Utility of the Measurement of Median Nerve Stenosis for Diagnosis of Carpal Tunnel Syndrome

Carpal tunnel syndrome (CTS) is the most common compression neuropathy. CTS results from the compression of the median nerve in the carpal tunnel. The main symptoms include pain and other unpleasant sensations in hand and wrist. In more advanced stage, weakness and wasting of the thenar and other muscles innervated by median nerve occurs, which may lead to permanent impairment of manual performance. Nerve conduction studies (NCS) remain the method of choice in diagnosing CTS. However ultrasonography (US) is increasingly used along with or instead of NCS. Most frequently, the increase of the cross-sectional area of the median nerve at the inlet to the carpal tunnel is regarded as the marker of CTS. A number of other measurements such as median nerve mobility, volar bulging of flexor retinaculum and others were also studied to increase diagnostic sensitivity and specificity. In this study the investigators aim to assess the utility of measurements made at the point of the maximal stenosis of the median nerve in the tunnel to diagnose CTS. So far, there were only few studies, which visualized the maximal nerve stenosis, which is the essential pathological feature of CTS. In general, the group of patients with CTS and controls will undergo NCS of symptomatic median and ipsilateral ulnar nerves and US of the symptomatic median nerve with measurements of the cross-sectional area, diameter and echogenicity at various points, including the point of the maximal stenosis. The location of the maximal stenosis with respect to external (distal crease) and internal (wrist and hand bones and thenar musculature) will also be evaluated. Subjects will also be asked to fill out the Boston Carpal Tunnel Questionnaire (BCTQ) and a demographic questionnaire. US measurements will be compared between patients and healthy volunteers. US measurements, especially those made at the point of stenosis will be correlated among patients with clinical severity of CTS, reflected by the score in BCTQ and with the grade of electrophysiological severity as introduced by Padua et al. [1].