Benign Paroxysmal Positional Vertigo Commonly Occurs Following Repair of Superior Canal Dehiscence

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1 The Laryngoscope VC 2015 The American Laryngological, Rhinological and Otological Society, Inc. Benign Paroxysmal Positional Vertigo Commonly Occurs Following Repair of Superior Canal Dehiscence Samuel R. Barber, MS; Yew Song Cheng, BM, BCh; Maryanna Owoc, BA; Brian M. Lin, MD; Aaron K. Remenschneider, MD, MPH; Elliott D. Kozin, MD; Daniel J. Lee, MD Objectives/Hypothesis: Repair of superior canal dehiscence (SCD) often results in the resolution of preoperative auditory and vestibular symptoms; however, many patients experience dizziness in the postoperative period. Postoperative dizziness may be the result of new-onset benign paroxysmal positional vertigo (BPPV). This study aims to investigate the prevalence of BPPV before and following SCD repair. Study Design: Retrospective chart review at a tertiary care center. Methods: Electronic medical records were reviewed for patients with a diagnosis of SCD syndrome (SCDS) between January 2002 and May Collected information included demographic data, incidence of BPPV diagnosed by Dix-Hallpike maneuver before and following surgery, operative technique, repair material, and the duration of time to BPPV onset. Results: A total of 180 patients with a diagnosis of SCDS were identified: 84 patients underwent surgery (operated subjects) and 96 were observed (nonoperated, control group). In operated subjects, 20 of 84 (23.8%) developed BPPV following SCD repair versus 6.2% of nonoperated (P < 0.005). Benign paroxysmal positional vertigo lateralized to the operated side in all but one subject whose laterality was unknown (P < ). There were no associations of BPPV with surgical approach (P ) or repair material (P ). The majority of subjects (58%) were diagnosed with BPPV within 3 months of surgery. Conclusion: New-onset BPPV occurs commonly after SCD repair and may be the result of mobilized otoliths from inner ear pressure changes. Although the exact etiology of post-scd repair BPPV remains unknown, postoperative dizziness is important to discuss with patients during preoperative counseling. Key Words: Benign paroxysmal positional vertigo, superior canal dehiscence, superior canal dehiscence syndrome, plugging, resurfacing, surgery, outcomes, dizziness. Level of Evidence: 4. Laryngoscope, 126: , 2016 INTRODUCTION Superior canal dehiscence (SCD) is a bony defect of the superior semicircular canal (SSC). 1 It is referred to as SCD syndrome (SCDS) when associated with auditory and/or vestibular symptoms such as aural fullness, pulsatile tinnitus, hyperacusis, autophony, and pressure- or noise-induced vertigo. 2,3 In some patients, SCD-related symptoms are severe and surgical repair is indicated. Surgical repair is performed using either middle fossa craniotomy (MFC) 4,5 or transmastoid approaches. 6,7 Common repair techniques include resurfacing the dehiscent area with bone graft and fat or fascia, or plugging the SSC with various materials, including bone wax. 5,6,8,9 From the Department of Otology and Laryngology, Harvard Medical School (S.R.B., Y.S.C., M.O., B.M.L., A.K.R., E.D.K., D.J.L.); and the Department of Otolaryngology Head and Neck Surgery, Massachusetts Eye and Ear Infirmary (S.R.B., Y.S.C., M.O., B.M.L., A.K.R., E.D.K., D.J.L.), Boston, Massachusetts, U.S.A. Editor s Note: This Manuscript was accepted for publication November 2, The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Daniel J. Lee, MD, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA daniel_lee@meei.harvard.edu DOI: /lary Surgical management of SCD results in symptom resolution in a high percentage of patients However, studies have demonstrated that in some patients disequilibrium may arise, persist, or even worsen during the postoperative period. 12,14,15 One potential explanation for postoperative dizziness may be the onset of benign paroxysmal positional vertigo (BPPV), a common form of peripheral vertigo believed to be caused by dislodged otoliths that migrate to the semicircular canals, resulting in acute episodic vertigo lasting several seconds to minutes in duration The lifetime prevalence of BPPV in the general population has been estimated at 2.4%. 18,19 To date, an association between SCD repair and the onset of BPPV has not been described in detail. Benign paroxysmal positional vertigo has been described following other otologic surgeries such as cochlear implantation. 20,21 Whereas post-scd repair disequilibrium has been commonly reported in the literature, 9 studies have not explored the specific nature of vestibular symptoms. 11 Herein, we aim to investigate the development of BPPV in patients following surgical management of SCD. We hypothesize that there is an increased rate of BPPV in patients undergoing SCD repair compared to nonoperated patients with SCDS. This study has implications for patient counseling in the preoperative period.

