By Marcello Cherchi, MD PhD
For patients
Superior semicircular canal dehiscence (SSCD) can sometimes be fixed by surgery, and there are different surgeries for this. The surgeries do not always work. There is some risk of hearing loss, and some risk that the surgery will not work. Some patients talk with two or more surgeons before deciding whether to undergo a surgery.
For clinicians
Overview
There are several possible surgical approaches to treating superior semicircular canal dehiscence (SSCD). There is little consensus on selection criteria for these procedures, and in some instances, more than one approach may be feasible. There is debate in the literature regarding which techniques pose the least risk to hearing. Sometimes a repair procedure will appear successful initially, but will not be durable. Some patients benefit from consulting with more than one surgeon when considering surgical intervention for SSCD.
Introduction
Superior semicircular canal dehiscence (SSCD) is a “third window phenomenon” in which there is an abnormal connection between the superior semicircular canal and the intracranial space due to dehiscence of the bony roof that usually separates these two spaces.
There are several approaches to surgical repair of SSCD, the main ones of which are:
- Canal re-roofing, which requires neurosurgical assist via craniotomy to access the floor of the middle cranial fossa (Mozaffari et al. 2021b; Salvinelli et al. 2022; Tugrul et al. 2022).
- Canal occlusion (colloquially referred to as “plugging”), usually by a transmastoid approach (de Wolf et al. 2021; Gersdorff et al. 2022; Hassannia, Douglas-Jones, Rutka 2019; Hussain, Irving, Baruah 2023; Kawamura et al. 2022; Kontorinis and Gaggini 2021; Lin et al. 2021; Shaul et al. 2023)
- Round window reinforcement (Ahmed, Rajagopal, Lloyd 2019; Bunne, Andersson, Myhrum 2022; Chemtob et al. 2019; Conway et al. 2021) or oval window reinforcement (Conway et al. 2021).
There is little agreement on the selection criteria for which surgical approach to take in a particular case. In some instances, more than one approach may be feasible.
Adverse effects
One of the main concerns for surgery on the labyrinth is the effect on hearing. Surgeries aimed at treating SSCD attempt to preserve hearing, and there are debates in the literature about which approach poses the least risk to hearing (Conway et al. 2021; Ellsperman et al. 2021; Elms, Canick, Kaylie 2023; Kawamura et al. 2022; Lin et al. 2021; Wolfovitz et al. 2019; Yang, Yang, Gopen 2023).
Another potential “adverse effect” is that the surgery, even if initially successful, will not be durable. Re-roofed canals can re-dehisce; plugged canals can become un-plugged; reinforced round and oval windows can lose reinforcement. There is a modest literature regarding surgical revision of prior attempts at treating SSCD (Mozaffari et al. 2021a).
Other notes
Some patients benefit from consulting with more than one otologic surgeon when considering an invasive procedure for the treatment of SSCD.
References
Ahmed W, Rajagopal R, Lloyd G (2019) Systematic Review of Round Window Operations for the Treatment of Superior Semicircular Canal Dehiscence. J Int Adv Otol 15: 209-214. doi: 10.5152/iao.2019.6550
Bunne M, Andersson H, Myhrum M (2022) Long-Term Outcomes of Round Window Reinforcement for Superior Semicircular Canal Dehiscence Syndrome. Otol Neurotol 43: 709-716. doi: 10.1097/MAO.0000000000003561
Chemtob RA, Noij KS, Qureshi AA, Klokker M, Nakajima HH, Lee DJ (2019) Superior Canal Dehiscence Surgery Outcomes Following Failed Round Window Surgery. Otol Neurotol 40: 535-542. doi: 10.1097/MAO.0000000000002185
Conway RM, Tu NC, Pinther S, Shareef Z, Hong RS, Zappia JJ, Babu SC (2021) Audiologic Outcomes After Oval and Round Window Reinforcement Surgery. Otol Neurotol 42: 1051-1057. doi: 10.1097/MAO.0000000000003115
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