converge.
[1] Local Anesthetics
The nerve impulse actually is a wave of electrical energy spreading along the
extended part of the nerve, the axon. Anesthetics abolish pain by blocking this wave,
or action potential. Usually a local anesthetic is injected directly into the nerve, but it
may also be injected (infiltrated) into the area surrounding the nerve. Unlike cocaine,
the original local anesthetic, its successors (lidocaine, procaine, etc.) halt pain
18
impulses without causing mental effects. Using a small amount of anesthetic it is
possible to block, say, sympathetic nerve fibers (those controlling many organ
functions) without altering nerve transmission in sensory or motor nerve fibers. This
makes it possible for a patient to remain active without suffering musculoskeletal
pain.
[a] Epidural Infusion A local anesthetic may be injected continuously (infused)
through a catheter placed in the epidural space surrounding the spinal cord.
Bupivacaine is often used for this purpose. The anesthetic stops pain transmission in
the nerve roots to abolish pain in the legs, pelvis, abdomen or chest, depending on
the spinal level where the injection is made. Epidural infusion of a local anesthetic is
a very effective way of controlling labor pain. It also is used diagnostically in an
attempt to relieve low back pain spreading to the legs (sciatica).
[b] Side Effects Unless special techniques are used, a nerve block generally
paralyzes the area injected as well as relieves pain. If a local anesthetic is given for
too long a time, it may damage the nerve. Rarely a patient will suffer an allergic
reaction to a local anesthetic. Too high a dose can affect the brain and cause
convulsions. Local anesthetics can impair the electrical activity of cardiac nerves and
thereby keep the heart from functioning normally. Newer local anesthetics that will
not affect the heart are being developed (de Jong, 1996).
[2] Neurolytic Agents Neurolysis (literally, lysing or killing a nerve) is an
aggressive measure used, for instance, to relieve cancer pain that is resistant to
even potent narcotics. It also is used in some patients with severe neuralgia or pain
from occlusion of blood vessels, and when neurosurgery is not possible for any
reason.
Alcohol and phenol are often used for neurolysis, as they destroy nerve proteins and
the myelin sheath that covers and protects the nerve axon. It is important to get the
material as close as possible to the target nerve. A nerve also may be destroyed by
freezing (cryoanesthesia), by alternately freezing and thawing the nerve or applying
radiofrequency energy.
When alcohol is used for neurolysis, very painful neuralgia may complicate the
procedure. The area served by the treated nerve may be numbed for a time, but
usually this resolves fairly quickly. When a neurolytic agent is injected into the lower
part of the spinal column, bowel or bladder function may be lost (Jain and Gupta,
1996).
[177.63] Diagnostic Nerve Blocks
A local anesthetic block is ideal for demonstrating just which nerve, or nerves, are
responsible for a patient's pain. A block can indicate whether pain is arising from the
body surface, an internal organ, or a site in the central nervous system. Exclusion of
all these possibilities might suggest psychogenic pain (but cannot establish it with
certainty). A neural block is helpful when neurolysis or neurosurgery is planned. It
may indicate how effective the more invasive treatment will be. It also can show
whether new pain develops elsewhere in the body. If this in fact happens, neurolysis
or neurosurgery might better be avoided (Wurm, 1992).
[177.64] Therapeutic Nerve Blocks
19
Either temporary nerve block with a local anesthetic or neurolysis, permanently
destroying a nerve or nerves, may be used to relieve pain.
[1] Local Anesthetic Block It is common to administer a series of temporary nerve
blocks to patients with chronic pain. Used with other appropriate measures, the
blocks can provide long-lasting relief, especially when muscle spasm is part of the
problem. Many painful conditions involve a cycle of increased muscle tension, poor
posture, immobility and pain. Injecting anesthetic into a trigger point can break the
cycle (Wurm, 1992).
Other indications for local anesthetic nerve block are reflex sympathetic dystrophy (a
chronic post-injury disorder caused by degenerating sympathetic nerves), neuralgia,
postoperative pain and phantom limb pain. In patients with cancer-related pain, it is
worth trying neural blockade before proceeding to neurolysis. Infusing an anesthetic
epidurally can relieve severe pain from cancer in the pelvic region.
[2] Neurolytic Blocks Pain may be relieved for as long as a year after neurolysis,
but the average time is less than a month. For this reason, and because of the risk of
side-effects, neurolysis often is used when less invasive measures have failed to
relieve cancer- related pain and when life expectancy is limited. Pain resulting from
interruption of an afferent nerve is not helped by neurolysis. Somatic nerves rarely
are lysed for reasons other than cancer (Wurm, 1992).
[3] Common Nerve Block Procedures
Among the commonest sites for neural blockade are the stellate ganglia (groups of
nerves in the neck and chest), lumbar sympathetic ganglia in the lower back and the
celiac plexus (a mass of ganglia in the region of the pancreas).
[a] Stellate Ganglion Block Sympathetic ganglia in the upper chest and lower neck
may be blocked to relieve pain from reflex sympathetic dystrophy following injury in
this region. Pain from whiplash injury is commonly managed in this way. A stellate
ganglion block can also relieve pain caused by herpes zoster and tumors in the upper
part of the lung. Other indications are Raynaud's disease (a disorder of the
sympathetic nerves controlling blood vessels), and pain arising from a clot (embolus)
lodging in a blood vessel of the arm (Raj, 1996).
[b] Lumbar Sympathetic Block Burning pain in the lower legs resulting from a
deficient supply of oxygenated blood is a prime indication for neural blockade at this
level. A lumbar block also may relieve posttraumatic reflex sympathetic dystrophy in
the legs, pain arising from disease of the pelvis or ureter (the tube conducting urine
from the kidneys) and pain arising from an amputation stump or phantom limb.
