Download 1. An introductions to clinical neurology: path physiology, diagnosis

MINISTRY OF THE HEALTHCARE OF THE REPUBLIC OF
UZBEKISTAN
TASHKENT MEDICAL ACADEMY
DEPARTMENT OF NEUROLOGY
Lecture # 9
Spinal cord diseases: Myelitis. Syringomyelia.
Poliomyelitis
For students of 5th course medical and physician-pedagogical faculty
Approved on 25.08.2012
Tashkent 2012
Lecture 9.
Myelitis. Syringomyelia. Poliomyelitis Etiology, pathogenesis, clinical presentation
and treatment.
The Purpose:
1. Informing the students with etiopathogenesis, diagnostics, treatment and preventing
measures of myelitis.
2. Informing the students with diagnostics and treatment measures of syringomyelia and
syringobulbia.
3. Informing the students with disease of grey matter of spinal cord. Poliomyelitis
treatment and prevention activities.
The Expected results (the problems).
student must know:
- a categorization (classification) of the myelitis
- Etiopathogenesis of the syringomyelia, syringobulbia
- a clinical presentation of poliomyelitis
- Treatment and prevention
Contents:
Infectious and Inflammatory Diseases of the Spinal Cord
The spinal cord and spinal nerve roots, like the brain, can be infected by bacteria,
viruses, and other pathogenic organisms. Combined infection of the brain and spinal
cord is common: simultaneous manifestations of encephalitis, meningitis, myelitis, and
radiculitis can be caused by spirochetes (borrelia, leptospira, treponemes;) and by many
viruses. Acute anterior poliomyelitis, on the other hand, affects only the motor neurons
of the anterior horns of the spinal cord.
Any infectious or inflammatory disease of the spinal cord, whatever its etiology,
is called myelitis. The causes of myelitis include direct infection, secondary autoimmune
processes in the wake of an infectious disease, and chronic autoimmune inflammatory
disease of the central nervous system, such as multiple sclerosis. The main causes of
acute myelitis include viruses (measles, mumps, varicella-zoster, herpes simplex, HIV),
as well as rickettsiae and leptospira. Postvaccinal and postinfectious myelitis have also
been described, as has myelitis in the setting of granulomatous disease. The clinical
manifestations range from progressive spastic paraparesis to partial spinal cord
transection syndrome.
Myelitis can be visualized by MRI
Transverse myelitis affects the entire cross-section of the spinal cord, producing a
complete spinal cord transaction syndrome. It has a variety of causes. Often, the
neurological manifestations are preceded by nonspecific flulike symptoms one to three
weeks before onset. The spinal cord deficits usually arise acutely or subacutely and
become maximally severe within a few days. Fever, back pain, and myalgia accompany
the acute phase. The cerebrospinal fluid displays inflammatory changes (lymphocytic
pleocytosis, elevated IgG and total protein concentrations).
A neuroimaging study (usually MRI) must be performed to rule out a mass or
ischemic event. The responsible organism is treated specifically if it can be identified;
otherwise, only symptomatic treatment can be given. The spinal cord transection
syndrome persists, or resolves less than completely, in two-thirds of all patients.
ANATOMICAL FUNDAMENTALS
Acute Anterior Poliomyelitis
Etiology and epidemiology.
This disease, caused by a poliovirus, almost exclusively affects the motor neurons
of the anterior horn of the spinal cord. Its incidence in countries with a well-developed
public health system has been reduced nearly to zero by prophylactic vaccination.
The disease is transmitted by the fecal−oral route under conditions of poor sanitation.
Clinical manifestations. After an incubation period ranging from three to 20 days,
nonspecific prodromal manifestations arise, consisting of fever, flulike symptoms, and,
in some patients, meningeal signs. The prodrome may resolve without further
consequence or be followed, within a few days, by a paralytic phase (likewise
accompanied by fever). Over the course of a few hours or days, flaccid paralysis arises
in various different muscles or muscle groups; it is asymmetrical, often mainly proximal,
and of variable extent and severity. There is no sensory deficit, but the affected muscles
may be painful and tender.
Diagnostic evaluation.
The diagnosis is based on the typical course and physical findings, combined with an
inflammatory CSF pleocytosis: at first, there are several hundred cells per microliter,
often mainly polymorphonuclear granulocytes. Later, there is a transition to a
predominantly lymphocytic picture. The responsible organism (poliovirus) can be
identified in the patient’s
stool.
