Superior Canal Dehiscence Research Articles

Method of registration of vestibular myogenic evoked potentials in the diagnosis of diseases of the inner ear

The literature review is devoted to the practical application of the method of recording vestibular evoked myogenic potentials (VEMPs) in the diagnosis of the inner ear diseases: superior semicircular canal dehiscence syndrome, Meniere's disease, benign paroxysmal positional vertigo (BPPV), vestibular neuritis. Registration of VMEP is an electrophysiological research method that allows to assess objectively the functional state of the otolith receptors (sacculus and utriculus) and their pathways, which expands the diagnostic capabilities in diagnosis of the inner ear diseases.

Superior semicircular canal dehiscence in the only hearing ear with no symptom: a case presentation

Superior semicircular canal dehiscence in the only hearing ear with no symptom: a case presentation

Diagnosis of Vestibular Diseases Using VEMP and vHIT

In this review, the author reviewed the change of diagnosis of vestibular diseases from the appearance of VEMP (vestibular evoked myogenic potential) and vHIT (video head-impulse test). VEMP is a clinical test for disorders of the otolith organ, while vHIT is a clinical test for disorders of the semicircular canals. Using VEMP and vHIT, it is possible to assess all parts of the vestibular labyrinth at a clinic. VEMP enables clinicians to diagnose “otolithic vertigo/dizziness” and “inferior vestibular neuritis”. Furthermore, VEMP provides valuable information for the diagnosis of endolymphatic hydrops, superior canal dehiscence syndrome, and impairments of the vestibulo-spinal tract and medial longitudinal fasciculus. In addition to the diagnosis of bilateral vestibulopathy and vestibular neuritis, vHIT also enables clinicians to diagnose impairments of the vertical semicircular canals, especially isolated posterior semicircular canal dysfunction. Finally, the author wishes to emphasize that combined use of VEMP and vHIT is very important because combinations of abnormal findings in these tests could provide us with clues to clarifying the etiology and pathophysiology.

Investigation of serum calcium and vitamin D levels in superior semicircular canal dehiscence syndrome: A case control study

ObjectiveIt remains unknown whether calcium metabolism has any effect on the clinical presentation of superior semicircular canal dehiscence (SSCD). Our aim was to analyse the adjusted calcium and vitamin D levels in SSCD patients compared to a control group. MethodsThis was a prospective case-control study performed in a tertiary referral center, university teaching hospital in the UK. It included all new patients with SSCD seen in a dedicated skull base clinic over a 5-year period (2015–2019) compared to a gender and age matched control group. The main outcome of the study was adjusted calcium and Vitamin D levels between the two groups. ResultsA total of 31 SSCD patients were recruited with a matched number of control patients. The mean Vitamin D level on the SSCD group was 44.8 nmoL/l (SD: 20.8) compared to 47.5 nmoL/l (SD: 27.4) on the control group (p = 0.702). Mean Adjusted calcium level was 2.34 mmoL/l (SD: 0.7) for SSCD compared to 2.41 mmoL/l (SD: 0.11) for controls (p = 0.01), being within normal limits for both the SSCD and the control group. ConclusionOur study did not identify a link between Vitamin D levels and presence of SSCD. Normal adjusted calcium values were found in both groups. Despite that a statistically significant lower calcium level was found in the SSCD group which could indicate that suboptimal levels of calcium may affect the micro-environment of the otic capsule at the SSC region.

Evaluation of Superior Semicircular Canal Morphology and Its Relationship with Glenoid Fossa Roof Thickness Using Cone Beam Computed Tomography.

