Temporal bone imaging findings in Waardenburg's syndrome

Objective: (a) To report computed tomography findings of eight new cases with Waardenburg's syndrome (WS) type I and review reported temporal bone radiographic and histopathological findings in WS with hearing loss; (b) To determine the frequency of inner ear pathologies that may contraindicate cochlear implantation. Methods: A review of 1166 pediatric patients with sensorineural hearing loss revealed 12 cases (1%) with WS, whose family screenings disclosed additional 12 subjects with the same disorder. Among these 24 cases, eight had WS type I and were subjected to computed tomography scanning of temporal bone. Imaging findings of 28 cases reported previously in English literature were evaluated together with our eight patients. Results: Malformation of the inner ear was found in none of the nine WS type I cases evaluated here, while the frequency of internal acoustic canal malformation was 11%. Regardless of the subtypes of the syndrome, 6 of 36 cases (17%) had radiological abnormality of the inner ear. Malformation and/or absence of the semicircular canals were the most common congenital abnormality of the inner ear. Hypoplasia of the cochlea was present in 3 of 36 cases (8%). Conclusions: Abnormality of bony labyrinth in WS with congenital deafness is not a frequent finding, particularly in WS type I. Therefore, the otologist and audiologist must keep in mind that most of these cases are suitable for cochlear implantation regarding inner ear anatomy. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved

Influence of spontaneous otoacoustic emissions on distortion product otoacoustic emission amplitudes

Although the influence of the levels and ratios of the primary stimulus on the amplitude of distortion product otoacoustic emissions (DPOAEs) has been studied intensely, the influence of the presence of spontaneous otoacoustic emissions (SOAEs) has been investigated less thoroughly. The present investigation analysed whether the unilateral presence of 58 SOAEs in 43 normal-hearing adults was related to larger DPOAEs in the ear with SOAEs compared to the contralateral ear having no SOAEs. The study was designed such that the only factor that could influence the amplitude of DPOAEs was the presence of SOAEs. Input/output (IIO) functions were collected in response to primary tones that were presented in 5-dB steps from 70 to 40 dB SPL at the frequency of the unilaterally recorded SOAE of each subject. The primary outcome was the demonstration of statistically significant (P < 0.05) larger DPOAEs in ears exhibiting SOAEs than in ears without measurable SOAEs, except at the highest stimulus level of 70 dB SPL. These results suggest that SOAEs play an additive role in the measurement of DPOAEs. The enhancing effect of the unilateral presence of SOAEs on DPOAEs was statistically significant for 65 dB SPL and lower levels of primary tones. The authors speculate that passive cochlear properties begin to participate in the generation of DPOAEs at primary-stimulus levels greater than 65 dB SPL. (C) 1999 Elsevier Science B.V. All rights reserved