Ring finger sensorial conduction studies in grading carpal tunnel syndrome: Part II

Article type: Research Article

Authors: Alemdar, Murat

Affiliations: Sakarya Üniversitesi Tıp Fakültesi, Eǧitim ve Araştırma Hastanesi, Nöroloji Kliniği, 2. Kat, Adnan Menderes c., Sağlık s., No: 195, 54100, Adapazarı, Sakarya , Turkey | Tel.: +90 532 2032744; E-mail: dr.alemdar@gmail.com

Abstract: BACKGROUND:Comparison of sensory conduction of median nerve (MN) with the one of ulnar nerve (UN) over writs-to-ring finger (RF) segment is useful in electrodiagnosis of carpal tunnel syndrome (CTS). However, there is not any consensus regarding the usage of this technique in grading of CTS. OBJECTIVES:To determine whether the hands of CTS with elicitable MN sensory responses on index finger, but not on RF (non-respondings) compose a more severe electrophysiologic grade than the hands with elicitable responses on both fingers (respondings). MATERIAL AND METHODS:The patients with bilateral moderate grade of CTS in whom one hand was responding and the contralateral hand was non-responding were included. Conduction study results of MN and UN were compared between respondings and non-respondings. RESULTS: A total of 19 patients were included. Mean distal sensory onset latency (DSOL) of MN over index finger was longer (4.26 ± 0.49 msec versus 3.44 ± 0.39 msec; p< 0.001), sensory conduction velocity (SCV) was slower (33.7 ± 4.3 m/sec versus 40.2 ± 3.0 m/sec; p< 0.001), SNAP amplitude was smaller (10.3 ± 3.3 μV versus 19.1 ± 7.7 μV; p< 0.001), distal motor latency was longer (5.69 ± 0.60 msec versus 4.63 ± 0.32 msec; p< 0.001), and minimum F wave latency was longer (29.3 ± 1.7 msec versus 26.8 ± 1.4 msec; p< 0.001) in non-respondings than respondings. The nonresponding hand had a longer MN DSOL and slower SCV on index finger compared with contralateral responding hand in all of 19 patients. CONCLUSION: Non-responding hands have more progressed median neuropathies, and represent a more severe electrophysiologic grade than responding hands. Further studies are warranted to determine whether the absence of MN sensory responses on ring finger is related with forthcoming NCS worsening and a preferable hallmark for deciding surgical intervention or not.

Keywords: Carpal tunnel syndrome, median nerve, ulnar nerve, sensory response, ring finger, electrophysiologic grade

DOI: 10.3233/BMR-171068

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. 31, no. 4, pp. 759-766, 2018