This study aimed to evaluate the bone thickness of the superior semicircular canal (SSC) roof and its relationship with the roof thickness of the glenoid fossa (RGF). The cone beam computed tomography (CBCT) images of 280 patients (560 temporal regions) were surveyed. The lowest thickness of the SSC roof was measured and categorized based on the radiological patterns of the Cisneros et al. classification. The thickness of GF and the presence of dehiscence in this part were determined, as well. The relationship between the thickness of the GF roof and the bone thickness covering the SSC was also assessed. The mean thickness of the SSC roof was 0.93 ± 0.48 mm, with no significant difference among different age groups and genders (p > 0.05). However, superior semicircular canal dehiscence (SSCD) was more prevalent among females over 45 years old. Similarly, the individuals with the dehiscence of the GF roof had a 12.93-fold higher chance of SSCD development. The results indicated that the thickness of the bone overlying the SSC was significantly related to the roof thickness of the GF. However, an increase in age resulted in no significant change in the bone thickness of the SSC roof. Gender also had no role in changing the thickness of the bone overlying the SSC. Considering the decrease in the thickness of the SSC roof among females over 45 years of age, menopause may be responsible for this occurrence as well as for the increase in the prevalence of SSCD.

Patterns of vestibular dysfunction in chronic traumatic brain injury.

Dizziness and imbalance are common following traumatic brain injury (TBI). While these symptoms are often attributed to vestibular dysfunction, the relative contribution of peripheral vs. central mechanisms is unclear. This study investigated the prevalence of semicircular canal and otolith abnormalities in a cohort of patients with chronic TBI and symptoms of dizziness or imbalance. The relationship between vestibular, oculomotor and posturography results was further explored. Clinical records of patients attending the New Zealand Dizziness and Balance Centre from January 2015 to December 2019 were reviewed for consideration in the study. Inclusion required: an age of 18-80 years, a diagnosed TBI, and vestibular assessment using three-dimensional video head impulses (vHIT), cervical and ocular vestibular-evoked myogenic potentials (c and o VEMPs, respectively) and caloric testing. Severe TBI, pre-existing vestibular diagnoses, and incomplete test results were excluded. Rates of abnormalities were determined for each test and compared with results of oculomotor function testing and postural control, measured using the sensory organization test (SOT). Of 158 reviewed records, 99 patients aged 49 ± 15 years (59 female) fulfilled criteria for inclusion in the study. The median time between the head injury and the clinical assessment was 12 (IQR 6-21) months. Abnormalities involving one or more components of the vestibular labyrinth and/or nerve divisions were identified in 33 of 99 patients (33.3%). The horizontal semicircular canal was most frequently affected (18.2%), followed by the saccule (14.1%), utricle (8.1%), posterior (7.1%) and anterior (2.0%) semicircular canals. Vestibular test abnormalities were associated with skull-base fractures, superior canal dehiscence, and focal ear trauma. Oculomotor dysfunction and postural instability were recorded in 41.1 and 75.5% of patients, respectively. Postural instability correlated with abnormal oculomotor function (p = 0.008) but not peripheral vestibular hypofunction (p = 0.336). Dizziness and/or imbalance in chronic TBI was associated with impaired postural stability for tasks requiring high levels of use of vestibular and visual input for balance. Vestibular hypofunction identified through vHIT, VEMP and caloric testing was recorded but was less common, except when the injury involved a fractured skull-base. There was no specific pattern of end-organ or nerve involvement which characterized this group of patients.

Matched Cohort Study of Radiographic Superior Semicircular Canal Dehiscence and Tegmen Dehiscence and Obstructive Sleep Apnea.

To report the frequency of radiographic superior semicircular canal dehiscence (SSCD) and tegmen dehiscence in patients with and without obstructive sleep apnea (OSA). Retrospective matched cohort study. Tertiary care center. Adults with OSA and fine-cut computed tomographic scans including the temporal bone were matched to patients without OSA by age, sex, and type of computed tomography (protocol, scanner type, slice thickness). Ears with otologic surgery or temporal bone tumors were excluded. Prevalence of SSCD and tegmen dehiscence assessed by two independent reviewers. The average body mass index of the OSA patients was 29.2 kg/m 2 with an average apnea-hypopnea index of 36.8. The control group had an average body mass index of 26.2 kg/m 2 . Of the 352 temporal bones, 34 (9.7%) had SSCD in the OSA cohort versus 37 (10.5%) in the control group ( p > 0.05). Seven OSA patients (25.6% of those with SSCD) had bilateral SSCD versus 8 controls (27.6% of those with SSCD; p > 0.05). The majority (87.3%) of dehiscences involved the temporal lobe, with the remaining involving the superior petrosal sinus or both. Of the 352 OSA ears, 90 (25.6%) had a tegmen dehiscence versus 95 (27.0%) in the control group ( p > 0.05). Neither group had a laterality preference for SSCD or tegmen dehiscence. The prevalence of radiographic SSCD and tegmen dehiscences in OSA patients does not significantly differ from age- and sex-matched controls. This is in contrast to a previous case-control study finding patients with symptomatic SSCD to have higher rates of OSA. This may suggest that the effect size of OSA on SSCD prevalence may be limited despite OSA being a risk factor for elevated intracranial pressure.

