Edited by: Jose Antonio Lopez-Escamez, Granada University Hospital, Spain
Reviewed by: Eduardo Martin-Sanz, Hospital de Getafe, Spain; Marcos Rossi-Izquierdo, Hospital Universitario Lucus Augusti, Spain
Need for defining minimal outcome measures to pool data in meta-analysis.
Specialty section: This article was submitted to Neuro-otology, a section of the journal Frontiers in Neurology
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Superior canal dehiscence syndrome (SCDS) can be treated surgically in patients with incapacitating symptoms. However, the ideal treatment has not been determined.
This systematic literature review aims to assess available evidence on the comparative effectiveness and risks of different surgical treatments regarding: (1) symptom improvement; (2) objectively measurable auditory and vestibular function; (3) adverse effects, and (4) length of hospitalization.
A systematic database search according to PRISMA statement was conducted on Pubmed, Embase, and Cochrane library. In addition, reference lists were searched. No correspondence with the authors was established. The last search was conducted on June 9, 2017.
Retrospective and prospective cohort studies were held applicable under the condition that they investigated the association between a surgical treatment method and the relief of vestibular and/or auditory symptoms. Only studies including quantitative assessment of the pre- to postoperative success rate of a surgical treatment method were included. Case reports, reviews, meta-analysis, and studies not published in English, Dutch, or German were excluded.
The first author searched literature and extracted data; the first and last analyzed the data.
Seventeen studies (354 participants, 367 dehiscences) met the eligibility criteria and were grouped according to surgical approach. Seven combinations of surgical approaches and methods for addressing the dehiscence were identified: plugging, resurfacing, or a combination of both through the middle fossa (middle fossa approach); plugging, resurfacing, or a combination of both through the mastoid (transmastoid approach); round window reinforcement through the ear canal (transcanal approach). Several studies showed high internal validity, but quality was often downgraded due to study design (
A standardized protocol including outcome measures and timeframes is needed to compare the effectiveness and safety SCDS treatments. It should include symptom severity assessments and changes in vestibular and auditory function before and after treatment.
Superior canal dehiscence syndrome (SCDS) is a rare condition in which a hole in the superior semicircular canal causes sound and pressure waves to evoke vestibular and auditory symptoms. Symptoms can include sound- or pressure-induced vertigo (Tullio phenomenon), autophony, pulsatile tinnitus, bone conduction (BC) hyperacusis, conductive hearing loss, and “brain fog” (
The ideal treatment should combine the safest approach with the most effective and durable closure technique. This ideal treatment has yet to be determined. A number of reviews have aimed to address this issue but have been limited to comparing highly variable outcome measures used to assess the different techniques (
This systematic review aims to assess the evidence on the comparative efficacy of the different surgical treatments with respect to: (1) alleviating symptoms (BC hyperacusis, tinnitus, autophony, hearing, aural fullness, noise- and pressure-induced vertigo, and general disequilibrium); (2) change in objectively measurable auditory and vestibular function; (3) presence of adverse effects, and (4) length of hospitalization.
To structure this systematic review, the PRISMA statement for reporting systematic reviews was applied.
Retrospective and prospective cohort studies were included if they analyzed the association between at least one surgical treatment method and its effect on symptom relief or auditory and vestibular function. To guarantee a minimum level of comparability, the success rates had to be assessed in a quantitative manner and had to be based on pre- and postoperative data.
In the context of this review, it was not feasible to translate literature, therefore only literature published in English, Dutch or German (i.e., languages spoken by the reviewing authors) was included. The search was constrained to studies on humans and to literature that was accessible through the library services of Maastricht University, the Academic Hospital Maastricht, or the Dutch Inter Library Loan Service.
Studies were excluded if they did not analyze success rates in a quantitative manner, did not assess outcomes of one particular surgical treatment method, or did not use symptom relief as an outcome measure. Furthermore, the following types of literature were excluded: case reports, reviews, meta-analyses, and studies not published in English, Dutch, or German.
A systematic search was performed in the PubMed database, Embase database, and Cochrane library of clinical trials. Furthermore, the reference lists of selected articles were screened for additional literature. No unpublished literature was integrated into this review. The last search was conducted on June 9, 2017.
We searched all three databases for abstracts, titles and key words containing suitable search terms. While searching PubMed we used the following terms:
Embase Database was searched using the following search terms:
Cochrane Database of Clinical Trials was consequently searched with equivalent terms:
The first author screened titles and abstracts of the found articles to evaluate whether the content fit the inclusion and exclusion criteria. The first and last author analyzed the data in consensus.
Data elements extracted from each study were as follows: study design, setting and duration of follow-up, country of origin, the number of participants, number of participants lost during follow-up, assessment tools and outcome measures.
