Carpal tunnel syndrome: neurographical parameters in different stages of median nerve compression.

In a series of 47 cases and 55 hands operated upon for carpal tunnel syndrome, the pre-operative electrodiagnostic findings have been compared retrospectively with the morphological findings within the carpal tunnel during operation. As a main result there was no significant correlation between the degree of electrophysiological changes and the degree of median nerve compression. Only the lack of any motor or sensory response seems to indicate a more severe median nerve compression. In about 20% of cases with operatively proven marked median nerve compression, both distal motor latency and motor nerve conduction velocity were well within normal limits and would not have led to the diagnosis of a carpal tunnel syndrome in these cases. The diagnosis, therefore, cannot be made on the basis of electrodiagnostic pathological values only of distal motor latency and motor nerve conduction velocity, but has to take into account as well the sensory nerve conduction velocity as well as the clinical picture and neurological findings.