Treatment.
There is no specific etiologic treatment; the most important aspect of treatment is the
management of respiratory insufficiency (if present).
Prognosis.
Brain stem involvement and respiratory paralysis confer a worse prognosis; in the
remainder of patients, paralysis may regress partially or completely in a few weeks or
months. There is usually some degree of residual weakness.
Postpolio syndrome.
This term refers to two different syndromes. Some authors use it for a symptom complex
seen a few years after the acute illness in polio patients with residual weakness,
characterized by fatigability, respiratory difficulties, pain, and abnormal temperature
regulation (with negative polio titers). Others use it for a syndrome with progressive
worsening of residual weakness occurring decades after the acute illness. Before this
problem can be ascribed to the earlier polio infection, other possible causes of weakness
must be ruled out, e. g., compression of the spinal cord or spinal nerve roots because of
secondary degenerative disease of the spine.
Spinal Abscesses
Spinal abscesses are most often epidural, less often subdural, and only rarely
intramedullary. The most common pathogen is Staphylococcus aureus, which reaches
the spinal canal from a site of primary infection outside it by way of the bloodstream
(hematogenous spread). The typical clinical features are general signs of infection
(fever, elevated erythrocyte sedimentation rate, leukocytosis, chills in some cases), pain,
referable to the spinal nerve roots or spinal cord, depending on the specific anatomic
situation. Spinal abscesses usually require prompt surgical treatment, followed by weeks
of high-dose antibiotics. and neurological deficits.
Syringomyelia and Syringobulbia
Syringomyelia, a condition coming under the general heading of spinal dysraphism, is
sometimes seen in combination with other congenital defects such as the Arnold−Chiari
syndrome or spina bifida. It has several different causes; it can be classified into primary
syringomyelia and symptomatic forms due to (for example) hemorrhage, infection, or a
tumor. Syringomyelia is defined by the pathological finding of a tubelike or cleftlike
cavity (syrinx) within the spinal cord, often lined by ependyma, and usually extending
over several spinal segments. The cavity may reach all the way up to the medulla, or
even the midbrain (syringobulbia, syringomesencephaly). Mere widening of the central
canal of the spinal cord is called hydromyelia.
Clinical manifestations of syringomyelia depend on the location of the syrinx within the
spinal cord and on its vertical extent; they usually arise in the patient’s second or third
decade
Cerebrospinal fluid normally flows in a pulsatile manner throughout the subarachnoid
space which envelops the spinal cord and brain, transporting nutrients and waste
products. The cerebrospinal fluid also serves to cushion the brain. Excess cerebrospinal
fluid in the central canal of the spinal cord is called hydromyelia. This term refers to
increased cerebrospinal fluid that is contained within the ependyma of the central canal.
When fluid dissects into the surrounding white matter forming a cystic cavity or syrinx,
the term syringomyelia is applied. As these conditions coexist in the majority of cases,
the term syringohydromyelia is applied. However, most physicians use the terms
interchangeably.
The pulsatile movement of the cerebrospinal fluid within the subarachnoid space is a
result of the phase difference in influx and outflow of blood within the cranial vault. The
total fluid pulsation per cardiac cycle is approximately 1 cc in a healthy adult. Since the
brain is contained within the nearly rigid cranial cavity, the cerebrospinal fluid pulsation
moves into the more compliant spinal canal having nearly zero net flow during each
cardiac cycle.
It has been observed that obstruction of the cerebrospinal fluid pulsation in the
subarachnoid space can result in syrinx formation. A number of pathological conditions
can cause an obstruction of the normal cerebrospinal fluid pulsation. These include
Chiari malformation, spinal arachnoiditis, scoliosis, spinal vertebrae misalignment,
spinal tumors, spina bifida, and others. The reasons that blockage of the cerebrospinal
fluid pulsation within the subarachnoid space can result in syrinx formation are not
known. Moreover, it is unclear if syrinx fluid originates from bulk movement of
cerebrospinal fluid into the spinal cord, from bulk transmural movement of blood fluids
through the spinal vasculature into the syrinx, or from a combination of both. Once a
syrinx has formed, pressure differences along the spine have been proposed to be one
mechanism causing fluid movement within the cyst, possibly resulting in damage to the
spinal cord.
Thoracic syringomyelia (MRI). a The axial image reveals the expanded central canal as
a cavity (syrinx) in the middle of the spinal cord. b The sagittal image shows the syrinx
extending from T4 to the lower border of T8.