2 MATERIALS AND METHODS The study (study ID: ) was approved by the Human Studies Committee at the Massachusetts Eye and Ear Infirmary, Boston, Massachusetts. Electronic medical records were reviewed for all patients with a diagnosis of symptomatic SCD at a single tertiary care center between January 2002 and May Patients were divided into two groups: operated patients and nonoperated patients (controls). Collected information included demographic data, side of symptomatic SCD, operative details, a history of BPPV, and new-onset BPPV following surgery. We defined the operated group as patients who underwent SCD repair via MFC or transmastoid approaches. We defined patients with new-onset BPPV as those who reported positional dizziness of brief duration who also were found to have either a positive Dix-Hallpike and/or BPPV diagnosed by formal vestibular testing. Details about new-onset BPPV included the date of first documentation, the laterality of symptoms, symptom duration, and resolution. Study inclusion criteria required a diagnosis of SCDS based on clinical signs and symptoms, imaging, and/or vestibular testing. Patients with SCDS had a bony defect of the arcuate eminence of the superior canal or a medial defect associated with the superior petrosal sinus. Asymptomatic patients with anatomical SCD found incidentally on computed tomography were excluded. In order to reduce potential confounders, patients undergoing revision procedures were excluded. Patients with a preoperative history of BPPV were analyzed as a separate group. In sequentially operated patients for whom a second surgery was performed on the contralateral ear, the second side procedure was excluded. Patients undergoing round window occlusion were also excluded. A flow chart illustrating study design is featured in Figure 1. Operative Technique The study occurred at a single tertiary care institution with six surgeons performing SCD repair. The specific surgical techniques used have been previously described. 5,6 Briefly, patients were treated with perioperative antibiotics and steroids, with a steroid taper of 5 to 7 days after the procedure. Patients underwent either an MFC or transmastoid approach. For the MFC approach, a temporal craniotomy centered over the external auditory canal was performed, followed by extradural dissection of temporal lobe dura from the skull base. Once the arcuate eminence defect was visualized, occlusion was performed with bone wax in the majority of cases, although bone, fascia, or fat grafts were also utilized. This was followed by reinforcement and repair of any associated tegmen defects by placement of a split calvarial bone graft and temporalis fascia grafting. Recently, a MFC approach using an angled endoscope was developed at our institution. 4 The procedure uses a smaller craniotomy and minimizes temporal lobe dissection and retraction. This approach was utilized more for medial, downsloping, and blue-lined dehiscences. The transmastoid approach exposed both ampullated and nonampullated limbs of the superior canal through the mastoid antrum, where both were occluded with bone wax followed by a layer of bone pate. Patients who had a bony defect of the medial aspect of the superior canal in association with the superior petrosal sinus underwent the transmastoid approach exclusively. Statistical Analysis Continuous variables that were normally distributed were expressed as means with standard deviation (SD). Variables not normally distributed were expressed as median and interquartile range. The Shapiro-Wilk test for normality was used to test for normal distribution. For group-wise comparisons of normally distributed continuous variables, a t test was used. Wilcoxon rank sum test was used for nonnormally distributed variables. For categorical variables, Fisher s exact test was used. Statistical corrections for multiple comparisons such as Holm-Bonferroni were not performed to ensure identification of all potential associated variables and minimize false negatives. All P values are two-sided, and a significance level of P < 0.05 was considered statistically significant. SAS 9.4 (SAS Institute Inc., Cary, NC) was used to perform all statistical analyses. RESULTS A total of 188 patients with a diagnosis of SCDS were identified. One hundred eighty patients were included, whereas five were excluded because they were undergoing revision surgery and three were excluded for undergoing SCD repair with a prior history of BPPV. Eighty-four patients underwent surgery for SCDS (operated subjects), whereas the remaining 96 did not (nonoperated, control subjects) (Fig. 1). The median follow-up time for operated subjects was 21.2 months and 13.9 months for controls. In six operated subjects who had bilateral procedures, the second-side surgery was excluded. Demographic features of the operated and control groups were not significantly different (Table I). The mean age at diagnosis for patients who underwent repair was 51 years old (SD ) versus 54 years old (SD years) for control subjects (P ). Females were more likely to be diagnosed with SCDS than were males in both operated and control groups (56% female in both groups, P ). The surgical approach was via MFC in 