Abstract #71, Date 2/14/99, Session E1, Poster (J39)

Temporal bone pathology in Pendred's Syndrome

*L. Michaels, J. Liang, T. Bibas, A. Wright, G. Harinder, P.D. Phelps, W. Reardon (University College London Medical School)

Modern imaging methods have revealed striking changes in the temporal bone in Pendred's syndrome (severe hereditary sensorineural hearing loss with thyroid pathology), notably a large vestibular aqueduct and endolymphatic sac, which was seen in one study, for instance, in all 20 cases examined by magnetic resonance imaging (Phelps PD et al Clinical Radiol 1998;53:268-273). There is, however, little knowledge of the histological changes in the temporal bone in Pendred's syndrome. We describe here the temporal bone pathology findings from the files of the Institute of Laryngology and Otology, in a 13-year-old hypothyroid girl, deaf from birth, who died in 1968 from aspirated vomitus. Her sister is now under investigation at our medical center with the clinical features of Pendred's syndrome.Archival sections were available mounted at 200 micrometer intervals. No intermediate sections are currently available.On the left side the membranous labyrinth is filled with eosinophilic fluid. The vestibular aqueduct and its opening into the subdural region are dilated to approximately 3.0 mm (maximum normal diameter at imaging 1.5 mm). There is no rugose portion of the endolymphatic sac which fills a large wide area in the subdural region.. The intraosseous endolymphatic sac/duct is short and on entry into the vestibule it opens directly into the saccule, which is hydropic and there is also moderate hydrops of the cochlear duct. The organ of Corti is normally formed, but outer hair cells are not identified. There is reduced coiling of the cochlea (Mondini's deformity).Appearances are similar in the right temporal bone except that a prominent rugose region is present in the markedly dilated subdural region of the endolymphatic sac and there were insufficient sections mounted to determine the mode of entry of the endolymphatic duct into vestibular labyrinthine structures.The histological appearances confirm and extend the significant temporal bone findings discovered by imaging in cases of Pendred's syndrome.