To evaluate the risk of bias for each study, specific methodological criteria were applied.
If relevant methodology was not addressed in the article, it was considered a risk for bias. The elements assessed for risk of bias that were included are presented in Table
Risk of bias per study.
Study ID | In- and exclusion criteria | Selection bias | Participant characteristics | Blinding of participants, personnel | Reproducibility (techniques well described) | Correction for confounding | Follow-up | Quality of outcome measure | Loss to follow-up | Information bias | Conflict of interest | Selective reporting of outcome |
---|---|---|---|---|---|---|---|---|---|---|---|---|
Remenschneider et al. ( |
+ | − | + | − | + | − | + | + | + | − | + | +/− |
Chung et al. ( |
+/− | − | + | − | + | − | +/− | − | + | − | + | + |
Thomeer et al. ( |
+ | − | + | − | + | − | + | + | + | − | +/− | ± |
Goddard and Wilkinson ( |
+ | − | +/− | − | + | − | + | + | + | − | +/− | ± |
Ward et al. ( |
+ | − | +/− | − | + | − | +/− | + | + | − | +/− | ± |
Agrawal et al. ( |
+ | − | +/− | − | + | − | +/− | + | + | − | +/− | ± |
Crane et al. ( |
+ | − | + | − | + | − | + | + | + | − | +/− | ± |
Crane et al. ( |
+ | − | + | − | + | − | + | + | + | − | +/− | ± |
Carey et al. ( |
+ | +/− | ± | − | + | − | +/− | + | − | +/− | + | + |
Phillips et al. ( |
+ | − | + | − | + | − | + | + | + | − | +/− | + |
Limb et al. ( |
+ | − | − | − | + | − | +/− | + | + | − | +/− | + |
Hillman et al. ( |
+ | − | + | − | + | − | + | − | + | − | +/− | − |
Van Haesendonck et al. ( |
+ | − | + | − | + | − | +/− | + | + | − | +/− | − |
Beyea et al. ( |
+ | − | +/− | − | + | − | +/− | + | + | − | + | − |
Agrawal and Parnes ( |
+ | − | +/− | − | + | − | +/− | + | + | − | + | +/− |
Fiorino et al. ( |
+ | − | + | − | + | − | + | +/− | + | − | +/− | + |
Amoodi et al. ( |
+ | − | − | − | + | − | + | +/− | + | − | +/− | ± |
Lundy et al. ( |
+ | − | +/− | − | + | − | + | + | + | − | +/− | + |
Silverstein et al. ( |
+ | − | +/− | − | −/+ | − | +/− | ± | + | − | +/− | + |
Different assessment tools were used (Table
Assessment tools for subjective and objective outcome measures.
Technique | Study | Assessment subjective symptoms | Assessment objective measurements |
Time of measurement post surgery | Adverse effects | |||||
---|---|---|---|---|---|---|---|---|---|---|
Audiometrics | Vestibular-evoked myogenic potentials (VEMPs) | Head impulse test | Calorics | Induced nystagmus | ||||||
Middle fossa approach | P | Remenschneider et al. ( |
Health utility value, autophony index (AI), dizziness handicap inventory (DHI), and Hearing Handicap Inventory | x | x | x | x | x | 3 months | x |
P + R | Chung et al. ( |
Anamnesis | x | x | x | x | x | x | x | |
Thomeer et al. ( |
Anamnesis | Cervical vestibular-evoked myogenic potentials (cVEMPs): threshold, amplitude | x | x | x | D7 and 1 month | Reported | |||
Goddard and Wilkinson ( |
Anamnesis | x | x | x | x | x | Reported | |||
Ward et al. ( |
x | x | x | x | x | x | Reported | |||
Agrawal et al. ( |
x | x | x | 1. Clinical | x | x | x | x | ||
2. Search coil: horizontal canals | ||||||||||
Crane et al. ( |
AI, DHI | cVEMPs: thresholds | x | x | x | 3 months: AI, DHI | Reported | |||
Crane et al. ( |
DHI | cVEMPs: thresholds, auditory stimuli | x | x | x | 3 months: DHI | x | |||
Carey et al. ( |
Anamnesis | x | x | Search coil: all canals | x | x | 1.5–7 months | Reported | ||
Phillips et al. ( |
Anamnesis | cVEMPs: thresholds | x | x | x | 4 months | Reported | |||
Limb et al. ( |
x | x | x | x | x | x | x | |||
R | Hillman et al. ( |
Anamnesis | x | x | x | x | >3 months | x | ||
Transmastoid approach | P | Van Haesendonck et al. ( |
Anamnesis | x | x | x | x | x | Reported | |
Beyea et al. ( |
Anamnesis | x | x | x | x | x | x | Reported | ||
Agrawal and Parnes ( |
Anamnesis | x | x | x | x | x | Reported | |||
P + R | Fiorino et al. ( |
Anamnesis | VEMPs: thresholds | x | Procedure not described | Sound and pressure induced, not described. | 1.5–2 months | Reported | ||
R | Amoodi et al. ( |
Anamnesis | x | x | x | Sound and pressure induced, procedure not described. | Not reported, follow-up varied between 1.5 and 4 years | Reported | ||
Lundy et al. ( |
Scale from “worsening” to “much better” | x | x | x | x | x | >3 months | x | ||
Transcanal approach | RW | Silverstein et al. ( |
Superior canal dehiscence syndrome questionnaire | x | x | x | x | x | x | x |
(7-point Likert type scale) |
Measures that evaluated auditory or vestibular function were considered secondary outcome measurements in this review. The following objective outcome measures considered valid: standard pure-tone audiometry, word recognition/speech discrimination score, speech reception threshold (SRT), cervical vestibular-evoked myogenic potential (cVEMP), caloric testing, rotational chair testing, and electronystagmography.
