Radial sensory nerve entrapment in carpal tunnel syndrome.

In 100 subjects with Carpal Tunnel Syndrome (CTS) and any other illness, the conduction velocity of the radial sensory nerve (RSN) was studied on the hypothesis that, because of the relation with the tendon of the brachioradialis and extensor carpi radialis longus muscles, microtrauma can injure the RSN. In 13 patients, for a total of 15 limbs involved, the SCV is reduced less than 2.5 SD, in 5 the distal latency is prolonged and in 1 there is both a slowing of SCV and prolonged distal latency. The involvement of RSN is more frequent in the dominant hand. There is no relation between the severity of CTS and damage of RSN or between clinical and electrophysiological data. It therefore seems that the entrapment of RSN is quite frequent and can explain some symptoms and modify the therapy.