A Brief Synopsis of Multiple Sclerosis
| Multiple Sclerosis is a slowly progressive
neurological disease characterized by patches of demyelination in brain
and spinal cord. The cause is unknown and the course is highly variable. |
Etiology & Incidence
The demyelination is associated with oligodendroglia not Schwann cells,
thus making this a CNS not PNS disorder. Although both cell types provide
similar function (form myelin sheaths around neurons), they are chemically
and immunologically distinct. The cause is unknown, but an immunologic
pathology is suspected. (The disease seems to involve an autoimmune response
where antibodies are formed which attack and destroy the olgodendroglia
cells.) Individual oligodendroglia cells are attached, producing a segmental
pattern of inflamation and demyelination. During periods of remission,
considerable recovery often occurs with regrowth of damaged cells and even
remyelination of neurons.
There are prominent regional clusters found throughout the world, suggesting
environmental influences. Geographic location appears to have no effect
after age 15 years. Some researchers have postulated that a latent virus
underlies the disorder. Age of onset is usually between 20 and 40 years,
and the incidence is somewhat higher in women than in men.
Symptoms
Some of the more common early symptoms are paresthesias, weakness in an
arm or leg, and visual disturbances. Minor gait disturbances, vertigo,
difficulty with bladder control, neuropathic pain, difficulty in speaking,
and mild emotional disturbances may also be present early in the course
of the disease. Symptoms may come and go with periods of active progression
and remission, and partial recovery is not uncommon and may be facilitated
by physiotherapy. Advanced stages of the disease lead to pronounced sensory-motor
impairment and can be accompanied by significant emotional problems.
Diagnosis
There are no specific tests for MS and diagnosis is usually made by exclusion
of other disorders. MRI may reveal plaques around demyelinated neurons
and even explicit lesions caused by cell loss. High contrast CT may show
MS lesions, but the MRI procedure is much more sensitive. Because the optic
tract often shows partial demyelination before clinical signs emerge, visual
evoked potentials may be especially valuable for early diagnosis. Similarly,
other sensory evoked potentials can detect demyelination of others relevant
pathways although the visual systems is most commonly affected.
Prognosis
MS is a progressive disorder but often with long periods of remission (sometimes
> 10 years). Life expectancy is usually not significantly affected.
Treatment
Because the progression of the disease is highly variable, it is impossible
to prescribe one course of treatment. MS often shows prolonged remission
requiring no explicit medical treatment. During active periods, corticosteroids
are usually prescribed. (Long-term use of corticosteroids have side-effects
that limit their use, e.g., osteoporosis, ulcers, diabetes.) b-interferon
may be helpful in preventing relapse and in delaying the progression of
the disease.
Notable Cases
Online Resources
THE
MERCK MANUAL--Home Edition, Sec. 6, Ch. 68, Multiple Sclerosis and Related
Disorders
THE
MERCK MANUAL, Sec. 14, Ch. 180, Demyelinating Diseases
Copyright 2001 Michael A. Bozarth
Revised 09 November 2001 00:51 EST
Report technical problems to: bozarth@buffalo.edu