Gauging the effectiveness of canal occlusion surgery: how I do it

Abstract

BackgroundTransmastoid occlusion of the posterior or superior semicircular canal is an effective and safe management option in patients with refractory benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. A method of quantifying successful canal occlusion surgery is described.MethodsThis paper presents representative patients with intractable benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence, who underwent transmastoid occlusion of the posterior or superior semicircular canal respectively. Vestibular function was assessed pre- and post-operatively. The video head impulse test was included as a measure of semicircular canal and vestibulo-ocular reflex functions.ResultsPost-operative video head impulse testing showed reduced vestibulo-ocular reflex gain in occluded canals. Gain remained normal in the non-operated canals. Post-operative audiometry demonstrated no change in hearing in the benign paroxysmal positional vertigo patient and slight hearing improvement in the superior semicircular canal dehiscence syndrome patient.ConclusionTransmastoid occlusion of the posterior or superior semicircular canal is effective and safe for treating troublesome benign paroxysmal positional vertigo or symptomatic superior semicircular canal dehiscence. Post-operative video head impulse testing demonstrating a reduction in vestibulo-ocular reflex gain can reliably confirm successful occlusion of the canal and is a useful adjunct in post-operative evaluation.

Biomechanics of Third Window Syndrome

“…The residual sensitivity at high-frequencies arises from acceleration-induced transmembrane fluid pressure that deforms the labyrinth and deflects the cupula (84). Observations in animal models are consistent with vestibulo-ocular reflexes (VOR) measured postoperatively in patients in that compensatory eye movements are present in response to rotary head thrusts but compromised relative to controls (86,92,97,98). The reduced VOR following surgical plugging putatively reflects broad-band attenuation of sensitivity caused by the procedure, while persistence of a partial VOR reflects residual sensitivity to high-frequency angular head movements.…”

Analysis of postoperative effects of different semicircular canal surgical technique in patients with labyrinthine fistulas

“…In this study, the surgeon used the “under water” surgical method after clearing the cholesteatoma ( Yamauchi et al, 2014 ; Hassannia et al, 2019 ; Creighton et al, 2021 ; Thangavelu et al, 2022 ). Specifically, before operating on the labyrinthine fistula, the researchers injected dexamethasone into the operation area.…”

Transmastoid Occlusion Surgery for Superior Semicircular Canal Dehiscence Syndrome Improves Patient-Reported Quality-of-Life Measures and corrects cVEMP Thresholds and Amplitudes

“…The greatest reduction was in the emotional handicap. At presentation, preoperative DHI scores were mild (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34) in 24%, and severe (>54) in 33%. A significant improvement in corrected cVEMP amplitudes occurred following plugging, therefore we considered if such changes correlated with the patientreported DHI scores.…”

“…Early postoperative vestibular hypofunction has been reported in up to 38% (29) (MCF plugging technique; bedside horizontal head thrust testing performed 1 wk after surgery). vHIT has been employed to assess preservation of semicircular canal function following plugging (32).…”