Tibial nerve motor conduction with recording from the first dorsal interosseous: a comparison with standard tibial studies.

PURPOSE: The lateral plantar nerve (LPN) branch of the tibial nerve provides the primary supply to the first dorsal interosseous (FDI) muscle of the foot. A consistent clear response has been observed with recording of the LPN from the FDI muscle. This clarity is not always found with the standard recording site for the LPN. As there are no published normative values for the FDI recording site, the purpose of this study is to describe these values and compare them with standard tibial values.

METHODS

Fifty four healthy adult volunteers with 102 limbs were studied to determine the nerve conduction velocity, distal latency, amplitude, and waveform characteristics.

RESULTS

The FDI recording demonstrated a significantly greater amplitude than did the standard recording, with the mean values being 7.7 and 3.6 mV respectively. The recording from the FDI also demonstrated much greater waveform clarity than did the standard tibial nerve recordings.

CONCLUSIONS

These findings may aid interpretation of data collected from the FDI in tibial nerve testing. LPN recording from the FDI may be particularly valuable in those with global axonal loss or preferential involvement of the LPN as may occur in posterior tarsal tunnel syndrome.