Renal colic is one of the most severe forms of pain, and can be relieved by neural
block in the area of the second to fourth lumbar vertebrae, the area of the loin
(Stanton-Hicks, 1996).
[c] Celiac Plexus Block The celiac plexus, a mass of sympathetic ganglia near the
first lumbar vertebrae, may be blocked by inserting a needle into the flank. It can
relieve pain from pancreatic cancer, which may be extremely severe. This block also
can help tell whether pain is arising in an organ like the pancreas or from the
abdominal wall (Wurm, 1992).
Recently temporary leg weakness was described as a complication of blocking the
20
celiac plexus with alcohol (Wong and Brown, 1995).
[d] Other Nerve Blocks Injecting anesthetic into the subarachnoid space
surrounding the spinal cord may relieve severe pelvic pain caused by cancer. It may
prove helpful to block a specific nerve root when the origin of limb pain is not clear
or if pain may result from disease of an intervertebral disk. Injecting specific
intercostal nerves can show just which of them have been injured (from an accident
or chest surgery). Pain caused by injury to various somatic nerves, such as the
greater occipital nerve of the scalp or the lateral femoral cutaneous nerve in the
thigh, can readily be blocked by injecting a local anesthetic (Rybock, 1994).
[177.65] Nitrous Oxide
The very first inhaled anesthetic, nitrous oxide (''laughing gas'') is becoming an
increasingly popular analgesic. Inhaled through a face mask, it can control pain from
minor surgery (such as dental extraction) or procedures such as spinal puncture. At
the other end of the scale, patients with terminal cancer may control episodes of
pain by inhaling nitrous oxide from a small tank kept at hand.
When a woman in labor does not want regional analgesia or it is unavailable, nitrous
oxide may be a very acceptable substitute. Typically the woman herself administers
the gas. It is cleared from the newborn infant in a matter of minutes (Eisenach,
1992).
FOOTNOTES:
Footnote 6. See also ch. 58 for additional information on nerve blocks.
P 177.70 NEUROSURGERY
When drugs fail to control pain and even neural blockade or neurolysis proves
inadequate, the next step is a neurosurgical procedure. Traditionally a nerve or
nerve pathway was severed at the proper point in order to stop the transmission of
pain impulses. Virtually every part of the nervous system - peripheral and central has been cut (sectioned) in order to control unrelenting pain. Even when this works,
however, the pain is likely to recur and may be even more marked than before
(Freidberg, 1992).
Conventional sectioning procedures still are used in some patients with intractable
pain, especially those with advanced cancer who are not expected to live long. For
many other patients, however, sectioning has been replaced by more refined
methods of creating small, discrete lesions at any level of the nervous system. These
procedures often can be done through the skin (percutaneously) under local or
regional anesthesia, and they entail little blood loss. Another approach that
sometimes relieves pain is to electrically stimulate rather than damage or destroy
the pain-carrying nerve fibers (Melzack and Wall, 1988).
[177.71] Radiofrequency Coagulation
Discrete nerve lesions of limited extent may be produced by placing a needle into the
target site and inserting an electrode through it. The nerve tissue is burn-damaged
by heat from a high-frequency current. This technique can be applied to tiny brain
sites through the use of stereotactic radiography. The head is rigidly fixed in place,
and a system of coordinates is used to map the site where a target lesion is to be
21
made. In most cases a series of small lesions are used to ablate pain-transmitting
nerve tissue. The patient remains conscious so that the surgeon is able to gauge the
effect of each lesion before placing the next one.
[177.72] Peripheral Lesions
Cutting a peripheral nerve, known as peripheral neurectomy, generally relieves pain
only when a particular nerve (and no other tissues) is involved by a tumor. Pain in
the chest wall caused by an invading tumor may be relieved by cutting one or more
intercostal nerves, those running alongside the ribs. With these exceptions, cutting
several peripheral nerves usually fails to relieve pain and may instead produce
numbness or feelings of burning and tingling (Freidberg, 1992).
[177.73] Spinal Root Lesions
When pain results from cancer or other disease in the chest, pelvis or spinal column,
cutting peripheral nerves will not help. Instead, the spinal root, where peripheral
nerve fibers come together to enter the spinal cord, is sectioned (cut). All sensation
including pain travels through the dorsal (sensory) root. Leaving the ventral (motor)
root intact will avoid paralysis or muscle wasting. The downside is that all sensation,
not only pain, is abolished when the dorsal root is cut.
[1] Multiple Lesions Any dorsal spinal root contains nerve fibers from overlapping
areas of the body. For this reason, at least three roots have to be treated to assure
that pain in any one part of the body will be relieved. The usual procedure is to inject
a nerve- damaging substance into the proper region of the spinal cord, and then turn
the patient so that only the nerve roots on the affected side are damaged. This is a
common treatment for patients who have cancer in the pelvis (Melzack and Wall,
1988).
[2] DREZ Lesions Patients with severe pain from post-herpes neuralgia or from
tearing (avulsion) of peripheral nerves or nerve roots themselves may be relieved by
cutting the dorsal nerve root where it enters the spinal cord. This point is termed the
dorsal root entry zone (DREZ). Avulsed spinal roots should be confirmed by contrast
(dye) radiography (myelography) before proceeding. Today many patients suffer
damaged nerve roots in the upper (cervical) spine as a result of a motorcycle, auto
or snowmobile accident.
Formerly the affected nerve roots were simply sectioned. A more refined approach is
to expose the involved area of spinal cord and produce a group of tiny thermal
radiofrequency lesions in the dorsal surface of the spinal cord itself (the dorsal horn).
