The neuromuscular system in patients with anorexia nervosa: electrophysiological and histologic studies.

The effects of cachexia on the neuromuscular system were investigated in ten young women with anorexia nervosa and in two patients with hysteric neurosis. Ten women, matched for age and height, served as controls. A neurologic examination was performed on all subjects and sensory and motor neurographic recordings were carried out in the upper and lower limbs. Biopsies from the vastus lateralis muscle were stained for myofibrillar ATPase activity and the size and distribution of both histochemical fiber types (types 1 and 2) were determined. Both types of muscle fibers were found to be significantly reduced in size in the cachectic patients but there was a predominant affection of the type 2 fibers. The average numerical distribution of fiber types was almost identical in the two groups. By subjective evaluation, four of the cachectic patients revealed small groups of angulated atrophic fibers, resembling denervation atrophy. Fiber necroses and other myopathic changes were not seen. Although the nerve conduction velocities (NCV) were within normal range in all cases, the motor NCV was generally slower in the cachectic patients than in the controls. The sensory NCV, on the other hand, was almost identical in the two groups. Five of the patients with anorexia nervosa and both cases with hysteric neurosis had clinical signs of a very mild sensory polyneuropathy. These seven cases had a lower body-mass index than the others and both types of muscle fibers and muscle responses were somewhat smaller in these cases. The sensory NCV did not differ from those of the other patients.(ABSTRACT TRUNCATED AT 250 WORDS)