Leprosy affects facial nerves at the main trunk: neurolysis can possibly avoid transfer procedures.

The predilective sites of lesions in leprous peripheral nerves are well established, and their surgical decompression is common practice when sensorimotor disorders persist after medication. By contrast, the precise localization of leprous facial neuropathy still remains unclear, and musculofascial transfers have been the only type of surgical treatment. The goal of this study was to clarify where leprosy affects facial nerves and to determine whether neurolysis might suffice to restore facial function. In five Indian and two Egyptian patients suffering from leprous facial neuritis, the nerves were stimulated transcranially at the brainstem to evoke efferent motor nerve action potentials, which were recorded from the exposed nerves. Lesions were detected at the main trunk proximally from the first bifurcation in all cases. Epineuriotomy revealed fibrosis of the interfascicular epineurium in all instances, as an indication for interfascicular neurolysis. One patient was able to close his eye and showed a better smile soon after surgery. After 16 and 21 months, respectively, one patient had improved distinctly, two patients slightly, two patients showing no progress, and two patients were lost to follow-up. It is concluded that (1) leprous facial neuropathy is located at the main trunk close to the first bifurcation and not exclusively at the peripheral zygomatic branches, (2) microsurgical neurolysis can be considered in leprous facial neuropathy before transfer procedures as long as voluntary or spontaneous activity is present in the affected muscles, and (3) intraoperative transcranial electrical stimulation is an effective means of localizing the site and proximal extent of leprous facial neuropathy.