Multiple SclerosisDz

ICD-9 Code: 340.0.

ICD-10 Code: G35

Definition: Multiple sclerosis is a immunologically mediated disease characterized by demyelination within the CNS. The typical clinical presentation is neurologic events separated in time (recurrent or relapsing) and space (arising from distinct parts of the brain, brainstem, and spinal cord).

Demographics: Multiple sclerosis occurs predominantly among whites of northern European descent. The prevalence of multiple sclerosis varies dramatically with longitude. Multiple sclerosis occurs in approximately 20 per 100,000 persons living in the southern United States and increases as one moves north; the prevalence exceeds 125 per 100,000 in Canadians. Although there is a small genetic predisposition to multiple sclerosis (monozygotic twins have a concordance of approximately 25%), environmental exposure to an unidentified antigen at a young age appears to be important. Peak onset age is 20 to 40 years. Women are affected twice as often as men.

Cardinal Findings: The characteristic clinical presentation of multiple sclerosis is neurologic defects separated in space and time. Most defects arise acutely, with 75% occurring within a few days. Typically, the defects persist for 6 to 8 weeks, and many resolve spontaneously. In most patients, this is followed by a recurrence of neurologic defects. The most common presenting symptoms include weakness in one or more limbs (50%), numbness in the limbs (45%), optic neuritis (20%), unsteady gait or ataxia (15%), and diplopia (10%). A useful clinical clue to the diagnosis of multiple sclerosis is that the symptoms reflect involvement of the white matter of the CNS. Thus, symptoms seen primarily with gray matter damage in the CNS (e.g., loss of consciousness, seizures, syncope, dementia, muscle atrophy, pain) are uncommon. Physical examination may reveal evidence of optic (e.g., internuclear ophthalmoplegia) or spinal cord involvement (e.g., a positive Babinski reflex, dysfunctional sphincter).

Diagnostic Tests: Standard laboratory and serologic tests are of little value. CSF studies may reveal normal cell counts or show a mild mononuclear pleocytosis, mildly increased CSF protein, increased CSF IgG index or synthetic rate (90%), or evidence of CSF oligoclonal bands or myelin basic protein (>85%). In addition, visual evoked potentials or brainstem evoked potentials may help confirm the diagnosis of multiple sclerosis.

Imaging: The diagnosis of multiple sclerosis may be supported by imaging studies. Perhaps the most important advance has been the availability of MRI. Areas of demyelination, or plaques, are readily revealed by MRI. However, some patients (e.g., those with predominant spinal cord involvement) may have entirely normal scans. Although consistent with multiple sclerosis, white matter lesions on MRI may also be seen in other conditions, including hypertensive vasculopathy, SLE with CNS involvement, and various infections (e.g., Lyme disease, HIV, human T-cell lymphotropic virus type 1).

Therapy: Conservative measures should include evaluation by physical and occupational therapy. Interferon beta 1-a and beta 1-b and glatiramer acetate have been approved for use in multiple sclerosis and are considered first-line agents. Corticosteroids are also effective first-line drugs, especially with opticneuritis. Second-line agents include intravenous gamma-globulin, azathio- prine, methotrexate, and cyclophosphamide.

BIBLIOGRAPHY

Rolak LA. The diagnosis of multiple sclerosis. Neurol Clin 1996;14:27–43.PMID:8676847