Characteristics of forearm mixed nerve conduction study in carpal tunnel syndrome: Comparison with ultrasound assessments.

This study aimed to characterize forearm mixed nerve conduction study (NCS) findings in carpal tunnel syndrome (CTS). Eighty-two patients with CTS and 48 healthy controls were enrolled. We directly compared the forearm mixed NCS and ultrasonography results from CTS patients with those from the controls. Correlation analyses were performed to identify the relationship between forearm mixed NCS parameters and ultrasound measurements in CTS. We observed reduced forearm mixed nerve amplitude and increased cross-sectional area (CSA) of the median nerve at the proximal carpal tunnel (CT) inlet in CTS. The forearm mixed nerve amplitude negatively correlated with the CSA at the proximal CT inlet. We found a negative correlation between Bland's neurophysiological grade and the forearm mixed nerve amplitude as well as a positive correlation between the CSA of the median nerve at the proximal CT inlet and Bland's neurophysiological grade. We confirmed that the reduced median mixed nerve amplitude is the distinguishing feature of forearm mixed NCS in CTS. Our findings suggest that the forearm mixed NCS is potentially useful in evaluating its severity.