If other parts of the cord are avoided the desired effect will be achieved without
serious side-effects (Nashold, Jr. et al., 1994). Use of a laser attached to an
operating microscope to make the lesions may be even safer (Powers et al., 1988).
[3] Rhizotomy Strictly speaking, rhizotomy refers to surgical cutting of a nerve or
nerve root. Formerly this was done as an open operation, but long-term success
rates were as low as one in five patients. Removing the ganglion (a collection of
nerve cells) is only slightly more effective. Today rhizotomy is done percutaneously
by injecting alcohol into the nerve tissue, or by using a radiofrequency current to
damage it thermally. This procedure does carry a risk of impairing motor or sensory
function (Coffey, 1992).
22
[4] Treatment of Trigeminal Neuralgia The trigeminal nerve is one of the major
cranial nerves serving large areas of the face. Neuralgia at this site is the commonest
pain disorder of the head/neck region that is treatable surgically. The goal is to
damage the nerves ganglion (the gasserian ganglion) either by radiofrequency
coagulation or injecting glycerol. Another option is to inflate a small balloon at the
end of a catheter to compress the nerve. All these techniques now may be done
through the skin by inserting a needle through an opening in the base of the skull.
Neuralgias affecting other cranial nerves may be managed in the same way (Coffey,
1992).
Open surgery to relieve pressure on the ganglion is seldom performed today. The
pain commonly returns, and normal sensation may be impaired (Melzack and Wall,
1988).
[177.74] Cordotomy
Cutting the spinothalamic tract of the spinal cord, a major nerve pathway leading to
the thalamus of the brain, is used especially to relieve pain localized to one side of
the body below the shoulder level. The thalamus is an important relay site sending
pain signals to other parts of the brain. If life expectancy is less than one year,
cordotomy is often strongly considered. If desired, the cord may be cut at a level
that preserves feeling in the upper limb but relieves pain in the lower chest,
abdomen and lower extremity. Either an open technique may be used, or cordotomy
can be done percutaneously using radiofrequency current. This operation must be
avoided in any patient who has trouble breathing.
Pain is relieved after a successful cordotomy and temperature sensation is lost, but
the patient still has feeling in the skin and retains normal motor function. When
combined with drugs and other measures, as many as 90 percent of patients have
good to excellent initial results. But pain relief tends to lessen as time passes, which
is why cordotomy is not advisable for those whose cancer may permit long-term
survival. Some patients develop uncomfortable feelings (dysesthesias), or actual
pain ''mirrored'' at the same site on the opposite side of the body (Rosen, 1996).
Another spinal cord operation, commissural myelotomy, uses an incision in the lower
spinal cord to relieve pain in the pelvic region. Leg weakness and other complications
are frequent, however, even when the surgery is done using a microscope
(Freidberg, 1994).
[177.75] Cerebral Operations
Often the last resort for relieving intractable pain is to cut nerve paths in the brain
itself. Lesions at certain regions in the central part of the brain (mesencephalon), the
thalamus, and a part of the limbic system called the cingulum that is important in
pain perception. Damaging the pituitary gland also may prove helpful in some cases.
[1] Mesencephalic Tractotomy This procedure no longer is done to interrupt the
spinothalamic fibers, those severed at cordotomy, at the level of the midbrain. Its
mortality is very high, and many surviving patients develop dysesthesias that can be
worse than the initial pain (Melzack and Wall, 1988). It is, however, possible to make
discrete radiofrequency lesions at this level to relieve pain on one side of the head or
neck. Using the stereotactic radiographic method the surgeon can be sure that only
pain-transmitting fibers are damaged (Bosch, 1991).
23
[2] Thalamotomy Stereotactic methods also may be used to produce small lesions
in the thalamus, where pain fibers from the spinothalamic tract of the spinal cord
converge. Cancer patients with chronic pain on one side of the body often gain relief
from unilateral thalamotomy. In those who do not respond, lesions may be made on
the other side with little added risk (Freidberg, 1994).
[3] Cingulotomy In earlier years an operation called lobotomy was done to cut
fibers connecting the cerebral cortex (the outer covering of the brain that controls
intellect and personality) with the rest of the brain. It did not actually relieve pain
but was intended to lessen the anxiety and depression that often accompanies it.
Unfortunately lobotomy also tended to seriously damage the patient's personality
and ability to think.
A modern substitute for lobotomy is cingulotomy. Lesions are made stereotactically
in the cingulum (a central brain structure close to the fibers connecting the two
cerebral hemispheres). The cingulum is part of the limbic system, which has a role in
both pain and behavior. When successful, cingulotomy can abolish some of the
negative emotions emanating from severe pain without substantially altering the
patient's personality. Nevertheless, the procedure is seldom performed in the US
because of a strong bias against lobotomy and other so-called ''psychosurgery''
(Freidberg, 1992).
[4] Pituitary Gland Surgery While not part of the brain proper, the pituitary gland
is a gland at the base of the brain that produces a number of hormones, some of
which support the growth of some cancers. When cancer has spread to the bones it
can cause excruciating pain that can seriously disrupt the patient's life and activities.
Damaging the pituitary by applying heat or injecting alcohol can bring much needed
relief to patients whose cancer has spread to multiple skeletal sites. Some cancers
not dependent on pituitary hormones also may respond (Augustinsson, 1996).
[177.76] Lesions of the Sympathetic System
The sympathetic nervous system (part of the autonomic, or ''automatic'' nervous
system) consists of chains of ganglia (nerve cell bodies) running along the spinal
cord. Sympathetic nerves send signals to and from the internal organs, glands and
blood vessels. Because these nerves release adrenaline (a substance that activates
injured sensory nerve fibers) lesioning these fibers may sometimes relieve pain. In
addition, noradrenaline constricts blood vessels, and limited blood flow to muscle
tissue (including the heart) may cause pain (Melzack and Wall, 1988).