Tympanostomy tube placement for pressure-sensitive vertigo.

To evaluate tympanostomy tube placement in patients with pressure-sensitive vertigo. Retrospective case series. Six patients with pressure-sensitive vertigo reported resolution of their vertigo and other vestibular symptoms after placement of the tympanostomy tubes. All recurrences of symptoms were due to either extrusion or plugging of the tubes. All patients fulfilled the criteria for vestibular migraine. None of the patients had superior canal dehiscence on imaging or precedent event that triggered the problem, and all had a negative fistula test. Tympanostomy tube placement should be considered in selected patients with vertigo exacerbated by seemingly small changes in atmospheric pressure (e.g., just prior to thunderstorms, air travel, or travel to the mountains). By eliminating the capability of the tympanic membrane to sense changes in pressure with a tube, patients with pressure-induced vertigo (in the absence of perilymph fistula or superior canal dehiscence) may have relief of their symptoms.

Superior Semicircular Canal Dehiscence Presenting as Long-Standing Vertigo

Superior semicircular canal dehiscence (SSCD) is a complex syndrome and the symptoms can mimic other otologic diseases. We describe a case of a female who presented with imbalance for 10 years which has been psychologically disturbing. Cervical vestibular-evoked myogenic potentials and high-resolution computed tomography scan of the temporal bone confirmed the diagnosis of SSCD. The patient's symptoms improved after the closure of the defect. SSCD should be considered as a differential diagnosis in a case of long-standing vertigo.

중두개와 접근법을 통한 상반고리관 피열 증후군의 수술적 치료 1예

Superior semicircular canal dehiscence (SSCD) syndrome is a rare disease characterized by sound and pressure induced vertigo accompanying vertical-torsional nystagmus, caused by dehiscence or absence of a bone overlying the superior semicircular canal. Patients show various extent of symptoms related to hearing and balance impairment, according to the degrees of bony dehiscence of superior semicircular canal. The authors have experienced a 41-year-old male patient with the chief complaint of severe hyperacusis and dizziness. The patient was finally diagnosed as left SSCD, and the symtoms were successfully treated surgically by repairing SSCD via middle cranial fossa approach. We thus report a rare case of SSCD syndrome accompanying not only dizziness but also severe hyperacusis and successfully managed by surgical method via middle cranial fossa approach.

Cochlear Implantation in Far Advanced Otosclerosis: A Systematic Review and Meta-Analysis.

To evaluate speech outcomes and facial nerve stimulation (FNS) rates in patients with far advanced otosclerosis (FAO) after cochlear implantation. A systematic review was performed using standardized methodology of Medline, EMBASE, PubMed, Cochrane, and Web of Science databases. Studies were included if adults with FAO underwent cochlear implantation. Exclusion criteria included concurrent otologic history (e.g., Meniere's disease, superior canal dehiscence), non-English-speaking implant users, case reports, abstracts, and letters/commentaries. Bias was assessed using the Newcastle-Ottawa Scale for cohort studies and the National Institute of Health Scale for case series. The primary outcome measure was speech discrimination and the secondary outcomes were rates of partial insertion and FNS. Twenty-seven studies evaluated cochlear implantation in FAO. Due to the heterogeneity of testing methods, statistical pooling of speech discrimination was not feasible, but qualitative synthesis indicated a positive effect of implantation. Pooled rates of FNS were 18% (95% confidence interval, CI 12%-27%) and the rate of partial insertion was 10% (95% CI 7%-15%). Cochlear implantation in FAO demonstrates significant gains in speech discrimination scores with higher rates of FNS and partial insertion. Laryngoscope, 133:1288-1296, 2023.

