title: Idiopathic generalized myokymia.
abstract: Idiopathic generalized myokymia (IGM) is a rare, heterogeneous, and poorly understood syndrome. We present analysis of 75 reported cases in the world literature. IGM affects men and women equally, with a mean age of onset 29 +/- 19 years. Patients' common presenting complaints are stiffness (60%), cramps (12%), weakness (12%), and muscle twitching (4%). Family history is positive in 30%. In addition to generalized clinical myokymia (92%), abnormal neurologic findings include: hyporeflexia (70%), weakness (45%), grip myotonia (39%), and calf hypertrophy (16%). Electrical activity consisting of spontaneous continuous motor unit activity and/or electrical myokymia was documented in all patients. When electrical myokymia was observed (66%), the grouped discharges where irregular and had an interburst frequency of 2-300 Hz. Both phenytoin and carbamazepine are effective treatments. We conclude that IGM has a wide spectrum of symptoms and severity and should be considered in all patients that present with stiffness, cramps, or muscle twitching. EMG greatly aids in diagnosis.
authors.affiliation: Department of Neurology, University of Kansas Medical Center, Kansas City 66160-7314.
authors.forename: P W
authors.initials: PW
authors.lastname: Jamieson
authors.forename: M B
authors.initials: MB
authors.lastname: Katirji
mesh_terms: D000328:Adult; D004594:Electrophysiology; D005207:Fasciculation / Q000150:complications* / Q000175:diagnosis / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D009046:Motor Neurons; D009120:Muscle Cramp / Q000209:etiology; D009132:Muscles / Q000503:physiopathology