[Apropos of a case of thyrotoxic periodic paralysis (TPP): electromyographic study (EMG)]

The authors report on a case of thyrotoxic periodic paralysis characterized by attacks of flaccid tetraplegia with hypokalemia in a patient with Basedow disease, the cure of which led to the disappearance of the neurological symptomatology. The EMG investigations, performed in the course of a spontaneous paralytic attack, showed the same abnormalities as in the few similar published cases: discordance between the rich interferential recordings and the weakness of the movements; low amplitude of the electrodetection tracings; reduced amplitude of the evoked muscle action potentials on nerve stimulation. These myogenic patterns are related to the aspect of the muscle biopsy which, when performed during the paralytic phase, shows a vacuolization of the muscular fibers. The pathophysiological underlying mechanisms of the thyrotoxic periodic paralysis still remain hypothetic.