Hearing Outcomes after Transmastoid Plugging of Superior Canal Dehiscence

Patients with a superior canal dehiscence syndrome display symptoms of the vestibular disorder except that of hearing loss. Therefore, any type of surgery should treat those symptoms without affecting the hearing threshold. The aim of this study was to evaluate the extent to which the hearing threshold has been affected; the evaluation process was carried out by a transmastoid plugging of the superior canal. Another aim was to estimate the risk in loss of hearing due to this surgery.

In a retrospective study, 31 patients with dehiscence of the superior canal, who underwent a transmastoid plugging, were included. Additionally, 8 of them with the clinical symptoms of the Menière's disease received an endolymphatic sac surgery. A b-c threshold at 0.25, 0.5, 1, 2, and 4 kHz was observed in all patients pre and postoperatively as well as in the long-term follow-up.

After a mean interval of 149 days, a change in the b-c threshold of 5.9 dB was detected. After 149 days, in the patient group comprising those who underwent an additional endolymphatic sac surgery, a b-c threshold change of 17.18 dB was detected.

The transmastoid plugging of the superior semicircular canal can be performed with an acceptable risk of hearing affection. If the surgery was combined with other techniques, (e.g. endolymphatic sac surgery) then the risk increases.