title: Isaacs' syndrome with muscle hypertrophy reversed by phenytoin therapy.
abstract: A 16-year-old boy was seen for severe episodic muscle cramps and generalized myokymia, consistent with Isaacs's syndrome. Bilateral calf hypertrophy (46-cm calf circumference) and ankle areflexia were noted. He was treated with phenytoin sodium, 300 mg/day. Within three months there was marked decrease in myokymia, total relief of cramps, return of ankle reflexes, and 6-cm reduction in calf circumference. We suggest that the excess muscle activity in Isaacs's syndrome may be responsible for the associated phenomena of muscle hypertrophy and areflexia.
mesh_terms: D000293:Adolescent; D005207:Fasciculation / Q000150:complications / Q000188:drug therapy; D006801:Humans; D006984:Hypertrophy; D008297:Male; D009120:Muscle Cramp / Q000150:complications / Q000188:drug therapy; D009127:Muscle Rigidity / Q000150:complications / Q000188:drug therapy; D009132:Muscles / Q000473:pathology; D009135:Muscular Diseases / Q000188:drug therapy*; D010672:Phenytoin / Q000627:therapeutic use*; D013577:Syndrome
chemical_list: D010672:Phenytoin