The fallopian canal and facial nerve in sclerosteosis of the temporal bone: a histopathologic study.

Sclerosteosis is an uncommon subtype of osteopetrosis that is frequently associated with recurrent facial nerve palsy. Because of the need for detailed measurements of the fallopian canal and facial nerve in this disease, a study was carried out using a new method of surface area measurement. The results show narrowing of the fallopian canal and facial nerve in the labyrinthine, distal tympanic and mastoid segments. Maximum surface area loss occurred in the labyrinthine segment for both the canal and nerve. In addition, bony occlusion of the stylomastoid artery was found. From these findings we conclude that ischemia and bony compression are the underlying causes of recurrent facial palsy in this disease. We also conclude that because the labyrinthine segment is the most severely affected, surgical decompression must include this portion of the fallopian canal.