IMPROVED AXON DIAMETER AND MYELIN SHEATH THICKNESS IN FACIAL-NERVE CABLE GRAFTS WRAPPED IN TEMPOROPARIETAL FASCIAL FLAPS

Injury to the facial nerve in the temporal bone presents a challenge t o the recovery of nerve function, in that the fallopian canal in which it lies is poorly vascularized. This study was designed to determine if wrapping an intratemporal facial nerve defect repaired with a cable graft with a well-vascularized temporoparietal fascial (TPF) flap wou ld improve facial nerve regeneration. To evaluate this question, a def ect was created in the intratemporal left facial nerve of 10 rabbits. All nerves were repaired using cable grafts. In 5 animals, the nerve g raft was wrapped with temporoparietal fascia, whereas in the other 5 r abbits it was not. Three additional animals underwent exposure only. T he contralateral nerve served as a control in all animals. Quantitativ e analysis of the nerve graft 12 weeks after repair revealed greater r ecovery of original fiber diameter and myelin sheath thickness in TPF flap-wrapped repairs. Histological evidence of improved neural regener ation and functional nerve recovery was also seen in the repairs where the TPF flap was utilized. Nerve conduction and electromyographic stu dies of the cable-grafted nerve at 6 and 12 weeks were equivocal, howe ver.