Autosomal dominant osteopetrosis: an otoneurological investigation of the two radiological types.

Otoneurological examination was performed on 14 patients with autosomal dominant osteopetrosis. Eight patients had radiological type I osteopetrosis, characterized by a pronounced osteosclerosis of the skull and an enlarged thickness of the cranial vault. Six patients had type II, in which osteosclerosis is most pronounced at the base of the skull. All investigated patients except one had otoneurological manifestations, but only two of of the 14 had otoneurological complaints. Symptoms were related to radiological types. Involvement of the trigeminal nerve was seen only in type I, whereas involvement of the facial nerve was found primarily in type II. Conductive hearing loss was particularly common in type I, and may reflect a high frequency of otosclerosis. Tomography of the petrous bones showed a significant narrowing of the internal acoustic meatus in type I (p less than 0.01) when compared to normal controls, but no significant narrowing in type II.