Thenar motor unit count estimates in the carpal tunnel syndrome.

Thenar motor unit counts were done in 19 subjects with symptoms characteristic of the carpal tunnel syndrome. Three-quarters of the patients had motor unit count estimates less than 2 SD lower limit of controls. Despite this, most did not have thenar wasting or weakness. Functional compensation by motor unit remodelling probably kept pace with motor axon loss and masked the true extent of axonal degeneration.