Sporadic distal myopathy with early adult onset.

With the exception of the large series of adult-onset hereditary distal myopathy from Sweden, few cases of primary muscle disease with a definite distal predilection have been published. We report 3 sporadic cases of distal myopathy with the following features: (1) early adult onset (26 to 33 years); (2) slowly progressive weakness affecting first the distal leg muscles and later the arms; (3) marked elevation of creatine phosphokinase (more than 10 times the normal value); and (4) electromyographic and histological evidence of myopathy in distal muscles. The differential diagnosis is discussed and other reported cases are reviewed. The differences between hereditary cases reported by others and the sporadic cases reported here form the basis for a tentative subclassification of this syndrome.