Quality of life outcomes after transmastoid plugging of superior semicircular canal dehiscence
Introduction
Over the past 20 years, clinicians have increasingly become aware of the symptoms now attributed to superior semicircular canal dehiscence (SSCCD). Minor first reported successful treatment of patients who had chronic disequilibrium, sound- or pressure-induced vertigo, and nystagmus [1]. Investigation revealed these patients had a bony dehiscence overlying the superior semicircular canal and all experienced benefit after undergoing resurfacing. As the recognition and understanding of the condition evolved, additional symptoms were identified, such as pulsatile tinnitus, autophony, and hyperacusis to otherwise benign bodily functions (i.e. eye movement and chewing). Clinical and experimental evidence has shown that these symptoms are the result of having a third window in the bony labyrinth. Acoustic energy from air conduction dissipates via this third window instead of at the round window and causes an increase in air conduction thresholds. Energy from bone conduction accesses the perilymph of the labyrinth and cochlea, attenuating the hearing levels and increasing thresholds. In addition, the pressure changes between the oval window and dehiscence can influence the flow of endolymph resulting in vertigo or nystagmus.
Even with recent advances in the understanding of this condition, there remains considerable controversy regarding the best treatment option. Traditional management paradigms have recommended superior semicircular canal resurfacing and/or plugging via a middle cranial fossa (MCF) approach. Recent literature has also shown good outcomes via transmastoid plugging/capping or round window re-enforcement [2]. However, despite numerous reports of subjective patient improvements, there have been fewer validated measurements of qualitative outcomes and quality of life.
Crane et al. validated a 26-item Autophony Index (AI) in their 19 patients who underwent SSCCD plugging via the MCF approach although subsequent implementation has been limited [3]. Other investigators have relied on subjective scales, such as 0–5 or 0–10 [4]. Another validated questionnaire, the Dizziness Handicap Index (DHI), has shown variable quantitative responses to transmastoid capping of the dehiscence or repair via MCF [[5], [6], [7]]. Jung et al. found patients still reported high scores with the DHI post-operatively although these results may have been clouded by the high number of patients who had migraine [8]. Evaluation of quality of life scoring systems has also yielded inconsistent results. Crane et al. failed to find a significant improvement in total scores when using the SF-36 health survey [3]. They postulated that symptoms of SSCCD might not be reflected in general health surveys. More recently, Remenschneider et al. evaluated the quality-adjusted life years and cost-effectiveness of surgical intervention in a cohort of patients (91.3% who were operated on via the MCF approach), with significant benefit seen [9].
Given that the majority of literature has focused on outcomes following the MCF approach, the aim of this study was to evaluate the previously validated DHI and AI in a population who had undergone superior semicircular canal plugging via the transmastoid approach. In addition, we aimed to evaluate the effects of surgery via an American Academy of Otolaryngology Head and Neck Surgery—accepted quality of life measure, the Glasgow Benefit Inventory (GBI).
Section snippets
Methods
A retrospective chart review was conducted to identify all patients who were surgically treated for SSCCD between February 2014 and February 2018. Adults who elected not to undergo surgical management were excluded. All patients who elected surgical management underwent a transmastoid superior semicircular canal dehiscence plugging, which was performed by the senior author. The patients were then contacted and asked to participate in a study evaluating the outcomes from surgical intervention.
Demographics and symptomology
On review, 10 patients (2 male, 8 female) were identified to have undergone transmastoid plugging of SSCCD during the period specified, and all agreed to participate in the study. The average age at presentation was 53.8 years, with a range of 23 to 76 years. One patient had previously undergone transmastoid capping, with minimal improvement in symptoms. Four patients (40%) had CT evidence of bilaterally SSCCD, but all had only unilateral surgery during their follow-up. An equal number of left-
Discussion
SSCCD is a relatively recently accepted condition, and there remains significant controversy regarding the optimal approach for surgical treatment. Approaches previously described include dehiscence plugging (via the MCF approach or transmastoid approach), transmastoid capping of the dehiscence, and round window occlusion. Improvement in clinical symptoms have been reported [4,9,13,14], with the majority of cases involving the MCF approach. In contract, a systematic review by Ziylan et al.
Conclusion
To our knowledge, we are the first to report a significant change in quality of life after surgical intervention for SSCCD when measured by the validated GBI. While other studies have demonstrated an improvement in DHI or AI using the MCF approach, this is the first study to demonstrate similar improvements using a transmastoid approach for SSCCD. Importantly, almost all the patients would recommend this approach to a friend who is considering surgical intervention for SSCCD. While not without
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Declaration of competing interest
None.
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2022, World NeurosurgeryCitation Excerpt :Symptoms commonly described in patients with SSCD include autophony (defined as a loud perception of one's own voice), hearing loss, hyperacusis, ear fullness, tinnitus, vertigo, disequilibrium, oscillopsia, and a characteristic hearing/pressure-induced vertigo (Tullio/Hennebert's signs).3,4,7,15,16 Such symptoms cause significant distress to patients and have a deleterious effect on the quality of life.3,17 Regarding symptoms in thin bone patients, Baxter et al. evaluated a wide variety of auditory, vestibular, and migraine symptoms in thin bone patients and compared the symptom profile to that of SSCD patients.10
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