LARGE VESTIBULAR AQUEDUCT SYNDROME - A GENETIC-DISEASE

OBJECTIVE. Our objective was to determine the familial incidence of la rge vestibular aqueduct syndrome (LVAS) detected by CT and MR imaging and to propose the genetic inheritance of LVAS. MATERIALS AND METHODS. We retrospectively reviewed cases of LVAS revealed by temporal-bone C T and MR imagine at the University of Utah Health Sciences Center. We interviewed 25 patients with LVAS regarding family history of hearing loss, Any family members with onset of hearing loss before 30 years ol d also underwent MR imaging. The vestibular aqueduct (on CT scans) or the endolymphatic duct (on MR images) was measured at the midpoint of the distal limb. A measurement greater than 1.5 mm in diameter was con sidered abnormally large, Diagnosis of LVAS was made if the patient ha d hearing loss and positive imagine findings. RESULTS. Of the 25 patie nts, five were found to have familial involvement, resulting in subseq uent study of eight additional symptomatic individuals. A total of 33 patients had positive CT or MR imaging findings, Twenty-nine underwent both studies, two underwent CT only, and two underwent MR imaging onl y. Among the 33 patients with LVAS, 39% familial occurrence was observ ed (13 patients). In four of the five different families, the involvem ent occurred among siblings in one generation. In one of the five fami lies, the involvement occurred in two generations, affecting an uncle and a cousin of the patient. CONCLUSION. In patients with LVAS, a sign ificant subgroup had familial involvement. Based on the pedigrees of t he familial cases, the pattern was most consistent with autosomal rece ssive inheritance, although a smaller component of autosomal dominant or multifactorial inheritance may exist.