Download Chronic pain - UMF IASI 2015

Liliana Tarţău, MD, PhD
Definition of pain (IASP)
An unpleasant sensory and emotional experience
associated with actual or potential tissue damage,
or described in terms of such damage.
Pain is subjective. Each individual learns the
meaning of the word "pain" through experiences
related to injury in early life.
Biologists recognize that those stimuli or illnesses
that cause pain are likely to damage tissue.
History
The ancient Greek believed that pain was associated with
pleasure because the relief of pain was both pleasurable
and emotional.
The Romans, coming closer to contemporary thought,
viewed pain as something that accompanied inflammation.
- 2nd century, Galen offered the Romans his works on the
concepts of the nervous system.
- 4th century, successors of Aristotle discovered anatomic
proof that the brain was connected to nervous system.
- Aristotle’s belief prevailed until the 19th century, when
German scientist provided irrefutable evidence that the
brain is involved with sensory and motor function.
History
Modern concepts of pain theory continue to advance from the
ideas of Aristotle. However, controversy still exists as to which
theories are correct.
The theories accepted at the turn of the century were the
specificity theory and the pattern theory, two completely
different and seemingly contradictory views.
The specificity theory suggests that there is a direct pathway
from peripheral pain receptors to the brain.
Proposed by Ronald Melzack and Patrick Wall during the early
1960s, gate control theory suggests that the spinal cord
contains a neurological "gate" that either blocks pain signals or
allows them to continue on to the brain. Unlike an actual gate,
which opens and closes to allow things to pass through, the
"gate" in the spinal cord operates by differentiating between
the types of fibers carrying pain signals.
General data
Pain is a conscious experience that results from brain activity
in response to a noxious stimulus and engages the sensory,
emotional and cognitive processes of the brain. In general
terms we can distinguish two dimensions or components of
pain:
• sensory - discriminative
• affective - emotional.
Nociception is the process by which information about a
noxious stimulus is conveyed to the brain. It is the total sum
of neural activity that occurs prior to the cognitive processes
that enable humans to identify a sensation as pain.
Nociception is necessary but not sufficient for the experience
of pain.
General data

pain threshold – level of noxious stimulus
required to alert an individual of a potential
threat to tissue.

pain tolerance – amount of pain a person
is willing or able to tolerate.
General data
Pain is a major health issue.

The number one cause of adult disability in
the US;

Prevalence of chronic pain in the general
population is estimated at 116 million people.

Pain costs an estimated $560 to $635 billion
annually in lost workdays, medical expenses,
and other benefit costs.
General data
Pain diminishes the quality of life for many people,
although it may also be a vital teacher or a warning
message to be heeded.
How humans process pain is a complicated,
individualized process affected by genetics,
personality, life experiences and straightforward
physiological processes.
When an injury disrupts homeostasis, and depending
upon the extent and severity of the injury,
genetically predetermined neural, hormonal, and
behavioral programs kick into action.
General data
The body’s response is as follows:
The injury triggers a process by which sensory
information is relayed rapidly to the brain, which
initiates the complex sequence of events to
reinstate homeostasis.
The body releases cortisol, a hormone produced
by the adrenal glands, in an effort to re-establish
homeostasis. Cortisol produces and maintains
high levels of glucose for quick response
following an injury, threat, or other form of
emergency (such as the fight or flight response).
General data
Negative consequences of pain
decreased socialization
 withdrawal from daily life
 fatigue
 sleep disturbance
 irritability
 physical deconditioning
 stress
 depression.

Congenital analgesia
A well-known case of congenital insensitivity to pain is
a girl referred to as 'miss C' who was a student at
McGill university in Montreal in the 1950s. She was
normal in every way, except that she could not feel
pain. When she was a child she had bitten off the tip
of her tongue and had suffered third-degree burns by
kneeling on a radiator,
When she was examined by a psychologist she did not
feel any pain when she was given strong electric
shocks or when exposed to very hot and very cold
water. When these stimuli were presented to her she
showed no change in heart rate, blood pressure or
respiration.
Factors affecting pain
Factors affecting pain
Factors affecting pain
Factors that alter the perception
of pain
Implications for clinical practice

There is no physiological, imaging, or laboratory test
that can identify or measure pain. Pain is what the
patient says it is. The clinician must accept the
patient's report of pain.