Destroying the sympathetic ganglia by injecting alcohol or phenol often helps lessen
the burning pain of causalgia that follows injury of a peripheral nerve. Lumbar
sympathectomy has relieved painful causalgia of the lower extremity as well as pain
caused by constricted blood vessels. A repeat procedure is sometimes needed. If
done on both sides, lumbar sympathectomy can impair ejaculation in males (Coffey,
1992).
[177.77] Neurostimulation
There are two problems with the idea that merely cutting a nerve or nerve pathway
will prevent pain messages from reaching the brain. It may in fact act like a nerve
injury, activating the cut ends of the nerve cells to fire and causing deafferentation
24
pain. In addition, the nervous system can undo the effects of destructive nerve
surgery by reorganizing its paths so that the pain signals will ascend to the brain via
a different route. An alternative is to electrically stimulate rather than destroy central
and peripheral nerves. Electrostimulation may be especially useful for patients who
resist analgesic drugs. It may be done surgically or using electrodes on the skin
surface (transcutaneous electrical nerve stimulation, or TENS).
With reference to the gate theory of pain, electrostimulation may act by activating
mechanisms that normally inhibit pain impulses, thereby ''closing the gate.''
[1] Technique For electrostimulation an electrode is implanted in the appropriate
part of the nervous system and attached to a wire leading to an implanted radio
receiver. The patient can begin stimulation, and control its intensity, by holding the
antenna of an external radio transmitter over the site of the receiver. Electrodes with
multiple contact points now are available to provide stimulation at just the right
points. Perhaps two of three patients with resistant chronic pain will respond to
modern forms of electrostimulation (Racz, et al., 1992).
[2] Stimulation of Dorsal Column of Spinal Cord The dorsal columns of the
spinal cord, carrying the pain fibers, are the commonest target site for
electrostimulation. It no longer is necessary to remove bony tissue from the spinal
column to implant electrodes. A set of electrodes may be placed using a needle,
anchored in place, and activated by an implanted pulse generator that can be
externally programmed. Many patients with low back pain in whom surgery has
failed have responded to electrostimulation of the dorsal columns (North, 1994).
[3] Stimulation of the Brain Electrical stimulation of deep brain structures is
generally used in two groups of patients. Electrodes are placed in the thalamus in
patients with deafferentation pain caused by interruption of a nerve. They include
patients with phantom limb pain, spinal cord injury, lesions of the brachial nerve
plexus of the upper extremity or the lumbosacral plexus of the lower limb and
neuralgia following herpes infection. Patients with chronic low back or leg pain and
some who have noncancer pain in the abdomen or perineal region may respond to
electrostimulation of neural tissue surrounding the cavities (ventricles) of the brain
(North, 1994).
Electrodes are implanted under local anesthesia, using a stereotactic radiographic
technique. Test stimuli are delivered and the awake patient is asked for a response.
When a tingling sensation replaces the customary pain, the electrode is correctly
placed. After further testing to learn the correct voltage and frequency of
stimulation, the electrode is attached to a receiver implanted in the chest wall.
Occasionally the procedure is complicated by bleeding into the brain (which may be
fatal) or infection (Melzack and Wall, 1988).
[4] Tolerance Patients tend to build up tolerance to electrostimulation of either the
spinal cord or brain, requiring stimulation at progressively higher levels and for
longer periods. This tolerance may be avoided, or delayed, by limiting stimulation to
no more than 20 minutes three or four times a day. The drug L-dopa, used to treat
Parkinson's disease, can greatly reduce tolerance in patients who require long
periods of stimulation (Melzack and Wall, 1988).
[177.78] Complications of Neurosurgery
25
A declining analgesic effect as time passes after neurosurgery is not, strictly
speaking, a complication. A relatively few patients, however, will develop a new type
of pain in the form of severe burning after cordotomy. This may be even worse than
the initial pain and is very difficult to treat. It probably is caused by abnormal firing
of hypersensitive spinal cord nerves following operative injury (Melzack and Wall,
1988).
Some ablative neurosurgical procedures carry a risk of numbing the target area or of
causing muscle weakness. Bladder dysfunction also is a possibility. Whenever a
catheter system is placed within the spinal column there is a risk of infection (Byers,
et al., 1995).
[177.79] An Experimental Approach to Pain Control
Recent laboratory studies suggest that pain is effectively reduced when tissue from
the adrenal medulla (the central hormone-secreting part of the adrenal gland) is
placed into the space surrounding the spinal cord. Tolerance did not develop. The
hope is that such a ''biological pump'' could provide a limitless, locally placed source
of pain-reducing substances. The method was tried in five patients with chronic pain,
three of whom had substantial and long-lasting relief (Winnie, 1996).
P 177.80 OTHER PHYSICAL METHODS
A very broad range of relatively noninvasive physical methods of alleviating pain,
particularly musculoskeletal pain, have long been available. Medical history tells of
cupping and scarification, the latter being the practice of cutting the skin with blades.
Heat and cold application are time-honored methods, and acupuncture itself is an
age-old remedy for pain anywhere on, or within the body.7 More modern methods
include passing an electric current through the skin, applying heat using ultrasound
energy and injecting the ''trigger points'' that give rise to pain. Some of these
methods work by causing pain in order to relieve it, a process long known as
counterirritation and more formally termed hyperstimulation analgesia (Melzack and
Wall, 1988).
