The Correlation between the Cutaneous Silent Period and Ultrasonographic Findings of Median Nerve in Patients with Carpal Tunnel Syndrome

ABSTRACT

OBJECTIVE: To determine the relation between the latency and duration of the cutaneous silent period (CuSP) and ultrasonographic findings of patients with carpal tunnel syndrome (CTS). METHOD: Subjects included 50 hands of 33 patients with CTS with electrophysiologic evidence of CTS and 50 hands of 39 adults with no evidence of CTS. CuSP was measured on abductor pollicis brevis (APB) and adductor digiti minimi (ADM) by stimulation of digit 3. All subjects were examined with ultrasonography (US). Using US, the cross-sectional area (CSA) and flattening ratio (FR) of the median nerve were calculated under carpal tunnel. Analysis of differences between the control group and the CTS group was performed using ANOVA. RESULTS: Differences of CSA, FR, latency, and duration of CuSP in both APB, ADM muscles were observed between the two groups. Correlations were observed in the patient group in latency and duration of the APB muscle and only in duration of the ADM (p=0.048, r=0.159; p=0.035, r=-0.315; p=0.039, r=-0.293) muscle. Correlations were found only in duration of ADM (p=0.011, r=0.358) in the control group with respect to CSA. However, there was no correlation with FR. CONCLUSION: There seems to be a significant correlation between the CSA of the median nerve and the latency and duration of CuSP in patients with CTS. In addition, there seems to be a significant difference of CSA, FR, and latency in both APB and ADM between the two groups. CuSP and CSA might be useful for study that reflects intact small fibers in patients with CTS.