The axonal carpal tunnel syndrome.

Five patients with typical unilateral carpal tunnel syndrome features were studied. Each patient had a normal electrodiagnostic evaluation, including needle examination (C5 to C8T1), distal motor latency, palm to wrist orthodromic sensory conduction velocity, and special tests: median-ulnar latency difference of the 4th digit, palmar centimetric technique. Only a new test, the orthodromic sensory ultra distal test of all the digits, revealed a significant axonal loss (60-90%) in at least two median digits allowing the diagnosis of median nerve impairment. These findings led us to propose the term, axonal carpal tunnel syndrome for this early stage of the disorder.