Physical therapy is intended to correct any condition, such as poor muscle tone,
spasm or weakness, that keeps a patient from functioning normally. With the correct
method or combination of methods, the patient will in time gain confidence in being
able to function better without suffering undue pain. Yeh and colleagues (1992)
believe strongly that all patients with chronic pain should at least be evaluated by a
physical therapist. Many medical professionals unfortunately place little value on the
potential role of physical therapy.
Through regular physical therapy a patient can learn what can be done to maintain
function and prevent, or at least slow deterioration of his or her physical state.
Physiatrists are medical doctors trained in physical medicine and rehabilitation, and
are expert in distinguishing between pain and disability. The physiatrist is the logical
choice to prescribe a comprehensive, team-managed rehabilitative program for
patients with painful musculoskeletal disorders (Cole and Herring, 1994).8 Physical
therapy may be delivered in an office or clinic, or at specialized rehabilitation
centers.
[177.81] Transcutaneous Electrical Nerve Stimulation (TENS)
26
The sensory nerves lying just beneath the skin surface can be stimulated in various
ways using a battery-powered electric pulse generator and electrodes attached to
the skin. TENS is widely considered to be very effective in relieving both acute and
chronic pain, but just how it works remains uncertain. In terms of the gate theory,
stimulation could interfere with the cycle of pain and muscle spasm by inhibiting
nerves in the spinal cord that transmit pain signals. TENS also might directly depress
the firing of damaged peripheral nerves.
Generally the patient adjusts the frequency and strength of pulses until a tingling
feeling is noted in the painful region. A lengthy trial-and-error process may be
needed to determine the most effective type of stimulation. Apart from conventional
high-intensity pulses, special modes are available (one of them resembling
acupuncture stimulation) that may prove helpful in particular patients. The
acupuncture-like mode of longer but fewer pulses at high intensity often relieves
chronic pain. High-voltage galvanic stimulation may be helpful if there is prominent
swelling in addition to pain. The electrodes may be placed over a trigger point, the
spinal nerve roots or a dermatome (an area of skin supplied by branches of a
particular spinal nerve).
TENS has proved very helpful to patients with such conditions as rheumatoid
arthritis, causalgia, and post-herpes neuralgia even when nerve blocks or
neurosurgery have failed. Another application of TENS is to limit postoperative pain
by attaching electrodes near the incision. In this way the patient may require less
narcotic medication. TENS causes no serious side-effects, but it should not be used
near a fetus in a pregnant woman or when a cardiac pacemaker is present (Yeh, et
al., 1992).
[177.82] Trigger Point Injections
Pain following injury most often arises from myofascial structures including bone
tissue, the muscle itself, tendon, ligament and other soft tissues. In fibrositis and
fibromyalgia, both very common painful conditions, focal areas within a muscle can
develop trigger points which can be felt as taut muscle bands that are tender when
pressed on. Painful trigger points can limit motion of a body and, in time, cause it to
weaken or waste away. Trigger points also may cause referred pain in a distant area.
[1] Causes Chemical changes in injured tissues may produce a state of constant
contraction, or spasm, accounting for the band of tight muscle tissue. In time acidic
chemicals accumulate and sensitize nearby pain receptors. Another cause may be an
increase in sympathetic nerve activity and noradrenaline release when nociceptors
are sensitized. This itself further activates nociceptors in a cycle of continuous selfgenerated pain. The longer trigger points remain, the likelier it is that new ones will
develop, resulting in expanded and overlapping areas of pain.
[2] Treatment It is most important to maintain function of the affected body part
by stretching out the trigger points, although it may first be necessary to relieve the
severe pain this causes. This may be done using a vapor coolant spray, by
compressing the part to cut down blood flow or by injecting a local anesthetic. Some
believe that a ''dry'' injection (needling) or injecting saline (salt solution) is equally,
or more, effective. If a number of trigger points are present in a confined area,
individual injections may be replaced by a nerve block of the entire region. Regional
sympathetic blockade may also be effective. Some patients gain relief using
relaxation methods or biofeedback based on a recording of muscle activity
27
(electromyogram). These latter measures are intended to supplement but not
replace the primary approach of injection and stretching (Hartrick, 1992).
[177.83] Acupuncture
Acupuncture to relieve pain (acupuncture analgesia) has been practiced in China for
nearly 2,500 years. The practice is based on stimulating specific points on the body
surface by inserting needles. Certain painful conditions, such as arthritis, headaches
and dental pain, are amenable to acupuncture treatments. Recent uses for
acupuncture include relief from the painful symptoms of AIDS. Now that infection is
no longer a risk, acupuncture is becoming increasingly popular in western countries.9
[177.84] Heat
Heat has been used to relieve pain at least since the time of the thermal baths in
Rome, and still is in the Finnish sauna and many other settings. Locally applied heat
relaxes muscles and dilates blood vessels. Increased circulation may remove painproducing substances from a site of injury or illness. Heat also could act by inhibiting
neural pain signals. This method should be avoided unless there is normal
cardiovascular and respiratory function (Yeh, et al., 1992).
Age-old methods of local heating include the ubiquitous hot pack and heating pad,
the use of liniments and plasters and the whirlpool. Two modern methods of
generating more penetrating heat to reach deeper structures are diathermy and
ultrasound.
[1] Diathermy Shortwave diathermy is a form of deep heating that uses a highfrequency current to raise the temperature in the soft tissue just beneath the skin
and the more superficial muscles. It can relieve pain even in deep-seated joints such
as the hip. Two precautions: contact lenses should first be removed, and the method
avoided if a metal implant is present as it may cause a burn. Another technique
called microwave diathermy uses energy that is absorbed by tissues having a high
water content (such as muscle tissue). Present units do not always operate
efficiently, however, and ''hot spots'' are a risk (Wilensky, 1992).
