Utility of cVEMPs in bilateral superior canal dehiscence syndrome

To determine the utility of cervical vestibular evoked myogenic potential (cVEMP) thresholds in the surgical management of bilateral superior canal dehiscence syndrome (SCDS).

Retrospective review.

We identified patients who underwent surgical treatment for SCDS from our database of 147 patients diagnosed with superior canal dehiscence (SCD) between 2000 and 2011 at our institution. The diagnosis of SCDS was based on clinical signs and symptoms, audiometric and cVEMP testing, and high-resolution computed tomography.

We identified 38 patients who underwent SCD surgery in 40 ears (2 bilateral). In seven patients with bilateral SCD, the more symptomatic ear had lower cVEMP thresholds, a larger air bone gap and a lateralizing tuning fork. In 13 patients with perioperative cVEMP testing, thresholds increased in 12 patients following primary repair, and no threshold shift was seen in one patient with persistence of symptoms after revision surgery. Audiometric data showed a significant mean decrease of the low-frequency air-bone gap and a mild (high-frequency) bone conduction loss after surgical repair.

We found that, 1) preoperative cVEMP thresholds, the magnitude of the air-bone gap and tuning-fork testing are important to confirm the worse ear in patients with bilateral SCD, 2) elevation of cVEMP thresholds following surgery correlates with improvement of symptoms and underscores the importance of postoperative testing in patients with bilateral disease or recurrence of symptoms and, 3) SCD plugging is associated with a partial closure of the air-bone gap and a mild (high-frequency) sensorineural hearing loss.