Different Origins
Generally, there are two forms of syringomyelia: congenital and acquired. (In addition,
one form of the disorder involves a part of the brain called the brainstem. The brainstem
controls many of our vital functions, such as respiration and heartbeat. When syrinxes
affect the brainstem, the condition is called syringobulbia.)
Congenital
The first major form relates to an abnormality of the brain called an Chiari
malformation, named after the physician who first characterized it. This is the most
common cause of syringomyelia, where the anatomic abnormality causes the lower part
of the cerebellum to protrude from its normal location in the back of the head into the
cervical or neck portion of the spinal canal. A syrinx may then develop in the cervical
region of the spinal cord. Because of the relationship that was once thought to exist
between the brain and spinal cord in this type of syringomyelia, physicians sometimes
refer to it as communicating syringomyelia. Here, symptoms usually begin between the
ages of 25 and 40 and may worsen with straining or any activity that causes
cerebrospinal fluid pressure to fluctuate suddenly. Some patients, however, may have
long periods of stability. Some patients with this form of the disorder also have
hydrocephalus, in which cerebrospinal fluid accumulates in the skull, or a condition
called arachnoiditis, in which a covering of the spinal cord—the arachnoid membrane—
is inflamed.
Some cases of syringomyelia are familial, although this is rare.
Acquired
The second major form of syringomyelia occurs as a complication of trauma, meningitis,
hemorrhage, a tumor, or arachnoiditis. Here, the syrinx or cyst develops in a segment of
the spinal cord damaged by one of these conditions. The syrinx then starts to expand.
This is sometimes referred to as noncommunicating syringomyelia. Symptoms may
appear months or even years after the initial injury, starting with pain, weakness, and
sensory impairment originating at the site of trauma.
The primary symptom of post-traumatic syringomyelia (often referred to using the
abbreviation of PTS) is pain, which may spread upward from the site of injury.
Symptoms, such as pain, numbness, weakness, and disruption in temperature sensation,
may be limited to one side of the body. Syringomyelia can also adversely affect
sweating, sexual function, and, later, bladder and bowel control. A typical cause of PTS
would be a car accident or similar trauma involving a whip-lash injury.
What can make PTS difficult to diagnose is the fact that symptoms can often first appear
long after the actual cause of the syrinx occurred, e.g. a car accident occurring and then
the patient first experiencing PTS symptoms such as pain, loss of sensation, reduced
ability on the skin to feel varying degrees of hot and cold, a number of months after car
accident.
Symptoms
Syringomyelia causes a wide variety of neuropathic symptoms due to damage of the
spinal cord. Patients may experience chronic pain, abnormal sensations and loss of
sensation particularly in the hands. Some patients experience paralysis or paresis
temporarily or permanently. A syrinx may also cause disruptions in the parasympathetic
and sympathetic nervous systems, leading to abnormal body temperature or sweating,
bowel control issues, or other problems. If the syrinx is higher up in the spinal cord or
affecting the brainstem as in syringobulbia, vocal cord paralysis, ipsilateral tongue
wasting, trigeminal nerve sensory loss, and other signs may occur. Rarely, bladder
stones can occur in the onset of weakness in the lower extremities. Classically,
syringomyelia spares the dorsal column/medial lemniscus of the spinal cord, leaving
pressure, vibration, touch and proprioception intact in the upper extremities. Neuropathic
arthropathy, also known as a Charcot joint, can occur, particularly in the shoulders, in
patients with syringomyelia. The loss of sensory fibers to the joint is theorized to lead to
damage of the joint over time.
Diagnostic evaluation.
Syringomyelia can be diagnosed from its typical symptoms and physical findings;
the characteristic picture is of a dissociated sensory deficit combined with trophic
disturbances. The diagnosis must then be confirmed with neuroimaging, specifically
Clinical course.
Syringomyelia is usually slowly progressive.
Treatment.
Neurosurgical methods are occasionally successful. The options include the Puusepp
operation (opening the posterior aspect of a large syrinx into the subarachnoid space),
drainage of the syrinx with a shunt, or operation of an accompanying Arnold−Chiari
malformation at the craniocervical junction.
