Mixed median nerve forearm conduction velocity in the presence of focal compression neuropathy at the wrist versus peripheral neuropathy.

OBJECTIVES

To establish normal values for the conduction velocity of the mixed median nerve in the forearm, and to determine the use of mixed median nerve conduction velocity (NCV) studies across the forearm in the differential diagnosis of carpal tunnel syndrome (CTS), peripheral neuropathy, and CTS with peripheral neuropathy.

DESIGN

Criterion standard. Mixed median NCV studies across the forearm were added to routine CTS investigational protocols.

SETTING

University outpatient setting, rural referral base.

PARTICIPANTS

Thirty healthy volunteers and 60 patients referred with symptoms and signs suggestive of CTS and/or peripheral neuropathy.

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: Motor sensory and mixed median nerve conduction velocity across the forearm.

RESULTS

The mean mixed median NCV across the forearm was 64.5 m/s in healthy subjects and subjects with CTS. The mean mixed NCV in subjects with peripheral neuropathy was 54 m/s, even in the presence of CTS.

CONCLUSION

Mixed median NCV in the forearm added to the standard protocols is helpful in differentiating the diagnosis of CTS from peripheral neuropathy and CTS with peripheral neuropathy.