Diathermy causes the muscles to relax and relieves painful spasms. Arthritis is a
frequent indication for its use, but actively inflamed tissues may be made worse.
Reasons to avoid diathermy include vascular disease, recent radiotherapy or heavy
bleeding and pregnancy. Also, patients who lack feeling in the target region or are
unable to describe what they feel should not receive diathermy treatment (Melzack
and Wall, 1988).
[2] Ultrasound Today ultrasound energy is the most popular form of deep heating.
High-frequency acoustic vibrations are converted to heat energy. Ultrasound energy
tends to localize at the borders between bone and soft tissues, where injuries and
lesions are very frequent. Bones, joints, muscle tendons, and large, deep-lying
nerves are easily reached by ultrasound. Ultrasound energy also makes collagen,
part of the soft tissue structure, more flexible and it induces muscle relaxation. This
method is especially helpful in making the tissues surrounding joints less stiff
(Vasudevan, 1992). The heart, malignant tumors, and areas of vascular insufficiency
should not be exposed to ultrasound energy. Joint replacements also should be
avoided, as the materials used absorb much ultrasound energy (Wilensky, 1992).
28
[177.85] Cold
Applying cold (cryotherapy) is an easy-to-use method of suppressing inflammation,
slowing nerve conduction, and countering muscle spasm. Ice is a popular
counterirritant that very often is used in treating acute sports-related injuries (the
acronym ICE means ice, compression, and elevation). Cold, always readily available,
can relieve acute pain and limit edema formation (swelling) in the injured tissues.
Methods of applying cold range from the simple ice pack to ''ice massage,'' cold
baths, and a vapor coolant spray such as ethyl chloride. A rare patient will be
hypersensitive to cold and of course should not be treated in this way. Raynaud's
phenomenon, when the digital vessels constrict in the cold, calls for great caution
(Vasudevan, 1992).
[177.86] Massage
Soft tissue massage is another easy way of relaxing muscles and promoting blood
flow. A broad range of techniques are practiced by professionals, ranging from
superficial, relaxing massage of much of the body to the application of deep pressure
to a localized site of pain. Massage can show the physical therapist where trigger
points or sites of muscle spasm are located. Hardened scar tissue can be softened by
repeated massage. After a total-body massage, the relaxed patient will be able to
engage in activities that formerly would have been too painful (Yeh, 1992).
[177.87] Therapeutic Movement
Pain limits motion and as such may seriously interfere not only with exercise but with
the simplest of daily activities. Therapeutically guided movements, manipulation
where indicated, and an individualized exercise regimen are key aspects of
rehabilitation. Therapeutic movement is designed to restore muscle balance and
correct limb and body posture, to extend the range of joint motion and through
exercise to restore body functions and enhance the patient's general health.
[1] Manipulation Just what manipulation of spinal and other structures consists of,
and how safe it is, continue to be controversial. Manipulation as practiced by
physiotherapists, osteopaths, physiatrists, or chiropractors,10 can undoubtedly help
relieve low back or neck pain and chronic headaches. The better the lesion can be
localized and defined, the likelier it is that manipulation will help. Some of the less
common indications for manipulation are torticollis (also called wry neck, an
abnormal posture of the head and neck), acute pain in the chest (which may be
referred from the cervical spine) and rib pain.
Many specific techniques exist for stretching, twisting and pulling on different parts
in order to break up scar tissues and relax chronically contracted connective tissue
and spastic muscles. The procedure sometimes is quite painful. The risk of serious
side-effects will be reduced in the hands of a competent and experienced
professional (Langley, 1994).
[2] Mobilization Maximizing the range of joint motion in order to mobilize joints
and improve limb motion involves taking a joint to its limit of passive motion, and
then somewhat beyond it through manipulation. Caution is all important because
excessive or too rapid mobilization may damage the ligaments attached to the joint.
Both small oscillating movements and sharp jerks may be used. Once an increased
29
range of movement is achieved, appropriate exercises are begun (Yeh, et al., 1992).
[3] Exercise In acute pain, exercise usually is limited to passive movements of the
affected joints to prevent stiffening and ''locking up'' (contracture). More active
exercises are indicated in patients with subacute pain (developing over days or
weeks rather than abruptly), to maintain and restore function in the affected region.
If pain is chronic, exercise is aimed at countering the effects of decreased activity,
which may include muscle weakness, wasting (atrophy) of muscle tissue and
contracted joints. In addition to its local effects, exercise, - especially aerobic
activities such as cycling and swimming - can increase levels of endorphin in the
brain and thereby lessen pain (Caillet, 1993).
Generally the physical therapist will prescribe exercises in the same way that drug
treatment is prescribed, and will supervise the patient's progress at frequent
intervals. What exercises are done and the level of intensity are continually adjusted
to the patient's progress. Often it is helpful for patients to exercise in a group
setting.
[4] Posture Faulty posture may contribute to many painful conditions resulting from
injury, overuse and advancing age. Often poor postural habits, such as slumping,
develop in childhood years. Spending long hours before a computer or wearing
bifocal glasses may compromise good posture, and footwear also may be a factor.
Emotions also are important; how we stand, sit and walk reflects how we feel.
Examples of how poor posture can lead to musculoskeletal pain include too forward a
head posture, which affects the upper spine, and shoulder pain caused by abnormal
upper spinal posture (Caillet, 1993).
[177.88] Vibrators and Percussion
Use of a mechanical vibrator and the application of pressure to the tissues may help
the patient relax or take attention away from pain. Percussion (the rhythmic
application of ''beats'' of pressure) can have similar effects. Pain sometimes will
increase before the patient feels relief (NCI, 1996).