Treatment
Surgery
The first step after diagnosis is finding a neurosurgeon who is experienced in the
treatment of syringomyelia. Surgery is the only viable treatment for syringomyelia. Not
all patients will advance to the stage where surgery is needed. Evaluation of the
condition is often difficult because syringomyelia can remain stationary for long periods
of time, and in some cases progress rapidly. Surgery of the spinal cord has certain,
characteristic risks associated with it and the benefits of a surgical procedure on the
spine have to be weighed against the possible complications associated with any
procedure. Surgical treatment is aimed at correcting the condition that allowed the syrinx
to form. It is vital to bear in mind that the drainage of a syrinx does not necessarily mean
the elimination of the syrinx-related symptoms, but rather is aimed at stopping
progression. In cases involving an Arnold-Chiari malformation, the main goal of surgery
is to provide more space for the cerebellum at the base of the skull and upper cervical
spine without entering the brain or spinal cord. This often results in flattening or
disappearance of the primary syrinx or cavity, over time, as the normal flow of
cerebrospinal fluid is restored. If a tumor is causing syringomyelia, removal of the tumor
is the treatment of choice and almost always eliminates the syrinx.
Surgery results in stabilization or modest improvement in symptoms for most patients.
Delay in treatment may result in irreversible spinal cord injury. Recurrence of
syringomyelia after surgery may make additional operations necessary; these may not be
completely successful over the long term.
In some patients it may also be necessary to drain the syrinx, which can be accomplished
using a catheter, drainage tubes, and valves. This system is also known as a shunt.
Shunts are used in both the communicating and noncommunicating forms of the
disorder. First, the surgeon must locate the syrinx. Then, the shunt is placed into it with
the other end draining cerebrospinal fluid (CSF) into a cavity, usually the abdomen. This
type of shunt is called a ventriculoperitoneal shunt and is particularly useful in cases
involving hydrocephalus. By draining syrinx fluid, a shunt can arrest the progression of
symptoms and relieve pain, headache, and tightness. Without correction, symptoms
generally continue.
The decision to use a shunt requires extensive discussion between doctor and patient, as
this procedure carries with it greater risk of injury to the spinal cord, infection, blockage,
or hemorrhage and may not necessarily work for all patients. Draining the syrinx more
quickly does not produce better outcomes, but a shunt may be required if the fluid in the
syrinx is otherwise unable to drain.
In the case of trauma-related syringomyelia, the surgeon operates at the level of the
initial injury. The syrinx collapses at surgery but a tube or shunt is usually necessary to
prevent re-expansion.
Research
The precise causes of syringomyelia are still unknown. Scientists at the National
Institute of Neurological Disorders and Stroke in Bethesda, Maryland, and at grantee
institutions across the country continue to explore the mechanisms that lead to the
formation of syrinxes in the spinal cord. For instance, Institute investigators have found
that as the heart beats, the syrinx fluid is abruptly forced downward. They have also
demonstrated a block to the free flow of cerebrospinal fluid that normally occurs in and
out of the head during each heartbeat. Duke University is conducting research to see if
syringomyelia might be genetic.
Surgical techniques are also being refined by the neurosurgical research community. In
one treatment approach currently being evaluated, neurosurgeons perform a
decompressive procedure where the dura mater, a tough membrane covering the
cerebellum and spinal cord, is enlarged with a graft. Like altering a suit of clothing, this
procedure expands the area around the cerebellum and spinal cord, thus improving the
flow of cerebrospinal fluid and eliminating the syrinx.
It is also important to understand the role of birth defects in the development of
hindbrain malformations that can lead to syringomyelia. Learning when these defects
occur during the development of the fetus can help us understand this and similar
disorders, and may lead to preventive treatment that can stop the formation of many
birth abnormalities. Dietary supplements of folic acid during pregnancy have already
been found to reduce the number of cases of certain birth defects.
Diagnostic technology is another area for continued research. Already, MRI has enabled
scientists to see conditions in the spine, including syringomyelia, even before symptoms
appear. A new technology, known as dynamic MRI, allows investigators to view spinal
fluid pulsating within the syrinx. CT scans allow physicians to see abnormalities in the
brain, and other diagnostic tests have also improved greatly with the availability of new,
non-toxic, contrast dyes.
Poliomyelitis
Poliomyelitis, often called polio or infantile paralysis, is an acute viral infectious disease
spread from person to person, primarily via the fecal-oral route.[1] The term derives from
the Greek poliós (πολιός), meaning "grey", myelós (µυελός), referring to the "spinal
cord", and the suffix -itis, which denotes inflammation.