The goal of pain therapies is to relieve pain whenever
possible: from nociception to the conscious
experience as well as to decrease the emotional
response to the unpleasant experience. Nociception
should be treated even in unconscious patients who
appear to be clinically unresponsive to pain to help
prevent sensitization of pain pathways which can lead
to chronic pain.
General data
Pain has a biologically important protective function. The
sensation of pain is a normal response to injury or
disease and is a result of normal physiological
processes within the nociceptive system, with its
complex of stages previously described.
There may also be other manifestations of pain related
to tissue injury including hyperalgesia, an exaggerated
response to a noxious stimulus, and allodynia, the
perception of pain from normally innocuous stimuli.
Hyperalgesia and allodynia are the result of changes in
either the peripheral or central nervous systems,
referred to as peripheral or central sensitization,
respectively.
General data
Pain is a multidimensional phenomenon which is
an attention grabbing sensation that can
produce strong emotional reactions that
adversely affect a patient's function, quality of
life, emotional state, social and vocational
status, and general well-being.
Therefore, pain assessment should also be
multidimensional.
It is important to evaluate these various elements
during the interview and examination, and
include them in the diagnostic formulation.
General data
A thorough history and physical exam are essential
for the medical and pain diagnosis and treatment
planning.
A pain history should include location, quality,
intensity, temporal characteristics, aggravating
and alleviating factors, impact of pain on function
and quality of life, past treatment and response,
patient expectations and goals.
Careful attention to the patient's reported symptoms
will help direct the physical examination and
narrow the pain differential diagnosis.
Classification of pain
-
based on pain physiology, intensity, temporal
characteristics, type of tissue affected, and syndrome:
• pain
physiology
(nociceptive,
neuropathic,
inflammatory)
• intensity (mild-moderate-severe; 0-10 numeric pain
rating scale)
• time course (acute, chronic)
• type of tissue involved (skin, muscles, viscera,
joints, tendons, bones)
• syndromes (cancer, fibromyalgia, migraine, others)
• special considerations (psychological state, age,
gender, culture).
Classification of pain

Acute pain: pain of less than 3 to 6 months
duration.

Chronic pain: pain lasting for more than 36 months, or persisting beyond the course
of an acute disease, or after tissue healing
is complete.
Classification of pain
There are several ways to categorize pain. One is to
separate it into acute pain and chronic pain.
 Acute pain typically comes on suddenly and has a
limited duration. It's frequently caused by damage to
tissue such as bone, muscle, or organs, and the
onset is often accompanied by anxiety or emotional
distress.

Chronic pain lasts longer than acute pain and is
generally somewhat resistant to medical treatment.
This type of pain can be the result of damaged tissue,
but very often is attributable to nerve damage. It's
usually associated with a long-term illness.
Classification of pain
Both acute and chronic pain can be debilitating, and both
can affect and be affected by a person's state of mind.
But the nature of chronic pain - the fact that it's ongoing
and in some cases seems almost constant - makes the
person who has it more susceptible to psychological
consequences such as depression and anxiety.
Chronic pain is further subdivided in to two classes:
chronic malignant pain and chronic non-malignant pain.
At the same time, psychological distress can amplify the
pain.
Pain
About 70% of people with chronic pain treated with
pain medication experience episodes of what's
called breakthrough pain.
Breakthrough pain refers to flares of pain that
occur even when pain medication is being used
regularly.
Sometimes it can be spontaneous or set off by a
seemingly insignificant event such as rolling
over in bed. And sometimes it may be the result
of pain medication wearing off before it's time for
the next dose.
Acute and chronic pain
Differences between treatment of acute and chronic pain
Acute
Chronic
Medical model of care
Reduced pain intensity is
primary goal in order to
facilitate recovery and
prevent chronic pain
Rehabilitation-disease
management model of care
Improved function (physical,
psychological and social) is
often primary goal
Generally time limited and
successful
Patients must actively
participate in care
Treatment ends when pain
resolves
Treatment and pain may
never end
Pathophysiological Classification
of Pain
Under this category, pain is divided into two types:
• nociceptive pain
• neuropathic pain.
Nociceptive Pain
includes somatic and visceral pain (directly
caused by the stimulation of pain nerve endings
due to tissue injury or tumor infiltration).
Its represents the normal response to noxious insult
or injury of tissues such as skin, muscles, visceral
organs, joints, tendons, or bones.