The query returned 67 articles in PubMed, 20 articles in the Embase database, and 4 articles in the Cochrane Library. After removing duplicates 65 titles and abstracts were evaluated and 44 were excluded due to study design (case reports and reviews), outcome measures or because they were not available in the required languages. Reference lists of the remaining 21 articles were screened by title and abstract, resulting in an additional 7 articles for further evaluation. These 28 eligible studies were further analyzed for conformity with the remaining inclusion and exclusion criteria. After a full text screening, eight studies were excluded because they did not contain a quantitative measure of success. In addition, one article was excluded because it did not report the surgical approach. Nineteen studies were therefore included in this review.
The majority (18) of studies were retrospective chart reviews. The patient data collected for these chart reviews all contained pre- and postoperative information. However, the postoperative follow-up varied between 1 and 7 years. Only one prospective trial met the inclusion criteria.
All 19 studies were conducted in countries with a mainly Caucasian population, either originating from the USA, Canada, France, Belgium, Italy, or Australia.
The number of cases in the retrospective studies varied between 3 (
The majority of studies (18) were set in single, tertiary referral otology centers. There was only one multi-center retrospective chart review that evaluated patients from four institutions (
In every study, the diagnosis of SCDS was based on vestibular and auditory symptoms and evidence of a dehiscence on CT imaging. In the majority of studies, VEMP thresholds were also used as a diagnostic tool but not uniformly and in many studies they were not mandatory for diagnosis. Clinically, patients mainly suffered from a combination of symptoms such as sound- and pressure-induced vertigo, chronic disequilibrium, autophony, aural fullness, pulsatile tinnitus, and hyperacusis. However, not all studies reported eligibility criteria for surgery and in some cases patients underwent surgery while suffering from one symptom alone (
As mentioned above there were two primary surgical approaches (middle cranial fossa and transmastoid) and three different reparative techniques (plugging or resurfacing the superior semicircular canal alone and resurfacing with canal plugging). An alternative was transcanal reinforcement of the round window. Twelve studies examined the success rates of the middle cranial fossa approach. In 1 of the 12 studies, the superior semicircular canal was plugged, in 10 studies, the canal was plugged and resurfaced, and 1 study described the middle cranial fossa approach with resurfacing of the canal. The success rates for the transmastoid approach were assessed in six studies. Of the six studies, three involved plugging, one involved a combination of plugging and resurfacing, and two involved resurfacing alone [i.e., “cartilage cap occlusion” (
The follow-up of the retrospective studies, meaning the time until the last recorded data, varied from 1 month (
No loss to follow-up was reported in any retrospective study. In the prospective study, a loss to follow-up of 13 patients was reported resulting in a final population of 19 patients (
Retrospective studies collected and evaluated existing pre-and postoperative data from medical records. The one prospective study compared the existing preoperative data with new postoperative clinical records and auditory and vestibular measurements.
All studies listed the inclusion and exclusion criteria.
All retrospective studies were prone to selection bias and were therefore all graded with a (−). The prospective study was graded with a (+/−) due to an unclear risk of bias due to a lack of information on the patient selection process.
With the exception of two studies, the patients’ symptoms were clearly described. However, other patient demographics like age, sex, comorbidities, or otological history were often not described.
Since blinding is not applicable to retrospective studies, 18 of the articles were graded with a minus (−). In the prospective study, the blinding of patients or surgeons was not required since there was no alternative treatment and therefore no control group.
The surgical technique was well described in all 19 studies. However, in one study, surgeons used different techniques and materials, limiting reproducibility (
Correction for confounding was not performed in any study.
The follow-up time differed greatly among studies. However, all studies had similar definitions for short-term and intermediate-term postoperative stages. This made it possible to compare early vs. late stage outcomes across the different studies.