Although around 90% of polio infections cause no symptoms at all, affected individuals
can exhibit a range of symptoms if the virus enters the blood stream. In about 1% of
cases the virus enters the central nervous system, preferentially infecting and destroying
motor neurons, leading to muscle weakness and acute flaccid paralysis. Different types
of paralysis may occur, depending on the nerves involved. Spinal polio is the most
common form, characterized by asymmetric paralysis that most often involves the legs.
Bulbar polio leads to weakness of muscles innervated by cranial nerves. Bulbospinal
polio is a combination of bulbar and spinal paralysis.
Poliomyelitis was first recognized as a distinct condition by Jakob Heine in 1840. Its
causative agent, poliovirus, was identified in 1908 by Karl Landsteiner. Although major
polio epidemics were unknown before the late 19th century, polio was one of the most
dreaded childhood diseases of the 20th century. Polio epidemics have crippled thousands
of people, mostly young children; the disease has caused paralysis and death for much of
human history. Polio had existed for thousands of years quietly as an endemic pathogen
until the 1880s, when major epidemics began to occur in Europe; soon after, widespread
epidemics appeared in the United States.
By 1910, much of the world experienced a dramatic increase in polio cases and frequent
epidemics became regular events, primarily in cities during the summer months. These
epidemics—which left thousands of children and adults paralyzed—provided the
impetus for a "Great Race" towards the development of a vaccine. Developed in the
1950s, polio vaccines are credited with reducing the global number of polio cases per
year from many hundreds of thousands to around a thousand.[7] Enhanced vaccination
efforts led by the World Health Organization, UNICEF, and Rotary International could
result in global eradication of the disease.
The term poliomyelitis is used to identify the disease caused by any of the three
serotypes of poliovirus. Two basic patterns of polio infection are described: a minor
illness which does not involve the central nervous system (CNS), sometimes called
abortive poliomyelitis, and a major illness involving the CNS, which may be paralytic or
non-paralytic.[10] In most people with a normal immune system, a poliovirus infection is
asymptomatic. Rarely the infection produces minor symptoms; these may include upper
respiratory tract infection (sore throat and fever), gastrointestinal disturbances (nausea,
vomiting, abdominal pain, constipation or, rarely, diarrhea), and influenza-like illness.
The virus enters the central nervous system in about 3% of infections. Most patients
with CNS involvement develop non-paralytic aseptic meningitis, with symptoms of
headache, neck, back, abdominal and extremity pain, fever, vomiting, lethargy and
irritability.
Approximately 1 in 1000 to 1 in 200 cases progress to paralytic disease, in which the
muscles become weak, floppy and poorly controlled, and finally completely paralyzed;
this condition is known as acute flaccid paralysis. Depending on the site of paralysis,
paralytic poliomyelitis is classified as spinal, bulbar, or bulbospinal. Encephalitis, an
infection of the brain tissue itself, can occur in rare cases and is usually restricted to
infants. It is characterized by confusion, changes in mental status, headaches, fever, and
less commonly seizures and spastic paralysis.[
Cause
Poliomyelitis is caused by infection with a member of the genus Enterovirus known as
poliovirus (PV). This group of RNA viruses colonize the gastrointestinal tract —
specifically the oropharynx and the intestine. The incubation time (to the first signs and
symptoms) ranges from 3 to 35 days with a more common span of 6 to 20 days. PV
infects and causes disease in humans alone. Its structure is very simple, composed of a
single (+) sense RNA genome enclosed in a protein shell called a capsid.[3] In addition to
protecting the virus’s genetic material, the capsid proteins enable poliovirus to infect
certain types of cells. Three serotypes of poliovirus have been identified—poliovirus
type 1 (PV1), type 2 (PV2), and type 3 (PV3)—each with a slightly different capsid
protein. All three are extremely virulent and produce the same disease symptoms.[3] PV1
is the most commonly encountered form, and the one most closely associated with
paralysis.
Individuals who are exposed to the virus, either through infection or by immunization
with polio vaccine, develop immunity. In immune individuals, IgA antibodies against
poliovirus are present in the tonsils and gastrointestinal tract and are able to block virus
replication; IgG and IgM antibodies against PV can prevent the spread of the virus to
motor neurons of the central nervous system. Infection or vaccination with one serotype
of poliovirus does not provide immunity against the other serotypes, and full immunity
requires exposure to each serotype.[
A rare condition with a similar presentation, non-poliovirus poliomyelitis, may result
from infections with non-poliovirus enteroviruses.