Combined Arterial and Venous Phase Computed Tomographic Imaging of the Skull Base in Pulsatile Tinnitus.

To describe the demographic, clinical, and radiologic findings in a consecutive series of patients presenting with a chief complaint of pulsatile tinnitus (PT). Retrospective review of 157 patients undergoing a combined arterial/venous phase computed tomographic (CT) imaging study. Tertiary referral center. Adult patients referred to neurotology faculty for evaluation of PT between 2016 and 2020. Triple phase high-resolution arteriography/venography/temporal bone CT. Prevalence of osseous, venous, and/or arterial pathology, clinicodemographic characteristics. One hundred fifty-seven adults (mean age, 52 years; 79.6% female) were evaluated. A history of migraine headaches was common (19.7%). The average body mass index was 30.0 (standard deviation, 6.8), and 17.2% of subjects had a diagnosis of obstructive sleep apnea. Idiopathic intracranial hypertension was diagnosed by elevated opening pressure on lumbar puncture in 13.4%. Comorbid depression and anxiety were common (25.5% and 26.1%, respectively). Overall, abnormalities were found in 79.0% of scans, with bilateral transverse sinus stenosis (TSS) seen in 38.9% and unilateral TSS found in 20.4%. Fifteen subjects (9.6%) had evidence of osseous etiologies, including superior canal dehiscence or thinning in 8.9% and sigmoid sinus dehiscence in one subject. There were 3 dural arteriovenous fistulae identified. Unilateral PT was ipsilateral to the side of TSS in 84.4% of subjects with unilateral TSS. In a large consecutive series of patients with PT referred for CT venography/arteriography, transverse sinus stenosis was the most common finding at 59%. Venous etiologies for PT should be suspected when patients are referred to neurotologists for evaluation.

Evaluation of Superior Semicircular Canal Dehiscence Anatomical Location and Clinical Outcomes: A Single Institution's Experience

Superior semicircular canal dehiscence (SSCD) is becoming increasingly recognized as a pathology underlying various auditory and vestibular complaints. To date, our understanding of the pathology has yet to attribute specific symptoms to the anatomic location of dehiscence in patients with SSCD. This study aims to address this issue by evaluating the relationship between symptomatology and anatomic location of dehiscence. A single-institution retrospective review of SSCD patients was performed. Information was collected on patient demographics, symptomatology, and anatomic location of dehiscence. High-resolution computed tomography scans of the temporal bones were used to categorize the anatomic SSCD location into 1 of 3 groups: anterior limb, apex, and posterior limb. Lastly, we performed statistical analysis to determine the degree of association between each of the various perioperative factors and anatomic SSCD location. We studied 54 patients in total (32 women, 22 men). Mean age at diagnosis was 53 years (range: 20-82 years) and mean follow-up length was 5.5 months (range: 0.03-27.0 months). The most common anatomical location of superior semicircular canal dehiscence was the apex, which was seen in 68.5% of cases. While preoperative symptomatology was similar among the 3 cohorts, those with apical dehiscences had a significantly higher rate of postoperative improvement of autophony (P= 0.03), aural fullness (P= 0.03), and tinnitus (P= 0.05) as compared to their counterparts. Although our results do not support an association between preoperative characteristics-including symptomatology-and anatomic SSCD location, our findings do suggest that apical dehiscences are associated with greater postoperative symptomatic resolution.

A Single Fast Test for Semicircular Canal Dehiscence-oVEMP n10 to 4000 Hz-Depends on Stimulus Rise Time.