Judgment on the length of follow-up depended upon the research question of each study. If a study aimed to investigate the short-term outcomes of the operation, several days could be considered a sufficient follow-up time. In comparison, a study that explored long-term outcomes required a follow-up of at least 12 months.
Out of the 19 studies, 10 presented a follow-up period of more than 3 months and were graded with a (+). We considered a follow-up of more than 3 months as sufficient since the immediate postoperative side effect should, by that time, be resolved. The remaining nine studies presented a follow-up time that was reasonably aligned with their research question (e.g., short-term follow-up when focusing on immediate effects) and were therefore graded with a (+/−).
The overall quality of outcome measures was moderate to low for the primary outcome measures that assessed subjective symptom improvement. They were mainly assessed through anamnesis and not standardized questionnaires that, for example, described “improvement,” “worsening,” or “no change in symptoms” (
The overall quality of outcome measure for the secondary objective outcome measurements was high. Theses included the following: audiometry (
All 18 retrospective reports were graded with a (+). The prospective study was considered to have a high risk of bias and was graded with a (−).
In a retrospective context, it was not possible to determine whether the information being used for the study was faulty or inaccurate. The risk for information bias was therefore considered high in all retrospective studies. All 18 retrospective chart reviews were therefore graded with a (−). Regarding the one prospective study, the risk for information bias was unclear and was graded with a (+/−).
No conflicts of interest were reported, and there was no reason to suspect such in any of the studies. All studies were marked with a (+).
Three articles were inconsistent with the reported numbers and results. They were therefore considered to have a high risk for bias and were therefore graded with a (−).
To increase comparability, the level of evidence and level of recommendation was added to each conclusion that follows a result analysis (
Subjective improvement in affected ears.
Study | Improvement of symptoms in affected ears |
|||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
HA | T | AP | H | AF | NIV | PIV | GD | Headache | Quality of life | |||
Middle fossa | P | Remenschneider et al. ( |
x | x | Pre: 32.7 (28.0) Post: 4.8 (8.3) |
Pre: 41.8 (27.9) Post: 26.7 (30.2) |
x | x | x | Pre: 48.7 (23.4) Post: 38.2 (30.7) |
x | Pre: 0.65 (0.12) Post: 0.79 (0.12) |
P + R | Chung et al. ( |
x | Pre: 12/18 Post: 3/18 Developed: 1/3 |
Pre: 16/18 Post: 5/18 |
Pre: 10/18 Post: 4/10 |
Pre: 7/18 Post: 3/18 Developed: 2/3 |
Pre: 13/18 Post: 6/18 Developed: 1/6 |
Pre: 13/18 Post: 6/18 Developed: 1/6 |
Pre: 11/18 Post: 5/18 Developed: 2/5 |
Pre: 5/18 Post: 4/18 Developed: 1/4 |
x | |
Thomeer et al. ( |
x | Resolved: Pulsatile: 12/12 Non-pulsatile: 0/1 |
Resolved: 9/9 | x | Resolved: 6/6 | Resolved: 14/16 | Resolved: 10/10 | Resolved: 14/16 | x | x | ||
Goddard and Wilkinson ( |
x | x | Resolved: 12/15 | x | Resolved: 16/20 | Resolved: 8/8 | Resolved: 8/11 | Resolved: 16/24 | x | x | ||
Ward et al. ( |
x | x | x | x | x | x | x | x | x | x | ||
Agrawal et al. ( |
x | x | x | x | x | x | x | x | x | x | ||
Crane et al. ( |
Pre: 42 ± 27 (range 0–86) Post: 9 ± 22 (range 0–82) |
Pre: 48.22 Post: 27.77 |
x | x | ||||||||
Crane et al. ( |
x | x | x | x | x | x | x | Pre: 44 ± 24 Post: 18 ± 15 Decreased: 17/19 Increased: 2/19 |
x | x | ||
Carey et al. ( |
x | x | x | x | x | Resolved: 19/19 | Resolved: 19/19 | x | x | x | ||
Phillips et al. ( |
Improved: 5/5 | Transient increase: 4/5 Improved: 5/5 |
x | x | ||||||||
Limb et al. ( |
x | x | x | x | x | x | x | x | x | x | ||
R | Hillman et al. ( |
x | Resolved: Pulsatile: 2/3 Non-pulsatile: – |
x | x | x | x | Resolved: 12/12 | Resolved: 12/13 | x | x | |
Transmastoid | P | Van Haesendonck et al. ( |
Resolved: 6/8 | Resolved: Pulsatile: 6/9 Non-pulsatile: – |
Resolved: 11/12 | x | x | Resolved: 4/5 | Resolved: 2/5 Developed: 1/5 |
x | x | x |
Beyea et al. ( |
Resolved: 1/1 | Resolved: Pulsatile: 10/10 Non-pulsatile: – |
x | Improved: 2/16 Preserved: 14/16 |
x | x | x | Transient increase: 16/16 | x | x | ||
Agrawal and Parnes ( |