Transmission
Poliomyelitis is highly contagious via the oral-oral (oropharyngeal source) and fecal-oral
(intestinal source) routes. In endemic areas, wild polioviruses can infect virtually the
entire human population. It is seasonal in temperate climates, with peak transmission
occurring in summer and autumn. These seasonal differences are far less pronounced in
tropical areas. The time between first exposure and first symptoms, known as the
incubation period, is usually 6 to 20 days, with a maximum range of 3 to 35 days. Virus
particles are excreted in the feces for several weeks following initial infection. The
disease is transmitted primarily via the fecal-oral route, by ingesting contaminated food
or water. It is occasionally transmitted via the oral-oral route, a mode especially visible
in areas with good sanitation and hygiene. Polio is most infectious between 7–10 days
before and 7–10 days after the appearance of symptoms, but transmission is possible as
long as the virus remains in the saliva or feces.
Factors that increase the risk of polio infection or affect the severity of the disease
include immune deficiency, malnutrition, tonsillectomy, physical activity immediately
following the onset of paralysis, skeletal muscle injury due to injection of vaccines or
therapeutic agents, and pregnancy. Although the virus can cross the placenta during
pregnancy, the fetus does not appear to be affected by either maternal infection or polio
vaccination. Maternal antibodies also cross the placenta, providing passive immunity
that protects the infant from polio infection during the first few months of life.
As a precaution against infection, public swimming pools were often closed in affected
areas during poliomyelitis epidemics.
Pathophysiology
Poliovirus enters the body through the mouth, infecting the first cells it comes in contact
with—the pharynx (throat) and intestinal mucosa. It gains entry by binding to an
immunoglobulin-like receptor, known as the poliovirus receptor or CD155, on the cell
membrane. The virus then hijacks the host cell's own machinery, and begins to replicate.
Poliovirus divides within gastrointestinal cells for about a week, from where it spreads
to the tonsils (specifically the follicular dendritic cells residing within the tonsilar
germinal centers), the intestinal lymphoid tissue including the M cells of Peyer's patches,
and the deep cervical and mesenteric lymph nodes, where it multiplies abundantly. The
virus is subsequently absorbed into the bloodstream.
Known as viremia, the presence of virus in the bloodstream enables it to be widely
distributed throughout the body. Poliovirus can survive and multiply within the blood
and lymphatics for long periods of time, sometimes as long as 17 weeks. In a small
percentage of cases, it can spread and replicate in other sites such as brown fat, the
reticuloendothelial tissues, and muscle. This sustained replication causes a major
viremia, and leads to the development of minor influenza-like symptoms. Rarely, this
may progress and the virus may invade the central nervous system, provoking a local
inflammatory response. In most cases this causes a self-limiting inflammation of the
meninges, the layers of tissue surrounding the brain, which is known as non-paralytic
aseptic meningitis. Penetration of the CNS provides no known benefit to the virus, and is
quite possibly an incidental deviation of a normal gastrointestinal infection. The
mechanisms by which poliovirus spreads to the CNS are poorly understood, but it
appears to be primarily a chance event—largely independent of the age, gender, or
socioeconomic position of the individual.
Paralytic poliomyelitis
Denervation of skeletal muscle tissue secondary to poliovirus infection can lead to
paralysis.
In around 1% of infections, poliovirus spreads along certain nerve fiber pathways,
preferentially replicating in and destroying motor neurons within the spinal cord, brain
stem, or motor cortex. This leads to the development of paralytic poliomyelitis, the
various forms of which (spinal, bulbar, and bulbospinal) vary only with the amount of
neuronal damage and inflammation that occurs, and the region of the CNS that is
affected.
The destruction of neuronal cells produces lesions within the spinal ganglia; these may
also occur in the reticular formation, vestibular nuclei, cerebellar vermis, and deep
cerebellar nuclei. Inflammation associated with nerve cell destruction often alters the
color and appearance of the gray matter in the spinal column, causing it to appear
reddish and swollen. Other destructive changes associated with paralytic disease occur
in the forebrain region, specifically the hypothalamus and thalamus. The molecular
mechanisms by which poliovirus causes paralytic disease are poorly understood.
