[Myasthenic syndrome induced by lithium]. / Syndrome myasthénique induit par le lithium.

BACKGROUND: Lithium salts can induce a dysfunction of the neuromuscular junction. CASE REPORT: A patient given lithium for bipolar psychosis developed a state of major fatigue revealing a myasthenia syndrome which resolved progressively after lithium withdrawal. DISCUSSION: In the literature, we found 4 cases of neuromuscular junction disorders in patients treated with lithium. A myasthenia syndrome was induced by lithium in 3 cases and underlying myasthenia was disclosed by lithium in the last one. The long-term course in our patient was in favor of an induced syndrome rather than underlying myasthenia. We discuss the pathophysiological mechanisms. Lithium is a commonly prescribed drug. Clinicians should be aware of the possibility of neuromuscular junction disorder in patients taking lithium who develop muscle fatigue.