92.9% of cases, and bone wax was utilized for the repair 94% of the time. In operated subjects, 20 out of 84 (23.8%) had documented BPPV following SCD repair, whereas only 6.2% of control subjects had BPPV (P < 0.005) (Table I). Of the 20 operated subjects with postoperative BPPV, 19 cases were ipsilateral to the side of SCD repair (7 right and 12 left), and one patient had symptoms and exam findings that were nonlateralizing (P value < ). There was no statistical significance for associations of BPPV with the type of surgical repair (P ) or the type of repair material utilized (P ) (Table II). The majority of subjects (58%) experienced BPPV symptoms within the first 3 months following SCD repair (Fig. 2). Most symptoms were subjectively reported to occur while turning over in bed. The median number of days to the onset of BPPV following surgery was 83, with a mean of 207 days and SD of (range ). All subjects with BPPV presented with symptoms of episodic positional vertigo and demonstrated geotropic rotatory nystagmus in the plane of the posterior canal on Dix- Hallpike testing. All patients were treated with the Epley Maneuver in the office at the time of BPPV diagnosis. Benign paroxysmal positional vertigo resolved in 10 subjects, persisted in eight subjects, and the outcome was unknown due to lack of follow-up in two subjects (P ). In a subgroup analysis of postoperative BPPV subjects, we found that four in 20 subjects (20%) had at least 2093

3 Fig. 1. Study design. Flowchart of study population, study groups, eligible subjects, and their outcomes. BPPV 5 benign paroxysmal positional vertigo; SCD 5 superior canal dehiscence; SCDS 5 superior canal dehiscence syndrome. mild postoperative high-frequency hearing loss. Threshold increases were between 7 db and 12 db for three subjects, and only one subject experienced severe to profound loss. This overall rate is consistent with reported outcomes for all SCD repairs and does not suggest an association between BPPV and sensorineural hearing loss postoperatively. Three patients reported a history of BPPV prior to SCD repair. At the time of surgery, none had active BPPV. One of the three patients encountered new-onset BPPV symptoms 3.3 months after surgery on the ipsilateral side. DISCUSSION In this retrospective review of 180 cases of SCDS, we find that greater than 20% of patients undergoing SCD repair develop new-onset BPPV in the postoperative setting. Symptoms typically occurred within 6 months of the operation, with the majority (58%) occurring in the first 3 months. The time course and propensity to affect the operated ear suggests an association between SCD repair and BPPV that has not previously been described. Based on the high percentage of BPPV cases following 2094 surgery for SCDS, a preoperative discussion about postoperative BPPV is warranted. Several studies have reported postoperative disequilibrium following SCD repair; however, few discuss a potential etiology. In a meta-analysis of SCD surgical outcomes, Vlastarakos et al. showed that persistent disequilibrium and sensorineural hearing loss were the most frequently reported postoperative complications; however, BPPV was not specifically mentioned as the clinical manifestation of dizziness. 9 A retrospective review by Niesten et al. examined clinical factors associated with prolonged recovery from SCD surgery. 15 Interestingly, although the study did not specifically investigate positional vertigo in relation to SCD surgery, the authors reported that 12% of subjects were found to have postoperative BPPV without substantiating data. Postsurgical positional vertigo has also been reported in studies evaluating cochlear implantation outcomes. 20,21 Similar to this study, a predominance for BPPV ipsilateral to the side of surgery was discovered in the report by Viccaro et al. 20 Our statistical analysis demonstrated a strong association between surgical SCD repair and the development of new-onset BPPV. The temporality and laterality of

4 TABLE I. Descriptive Data of Operated and Nonoperated Cases. Variable Nonoperated Cases (n 5 96) Mean (SD); n (%) Operated Cases (n 5 84) Mean (SD); n (%) P Value Age at Diagnosis 54.1 (11.6) 51.0 (12.6) P Gender P Female 54 (56.3) 47 (56) Male 42 (43.7) 37 (44) SCD Side P < 0.05 Right 22 (22.9) 30 (35.7) Left 38 (39.6) 38 (45.2) Bilateral 36 (37.5) 16 (19.1) Surgical Repair TM 6 (7.1) MFC 62 (73.8) MFC 1 endoscopic assistance 16 (19.1) Surgical Repair Material Bone wax only 79 (94.1) Other 5 (5.9) History of Prior BPPV P < No 90 (93.8) Yes 6 (6.2) Postoperative BPPV No 64 (76.2) Yes 20 (23.8) Side of BPPV P Right 3 (50.0) 7 (35) Left 3 (50.0) 12 (60) Unknown 0 (0.0) 1 (5) BPPV Resolved P No 2 (33.3) 8 (40.0) Yes 1 (16.7) 10 (50.0) Unknown 3 (50.0) 2 (20.0) For continuous variables, t test was used for P values. For all other variables, Fisher s exact test was used. BPPV 5 benign paroxysmal positional vertigo; MFC 5 middle fossa craniotomy; SD 5 standard deviation; TM 5 transmastoid. vertiginous symptoms suggests a causal relationship, but the exact mechanism is currently unknown. Although speculative, a few proposed mechanisms stand to reason TABLE II. Association of BPPV With Surgical Technique, Repair Material, and