Factors associated with a malignant or benign course of multiple sclerosis
V. A. Clark, R. Detels, B. R. Visscher, N. L. Valdiviezo, R. M. Malmgren and J. P. Dudley
Eight hundred thirty-four patients with multiple sclerosis (MS) in King and
Pierce Counties, Washington, and in Los Angeles County, California, with
symptomatic onset between 1960 and 1969 were followed up for disability
status in 1980. A higher proportion of the 375 patients who were not
walking or deceased in 1980 had a late age of onset, resided in Los Angeles
County, had motor or coordination symptoms at onset, and reported adverse
responses to heat exposure and favorable responses to cold exposure,
whereas a higher proportion of the 299 patients still walking without aids
had early onset age and vision, speech, or sensory symptoms, or all three,
at onset. The results suggest (1) that both host factors (age at first
manifestation of symptoms and types of symptoms at onset) and environmental
factors (place of residence and exposure to heat and cold) are determinants
of disease course and (2) that most patients with MS should avoid exposure
to heat.
