Clinical review of inner ear malformation

We had 126 patients with inner ear malformation diagnosed with temporal bone computed tomography (CT) scans at Azabu Triology Hospital between 1996 and 2002. We classified cases of inner ear malformation according to Jackler et al. The incidence of inner ear malformation in our series was as follows; 1. Labyrynthine anomalies 61% (isolated lateral semicircular canal dysplasia 56%, compound semicircular canal dysplasia 4%, semicircular canal aplasia 1%), 2. Cochlear anomalies 24%, 3. Enlargement of the vestibular aqueduct 12%, 4. Narrow internal auditory canal 2%, 5. Complete labyrinthine aplasia 1%, 6. Enlargement of the cochlear aqueduct 0%. The most frequent anomaly was isolated lateral semicircular canal dysplasia. We did not detect any significant clinical features in this anomaly. There were 2 patients with cochlear anomalies who had past histories of meningitis. Some patients with enlargement of the vestibular aqueduct had frequent attacks of fluctuating hearing. Clinically it is important to detect patients with inner ear malformation such as cochlear anomalies and enlargement of the vestibular aqueduct usually accompanied by congenital sensorineural hearing loss. For patients with congenital sensorineural hearing loss, we recommend temporal bone CT scan.