Long-term follow-up of nerve conduction velocity in cross-face nerve grafting for the treatment of facial paralysis.

Motor nerve conduction velocity in a sural nerve graft crossing the face for the treatment of facial paralysis was measured postoperatively for more than 3 years. Forty-three cases of free gracilis muscle transplantation combined with a cross-face nerve graft were evaluated. The cross-face nerve graft was stimulated at two sites more than 5 cm apart by bipolar stimulating electrodes, and conduction velocity was calculated by dividing the length of this segment by the difference between the latencies of the evoked action potentials recorded from the grafted muscle. A tendency toward increase in motor nerve conduction velocity was noticed even 3 years after the sural nerve graft. This suggests that the grafted nerve has the potential to recover over a long period of time. The average velocity in measurements after the third postoperative year was 40.5 +/- 6.2 m/s (mean +/- SD), which corresponds to the lower limit of the normal value for the sural or facial nerve.