Diagnosing mild Carpal Tunnel Syndrome with interpolation.

Carpal Tunnel Syndrome (CTS) is the most common peripheral nerve entrapment. In the diagnosis of Carpal Tunnel Syndrome, velocity is determined by either measuring the average velocity over a segment by dividing the distance by the difference in latencies. Polynomial interpolation can determine the velocity at any point along a nerve. Applying interpolation techniques correctly classified 58/60 electrophysiologically proven CTS cases (96.7%) and 36/38 normals (94.7%). Of 7 cases with CTS by standard sensory criteria alone, 6 (86%) had abnormal motor conduction using the interpolation technique. This shows that interpolation techniques can improve diagnostic accuracy in CTS. It also indicates that there is motor involvement in most cases of CTS, including a majority of cases previously classified as only sensory involvement.