title: Which motor nerve conduction study is best in ulnar neuropathy at the elbow?
abstract: There is debate regarding how best to utilize ulnar motor nerve conduction velocity (MNCV) to identify ulnar neuropathy at the elbow (UNE). We used receiver operator characteristic (ROC) curves to compare absolute across-elbow MNCV with MNCV difference between elbow and forearm segments (VDIF) when recording from abductor digiti minimi (ADM) and first dorsal interosseous (FDI) muscles. Also, we determined how their utility was impacted by low amplitudes of compound muscle action potentials (CMAPs). We studied 85 subjects with UNE and 77 subjects with carpal tunnel syndrome but without clinical evidence of UNE. The UNE group was divided into three subgroups based on CMAP amplitude. At 95% specificity, MNCV sensitivities were 80% at ADM and 77% at FDI, and VDIF sensitivities were 51% at ADM and 38% at FDI. The ROC curves showed MNCV to be superior to VDIF across all amplitude subgroups; however, confidence intervals overlapped when amplitude was high.
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, Harborview Medical Center, Box 359740, 325 Ninth Avenue, Seattle, Washington 98104, USA. docshakir@hotmail.com
authors.forename: Ali
authors.initials: A
authors.lastname: Shakir
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Micklesen
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Robinson
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001369:Axons / Q000502:physiology; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis / Q000503:physiopathology; D004550:Elbow / Q000294:innervation / Q000503:physiopathology*; D004568:Electrodiagnosis; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000503:physiopathology; D009431:Neural Conduction / Q000502:physiology*; D020424:Ulnar Neuropathies / Q000175:diagnosis* / Q000503:physiopathology