Current perception thresholds in toe-to-digit transplantation and digit-to-digit replantation

Recovery of digital nerve function in toe-to-digit transplantation and digit-to-digit replantation was evaluated by transcutaneous constant current sine wave stimulation at 5-, 250-, and 2000-Hz frequencies to determine the current perception thresholds (CPT). For toe transplantation and digit replantation, the mean interval between injury and surgery was 9 months and 7 h, respectively, while the mean interval between surgery and CPT study was 52 months and 20 months, respectively. Control CPTs evoked by three frequency stimuli were obtained from contralateral corresponding normal finger and normal toe. Normal finger had significantly lower 250- and 2000-Hz CPTs than normal toe, but the 5-Hz CPT was not different between them. Replanted digit achieved nearly complete recovery of these three frequency CPTs when compared to normal finger. In toe transplantation, 2000-Hz CPT was comparable to normal finger, while 5- and 250-Hz CPTs were comparable to normal toe. The present findings suggest that the transplanted toe was intermediate between normal finger and normal toe, but more like normal toe than normal finger with regard to detection thresholds of the current-evoked sensation.