Learning Objectives: To highlight potential approaches to open the semicircular canals while preserving hearing.
Introduction: In case of incapacitating symptoms, surgical treatment can be offered to patients with confirmed superior semicircular canal dehiscence syndrome. Plugging and capping of the superior semicircular canal are most effective in terms of symptom relief. Both the middle fossa and the transmastoid approach have been reported to reach the superior semicircular canal. However, the middle fossa approach has potential complications including epidural hematoma, seizures, cerebrospinal fluid leakage, facial palsy, etc. Moreover, plugging through the middle fossa approach has been reported to produce up to 25% of sensorineural hearing loss.
Aim: Our aim was to gain insight in the effect of opening and plugging the semicircular canal on postoperative hearing thresholds when using the presented surgical technique.
Methods: We performed a retrospective review on hearing outcomes of 16 cases that underwent transmastoid semicircular canal plugging by two surgeons in a tertiary referral center between October 2008 and January 2016. All patients received systemic corticosteroids during and after surgery. The relevant refinements in surgical technique will be presented. We evaluated air conduction (AC) pure-tone averages (PTA) of 0.5 kHz, 1 kHz and 2kHZ and bone conduction (BC) PTA of 1, 2 and 4 kHz before and after surgery.
Results: In our case series of 16 patients that underwent transmastoid plugging, none of the patients experienced postoperative sensorineural hearing loss. None of the patients experienced epidural hematoma, seizures, cerebrospinal fluid leakage or facial palsy. Mean BC PTA was 16 dB preoperatively and 18 dB postoperatively. No BC PTA over 15 dB was observed in the individual patients. Mean AC PTA was 28 dB preoperatively and 24 dB postoperatively. All of the patients had resolution of their autophony or hyperacusis of bone-conducted sounds.
We can confirm the high rate of symptom relief reported in earlier studies on superior semicircular canal plugging, which presents a reliable treatment option to the patient that suffers from incapacitating autophony and hyperacusis of bodily sounds.
Conclusion: The presented technique for opening (and plugging) of the semicircular canal through a transmastoid approach proves to be safe and effective in preserving hearing. We can confirm the high rate of symptom relief reported in earlier studies. No sensorineural hearing loss was observed in our series.