[Pseudohypertrophic myopathy caused by cysticercosis. Report of a case].

A 25 years old woman was admitted with a history of apparent hypertrophy of the calves, specially on the left, slight pain in the legs and difficulty in walking. Electromyography showed giant motor unit potentials with complete interference pattern. Biopsy of both gastrocnemii was performed revealing a cysticercus among inflammatory infiltrate and changes of the muscle fibers. Review of the literature disclosed 12 other reported cases. The age ranged from 10 to 35 years with a median of 25 years. Pseudohypertrophic myopathy due to cysticercosis has been found twice more common in males than in females. History of epilepsy and muscle pain occurs in about one half of the cases and muscle weakness in about one third of them. Usually there is simultaneous involvement of the upper and lower limb girdles. Myotonia is rare but subcutaneous nodules are frequently found. Our case is unique in the literature in which the pseudohypertrophy was confined to the legs and electromyography showed giant motor unit potentials. The pathogenesis of this condition is discussed and attention is called to the differential diagnosis with other pseudohypertrophic muscular conditions such as pseudohypertrophic muscular dystrophy, myotonia congenita, trichinosis, hypothyroidism, amyloidosis and glycogenosis of type I (Pompe's disease) in its juvenile form.