ABR and temporal bone pathology in Hurler's disease.

This is believed to be the first report on estimating hearing loss in Hurler's disease, based on the correlation between ABR and temporal bone pathology. ABR findings revealed hearing loss to be about 70 dB or more as result of peripheral mixed impairment. A histological study of the temporal bones revealed almost all pathological findings in the conductive system, except for the hyperplastic arachnoid in the internal auditory canal. In the middle ear cavity, otitis media, residual mesenchyme and deformity of ossicles were found. We explain the conductive component to be due to otitis media and poor ossicular connection. However, the etiology of the sensorineural component remains speculative. In Hurler's disease, hearing loss with mental retardation is often found at infantile age. Therefore, assessing the extent of hearing loss exactly was difficult, for example, the severity. the etiology and incidence of sensorineural impairment. We emphasize the need for not only well-described pathological studies but also for more objective functional investigations, at least ABR.