Semicircular Canal Research Articles

External auditory canal atresia affecting the horizontal canal of a 2‐year‐old Labrador Retriever dog

AbstractA 2‐year‐old, female neutered, Labrador Retriever dog was presented with left otalgia. Otoscopic examination revealed a blind ending left external ear canal. Magnetic resonance imaging confirmed an abrupt narrowing of the lateral aspect of the horizontal canal, medial to which the remaining horizontal ear canal and middle ear cavities contained well‐delineated, homogenous, T2w, fluid‐attenuated inversion recovery and T1w hyperintense, non‐contrast enhancing material. A diagnosis of external auditory canal atresia was made based on the imaging findings. Considering the patient's age and absence of preceding trauma, a congenital cause was considered most likely. Surgical treatment by way of a total ear canal ablation with lateral bulla osteotomy was performed. At the re‐check appointment, the surgical site had healed well and there were no associated complications noted; a telephone call with the owner 5 months later documented no clinical concerns.

Impact of audiovestibular factors on prognosis in patients with sudden sensorineural hearing loss without vertigo.

This study aimed to investigate the hearing outcomes in patients with sudden sensorineural hearing loss without vertigo (SSNHLwoV). Patients with SSNHLwoV managed from December 2016 to March 2020 were prospectively enrolled in an academic tertiary referral center. Fifty-one patients with SSNHLwoV who completed high-dose steroid treatment. The hearing prognosis was analyzed using a multivariate Cox regression model. The rates of complete, partial, and no hearing recovery were 52.9%, 17.6%, and 29.4% in patients with SSNHLwoV, respectively. The video head impulse test (vHIT) of the posterior semicircular canal (PSC), high-tone hearing loss (4-8kHz) ≥ 30 dB, and average hearing threshold (0.5-1-2-4kHz) were significantly associated with incomplete recovery of hearing after treatment. In multivariate analysis, the vHIT of the PSC (hazard ratio [HR], 14.502; 95% confidence interval [CI], 1.371-153.355) and high-tone hearing loss ≥ 30 dB (HR, 9.170; 95% CI, 2.283-36.830) remained robust. Abnormal vestibular function tests were performed in 80.4% of the patients with SSNHLwoV. Abnormal vHIT of the PSC and high-tone hearing loss ≥ 30 dB were independent factors resulting in incomplete recovery of hearing in patients with SSNHLwoV. In the SSNHLwoV cohort, the caloric test was not significantly associated with hearing prognosis, and vHIT was a feasible predictor of treatment outcome.

Adoption of the international classification of vestibular disorders criteria in cases of Benign positional paroxysmal vertigo: a single-center experience.

Benign positional paroxysmal vertigo (BPPV) stands as the commonest cause for vertigo. It accounts for 20% of all cases of vertigo, even with its high prevalence rate it often goes underdiagnosed and undertreated. Development of the consensus document by the Bárány society's International Classification of Vestibular Disorders (ICVD)significantly facilitates the diagnosis of BPPV and its variants. This study assesses the utilisation of ICVD criteria for managing BPPV. This is a cross-sectional descriptive study conducted at a tertiary care hospital in Northern India spanning from November 1, 2022, to November 30, 2023. A total of 110 participants diagnosed with BPPV were enrolled consecutively. All participants underwent Dix-Hallpike and supine log roll positional maneuvers. Diagnosis was made based on the history and type of nystagmus seen, and classified as per the ICVD criteria. Posterior semicircular canalolithiasis (pc-BPPV) accounted for 25.45% of cases and horizontal canal canalolithiasis (hc-BPPV) accounted for 20.91% of cases. Probable BPPV, spontaneously resolved (pBPPVsr) was diagnosed in 16.36% of participants and possible BPPV(pBPPV) was diagnosed in 18.18% of participants. Multiple canal BPPV (mc-BPPV) accounted for 17.27% of cases. One participant was diagnosed with horizontal canal cupulolithiasis and anterior canal canalolithiasis respectively. No participant was diagnosed with posterior canal cupulolithiasis. The most common type of BPPV was pc-BPPV followed by hc-BPPV. The affected canal in possible BPPV, can be identified, and appropriate repositioning maneuvers are effective in treating them as well as aids in confirming the diagnosis. The diagnostic clarity provided by ICVD, aids in effective management of BPPV. More studies with larger sample size are required to further validate its clinical utility.

