Lateral semicircular canal and vertigo in patients with large vestibular aqueduct syndrome.

OBJECTIVE: To evaluate the hypothesis that there are differences in the morphology of the lateral semicircular canal (LSCC) between patients with large vestibular aqueduct syndrome (LVAS) and control subjects and to investigate the clinical implications of these differences.

STUDY DESIGN: Retrospective case review.

SETTING: Tertiary referral center.

PATIENTS: Nine patients (two male patients and seven female patients; age range, 8-54 yr) with LVAS (one patient had unilateral LVAS, and eight patients had bilateral LVAS). Five patients had vertigo, and four patients, including the one with unilateral LVAS, did not have vertigo.

MAIN OUTCOME MEASURES: The area of the LSCC was traced on the magnetic resonance imaging console and compared between LVAS patients and 12 control subjects who did not have sensorineural hearing loss. The LSCC fluid-containing area was divided by the sum of the LSCC inner area and the LSCC fluid-containing area for evaluation of the degree of the LSCC dysplasia.

RESULTS: The LSCC fluid-containing ratio was significantly larger in LVAS patients than in control subjects. Moreover, the LSCC fluid-containing ratio was significantly larger in the eight ears with vertigo than in the nine ears without vertigo. There was no relationship between hearing level and the LSCC fluid-containing ratio.

CONCLUSION: Patients with LVAS may have disturbed morphogenesis of both membranous and bony labyrinths. Our results reveal that the morphology of semicircular canals is clinically associated with vertigo.