Pressure Transmission to the Inner Ear by Mastoid Palpation After Transmastoid Surgery for Superior Canal Dehiscence

Hearing Outcomes for an Underwater Endoscopic Technique for Transmastoid Repair of Superior Semicircular Canal Dehiscence

OBJECTIVES

To compare hearing outcomes between traditional microsurgical transmastoid repairs and underwater, endoscopic transmastoid repairs of superior semicircular canal dehiscence syndrome (SCDS).

METHODS

A retrospective review of 14 patients undergoing transmastoid repair of SCDS between 2013 and 2017. Preoperative, immediate (7-10 d) postoperative, and long-term (>6 wk) postoperative speech discrimination scores, pure-tone averages, as well as pure-tone air conduction and bone conduction thresholds were obtained at 250 Hz, 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz. Hearing threshold changes were all calculated as preoperative thresholds subtracted from postoperative threshold at each frequency. Wilcoxon rank-sum tests were conducted to assess changes in postoperative hearing thresholds at both the immediate and long-term postoperative period between those undergoing the traditional transmastoid technique and the underwater, endoscopic transmastoid technique.

RESULTS

Our results demonstrate patients who underwent underwater transmastoid repairs had significantly less increase in their high-frequency bone conduction thresholds at both time periods, indicating less sensorineural hearing loss, compared to the traditional microscopic repair (p = 0.02 [effect size, r = 0.4], p = 0.006 [r = 0.6]). At long-term follow-up, there was also significantly improved pure-tone averages in the patients in the underwater repair cohort compared to the traditional group (p = 0.004 [r = 0.6]). There were no differences in air-bone gaps at any frequency or any time period between the two cohorts.

CONCLUSIONS

Preliminary findings show that the underwater endoscopic technique may prevent sensorineural hearing loss during transmastoid repair of SCDS.

Transmastoid Superior Semicircular Canal Plugging: A Prospective Analysis of Surgical Outcomes

OBJECTIVES

To assess the outcomes of the transmastoid superior semicircular canal plugging in patients with superior semicircular canal dehiscence (SSCD).

STUDY DESIGN

Prospective cohort study.

SETTING

Tertiary, university center.

PATIENTS

Patients with SSCD undergoing transmastoid superior semicircular canal plugging within a 30-month period.

INTERVENTIONS

Transmastoid superior semicircular canal occlusion.

MAIN OUTCOME MEASURES

We documented the surgical technique, pre- and postoperative (3-month review) dizziness handicap inventory scores, average hearing thresholds, low-frequency air-bone gap, six-canal video head-impulse-test responses, improvement of the auditory symptoms and complications.

RESULTS

Out of 30 patients with SSCD, 11 patients (12 ears) were enrolled with an average age 41.17 years (range 32-65 years). Oscillopsia resolved in all patients; DHI score improved from 56.7 (range 22-84) preoperatively to 25.83 (10-46) postoperatively (p = 0.001), while out of the nine patients with troublesome auditory symptoms, five patients noticed an improvement. The average pre- and postoperative hearing thresholds were 15.2 dB (range 3-32.5 dB) and 14.17 dB (range 5-30 dB) (p = 0.73), respectively. The average pre- and postoperative low-frequency air bone gap was 12.3 dB (range 5-20 dB) and 9.4 dB (range 0-20 dB), respectively (p = 0.24) (Table 1). There were no major complications; two patients developed postoperative benign paroxysmal positional vertigo.

CONCLUSION

Transmastoid plugging of the superior semicircular canal can safely and significantly improve the vestibular symptoms of the patients with SCDS, as well as the auditory symptoms in a substantial number of patients in a hearing-preservation way.