Transmastoid Surgery for Superior Canal Dehiscence: Prospective Longitudinal Objective and Patient-Reported Audiovestibular Outcomes

ObjectiveWe assess symptom control, reversal and stability of objective third-window indicators, and hearing and balance function after transmastoid superior canal dehiscence plugging. To do this, we combine patient self-assessment questionnaires with auditory and vestibular test data collected at a preoperative and multiple postoperative visits.Study DesignProspective cohort study.SettingTertiary referral center.PatientsPatients who underwent transmastoid plugging for superior canal dehiscence from 2012 to 2020.Intervention(s)Plugging of the superior semicircular canal using the transmastoid approach.Main Outcome Measure(s)Patients were evaluated preoperatively, 3-month postoperative, and at yearly follow-ups (up to 8 yr postoperative). Self-assessment questionnaires included Autophony Index, Dizziness Handicap Inventory, Tinnitus Handicap Inventory, and Hearing Handicap Inventory. Objective tests included audiometry, cervical vestibular evoked myogenic potential, ocular vestibular evoked myogenic potential, and video head impulse test.ResultsThere was a statistically significant improvement in Autophony Index and Hearing Handicap Inventory total scores from the preoperative evaluation to 1 year postoperative. Dizziness Handicap Inventory and Tinnitus Handicap Inventory total scores also improved but statistically insignificant. Cervical and ocular vestibular evoked myogenic potential amplitudes and low-frequency air-bone gap showed statically significant reversal of the third-window effect preoperative versus 1 year postoperative. Video head impulse test of the superior semicircular canal revealed cases of pathological function preoperative with postoperative recovery. Results were stable over time.ConclusionsSuperior canal dehiscence repair resolves symptoms of autophony and improves hearing disability. Objective third-window indicators reverse and show long-term stability. Auditory and vestibular function is preserved postoperative, even superior semicircular canal function may be normal. Data suggest that surgical outcomes should not be evaluated until 1 year postoperative.