[177.89] Supporting Devices
The use of a brace, collar, cane or crutches may be very helpful or even essential at
times for limiting pain and allowing the patient to be as active as possible. A lumbar
brace or support, by compressing the abdomen, increases pressure within the
abdomen and lowers stress on the spine. The idea of using any support device is to
restore correct posture and body mechanics and help gain muscle strength.
The patient should stop using any support device as soon as possible so as not to
become dependent on it. Restricting movement over the long term will weaken the
muscles, restrict joint motion and produce abnormal postural changes. In patients
with chronic pain it is especially important to periodically review and justify the use
of a support device (Yeh, et al., 1992).
FOOTNOTES:
Footnote 7. See also ch. 12A for a complete discussion of acupuncture.
Footnote 8. See also ch. 182.
30
Footnote 9. See also ch. 12A for a complete discussion of acupuncture.
Footnote 10. See also ch. 12.
P 177.90 BEHAVIOR MODIFICATION
Chronic pain, with all its emotional, cognitive, behavioral, and psychosocial
concomitants, may legitimately be viewed as a type of learned behavior. Just what
pain means to, and for, a particular patient, and how much control the patient can
exert over the pain experience, have a great deal to do with how pain is perceived.
Accordingly, methods such as relaxation training, hypnosis, and ''re-learning''
(cognitive-behavioral approaches) have been widely used in conjunction with
traditional pharmacological and physical methods of alleviating pain. Relaxation
techniques lessen the state of arousal and make it possible, through suggestion and
use of one's imagination, to gain some degree of control over chronic pain. Hypnosis
operates in the area of suggestion. Its effectiveness, though acknowledged, still is
largely unexplained, but hypnosis does provide a sense of peace and comfort and
lessens pain over the short term. Finally, cognitive methods of pain management
focus on the patient's expectations, beliefs and attitudes concerning pain. Patients
can be taught specific methods for dealing with pain. The ''behavioral,'' or operant
element of cognitive-behavioral therapy attempts to reinforce appropriate behaviors
and to not reward pain behavior itself.
[177.91] Relaxation
The stress of suffering chronic pain, or of living under the threat that severe pain can
occur at any time, can lead to a chronic state of muscle tension, high blood pressure,
and excessive production of adrenaline. The latter, by increasing sympathetic neural
activity, can worsen muscle tension or hasten the transmission of pain signals to the
brain. Chronic sufferers may have ''forgotten'' how to relax, and must learn again
how to do so in order to break this cycle.
Focusing on one part of the body or on the breathing process can dispel the patient's
constant preoccupation with pain. Relaxation often is used along with biofeedback
methods. There is convincing evidence that relaxation helps relieve muscle
contraction headaches, migraine, chronic back pain, pain arising form the
temporomandibular joint (TMJ) of the jaw and myofascial pain syndrome anywhere
in the body (Kelly and Lynch, 1992).
[1] Progressive Relaxation PMR (progressive muscular relaxation) is the most
widely used relaxation method for relieving chronic pain. It was popularized in the
U.S. by Indian practitioners. Successive muscle groups (or a particular group such as
the jaw muscles) are tensed for several seconds and then released, concentrating on
how the muscles feel in these two states. Most often this sequence is applied to all
major muscle groups, starting with the lower extremities. It may be combined with
deep, rhythmical breathing, expiring when relaxing the muscles, and also with
pleasant imagery (Gaupp, et al., 1994).
[2] Benson Technique This method, too, is based on Eastern meditative practices.
The patient sits quietly with the muscles relaxed, and focuses on breathing while
repeating the word ''one'' (or ''om,'' or some other mantra) for 20 minutes. The more
one practices, the more easily a fully relaxed state and sense of well-being are
achieved (Melzack and Wall, 1988).
31
[3] Other Methods Autogenic training instructs the patient to concentrate on
several states such as a steady heartbeat, a calm inner feeling, and warmth or
heaviness of an extremity. In time the patient is able to rapidly assume a state of
low arousal while remaining fully awake. Patients can learn to focus on some
pleasing, personally meaningful event or experience, and make this part of whatever
formal relaxation methods is being used. This tactic is called dissociative visualization
(Gaupp, et al., 1994). Some patients are distracted from their pain when listening to
favorite musical pieces (PHS, 1992).
[177.92] Biofeedback
Through the process called biofeedback, a patient can learn, to some degree, to
influence body responses that ordinarily occur automatically, such as contraction and
relaxation of the walls of blood vessels. Tension and migraine types of headache
often respond to biofeedback training. Chronically tense neck muscles, fibromyositis
and pain in the jaw or shoulder are other indications (Caillet, 1993).
Examples of biofeedback are the recording of electrical muscle activity (the
electromyogram) to lower muscle tension, thermal feedback from a finger to
increase the temperature (through dilating the blood vessels) and recording the
pulse of the temporal artery in the scalp to lower the pulse and counter distention of
the vessel (a cause of headache). It is reported that biofeedback training can relieve
phantom limb pain, angina (chest pain), painful menstruation, the severe pain
episodes of sickle cell disease and pain from burn injury. There is growing interest in
trying biofeedback in both children and the elderly (Gaupp, et al., 1994).
No firm scientific basis for biofeedback training has been offered. Some or even most
of its effect may result from the relaxation training which is often part of the process,
on distracting patients from their pain and by providing some sense of control over
pain.