As previously reported, a single test measuring oVEMP n10 to 4000 Hz stimuli (bone-conducted vibration (BCV) or air-conducted sound (ACS)) provides a definitive diagnosis of semicircular canal dehiscence (SCD) in 22 CT-verified patients, with a sensitivity of 1.0 and specificity of 1.0. This single short screening test has great advantages of speed, minimizing testing time, and the exposure of patients to stimulation. However, a few studies of the 4000 Hz test for SCD have reported sensitivity and specificity values which are slightly less than reported previously. We hypothesized that the rise time of the stimulus is important for detecting the oVEMP n10 to 4000 Hz, similarly to what we had shown for 500 and 750 Hz BCV. We measured oVEMP n10 in 15 patients with CT-verified SCD in response to 4000 Hz ACS or BCV stimuli with rise times of 0, 1, and 2 ms. As a result, increasing the rise time of the stimulus reduced the oVEMP n10 amplitude. This outcome is expected from the physiological evidence of guinea pig primary vestibular afferents, which are activated by sound or vibration. Therefore, for clinical VEMP testing, short rise times are optimal (preferably 0 ms).

Supralabyrinthine air cell is not present in superior semicircular canal dehiscence.

Objectives:Superior semicircular canal dehiscence (SSCD) is defined as a defect in the bone overly the superior semicircular canal (SSC). The purpose of this study is to evaluate the pre-operative imaging examinations of patients who have undergone SSCD repair. We hypothesize that these patients will not have a supralabyrinthine air cell on the side of surgery.Material and Methods:Our group retrospectively reviewed 50 consecutive pre-operative computed tomography (CT) temporal bone examinations who had confirmed SSCD on intraoperative examination and underwent repair for the presence of a supralabyrinthine air cell.Results:100% of patients who had confirmed SSCD on intraoperative examination had no supralabyrinthine air cell on pre-operative CT of the temporal bone.Conclusion:This study shows that a supralabyrinthine air cell is not present in SSCD. When a supralabyrinthine air cell is present, the roof of the SSC is intact. CT and magnetic resonance imaging (MRI) are often performed together to evaluate for SSCD and exclude other etiologies. We propose that if a supralabyrinthine air cell is seen on MRI, no CT is necessary, thus avoiding unnecessary radiation exposure and additional imaging costs to the patient.

Vestibular Migraine Confounds Management of Superior Canal Dehiscence Syndrome.

To investigate the prevalence of vestibular migraine (VM) in a cohort of patients with radiologic confirmation of superior canal dehiscence (SCD) and to compare management of superior canal dehiscence syndrome (SCDS) in patients with and without comorbid VM. Retrospective review of a SCD database. University-based tertiary medical center. Ninety-one patients identified with SCD from 2009 to 2017. None. Coincidence of VM and SCD, and resolution of symptoms. Ninety-one patients with SCD met the inclusion and exclusion criteria. VM was diagnosed in 36 (39.6%) patients. Of those receiving medical therapy for VM alone, five (45.5%) reported symptom resolution, five (45.5%) reported partial improvement, one (9.1%) had no change, and none worsened. Fifteen patients (41.7%) were treated with both surgery (for SCD) and medical therapy (for VM). Seven (46.7%) reported symptom resolution, seven (46.7%) reported partial improvement, and one (6.7%) worsened. There was no statistically significant difference in symptom resolution between SCD + VM patients who were treated medically compared with those treated with medical therapy and surgery (p = 0.951). There was no significant difference in symptom resolution after surgery between SCD + VM and SCD-only cohorts (p = 0.286). This is the first study describing the incidence of VM in a cohort of patients with SCDS. The symptoms of VM confound those of SCDS and unrecognized or undertreated VM may contribute to surgical failure in SCDS. Therefore, we recommend a high index of suspicion for VM in patients with SCDS and a trial of medical therapy in the setting of suspected VM.