x | x | Resolved: 1/1 | x | x | Resolved: 3/3 | Resolved: 1/1 | Transient increase: 3/3 Resolved: 3/3 |
x | x | ||
P + R | Fiorino et al. ( |
x | x | x | x | x | Improved: 6/6 | Improved: 6/6 | Improved: 6/6 | x | x | |
R | Amoodi et al. ( |
x | x | x | x | x | x | x | Transient increase: 4/4 | x | x | |
Lundy et al. ( |
x | x | x | x | x | x | x | Questionnaire: Much better: 29 Some better: 5 Same: 2 Worse: 1 |
x | x | ||
Transcanal | RW | Silverstein et al. ( |
x | Pulsatile: Pre: 4.6 (SD 2.0) Post: 2.2 (SD 1.4) (1 = not bothered, 7 = disabled) Non-pulsatile: – |
Autophony: Pre: 4.6 (SD 1.9) Post: 2.2 (SD 1.7) Bone conduction sensitivity: Pre: 4.5 (SD 2.0) Post: 2.0 (SD 1.5) |
Pre: 2.5 (SD 1.6) Post: 2.2 (SD 1.4) |
Pre: 4.2 (SD 1.6) Post: 2.5 (SD 1.4) |
Pre: 5.4 (SD 1.5) Post: 2.3 (SD 1.3) |
Pre: 3.6 (SD 1.3) Post: 2.0 (SD 1.3) |
Pre: 4.2 (SD 1.7) Post: 2.1 (SD 1.2) |
x | x |
Bone conduction hyperacusis was not addressed in the studies that analyzed the effect of resurfacing, or a combination of resurfacing and plugging
Conclusion: Taking these results into account, no comparison could be made among the different approaches; however, BC hyperacusis was often resolved by transmastoid plugging. Grade of evidence: IV; grade of recommendation: D.
Pulsatile tinnitus was assessed in six studies of which two studies also reported cases of non-pulsatile tinnitus. No evidence was available regarding plugging
Conclusion: Plugging, resurfacing and a combination of both
Plugging
Conclusion: Plugging or plugging and resurfacing the dehiscence using the middle fossa or transmastoid approach as well as round window reinforcement led to significant improvements of autophony symptoms. Comparison of the different techniques was not possible due to different outcome measures. No evidence was available on the effect of resurfacing alone. Grade of evidence: IV; grade of recommendation: D.
Subjective change in hearing after surgery was addressed in four studies. One study addressed the effect of plugging
Conclusion: Existing evidence showed a non-significant improvement in subjective hearing following middle fossa plugging or plugging in combination with resurfacing and a preservation of hearing in the majority of patients following transmastoid plugging. Studies showed no subjective worsening after transcanal round window reinforcement. No evidence was available regarding the effect of other techniques. Grade of evidence: IV; grade of recommendation: D.
Aural fullness was assessed in four studies. Plugging plus resurfacing
Conclusion: Plugging plus resurfacing
Improvement of noise-induced vertigo was assessed in seven studies. No evidence was available on plugging
Conclusion: Noise-induced vertigo improved in the majority of cases following plugging plus resurfacing
Improvement of pressure-induced vertigo was assessed in 10 studies. No evidence was available regarding plugging
Conclusion: All assessed techniques led to improvement on pressure-induced vertigo in at least 50% of patients. Further comparison of the different techniques was not possible due to difference in outcome measures and a lack of evidence for some techniques. Grade of evidence: IV; grade of recommendation: D.
Disequilibrium was the most frequently assessed symptom throughout the studies. However, its severity was presented in several different outcome measures and was therefore difficult to compare. Plugging
Conclusion: Disequilibrium improved or resolved in the majority of patients following all approaches that were assessed. Only transmastoid plugging plus resurfacing was not assessed. However, results were difficult to compare due to the variety of outcome measures. Grade of evidence: IV; grade of recommendation: D.
Improvement of headache was assessed in one study. Plugging plus resurfacing
Conclusion: Considering the small number of cases assessed it is not yet possible to draw a conclusion regarding the effect of surgery on symptoms of headache. Literature suggests that plugging plus resurfacing
The quality of life is often represented by quality of adjusted life years, which can be calculated by different scores such as the HUV. The mean HUV of the general U.S. population is 0.80 (SD 0.29), while SCDS patients (including individuals not undergoing surgery) have a significantly lower mean score of 0.68 (SD 0.13,
Conclusion: Literature suggests that plugging
Objective improvement of auditory and vestibular function.
