[Periodic paralysis. Histological, histochemical and ultrastructural studies in five cases (author's transl)].

Muscle changed found in five patients with periodic paralysis are described. Three patients had familial hypokaliemic paralysis, one had familial periodic paralysis with hyperkaliemia, and one had periodic attacks of muscular weakness with thyrotoxicosis. According to the stage in the clinical course at which biopsy was performed, several pathological patterns are described. Vacuolization was the main feature in the early stages of periodic paralysis. Later in the clinical course, tubular aggregates were the characteristic findings. In addition, degenerative changes of the muscle fibres were found in patient exhibiting a permanent myopathic condition. In thyrotoxic periodic paralysis, the longer the clinical course, the more severe the changes appeared to be. Possible mechanisms leading to such structural abnormalities remain in question.