Early symptoms of paralytic polio include high fever, headache, stiffness in the back and
neck, asymmetrical weakness of various muscles, sensitivity to touch, difficulty
swallowing, muscle pain, loss of superficial and deep reflexes, paresthesia (pins and
needles), irritability, constipation, or difficulty urinating. Paralysis generally develops
one to ten days after early symptoms begin, progresses for two to three days, and is
usually complete by the time the fever breaks.
The likelihood of developing paralytic polio increases with age, as does the extent of
paralysis. In children, non-paralytic meningitis is the most likely consequence of CNS
involvement, and paralysis occurs in only 1 in 1000 cases. In adults, paralysis occurs in
1 in 75 cases. In children under five years of age, paralysis of one leg is most common;
in adults, extensive paralysis of the chest and abdomen also affecting all four limbs—
quadriplegia—is more likely. Paralysis rates also vary depending on the serotype of the
infecting poliovirus; the highest rates of paralysis (1 in 200) are associated with
poliovirus type 1, the lowest rates (1 in 2,000) are associated with type 2
Spinal poliomyelitis
Is the most common form of paralytic poliomyelitis; it results from viral invasion of the
motor neurons of the anterior horn cells, or the ventral (front) gray matter section in the
spinal column, which are responsible for movement of the muscles, including those of
the trunk, limbs and the intercostal muscles. Virus invasion causes inflammation of the
nerve cells, leading to damage or destruction of motor neuron ganglia. When spinal
neurons die, Wallerian degeneration takes place, leading to weakness of those muscles
formerly innervated by the now dead neurons. With the destruction of nerve cells, the
muscles no longer receive signals from the brain or spinal cord; without nerve
stimulation, the muscles atrophy, becoming weak, floppy and poorly controlled, and
finally completely paralyzed. Progression to maximum paralysis is rapid (two to four
days), and is usually associated with fever and muscle pain. Deep tendon reflexes are
also affected, and are usually absent or diminished; sensation (the ability to feel) in the
paralyzed limbs, however, is not affected.
The extent of spinal paralysis depends on the region of the cord affected, which may be
cervical, thoracic, or lumbar. The virus may affect muscles on both sides of the body,
but more often the paralysis is asymmetrical. Any limb or combination of limbs may be
affected—one leg, one arm, or both legs and both arms. Paralysis is often more severe
proximally (where the limb joins the body) than distally (the fingertips and toes)
Making up about 2% of cases of paralytic polio, bulbar polio occurs when poliovirus
invades and destroys nerves within the bulbar region of the brain stem. The bulbar
region is a white matter pathway that connects the cerebral cortex to the brain stem. The
destruction of these nerves weakens the muscles supplied by the cranial nerves,
producing symptoms of encephalitis, and causes difficulty breathing, speaking and
swallowing.[11] Critical nerves affected are the glossopharyngeal nerve, which partially
controls swallowing and functions in the throat, tongue movement and taste; the vagus
nerve, which sends signals to the heart, intestines, and lungs; and the accessory nerve,
which controls upper neck movement. Due to the effect on swallowing, secretions of
mucus may build up in the airway causing suffocation. Other signs and symptoms
include facial weakness, caused by destruction of the trigeminal nerve and facial nerve,
which innervate the cheeks, tear ducts, gums, and muscles of the face, among other
structures; double vision; difficulty in chewing; and abnormal respiratory rate, depth,
and rhythm, which may lead to respiratory arrest. Pulmonary edema and shock are also
possible, and may be fatal.
Bulbospinal poliomyelitis
Approximately 19% of all paralytic polio cases have both bulbar and spinal symptoms;
this subtype is called respiratory polio or bulbospinal polio. Here, the virus affects the
upper part of the cervical spinal cord (C3 through C5), and paralysis of the diaphragm
occurs. The critical nerves affected are the phrenic nerve, which drives the diaphragm to
inflate the lungs, and those that drive the muscles needed for swallowing. By destroying
these nerves this form of polio affects breathing, making it difficult or impossible for the
patient to breathe without the support of a ventilator. It can lead to paralysis of the arms
and legs and may also affect swallowing and heart functions.
Diagnosis
Paralytic poliomyelitis may be clinically suspected in individuals experiencing acute
onset of flaccid paralysis in one or more limbs with decreased or absent tendon reflexes
in the affected limbs that cannot be attributed to another apparent cause, and without
sensory or cognitive loss.
A laboratory diagnosis is usually made based on recovery of poliovirus from a stool
sample or a swab of the pharynx. Antibodies to poliovirus can be diagnostic, and are
generally detected in the blood of infected patients early in the course of infection.