Pathophysiological Classification
of Pain
Somatic: musculoskeletal (joint
pain, myofascial pain), cutaneous;
often well localized.
• Somatic pain is often described
by patients as dull or aching pain.
Patients are also able to point
directly to the pain as the location
is well defined. Pain is often worse
with movement.
Common causes of somatic pain
include cancer metastasis to the
bones or muscles due to
chemotherapy drugs.
Pathophysiological Classification
of Pain
Visceral: hollow organs and smooth
muscle; usually referred.
Visceral pain is difficult to locate and
the site may be actually distant
from the source of the pain.
It may be determined by distention of
ducts leading to major organs,
smooth muscle spasm, muscle
ischemia, obstruction.
Pathophysiological Classification
of Pain
Neuropathic: pain initiated or caused by a primary lesion
or disease in the somatosensory nervous system.
Patients describe this type of pain as sharp, numbing,
burning, or shooting in quality.
This type of pain may be seen in patients:
-
-
with poorly controlled diabetes,
after viral infection (herpes zoster, chicken pox).
with cancer (metastasis to the spinal cord).
with spinal cord injury pain, phantom limb pain, and
post-stroke central pain.
Aspects of neuropathic pain
COMPONENT
Steady,
Dysesthetic
CHARATERS
• burning, tingling
• constant, aching
• squeezing, itching
• allodynia
Paroxysmal,
Neuralgic
• hypersthesia
• stabbing
• shock-like, electric
• shooting
• lancinating
EXAMPLES
• diabetic neuropathy
• post-herpetic
neuropathy
• trigeminal neuralgia
• may be a component
of any neuropathic
pain
Pathophysiological Classification
of Pain
Inflammatory: a result of activation and sensitization
of the nociceptive pain pathway by a variety of
mediators released at a site of tissue inflammation.
The mediators that have been implicated as key
players are proinflammatory cytokines such IL-1alpha, IL-1-beta, IL-6 and TNF-alpha, chemokines,
reactive oxygen species, vasoactive amines, lipids,
ATP, acid, and other factors released by infiltrating
leukocytes, vascular endothelial cells, or tissue
resident mast cells
Examples include: appendicitis, rheumatoid arthritis,
inflammatory bowel disease, and herpes zoster.
Pain Intensity
Can be broadly categorized as: mild,
moderate and severe (numeric analogue
scale):
• 0 = no pain
• mild: <4/10
• moderate: 5/10 to 6/10
• severe: >7/10
• 10 is the worst pain imaginable.
Types of pain in pathology
Diagnosis of pain
• Medical
diagnoses related to the pain:
underlying diagnoses causing pain.
• Pain
type (acute, neuropathic, visceral),
intensity, impact on quality of life and function.
• Medical comorbidities contributing to pain
and/or affecting treatment: cardiovascular,
cerebro-vascular or neuromuscular diseases.
• Medications that may interfere with the usual
choices of drug or nondrug treatments.
Diagnosis of pain
Psychosocial issues and patient's ability to cope with
pain.
Factors that impact treatment planning and may
affect response to treatment include:
- depression,
- anxiety,
- negative emotions,
- past experiences,
- illness perception,
- alcohol dependence,
- substance abuse and
- current social situations.
Treatment of pain
Treatment planning establishes goals,
expectations, methods and time course for
treatment.
The goals of pain treatment differ depending
upon the type of pain and the nature of the
individual case.
Patient and family goals must be informated
with what is possible and reasonable given
the situation.
Treatment of pain
Acute pain
The major goals are pain control and relief while
efforts are made to identify and treat the underlying
disease and to enhance healing and recovery.
Adequate management of acute pain may also
prevent the development of chronic pain.
Analgesics are the mainstay of acute pain treatment,
but nondrug methods (patient education, heat/cold,
massage,
distraction/relaxation,
others)
are
essential too.
In some situations regional analgesia and anesthesia
are also indicated.
Treatment of pain
Chronic pain
In most cases of chronic pain, multiple mechanisms are at
play and the cause of the pain may be difficult to identify
and cannot be completely eliminated. Pain relief is still
primary but the goals of improvement in function and
quality of life gain even greater importance.
In addition to rational multidrug therapy, physical medicine
and rehabilitation modalities to treat deconditioning and
disability, and behavioral/psychological treatment to
enhance coping and improve mood are all important.
Aim for maintained or improved daily activity, family life,
and return to work if possible.