title: Relative utility of different electrophysiologic techniques in the evaluation of brachial plexopathies.
abstract: We report the results of detailed electrophysiologic studies in 23 patients with suspected brachial plexopathies. In five with neurogenic thoracic outlet syndrome, needle EMG and determination of size of ulnar sensory nerve action potentials (SNAPs) and thenar M waves were important in localizing the lesion; F-response and somatosensory evoked potential (SEP) studies were of more limited utility. All electrodiagnostic studies were normal in 10 patients with nonneurogenic thoracic outlet syndrome. In traumatic (three patients) or idiopathic brachial plexopathy (five patients), needle EMG was especially helpful but, in the former, SEP studies helped to guide management and, in the latter, to confirm the proximal site of the lesion when peripheral SNAPs were normal. The presence of preserved but small SNAPs but absent M waves in patients with traumatic plexopathies suggested a combined pre- and postganglionic lesion.
authors.affiliation: Department of Neurology, School of Medicine, University of California, San Francisco 94143.
authors.forename: M J
authors.initials: MJ
authors.lastname: Aminoff
authors.forename: R K
authors.initials: RK
authors.lastname: Olney
authors.forename: G J
authors.initials: GJ
authors.lastname: Parry
authors.forename: N H
authors.initials: NH
authors.lastname: Raskin
mesh_terms: D000200:Action Potentials; D000328:Adult; D000368:Aged; D001917:Brachial Plexus / Q000503:physiopathology*; D004576:Electromyography; D004594:Electrophysiology; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010523:Peripheral Nervous System Diseases / Q000503:physiopathology*; D013901:Thoracic Outlet Syndrome / Q000503:physiopathology; D014459:Ulnar Nerve / Q000503:physiopathology