Revision Procedure. Variable BPPV Following Repair No BPPV Following Repair P Value Surgical Technique P MFC MFC 1 endo 4 12 TM 0 6 Repair Material P Bone wax only Other 0 5 BPPV 5 benign paroxysmal positional vertigo; endo 5 endoscopic approach; MFC 5 middle fossa craniotomy; TM 5 transmastoid. in explaining an iatrogenic etiology. First, it is possible that the occlusive material in the nonampullated end of the superior canal could fragment and travel toward the ampulla of the posterior canal. Fragments of bone wax, soft tissue, or even bone dust may be introduced to the semicircular canal during repair, resulting in positional disturbance of the cristae ampullaris or utricle postoperatively. In our study, all subjects who experienced postoperative BPPV had SCD repair with bone wax. This is likely due to the fact that bone wax was used in the vast majority of repairs; however, there is insufficient statistical power in our data set to either compare repair materials. In addition to wax fragmentation, it is possible that postoperative BPPV may be related to an inflammatory reaction from wax occlusion. 6,22,23 An animal study by Kim et al. identified serous inflammation in lateral canals occluded with wax. These clinical and animal studies are far from definitive. Future studies, including postmortem otopathology investigations, may provide further insight into pathophysiology of wax occlusion. 2095

5 Fig. 2. Time of onset for BPPV following SCD repair. The majority of patients were diagnosed with BPPV zero to 3 months following surgery. BPPV 5 benign paroxysmal positional vertigo; SCD 5 superior canal dehiscence. [Color figure can be viewed in the online issue, which is available at Additionally, previous studies have hypothesized that the vibratory force of drilling could be responsible for loosened otoliths on the side of surgery. 20 Diamond burs are utilized in transmastoid SCD repair to fully expose the canal endosteum prior to plugging or resurfacing; however, the otic capsule is rarely, if ever, drilled in MFC surgery. Our results did not suggest a preponderance of TM cases to incur a higher postoperative rate of BPPV. Lastly, the occlusion of the SCD itself could create a sudden change in pressure inside the canals, resulting in a pressure wave that agitates the otoconia of the posterior canal cristae ampullaris or the utricle. Indeed, postsurgical BPPV may be a misnomer; a more accurate description may be iatrogenic paroxysmal positional vertigo (IPPV). Further investigation is required to better understand the etiology of this observed association, definitively understand a causal relationship, and potentially define methods of preventing iatrogenic injury. Only 50% of subjects with new-onset BPPV had documented resolution of symptoms in our study, which is much lower than published rates of up to 91% found in the literature. 24 Symptom resolution was observed in patients following treatment with the Epley maneuver, vestibular physical therapy, or following watchful waiting. It is not known whether this new-onset dizziness is truly classical BPPV with associated displaced canaliths or perhaps a feature of postoperative vestibular hypofunction. In either case, evidence points toward an iatrogenic cause: IPPV. There are several limitations to this study. First, as a retrospective review, chart data may be limited and there is the potential for sample bias. To minimize bias, all known patients diagnoses with SCDS were evaluated. Secondly, statistical corrections for multiple comparisons such as Holm-Bonferroni were not performed to ensure identification of all potential associated variables and minimize false negatives. Third, the follow-up length was not standardized between study groups and was shorter for control patients. New cases of BPPV in nonoperated subjects would have been missed if patients 2096 did not return for subsequent evaluation. Moreover, BPPV symptom resolution could be underreported with a lack of long-term follow-up. This may be particularly true in SCD repair subjects with successful outcomes who otherwise had no persistent vestibular issues. Last, formal vestibular testing was not performed on all patients. Although symptoms were elicited in the plane of the posterior canal for all subjects, details such as the direction of nystagmus and formal testing may more specifically aid in localizing and describing postoperative dizziness. Future studies should include pre- and postoperative vestibular testing to better localize and quantify patient complaints. CONCLUSION Benign paroxysmal positional vertigo commonly occurs following SCD repair. The exactly etiology of postoperative development of BPPV remains unknown. Surgeons may wish to discuss BPPV during patient surgical consultations. Acknowledgments Authors (S.R.B., Y.S.C., M.O.) contributed equally to this article. BIBLIOGRAPHY 1. Minor LB, Solomon D, Zinreich JS, Zee DS. Sound- and/or pressureinduced vertigo due to bone dehiscence of the superior semicircular canal. Arch Otolaryngol Head Neck Surg 1998;124: Minor LB. Clinical manifestations of superior semicircular canal dehiscence. Laryngoscope 2005;115: Minor LB. 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