Hypothesis Cochlear implant (CI) electrode insertion into the round window induces pressure transients in the cochlear fluid comparable to high intensity sound transients. Background Many patients receiving a CI have some remaining functional hearing at low frequencies, thus devices and surgical techniques have been developed to utilize this residual hearing. To maintain functional acoustic hearing, it is important to retain function of any hair cells and auditory nerve fibers innervating the basilar membrane; however, in a subset of patients, residual low frequency hearing is lost following CI insertion. Here, we test the hypothesis that transient intracochlear pressure spikes are generated during CI electrode insertion, which could cause damage and compromise residual hearing. Methods Human cadaveric temporal bones were prepared with an extended facial recess. Pressures in the scala vestibuli (PSV) and tympani (PST) were measured with fiber-optic pressure sensors inserted into the cochlea near the oval and round windows while CI electrodes (five styles from two manufacturers) were inserted into the cochlea via a round window approach. Results PST tended to be larger in magnitude than PSV, consistent with electrode insertion into the scala tympani. CI electrode insertion produced a range of pressure transients in the cochlea that could occur alone or as part of a train of spikes with equivalent peak sound pressure levels in excess of 170dB SPL. Instances of pressure transients varied with electrode styles. Conclusions Results suggest electrode design, insertion mechanism, and surgical technique affect the magnitude and rate of intracochlear pressure transients during CI electrode insertion. Pressure transients showed intensities similar to those elicited by high level sounds and thus could cause damage to the basilar membrane and/or hair cells.

Objective To compare outcomes for patients undergoing a transmastoid approach versus a middle fossa craniotomy approach with plugging and/or resurfacing for repair of superior semicircular canal dehiscence. Outcome measures include symptom resolution, hearing, operative time, hospital stay, complications, and revision rates. Study Design Multicenter retrospective comparative cohort study. Settings Three tertiary neurotology centers. Subjects and Methods All adult patients undergoing repair for superior canal dehiscence between 2006 and 2017 at 3 neurotology centers were included. Demographics and otologic history collected by chart review. Imaging, audiometric data, and vestibular evoked myogenic potential measurements were also collected for analysis. Results A total of 68 patients (74 ears) were included in the study. Twenty-one patients underwent middle fossa craniotomy repair (mean age, 47.9 years), and 47 underwent transmastoid repair (mean age, 48.0 years). There were no significant differences in age or sex distribution between the groups. The transmastoid group experienced a significantly shorter duration of hospitalization and lower recurrence rate as compared with the middle fossa craniotomy group (3.8% vs 33%). Both groups experienced improvement in noise-induced vertigo, autophony, pulsatile tinnitus, and nonspecific vertigo. There was no significant difference among symptom resolution between groups. Additionally, there was no significant difference in audiometric outcomes between the groups. Conclusion Both the transmastoid approach and the middle fossa craniotomy approach for repair of superior canal dehiscence offer symptom resolution with minimal risk. The transmastoid approach was associated with shorter hospital stays and lower recurrence rate as compared with the middle fossa craniotomy approach.

Hypothesis-Cochlear implant (CI) electrode insertion into the round window induces pressure transients in the cochlear fluid comparable to high intensity sound transients. Background-Many patients receiving a CI have some remaining functional hearing at low frequencies, thus devices and surgical techniques have been developed to utilize this residual hearing. To maintain functional acoustic hearing, it is important to retain function of any hair cells and auditory nerve fibers innervating the basilar membrane; however, in a subset of patients, residual low frequency hearing is lost following CI insertion. Here, we test the hypothesis that transient intracochlear pressure spikes are generated during CI electrode insertion, which could cause damage and compromise residual hearing. Methods-Human cadaveric temporal bones were prepared with an extended facial recess. Pressures in the scala vestibuli (P SV) and tympani (P ST) were measured with fiber-optic pressure sensors inserted into the cochlea near the oval and round windows while CI electrodes (five styles from two manufacturers) were inserted into the cochlea via a round window approach. Results-P ST tended to be larger in magnitude than P SV , consistent with electrode insertion into the scala tympani. CI electrode insertion produced a range of pressure transients in the cochlea that could occur alone or as part of a train of spikes with equivalent peak sound pressure levels in excess of 170dB SPL. Instances of pressure transients varied with electrode styles. Conclusions-Results suggest electrode design, insertion mechanism, and surgical technique affect the magnitude and rate of intracochlear pressure transients during CI electrode insertion. Pressure transients showed intensities similar to those elicited by high level sounds and thus could cause damage to the basilar membrane and/or hair cells.

Objectives (1) Evaluate changes in subjective symptoms in patients following transmastoid canal plugging for superior semicircular canal dehiscence (SSCD) syndrome. (2) Quantify changes in hearing in patients who have undergone transmastoid canal plugging for SSCD syndrome. Study Design Case series with chart review. Setting Single tertiary care institution. Subjects and Methods We retrospectively reviewed patients with SSCD who underwent repair with canal plugging via a transmastoid approach between January 2012 and January 2017. Symptom severity was assessed prospectively (autophony, sound/pressure-induced vertigo, disequilibrium, aural fullness, and pulsatile tinnitus) and after surgery. Pure-tone and speech audiometry were measured before and after surgery. Two-sided Wilcoxon rank-sum tests were used to evaluate changes in subjective symptoms and audiometric outcomes. Results Seventeen patients (19 ears) met inclusion criteria. The superior canal was successfully plugged via the transmastoid approach in all cases. Patients reported a statistically significant improvement in autophony, vertigo, aural fullness, and pulsatile tinnitus ( P < .01), without significant improvement in disequilibrium rating ( P = .06). There were no changes noted in pure-tone average or word recognition score; however, there was a statistically significant improvement in air-bone gap at 250 Hz of 10.9 dB ( P = .04) with 12.9-dB improvement in air conduction thresholds ( P = .02) and no difference (0.9 dB, P = .9) in bone conduction thresholds. Conclusion In our study, patients with SSCD demonstrated excellent hearing outcomes and resolution of most otologic symptoms after surgical repair. Transmastoid canal plugging, which has been described to date only in smaller case series, is a safe and effective alternative to the traditional middle cranial fossa approach.