Avulsion of the anomalous facial nerve at stapedectomy.

Injury to the facial nerve in an anomalous location overlying the oval window at the time of stapedectomy has rarely been reported. The authors recently have encountered three patients with such injuries. The facial nerve was found at the time of reexploration to run directly over the oval window. A fourth patient was explored primarily for a conductive hearing loss and the same anomalous course was discovered. The purpose of this report is to alert the otologic surgeon to this rare but potentially catastrophic anomaly and to review the pertinent embryology and management of these malformations.