Study | Results objective measures postoperative relative to preoperative |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|
Audiometry | Vestibular-evoked myogenic potentials (VEMPs) | Head impulse test | Calorics | Induced nystagmus | Time | Adverse effects | Hospital stay (days) | |||
Middle Fossa | P | Remenschneider et al. ( |
x | x | x | x | x | x | x | |
P + R | Chung et al. ( |
x | x | x | x | x | x | x | x | |
Thomeer et al. ( |
Air conduction (AC): mean ↑: +7.4 dB (SD 7.7) Bone conduction (BC): mean ↓: −2.5 dB (SD 7.2) Air bone gap (ABG): mean ↓: −9.0 dB (SD 10.9) AC: mean ↑: +4.5 dB (SD 5.3) BC: mean ↓: −0.2 dB (SD 5.6) ABG: mean ↓: −4.7 dB (SD 6.9) 7 days: +11.6−dB 1–6 months: −2.2 dB |
Pre Mean: 76.1 dB (range 70–90) (abnormal <90 dB nHL) Post mean: 94.4 dB (range 80–100) ( Not further defined |
x | x | x | x | x | 7.8 (range 4–13) ICU: 2.7 (2–8) |
||
Goddard and Wilkinson ( |
AC ( Pre mean pure-tone average (PTA): 21.1 dB (SD 21.6) Post mean PTA: 22.5 dB (SD 16.7) BC ( Pre mean PTA: 15.6 dB (SD 14.1). Post mean PTA: 16.2 dB (SD 17.1) ABG ( Pre: 95.8% Post: 95.1% |
x | x | x | x | x | Tegmen mastoideum Defect: 4/24 Temporary facial weakness: 1/24 |
x | ||
Ward et al. ( |
2–8 kHz: significant increasein mean thresholds BC: Pre Mean PTA: 8.4 dB (SD 10.4) 7–10 days: 19.2 dB (SD 10.4) >1 month: 16.4 dB (SD 18.8) ABG: Pre: 16.0 dB (SD 7.6) 7–10 days: 16.4 dB (SD 11.1) >1 months: 8.1 dB (SD 8.4) Pre: 98.6 (SD 4.1) 7–10 days: 94.4 (SD 14.5) >1 months: 93.1 (SD 19.6) |
x | x | x | x | x | Hemotympanum/middle ear effusion (7–10 days post): 84% Subgroup had significantly larger ABG: 18.1 dB (SD 11.4) vs. 8.8 dB (SD 3.9) |
x | ||
Agrawal et al. ( |
x | x | Horizontal: >0.7 OR clinically normal: Pre: 18/18 1 week post: 11/18 |>6 weeks post: 16/18 |
x | x | x | x | x | ||
Crane et al. ( |
ABG (largest): Pre: 25.83 dB (usually 0.25 kHz) Post: 15.55 dB (frequency not reported) Decreased: 11/18 Increased: 3/18 No change: 4/18 |
Pre mean: 67.5 dB Post mean: 69.1 (absent in 2) Increased: 5/6, unchanged: 1/6 Normal: >80 dB nHL |
x | x | x | x | x | |||
Crane et al. ( |
AC: mean ↑: 10 ± 23 dB (range −45 to +45 dB) BC: mean: not reported |
Pre ( Threshold <85 dB: 16/19 Post ( Absent: 10/11 |
x | x | x | x | x | |||
Carey et al. ( |
x | x | Horizontal: Pre: 0.94 ± 0.07 Post: 0.90 ± 0.24 % Change −5% ( Superior: Pre: 0.75 ± 0.13 Post: 0.42 ± 0.11 % Change: −44% ( Posterior: Pre: 0.84 ± 0.09 Post: 0.73 ± 0.20 % Change: −13% ( |
x | x | x | Epidural hematoma: 1/19 Cellulitis of the wound: 1/19 Transient diabetes insipidus: 1/19 |
x | ||
Phillips et al. ( |
AC, BC: correction of pseudo-conductive hearing loss: 4/5 Residual (>4 months): none |
Pre: 65 dB (60–70) Post: 82 dB (75–90) Normalized: 5/5 |
x | x | x | 4 months | Vertigo: Transient: 4/5 Persistent: 1/5 |
x | ||
Limb et al. ( |
AC: no sign.change BC: no sign.change ABG: partial closure: 5/29 Pre: 96.5 ± 5.0% Post: 96.8 ± 3.8% ( Pre: 98 ± 2.3% Post: 99 ± 2.1% ( Pre: 98.7 ± 2.3 Post: 65 ± 56.6%( |
x | x | x | x | x | x | x | ||
R | Hillman et al. ( |
AC, BC not reported ABG >10 Pre: 2/16 Post: 2/2 decreased |
x | x | x | x | >3 months | Reoccurrence of symptoms after 5 months due to a shift of the bone cement: 1/14 | x | |
Transmastoid | P | Van Haesendonck et al. ( |
AC: Pre median PTA: 25 dB post median PTA: 18 dB Median change: 1 dB BC PTA: Pre median PTA: 11 dB Post: 16 dB Median change: −4 dB ABG Pre: 13 dB Post: 5 dB(median change:8 dB) |
x | x | x | x | 1–6 months | Posterior canal BPPV: 2/12 (solved through Epley maneuver) | x |
Beyea et al. ( |
x | x | x | x | x | x | Temporary vertigo: 16/16 Dural tear: 2/16 (low-lying tegmen both cases) |
x | ||
Agrawal and Parnes ( |
