[Periodic hypokalemic paralysis as the manifestation of Graves' disease: clinical and electrophysiological study].

A 30-year-old Vietnamese man experienced severe weakness of four limbs revealing hypokalaemia. Tachycardia and goiter allowed to diagnose a Graves' disease. Thyrotoxic hypokaliemic periodic paralysis is a rare complication of hyperthyroidism in western populations. Electromyogram performed after resolution of the paralysis episodes revealed marked abnormalities of the muscular excitability. Duration of compound muscular action potential was markedly increased after a brief exercise. This increase might indicate a delayed repolarization of muscle fibres.