Etiopathogenesis behind Semicircular Canal Dehiscence Syndrome: Review Article

AbstractSemicircular canal dehiscence remains one of the rare and least touched chronic vestibular diseases worldwide. Even though microbial, congenital, and genetically determined, as well as mixed characteristics are known to be involved in the pathogenesis of superior semicircular canal dehiscence syndrome (SSCDS), many facets of the pathogenesis of semicircular canal dehiscence syndrome still need to be simplified. Management plan related to pathogenesis has not yet been established. The primary objective of this review is to present and evaluate the etiopathogenesis behind SSCDS. This study is a systematic narrative review. A PubMed search (1970–2022) was performed for studies on epidemiology and pathogenesis of SSCDS. All included articles were categorized according to level of evidence. Five hundred and sixty papers were identified, of which 25 were found to be relevant for this review. SSCDS is a multifactorial disease. There is still no consensus as to what the specific etiology is behind the syndrome. No convincing evidence is available for most associated factors and pathogenesis. Important objectives in research of SSCDS should be achieving consensus about the definition of SSCDS and gaining more in-depth knowledge of the pathogenesis of SSCDS, especially the role of congenital and acquired causes. There is still a need for further well-designed studies on the various etiopathogenesis and management of SSCDS.

Positioning for Middle Cranial Fossa Repair of Superior Semicircular Canal Dehiscence.

Positioning for Middle Cranial Fossa Repair of Superior Semicircular Canal Dehiscence.

Long-Term Outcomes of Round Window Reinforcement for Superior Semicircular Canal Dehiscence Syndrome.

To report long-term patient reported outcome measures (PROMs) after standardized round window rein-forcement (RWR) with thin cartilage and perichondrium for superior semicircular canal dehiscence syndrome (SSCDS). Cross-sectional survey in 2020 and retrospective longitudinal study of outcomes at 3 months, 1 year, and last follow-up after 28 consecutive RWRs. Endpoints were the last follow-up for PROMs and 1 year postoperatively for audiometry and cVEMP. At the last follow-up (mean 2.4 years postoperatively), improvement was reported for 19/28 ears (68%) in symptoms overall; for 17/27 ears (63%) in auditory symptoms, and for 12/24 (50%) in vestibular symptoms. Nine ears (32%) required further surgery. No major complications occurred. On the group level, postoperative improvement at 3 months declined significantly for auditory and vestibular symptoms over time, and stayed stable beyond 1 year. Improved ears had on average 2.9 years follow-up. Improvement correlated significantly with SSCD length, and was associated with contralateral dehiscence. Thirteen ears (46%) had another potential cause of vestibular symptoms. This group showed significantly less improvement. Audiometric test results did not predict PROMs. Since long-term outcomes do not compare with those reported for plugging and repair, RWR is not suggested as a first line intervention for SSCDS. Considering the stable rates of improvement on average 2.9 years postoperatively and the absence of major complications, RWR may be an alternative to plugging or repair in fragile patients who do not accept the risk of complications with more invasive surgery, and who accept that results may deteriorate over time.

Postoperative Outcomes of Patients with Thin Bone Overlying the Superior Semicircular Canal: A Single Institution's Experience

Superior semicircular canal dehiscence (SSCD) is defined by a bony defect overlying the superior semicircular canal (SSC) in the middle cranial fossa floor, causing a myriad of vestibular and auditory symptoms. Patients with thin bone without full dehiscence overlying the SSC also present with similar symptoms. There are currently no guidelines for surgical management of patients with thin bone. The authors offer their experience with thin bone patients to characterize their symptomatology and explore whether these patients benefit from surgical intervention typically offered to SSCD patients. Two hundred fifty-six patients evaluated for SSCD from 2011 to 2019 were reviewed. High-resolution coronal computed tomography scans with 0.6-mm slice thickness of the temporal bones were assessed to determine whether the patient had a true dehiscence or a thin bone covering overlying the SSC. Bone that was ≤0.5mm was considered to be "thin bone." Parameters of interest included patient demographics as well as preoperative and postoperative symptomatology. A P value < 0.05 was considered statistically significant. Forty-eight patients met inclusion criteria of having "thin bone." The mean age was 48.13±12.03years, and 65.5% of patients were female. Of the preoperative symptoms evaluated, the greatest postoperative symptomatic resolution was noted in hearing loss (92.3%), vertigo (94.4%), and oscillopsia (100%). Dizziness (56.5%) had the lowest symptomatic resolution rate. Surgical management of thin bone patients via middle fossa craniotomy, a similar technique to SSCD repair, provides significant symptomatic resolution. Therefore, surgery should be considered in thin bone patients with debilitating symptoms, albeit not having a true dehiscence.