Large vestibular aqueduct syndrome: a genetic disease?

OBJECTIVE

Our objective was to determine the familial incidence of large 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 CT and MR imaging 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 old also underwent CT and 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 considered abnormally large. Diagnosis of LVAS was made if the patient had hearing loss and positive imaging findings.

RESULTS

Of the 25 patients, five were found to have familial involvement, resulting in subsequent 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 only. Among the 33 patients with LVAS, 39% familial occurrence was observed (13 patients). In four of the five different families, the involvement occurred among siblings in one generation. In one of the five families, the involvement occurred in two generations, affecting an uncle and a cousin of the patient.

CONCLUSION

In patients with LVAS, a significant subgroup had familial involvement. Based on the pedigrees of the familial cases, the pattern was most consistent with autosomal recessive inheritance, although a smaller component of autosomal dominant or multifactorial inheritance may exist.