[Facial motricity of trigeminal origin. Apropos of a typical case and review of the literature].

The authors report the case of a patient who underwent the neurosurgical exeresis of an acoustic neuroma 14 years ago, and subsequently presented with a total facial palsy in spite of a spinofacial anastomosis. This patient had to be reoperated because of tumoral recurrence compressing the trigeminal nerve (V). This operation, through atranslabyrinthic that also emptied the entire internal auditory canal of its neural elements, allowed removing the neuroma. Once the facial nerve had been resected, the patient recovered some facial motricity and his masticatory function improved on the day following the operation. Since the contralateral facial nerve was not involved and the spinofacial anastomosis was absolutely not functional, only motor reinnervation from the trigeminal nerve was possible. The anatomy of the facial and trigeminal nerves in summarized, and their central connexions and peripheral anastomoses are studied. Out of the 27 cases of spontaneous motor reinnervation following the resection of the facial nerve described in the literature, only one similar case of recovery of motricity after a major nerve resection in the cerebellopontine angle is reported. Such a phenomenon can be explained only by the transformation of some sensory fibers of the 5th cranial nerve into motor fibers, which are activated by the resection of the 7th nerve and receive their nervous influx from the motor nucleus of the 5th or 7th nerve through protuberantial communications.