Multiple sclerosis after age 50.

When multiple sclerosis (MS) presents late in life (after the age of 50), it frequently gives diagnostic difficulty. In a large MS clinic population (N = 838), 9.4% of the patients had late onset of MS. Slow deterioration of motor function characterized the initial symptoms and subsequent course of this group of older patients. Progression of disability was more rapid than in younger patients. Evoked response studies and CSF electrophoresis were of high diagnostic yield in the older patient group. Reasons for the differing clinical features in the late-onset patients are discussed. We suggest that the age-of-onset criterion for MS be raised to 60 in adequately investigated cases.