3-Dimensional Printed Model of the Temporal Bone for Neurosurgical Training.

The development of neurosurgical skills stands out as a paramount objective for neurosurgery residents during their formative years. Mastery of intricate and complex procedures is a time-intensive process marked by a gradually ascending learning curve. Consequently, the study and simulation on surgical models assume significant importance. One of the most intricate neuroanatomical regions includes the petrous and mastoid portions of the temporal bone. These regions host critical, highly functional, and vital neurovascular structures, including the facial nerve, cochlea, semicircular canals, internal carotid artery, and middle ear. This fully open-source 3-dimensional (3D) model of the temporal bone, created for educational purposes, should be easily and economically reproducible using a 3D printer, offering all residents the opportunity to understand the spatial location, three-dimensional anatomical structures, and fundamental intricacies of mastoidectomy. A 3D model of the temporal bone was fabricated using a computed tomography (CT) scan derived from an actual human body. The CT scan of the model was meticulously juxtaposed with the reference sample CT scan. Neurosurgical residents were recruited as participants for this study. Each participant was tasked with executing a mastoidectomy on 2 separate occasions, with a 2-week interval between attempts. Throughout these sessions, various parameters, including the time taken for task completion, the volume of bone removal, and any potential complications, were systematically registered. The mean volume of bone removed increased by 34.5%, and the mean task time and the mean number of complications decreased by 10.3% and 25%, respectively, during the training. Engaging in training with cost-effective anatomical models constitutes a valuable tool for refining technical skills during residency. We posit that this type of model training should be incorporated as part of the trainee's curriculum during the residency program because of the myriad advantages evidenced by the findings of this study.

Goggle Versus Remote-Camera Video Head Impulse Test Device Comparison.

This study compared remote versus goggle video head impulse testing (vHIT) outcomes to validate remote-camera vHIT, which is gaining popularity in difficult to test populations. Seventeen controls and 10 individuals with vestibular dysfunction participated. Each participant completed remote-camera and goggle vHIT. The main outcome parameters were canal gain, frequency of corrective saccades, and a normal versus abnormal rating. Horizontal and vertical canal vHIT gain was significantly lower in the vestibular compared with the control group; remote-camera gains were significantly lower compared with goggle gain for the vestibular group only. The devices categorized control versus vestibular canals identically except for one vertical canal. In the vestibular group, there was not a significant difference in the percentage of compensatory saccades between devices. These data provide validation that results obtained with a remote-camera device are similar to those obtained using a standard goggle device.

A morphometric comparison of the ductus reuniens in humans and guinea pigs, with a note on its evolutionary importance.

The mammalian inner ear contains the sensory organs responsible for balance (semicircular canals, utricle, and saccule) and hearing (cochlea). While these organs are functionally distinct, there exists a critical structural connection between the two: the ductus reuniens (DR). Despite its functional importance, comparative descriptions of DR morphology are limited, hindering our understanding of the evolutionary diversification of hearing and balance systems among mammals. Using virtual 3D models derived from micro-CT, we examine the morphology of the DR and its relationship to the bony labyrinth in humans compared to that in a commonly used animal model, the guinea pig. Anatomical reconstructions and univariate measurements were carried out in the software 3D Slicer. Data indicate similarities in DR morphology between humans and guinea pigs in terms of overall shape. However, there are considerable differences in relative DR length and width between humans and guinea pigs. Humans possess a relatively shorter and narrower DR but with wider openings to the saccule and cochlear duct. This results in a relatively more constricted DR lumen in humans which may differentially limit fluid transfer between the saccule and cochlea. Our results reveal previously hidden morphological diversity in the communication between the hearing and balance systems of the mammalian inner ear which may indicate alternative strategies for isolating the Organ of Corti from the peripheral vestibular system throughout mammalian evolution.

