title: Second lumbrical-interossei nerve test predicts clinical severity and surgical outcome of carpal tunnel syndrome.
abstract: The purpose of this study was to examine the utility of the second lumbrical-interossei nerve (2L-IN) test in the diagnosis of carpal tunnel syndrome (CTS). We examined 65 patients with suspected unilateral CTS using the 2L-IN test, in addition to the standard electrophysiological test. The operative cases were divided into three classes of severity based on Padua's neurophysiological classification: extreme CTS (absence of median motor and sensory response); severe CTS (absence of sensory response, abnormal distal motor latency [DML]); and moderate CTS (abnormal sensory nerve conduction velocity, abnormal DML). With the 2L-IN test, the extreme CTS group could be further subdivided into extreme CTS-A (both abductor pollicis brevis [APB]- compound muscle action potential [CMAP] and 2L-CMAP not recordable) and extreme CTS-B (2L-CMAP recordable, APB-CMAP not recordable). Patients with extreme CTS and severe CTS were older, had chronic symptoms, and poorer outcome compared with the moderate CTS patients. Patients of the moderate CTS group were almost all satisfied with the results of surgery. The electrodiagnostic severity correlated with the clinical outcome. Severe strangulation of the thenar muscle branch was identified in patients in the extreme CTS-B group, requiring decompression of the thenar muscle branch rather than conventional simple transverse ligament detachment.
authors.affiliation: Department of Orthopaedics, National Hospital Organization, Fukui National Hospital, Sakuragaoka 33-1, Tsuruga, Fukui 914-0144, Japan. tinukai@nhofukui.org
authors.forename: Tomoo
authors.initials: T
authors.lastname: Inukai
authors.forename: Kenzo
authors.initials: K
authors.lastname: Uchida
authors.forename: Chikara
authors.initials: C
authors.lastname: Kubota
authors.forename: Takaharu
authors.initials: T
authors.lastname: Takamura
authors.forename: Hideaki
authors.initials: H
authors.lastname: Nakajima
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Baba
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002349:Carpal Tunnel Syndrome / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000502:physiology*; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology*; D011237:Predictive Value of Tests; D012720:Severity of Illness Index; D016896:Treatment Outcome; D014459:Ulnar Nerve / Q000502:physiology*
keywords: Carpal tunnel syndrome; Lumbrical-interossei test; Nerve conduction studies