MKSAP Quiz: multiple sclerosis
MKSAP Quiz: multiple sclerosis
A 30-year-old man has a recent diagnosis of multiple sclerosis (MS). He experienced two transient neurologic episodes in the past six months, one involving optic neuritis and the other minor partial myelitis; he recovered completely from both events and is currently asymptomatic. MS was diagnosed after an MRI of the brain showed white matter lesions typical of the disease. He has no other pertinent personal or family medical history.
Which of the following MS subtypes best describes the course of his disease?
A. Benign
B. Primary progressive
C. Relapsing-remitting
D. Secondary progressive
MKSAP Answer and Critique
The correct answer is C) Relapsing-remitting. This item is available to MKSAP 15 subscribers as item 25 in the Neurology module.
This patient experienced an episode of transient neurologic dysfunction (an attack) at disease onset and thus has relapsing-remitting MS. Eighty-five percent of patients with MS have this type of disease onset. In relapsing-remitting MS, relapse frequency declines over time, and relapses do not become more severe with increasing disease duration; however, recovery from individual events may be slower and less complete.
Primary progressive MS, which the other 15% of patients with MS have at disease onset, is defined as gradually worsening neurologic function over more than 1 year without recovery. This patient has recovered completely from two neurologic episodes and is currently asymptomatic. Therefore, he cannot be classified as having primary progressive MS.
Secondary progressive MS is characterized by gradual, unremitting development of new symptoms over months to years in a patient who previously had a relapsing-remitting course. The lifetime risk of conversion from relapsing-remitting to secondary progressive disease is greater than 50%, but the onset and rate of the progressive phase are highly variable and not predictable for individual patients. The median time from MS onset until conversion to the secondary progressive phase typically ranges from 10 to 15 years. The establishment of a secondary progressive course is a risk factor for substantial disability, such as loss of independent ambulatory function; the median time from MS onset to the point at which unilateral gait assistance (such as a cane) is required is 15 to 25 years. This patient first had transient symptoms only 6 months ago and thus cannot be characterized as having secondary progressive disease.
Benign MS is defined loosely as no or minimal neurologic impairment 15 or more years after MS onset. This category may encompass as many as 20% of all patients with MS. The definition of benign MS is controversial because continued follow-up of such patients often uncovers late progressive disease and disability accrual. However, a small minority of patients with MS live a long and essentially unrestricted life. The factors that predict a benign course early in the disease have not yet been identified. This patient's MS diagnosis is too recent to be categorized as benign at this point.
Key Point
- Multiple sclerosis begins as a relapsing-remitting disorder in 85% of patients and a primary progressive disorder in 15% of patients; those with the relapsing-remitting type have a greater than 50% risk of developing a secondary progressive disease course.