The resuits and value of single fiber electromyography in the diagnosis of CTS

Abstract

Objective To analysis and evaluate the results of single fiber electromyography (SFEMG) in the diagnosis of carpal tunnel syndrorne (CIS). Methods According to results acquired by routine nerve conduction studies, 14 clinically diagnosed CTS patients (20 sides) were divided into 2 groups. In group Ⅰ(10 sides) although there was slowing of sensory nerve conduction velocity (SNCV) across the wrist, latency of the compound muscle action potential (CMAP) of abductor pollieis brevis (APB) was normal. In group Ⅱ(10 sides) in sdditiun to slow SNCV, CMAP latency of APB was more than 4.3 ms. Another 10 normal volunteers served as control. SFEMG was done to all the study subjects to obtain fiber density (FD) of the abductor pollicis brevis and mean of consecufive difference (MCD). Results Preoperative SPEMG showed that MCD of group Ⅰ was 67.86 μs on average, being 27.47 μs longer than that of the control group. MCD of group Ⅱ was 83.36μs on average, 42.97μs longer comparing to the control group. FD of abductor pollicis brevis was higher in both group Ⅰ and Ⅱ, with an increase of 0.46 and 0.60, respectively. MCD and FD in CTS patients were significanfly higher than those of normal control. MCD of group Ⅱ was significantly greater than MCD of group Ⅰ. However there was no significant difference in FD of both groups. Conclusion SFEMG provides more objective and direct evidence for the diagnose of Carpal tunnel syndrome, especially for cases in early stage. Key words: Carpal tunnel syndrome; Diagnosis; Single fiber electromyography