[Subacute motor neuropathy induced by T3 hyperthyroidism]

Subacute motor neuropathy involving bulbar nerves is an unusual complication of hyperthyroidism. Clinical and neurophysiologic follow-up of such patients has been rarely reported. We describe a 41-year-old Colombian patient who developed respiratory failure associated with motor neuropathy and severe weight loss. The major clinical features included diffuse amyotrophy, bilateral facial paresis, and fasciculations, suggesting motor neuropathy. Electromyography confirmed the presence of axonal neuropathy, with predominant motor involvement. Goiter with hypervascularization was noticed, associated with pure T3 hyperthyroidism (T3l=26 pg/ml; N<3.8). The patient was given carbimazole which induced a severe skin vasculitis 10 days later. Carbimazole was stopped and replaced by propylthiouracile, which also induced vasculitis with secondary cardiac failure. Total thyroidectomy was then performed. General status improved rapidly as well as motor deficit, amyotrophy and pyramidal syndrome. Electromyographic abnormalities improved significantly within 3 months. This observation demonstrates that hyperthyroidism can produce motor axonal neuropathy, curable with radical surgery.