Analysis of the patient's cerebrospinal fluid (CSF), which is collected by a lumbar
puncture ("spinal tap"), reveals an increased number of white blood cells (primarily
lymphocytes) and a mildly elevated protein level. Detection of virus in the CSF is
diagnostic of paralytic polio, but rarely occurs.
If poliovirus is isolated from a patient experiencing acute flaccid paralysis, it is further
tested through oligonucleotide mapping (genetic fingerprinting), or more recently by
PCR amplification, to determine whether it is "wild type" (that is, the virus encountered
in nature) or "vaccine type" (derived from a strain of poliovirus used to produce polio
vaccine).It is important to determine the source of the virus because for each reported
case of paralytic polio caused by wild poliovirus, it is estimated that another 200 to
3,000 contagious asymptomatic carriers exist.
Prevention
Passive immunization In 1950, William Hammon at the University of Pittsburgh
purified the gamma globulin component of the blood plasma of polio survivors.
Hammon proposed that the gamma globulin, which contained antibodies to poliovirus,
could be used to halt poliovirus infection, prevent disease, and reduce the severity of
disease in other patients who had contracted polio. The results of a large clinical trial
were promising; the gamma globulin was shown to be about 80% effective in preventing
the development of paralytic poliomyelitis. It was also shown to reduce the severity of
the disease in patients that developed polio. The gamma globulin approach was later
deemed impractical for widespread use, however, due in large part to the limited supply
of blood plasma, and the medical community turned its focus to the development of a
polio vaccine.
Treatment
There is no cure for polio. The focus of modern treatment has been on providing relief of
symptoms, speeding recovery and preventing complications. Supportive measures
include antibiotics to prevent infections in weakened muscles, analgesics for pain,
moderate exercise and a nutritious diet. Treatment of polio often requires long-term
rehabilitation, including physical therapy, braces, corrective shoes and, in some cases,
orthopedic surgery.
Portable ventilators may be required to support breathing. Historically, a noninvasive
negative-pressure ventilator, more commonly called an iron lung, was used to artificially
maintain respiration during an acute polio infection until a person could breathe
independently (generally about one to two weeks). Today many polio survivors with
permanent respiratory paralysis use modern jacket-type negative-pressure ventilators
that are worn over the chest and abdomen.
Other historical treatments for polio include hydrotherapy, electrotherapy, massage and
passive motion exercises, and surgical treatments such as tendon lengthening and nerve
grafting. Devices such as rigid braces and body casts—which tended to cause muscle
atrophy due to the limited movement of the user—were also touted as effective
treatments.
Prognosis
Patients with abortive polio infections recover completely. In those that develop only
aseptic meningitis, the symptoms can be expected to persist for two to ten days,
followed by complete recovery. In cases of spinal polio, if the affected nerve cells are
completely destroyed, paralysis will be permanent; cells that are not destroyed but lose
function temporarily may recover within four to six weeks after onset. Half the patients
with spinal polio recover fully; one quarter recover with mild disability and the
remaining quarter are left with severe disability. The degree of both acute paralysis and
residual paralysis is likely to be proportional to the degree of viremia, and inversely
proportional to the degree of immunity. Spinal polio is rarely fatal.
Diseases Mainly Affecting the Long Tracts of the Spinal Cord
The diseases described up to this point affect both the gray and the white matter of the
spinal cord. Other diseases of the spinal cord remain confined to the white matter,
primarily involving one or more of its long tracts. The origin of these diseases is genetic
in many patients (e. g., the spinocerebellar ataxias) but can also be metabolic (e. g.,
vitamin B12 deficiency), endocrine, paraneoplastic, or infectious.
The List of the used literature.
1. An introductions to clinical neurology: path physiology, diagnosis and
treatment 1998
2. Dr. Khalid El-Salem. Seizures. Differential diagnostics, general principals of
treatment 1998
3. Neuroscience: Exploring the Brain. 1996
4. Anatomical Science. Gross Anatomy. Embryology. Histology. Neuroanatomy.
1999
5. Headache. Diagnosis and Treatment. 1993
6. Color Atlas of Human Anatomy Sensory organs And Nervous System (Werner
Kahle) – 1986
7. Fundamentals of Neurology (Thieme 2006). Mark Mumenthaler, Heinrich
Mattle with Ethan Taub