AC, BC: not reported ABG: decreased: 1/2 |
x | x | x | x | Temporary vertigo: 3/3 Dural tear: 1/3 |
x | |||
P + R | Fiorino et al. ( |
AC, BC: PTA change <10 dB: 4/6 Conductive hearing loss: Unchanged: 1/1 Newly developed due to MEE: 1/6 |
Pre Mean: 74 dB (1 absent) Post: >90 dB nHL: 5/6 Stayed absent: 1/6 |
x | Procedure not described ( Reduced caloric response: 2/6 |
Procedure not described ( Present: 0/6 |
1.5–2 months | Pneumonia: 2/6 | 2–5 | |
R | Amoodi et al. ( |
x | x | x | Procedure not described ( Present: 0/4 |
Not reported. Follow-up: 1.5–4 years | Temporary vertigo: 4/4 | <1 | ||
Lundy et al. ( |
AC, BC: not reported |
x | x | x | x | >3 months | x | <12 h: 13/37 24 h: 24/37 |
||
Transcanal | RW | Silverstein et al. ( |
x | x | x | x | x | x | x |
Among all studies, 13 reported their audiometric outcomes. Due to the difference in outcome measures, it was, however, not feasible to pool the results (Table
Following plugging plus resurfacing
Another study reported a decrease in hearing in the majority of patients (11/18), despite a reduction in mean of the largest ABGs. This effect is most likely due to an overall decrease in BC and not an increase in AC (
One large-series study found no significant change in AC, BC, and ABG over the frequencies 0.5–3 kHz. It did not address higher frequencies (
Resurfacing the dehiscence
Following transmastoid plugging one study found decrease in median AC PTA from 25 to 18 dB and an increase in median BC PTA from 11 to 16 dB. The ABG shrunk from 13 to 5 dB and no SNHL was observed (
Plugging plus resurfacing led to a change of PTA <10 dB in 4/6 patients, meaning there was no significant change in these patients. It was not described whether PTAs increased or decreased (
Transmastoid resurfacing led to an AC improvement (4/4) and no BC (4/4) in one study. The study reported at least partial closure of the ABG in all patients (4/4) (
Conclusion: The way of assessing the results on AC, BC and ABG varied significantly among the studies. No conclusion could be drawn regarding the effect of plugging plus resurfacing
Speech audiometry was performed in very few studies and also assessed using different outcome measures, which did not allow pooling of the results. Outcome measures included: the SRT (
The SRT increased in the first week after surgery and decreased again under the baseline after 1–6 months (
Conclusion: Speech audiometry is performed in very few studies and the outcome measures vary. However, the assessment of speech audiometry is often part of the publication criteria when reporting hearing outcomes (
Vestibular-evoked myogenic potentials were assessed in five studies of which four assessed cVEMPs and one did not announce if it concerned cVEMPs or oVEMPs (
Three studies assessed results after plugging plus resurfacing
Regarding the transmastoid approach, VEMPs were studied only in one study where plugging plus resurfacing was performed (
Conclusion: Generally when the change in VEMP threshold was analyzed, an increase of the threshold was reported. However, one study did not report the exact type of VEMP that was assessed and a number of studies did not report VEMP thresholds at all.
Plugging plus resurfacing the canal
Little literature was available on the effect of transmastoid plugging plus resurfacing, but the existing studies showed that it leads to an increase in VEMP threshold >90 dB in most cases.
No assessment was done following round window reinforcement. Furthermore, it is important to recognize that reference values for VEMP thresholds differ vastly between laboratories. Therefore, consensus is needed how to report on VEMPs. Grade of evidence: IV; grade of recommendation: D.
