Effect of neurotization upon degree of sensory recovery in toe-to-hand microvascular transplantation

The relationship between the number of myelinated nerve fibers from the hand that are reinnervating the distal glabrous skin of the toe and the number of myelinating nerve fibers originally innervating that toe target was investigated utilizing the toe-to-hand microvascular transplantation model. Digital nerve biopsy specimens suitable for morphometric analysis were obtained from the hand and toe at the time of surgery from 15 patients. Patients received sensory reeducation in the postoperative period to standardize rehabilitation. At a mean of 10.8 months after surgery, the degree of sensory recovery was determined by the hand therapist. Morphometric analysis was done by a neurologist blinded as to final sensory outcome. There was a statistically significant relationship between recovered moving two-point discrimination and ratio of the total number of reinnervating (neurotizing) finger axons compared with the original toe axons (r = 0.703, p < 0.003). A similar relationship was observed for static two-point discrimination (r = 0.802, p < 0.001). These results suggest that degree of sensory recovery in toe-to-hand transfer may be improved by increasing the number of reinnervating myelinated nerve fibers from the hand that neurotizes the free tissue transfer.