Hyperthyroidism and periodic paralysis.

The periodic paralyses are a rare group of disorders which may be familial, sporadic, occur in association with hyperthyroidism or as a result of potassium loss. A 46-year-old otherwise healthy Filipino male is described who presented with a second episode of paroxysmal painless weakness. Examination revealed a pattern of weakness consistent with a myopathic process (symmetric/proximal). The neurologic examination was otherwise physiologic. The clinical features are described as well as the differential diagnosis, pathophysiology, and treatment. This case also demonstrates the phenomenon wherein periodic paralysis may precede clinical hyperthyroidism.