Only two studies assessed the effect of surgery on the HIT. One other study mentioned HIT results for only two patients. No further pre- and postoperative data of the remaining population were reported (
The other study assessed the VOR gain for all canals using vHIT. A significant decrease in gain of 44% (
Conclusion: The evidence was not sufficient to compare the effect of the different surgical techniques on VOR gain. However, literature suggests that plugging plus resurfacing the dehiscence
No literature was available on the change in caloric response following plugging, plugging plus resurfacing or resurfacing
Conclusion: The evidence for the effect of surgery on caloric response was not sufficient enough to draw conclusions, but existing literature suggests that there is no decrease in caloric response following transmastoid plugging plus resurfacing. Grade of evidence: IV; grade of recommendation: D.
No literature was available on the presence of induced nystagmus following plugging, plugging plus resurfacing or resurfacing
Conclusion: The evidence for the effect of surgery on the presence of induced nystagmus was not sufficient enough to compare the different surgical techniques, since only transmastoid plugging plus resurfacing was investigated. Grade of evidence: IV; grade of recommendation: D.
The presence of adverse effects was assessed in 11 studies. No evidence was available on the effects of plugging
Resurfacing
Transmastoid plugging caused posterior canal BPPV in 2/12 patients (
Following plugging plus resurfacing, 2/6 patients developed pneumonia (
Transmastoid resurfacing was complicated by a dural tear in 1/3 cases (
Conclusion: The severity of local adverse effects was higher following the middle fossa approach than the transmastoid approach. A transient increase in vertigo seemed to develop in the majority of cases regardless of the approach. The risk for intraoperative dural tears using the transmastoid approach seemed to be higher in patients who had evidence of a low-lying tegmen. Grade of evidence: IV; grade of recommendation: D.
The length of hospital stay was reported in four studies. No evidence was available on the effects of plugging
Transmastoid plugging plus resurfacing was followed by an average hospital stay of 2–5 days (
Conclusion: According to the available evidence, plugging plus resurfacing
This literature review highlights difficulties that researchers face when investigating a relatively new condition. The majority of included studies were retrospective and since SCDS is rare, studies inevitably have small sample sizes. Furthermore, the lack of standardized outcome measures made it difficult to pool or compare outcomes (Table
Even though a number of significant reviews have been published since the last database search of this review, the majority of them did not address this particular issue (
Some findings, however, were consistently reported. Overall an improvement of clinical symptoms and objective measures was found in the majority of patients regardless of the approach or closure technique. In most cases adverse effects or worsening of vertigo or hearing were temporary, typically resolving after several weeks. The surgical approach appears to determine the length of hospital stay, although differences in health care organization need to be considered. On average the middle fossa approach was followed by a longer hospital stay than the transmastoid and transcanal approaches. Adverse effects varied depending on the type of approach and anatomical features of the patient.
From the literature reviewed, it appears that surgery has a positive impact on the symptoms of SCDS but due to the use of different non-standardized outcome measures, surgical techniques could not reliably be compared. This is consistent with recent findings (
It is important to mention that not all the available diagnostic tools were addressed within this literature review, as some of them were not applied in any of the eligible studies. For example, it has previously been reported that the air conducted ocular VEMPs are superior to cVEMPs in the diagnosis of SCDS, and that electrocochleography could reflect the presence of a third mobile window (
For a standardized protocol we strongly recommend the inclusion of assessments of symptom severity and changes in vestibular as well as auditory function in patients with SCDS before and after surgery at set times.
Although this review aimed to evaluate the available literature in a systematic fashion, the literature search was done by the first author alone. The evaluation was done by the first and last author. Furthermore, not all available databases have been searched and the reviewing process was restricted only to published reports. No correspondence was established with the authors of the individual studies to obtain unpublished data. Therefore, publication bias might have influenced the conclusion of this review.
On the study level, this review is limited by the retrospective nature of the majority of the analyzed studies. All reviewed studies show relatively weak internal validity due to small populations, high risk for both selection and information bias. The prospective study presented in this review consisted of a larger population, but was neither blinded nor randomized. Therefore, internal validity of this study was also moderate. The differences in methodology among studies made a comparison and pooling of the results impractical.
Generally, surgery has a positive impact on the symptoms of SCDS but due to the use of different outcome measures among studies, surgical techniques could not be compared quantitatively. Standardized assessment tools, outcome measures and set timeframes for patient follow-up are needed. Based on this review, we recommend the inclusion of assessments of symptom severity and changes in both vestibular as well as auditory function in patients with SCDS before and after surgery into the standardized protocol.
MO: study design, literature search, data analysis, and writing of the article. RS: study design and reviewing manuscript. HK, JT, VR, and YT: reviewing manuscript. RB: study design, data analysis, and reviewing manuscript.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The authors would like to thank Bryan Ward and John Carey from the Department of Otolaryngology-Head and Neck Surgery of Johns Hopkins School of Medicine for reviewing a pre-publication version of this manuscript and suggesting edits that made it more precise and comprehensible.