Audiological findings in large vestibular aqueduct syndrome.

An enlarged vestibular aqueduct is a congenital disorder causing early onset and progressive hearing loss in children. This paper presents the audiological findings at first presentation and the audiological evolution in 10 consecutive cases presenting with hearing loss and showing a large vestibular aqueduct on imaging. The reported onset of the hearing loss is within the first few years of life. Most of the cases (80%) showed bilateral involvement. The sex ratio was 1. Patients presented on average at age 5 with a median hearing loss of 62 dB at the speech frequencies. The hearing loss was essentially asymmetrical with an interaural difference, of 33 dB and it was a mixed type of hearing loss in 90% of the cases. The authors claim that the conductive component of this hearing loss is a pure cochlear conductive loss which may be pathognomonic for the disease. The presence of a conductive component in a child is easily misinterpreted as a middle ear ventilation problem or in case of good ventilation as an ossicular problem (type otosclerosis). In addition and in contrast to most literature data, the authors did not find evidence for stabilization of the hearing loss but they found a steady decrease of the hearing at an average rate of 4 dB/year.