Myotonic and repetitive discharges in hypokalemic myopathy associated with glycyrrhizin-induced hypochloremia

Abstract

Electromyographic studies were performed in two patients with hypokalemic myopathy induced by the administration of glycyrrhizin, 270–273 mg per day for a period of two and eight months, respectively. Myotonic and repetitive discharges were observed when the serum chloride level fell below 90 mEq/l. Following the administration of potassium chloride, when the chloride level rose above 90 mEq/l, these discharges disappeared. These findings support the causal role of hypochloremia in myotonic discharges. A serum chloride level below 90 mEq/l appears to be critical in producing the myotonic and repetitive discharges.