Multiple Sclerosis

Multiple sclerosis - demyelination in the white matter– A chronic, progressive central nervous system disease with a disseminating demyelination of the nerve fibers of the brain and spinal cord characterized by exacerbation and remission of varied multiple neurologic symptoms.

Causes and Incidence

The exact etiology of multiple sclerosis (MS) is unknown, but an immunologic abnormality, allergic response, or slow-acting virus is suspected. MS is the most prevalent demyelinating disease and the third leading cause of disability in young and middle adulthood. More than 8,000 cases are diagnosed in the United States each year.

Disease Process

Multifocal plaques of demyelination form continuously and are distributed randomly throughout the white matter of the central nervous system, with accompanying destruction of oligodendroglia and perivascular inflammation. As myelin breakdown continues, lipid byproducts undergo phagocytosis, and the myelin sheath is destroyed. This leads to a decrease in velocity and blockage of nerve conduction, and interference with or failure of impulse transmissions. Cell bodies and axons are preserved early in the disease, but eventually the axons are stripped bare. Discrete lesions extend and coalesce into larger lesions. Astrocytic processes proliferate, transforming older lesions into glial scars. The scars stop the inflammation and edema of the lesion, leading to remission early in the disease process. However, as the disease progresses, symptoms become permanent.

Symptoms

Signs and symptoms depend on the size, age, activity, and location of the lesions. Remissions may last months or years early in the disease. Later remission intervals are shorter, and eventually permanent, progressive disablement occurs.

Early
The onset is generally insidious and symptoms are transient, beginning with paresthesias in extremities, trunk, or face; clumsiness and muscle weakness; transient visual disturbances and optic pain; ataxia; bladder incontinence; and vertigo

Midcourse
Emotional lability, apathy, shortened attention span; seizures; diplopia; dysarthria; static tremor; spasticity, gait disturbances; transient bowel incontinence

Late
Dementia; scanning speech; nystagmus; intention tremor; hemiplegia; generalized muscular weakness and atrophy; inability to stand and walk; loss of bowel and bladder control

Potential Complications

Some individuals have frequent attacks, leading to rapid incapacitation with an unremitting, progressive course that ends in death within 1 to 2 years. Others are prone to complications related to progressive disease and disuse syndrome, such as pressure sores, contractures, pathologic fractures, pneumonia, renal infection, and septicemia. Death usually is caused by complications rather than the primary disease.

Diagnostic Tests

Diagnosis is elusive and indirect and is deduced from clinical features and laboratory tests, which include elevated cerebrospinal fluid (CSF) IgG coupled with normal serum IgG; normal CSF protein; slowed nerve conduction in evoked potential studies; and computed tomography and magnetic resonance imaging scans of lesions.

Treatments

Surgery
Rhizotomy for unresponsive spasms; contracture releases.

Drugs
Muscle relaxants for spasticity; corticosteroids for acute attacks; immunosuppresive use is in clinical trials.

General
Balance of rest and activity; long-term rehabilitation (occupational, physical, and speech therapy) to maintain activities of daily living, adapt to progressive loss of function, prevent disuse syndrome, and promote bowel and bladder control; assistive devices (canes, walkers, bracing, casting, wheelchairs); counseling and psychologic support of individual and family; respite home care; ventilatory assistance and communication devices in end-stage disease; care in feeding if dysphagia is present; evaluation for cognitive dysfunction; plasmapheresis and total lymphoid irradiation are under investigation.