"Myopathic" changes in chorea-acanthocytosis. Clinical and histopathological studies.

Four cases of chorea-acanthocytosis were studied with special reference to muscular changes. All the cases showed the clinical stigmata of oro-linguo-facial dyskinesia with tongue biting, mild neurogenic muscular involvement and acanthocytosis. Serum creatine kinase (CK) was persistently elevated, showing MM type isozyme predominance. Histopathological studies of the peroneus brevis muscle showed prominent small group atrophy, increase of small fibers on diameter analysis, frequent angulated fibers, and angulated fibers with increased acid phosphatase activity. These findings are compatible with chronic denervation. However, central nucleation (approximately 10%) and fiber splitting (2-8%) were also found in all cases. These are compatible with myopathic changes. No correlation of these "myopathic" changes and serum CK levels was found. The "myopathic" findings are probably secondary to chronic denervation.