Electrocochleographic changes in the hearing loss associated with X-linked hypophosphataemic osteomalacia.

Transtympanic electrocochleography was carried out on 13 patients (21 ears) suffering from X-linked hypophosphataemic osteomalacia, and known to have cochlear hearing loss. The majority of ears exhibited a cochlear pattern of cochleogram with a recruiting input/output function and a markedly biphasic action potential. In addition 14 ears yielded a greatly enhanced negative summating potential, suggesting the presence of endolymphatic hydrops. It is proposed that the hearing loss so frequently associated with this condition is in part due to endolymphatic hydrops.