Bifid Intratemporal facial nerves in an adult without other congenital anomalies

OBJECTIVE: To describe a case of bifid intratemporal facial nerves without associated middle or inner ear abnormalities encountered on computed tomography (CT) imaging during preoperative preparation for unilateral cochlear implant placement in an adult male with profound sensorineural hearing loss (SNHL). METHODS: A rare case of bilateral bifid intratemporal facial nerves in an adult male is presented. The finding's impact on approach to safe cochlear implantation is discussed. RESULTS: Bifurcation of the intratemporal facial nerve is rarely seen and is usually associated with congenital middle or inner ear anomalies. A unique case of bilateral bifid intratemporal facial nerves without other middle or inner ear abnormalities was encountered incidentally on CT imaging during preparation for unilateral cochlear implant placement in an adult male with profound SNHL. The nerve was bifid along the mastoid segment with a nerve branch traversing through the facial recess precluding safe traditional approach to cochlear implant placement. Accessory stylomastoid foramina were noted bilaterally. Unilateral subtotal petrosectomy was performed with successful implantation and excellent hearing outcome. No additional clinical or radiographic otologic abnormalities were noted. CONCLUSION: Abnormal bifurcation of the facial nerve may occur in adults without other middle or inner ear anomalies. This case highlights the importance of independent imaging review by the surgeon and vigilance to potential rare anatomic aberrations of the facial nerve during cochlear implantation. LEVEL OF EVIDENCE: IV