[177.93] Hypnosis
Before the first anesthetics became available, hypnosis was used in an attempt to
combat the pain of major surgery. Even today there are examples where hypnosis
alone has sufficed, even for major abdominal surgery and open heart surgery. How
deeply a person can be hypnotized (only about one-third can reach deep hypnosis,
and 40 percent of all persons can be lightly hypnotized if at all) has much to do with
whether significant pain relief is achieved. Hypnosis has relieved severe pain in burninjured children who require frequent dressing changes and cutting away of dead
tissue. Cancer patients frequently are helped by hypnosis, even if some pain
remains. Those who are able to achieve a deep trance may have dramatic relief of
pain. Hypnosis has often proved useful in dental practice.
The mechanisms underlying hypnotic effects remain poorly understood, but its ability
to induce relaxation may be a key factor. How hypnotizability may relate to the
placebo response is also an enigma. Patients under hypnosis tend to suppress
outward signs of pain, and later they will report that they felt more comfortable while
in the trance state (Orne, 1992).
[177.94] Cognitive-Behavioral Approach
32
The cognitive-behavioral approach to relieving pain operates at two levels. Like any
behavior, pain-related behavior can be altered through reward and punishment.
Patients may be rewarded for appropriate behavior by receiving more attention or
medication, and ''punished'' through actual adverse measures or simply by
withholding reward. At the cognitive level, patients can learn new strategies that can
change the way pain is perceived and experienced. Basic to this approach is to
increase the patient's confidence in gaining some measure of control over pain
responses.
Contrary to what many believe, behavioral therapy does take into account the
patient's past history, family and social relationships, educational level and work
history. Relatives and friends are brought into the process whenever possible. The
patient's interests and hobbies can provide valuable clues as to what will be the best
reinforcers of desired behavior. The patient constantly receives feedback on whether
and how much progress is being made.
Cognitive therapy makes use of mental imagery and self-statements about the state
of ones body as it changes over time. Patients can learn to distract themselves from
their pain. Increased socialization may be very helpful. A given patient may benefit
from reading, listening to music, exercising or watching television. The process by
which a patient learns how to think about pain in a positive way and how to become
less obsessed with the pain is called cognitive restructuring (Ott, 1992).
Efforts should always be made to persuade patients that nearly all pain, no matter
how severe, can be effectively managed. Some patients, especially those who are
substance abusers or are clinically depressed, will benefit from short-term
psychotherapy. Suicidal thoughts should never be ignored. All patients should be
informed about support groups in their area. Often a religious counselor can help to
define the patient's needs and offer spiritual support (NCI, 1996).
P 177.100 PAIN CLINICS
The various adjunctive measures to relieve pain as well as cognitive-behavioral
treatment offer examples of the advantage of combining two or more treatments for
the same patient. It is this impetus toward an interdisciplinary approach that inspired
the establishment of pain clinics, or pain centers, where patients suffering chronic
pain can participate in an individualized management program. Any and all
modalities are offered, but management often attempts to minimize drug use,
modify pain-related behavior, maximize function and promote psychosocial
rehabilitation. Strong emphasis is placed on enabling the patient to return to work,
even though the suggested job may differ from past employment. The overall goal is
not to totally eliminate pain, but to make patients better able to cope with it and
more confident in living a normal lifestyle (Aronoff and McAlary, 1992).
Whatever specific measures are offered patients at pain centers, certain attributes
are constantly emphasized. They include:
comprehensive patient education by interested staff;
stress management skills;
the ability to communicate assertively;
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how to interact positively with others; and
maintenance of high self-esteem.
Follow-up planning is a key aspect of management. Maintaining positive behavioral
changes over the long term calls for careful planning. Any quality program will
develop meaningful ways of monitoring its effectiveness on a regular basis. Part of
this process is to ascertain how satisfied patients are with their management and
outcome (Chapman, 1994).
P 177.110 HOME CARE
Economic considerations have prompted increasing interest in home health care in
general. Pain management is one of the latest forms of home care. Home care
agencies provide for laboratory and pharmacy services, financial arrangements, and
whatever social, dietary, or other services may be needed in a given case. For many,
perhaps most, seriously ill patients, home is the optimal site at which to be cared for.
It must be clear that home treatment will be more cost- effective than a prolonged
stay at a hospital or other institution.
Infusion of medication is the cornerstone of home pain management. Catheters
placed either beneath the skin or within a body cavity are used to constantly infuse
analgesic drugs. Infection is a major concern, but intraspinal infusion, a common
approach, carries a relatively low risk of infection. A leaking or broken catheter and
bleeding are the other major complications. Good clinical results are reported in
patients given combinations of drugs by infusion for prolonged periods at home.
Hopefully the future will bring to home pain management smaller, more efficient,
and safer delivery systems, easier means of monitoring patients and analgesic drugs
that are safer and cause fewer side-effects. It should not be long before the patient's
condition can be automatically monitored and transmitted by radiofrequency
communication (Leak, 1992).
P 177.120 PATIENT EDUCATION
Today's patients being treated for chronic pain must understand the needed
procedures, what to expect from them both positively and in terms of side-effects
and what they can do to optimize their status at any given time. In the area of
chronic pain, even more than with other conditions, it is vital that the patient be a
knowledgeable and active part of the treatment team. Patients should be encouraged
to ask questions, not only of their physicians but of all practitioners, such as nurses
and physical therapists, who contribute to their care.
A biomechanical explanation of what has gone wrong and how it may be approached
therapeutically is often a good starting point. A patient with chronic low back pain,
for instance, will learn the importance of proper posture, how to perform various
activities with the least stress on the lower spine and how to maintain strength
elsewhere in the body. The result will be a patient who enjoys physical activities
more confidently and with less fear of reinjury or worsening pain (Yeh, et al., 1992).
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