The application and effectiveness of neuroelectrophysiology and MRI in the early diagnosis of carpal tunnel syndrome

Abstract

Objective To study the application of neural electromyogram (EMG) and MRI in the diagnosis of carpal tunnel syndrome (CTS) and their correlation. Methods Neuroelectrophysiologic examination was conducted in 36 CTS patients. Based on the electrophysiological staging criteria, these cases were divided into early, intermediate and late stage CTS. These patients along with 40 healthy volunteers were subject to MRI examination to measure and record median nerve swelling rate (MNSR) and median nerve flatness ratio (MNFR). These measurements were compared between these two groups of individuals. Patients with intermediate and late stage CTS underwent surgical carpal tunnel release. Intraoperative findings of the median nerve were compared with the preoperative MRI examination results. Results For early stage CTS patients, MNSR and MNFR were not significantly different from those of the healthy controls. For intermediate and late stage CTS patients, MNSR and MNFR were higher than those of the healthy controls, the difference being statistically significant (P<0.05). Intraoperative observation of the pathological changes of the median nerve was consistent with the preoperative MRI examination results. There was a positive correlation between the distal motor latency (DML) of the median nerve and MNSR and MNFR, and a negative correlation between sensory nerve conduction velocity (SCV) of the median nerve and MNSR. There was no correlation between SCV and MNFR. Conclusion Neural EMG examination can provide evidence for early stage CTS. For intermediate and late stage CTS patients, MRI examination can identify median nerve compression site and etiology, and also provide guidance for surgical decompression. Therefore, MRI is a valuable examination for CTS. However, it cannot replace neural EMG examination for the diagnosis of CTS. Key words: Carpal tunnel syndrome; MRI; Nerve conduction velocity