ABSTRACT
Fourteen patients with a Pendred syndrome gene (Pds) mutation and three patients without the mutation were studied to evaluate long-term vestibular and auditory manifestations among patients with bilateral enlarged vestibular aqueducts (EVA). Charts were reviewed retrospectively for age, gender, otological history, presence or absence of vertigo, results of magnetic resonance imaging, relevant gene mutations and perchlorate discharge test. A missense mutation, His 723 Arg (H723R), was identified in the homozygous state in six patients and in the heterozygous state in seven patients. Another missense mutation, Tyr 410 Met (T410 M), was identified in the heterozygous state in one patient. Patients with vertigo tended to have hearing fluctuation, compared with the patients without vertigo. Patients homozygous for H723R tended to have more episodes of vertigo than the heterozygous individuals. Only one patient who was homozygous for H723R had goiter. The long-term outcome of hearing level in patients with the H723R mutation was significantly better compared with published results for patients with a Pds mutation, but not for those with the H723R mutation. Whether environmental factors or a subtype of the Pds mutation H723R are related to the long-term outcome for these patients must be clarified.
Subject(s)
Goiter/genetics , Hearing Loss, Sensorineural/genetics , Membrane Transport Proteins/genetics , Vertigo/genetics , Vestibular Aqueduct/abnormalities , Adolescent , Adult , Auditory Threshold , Chi-Square Distribution , Child , Child, Preschool , Female , Follow-Up Studies , Heterozygote , Homozygote , Humans , Magnetic Resonance Imaging , Male , Mutation, Missense , Nystagmus, Pathologic , Phenotype , Retrospective Studies , Sulfate Transporters , SyndromeABSTRACT
OBJECTIVES: The purpose of this study was to study systematically some relationships between the resonance frequency of the middle-ear transmission system and the volume of the endolymphatic duct and sac in patients with an enlarged vestibular aqueduct (EVA). STUDY DESIGN: Prospective study. METHODS: Thirteen patients (24 ears) with EVA, 17 subjects (29 ears) with normal hearing, and 17 patients (21 ears) with sensorineural hearing loss without EVA served as experimental subjects. Standard pure-tone audiometry, standard clinical tympanometry (using a 226-Hz probe tone), and multifrequency tympanometry were performed on each ear. Magnetic resonance imaging was used to determine the area of the cochlear modiolus and the volume of the endolymphatic duct and sac. RESULTS: The audiometric configurations for most patients sloped downward from the low to the high frequencies. A significant air-bone gap was computed at each of these test frequencies. Multifrequency tympanometry yielded resonance frequencies for the patients with EVA that was significantly lower than those measured for the control subjects. In general, for patients with EVA, the resonance frequency of the middle ear system decreased as the volume of the endolymphatic duct and sac increased. This inverse relation was significant (correlation coefficient = -0.483, P =.0157). However, there was no correlation between resonance frequency and the degree of cochlea modiolar deficiency. CONCLUSIONS: Clinically, our findings suggest that EVA probably should be included in the differential diagnosis for a patient who presents with a moderate to severe mixed hearing loss, a normal tympanogram at 226 Hz, and a resonance frequency that is abnormally low.