Symptomatology in Unilateral Versus Bilateral Superior Canal Dehiscence Patients Undergoing Unilateral Surgery.

To compare symptomatology in patients with unilateral versusbilateral superior semicircular canal dehiscence who underwent unilateral surgical repair. Retrospective cohort study. Single surgeon series at tertiary academic medical center from 2002 to 2021. Patients were administered a standardized questionnaire regarding the presence or absence of 16 symptoms (11 auditory and 8 vestibular) pre- and postoperatively. Symptom rates were compared between patients with unilateral and bilateral dehiscence, and paired statistical testing was used to analyze symptom improvement with surgery. Our final cohort included 125 patients, 93 (74%) with unilateral superior canal dehiscence syndrome(SCDS) and 32 (26%) with bilateral SCDS. Bilateral patients had an increased burden of auditory and vestibular symptoms compared to unilateral patients before surgery (7.6 vs 6.2, P = .03) and after surgery (3.1 vs 1.9, P = .02). Both groups experienced a significant reduction of symptoms following repair (P < .01 for both). Our study has 2key findings: First, patients with bilateral dehiscence seem to be more symptomatic, reporting more auditory and vestibular symptoms both before and after surgery. Second, bilateral patients still seem to benefit from unilateral repair, demonstrating a significant reduction in the number of symptoms with surgery. Our findings may help inform the management of the sizable proportion of SCDS patients with bilateral defects.

Multifunctional redox modulator prevents blast-induced loss of cochlear and vestibular hair cells and auditory spiral ganglion neurons

Blast wave exposure, a leading cause of hearing loss and balance dysfunction among military personnel, arises primarily from direct mechanical damage to the mechanosensory hair cells and supporting structures or indirectly through excessive oxidative stress. We previously reported that HK-2, an orally active, multifunctional redox modulator (MFRM), was highly effective in reducing both hearing loss and hair cells loss in rats exposed to a moderate intensity workday noise that likely damages the cochlea primarily from oxidative stress versus direct mechanical trauma. To determine if HK-2 could also protect cochlear and vestibular cells from damage caused primarily from direct blast-induced mechanical trauma versus oxidative stress, we exposed rats to six blasts of 186 dB peak SPL. The rats were divided into four groups: (B) blast alone, (BEP) blast plus earplugs, (BHK-2) blast plus HK-2 and (BEPHK-2) blast plus earplugs plus HK-2. HK-2 was orally administered at 50 mg/kg/d from 7-days before to 30-day after the blast exposure. Cochlear and vestibular tissues were harvested 60-d post-exposure and evaluated for loss of outer hair cells (OHC), inner hair cells (IHC), auditory nerve fibers (ANF), spiral ganglion neurons (SGN) and vestibular hair cells in the saccule, utricle and semicircular canals. In the untreated blast-exposed group (B), massive losses occurred to OHC, IHC, ANF, SGN and only the vestibular hair cells in the striola region of the saccule. In contrast, rats treated with HK-2 (BHK-2) sustained significantly less OHC (67%) and IHC (57%) loss compared to the B group. OHC and IHC losses were smallest in the BEPHK-2 group, but not significantly different from the BEP group indicating lack of protective synergy between EP and HK-2. There was no loss of ANF, SGN or saccular hair cells in the BHK-2, BEP and BEPHK-2 groups. Thus, HK-2 not only significantly reduced OHC and IHC damage, but completely prevented loss of ANF, SGN and saccule hair cells. The powerful protective effects of this oral MFRM make HK-2 an extremely promising candidate for human clinical trials.

Endoscopic-Assisted Presigmoid Approach to the Internal Auditory Canal. A Feasibility Study.

The retrolabyrinthine (presigmoid) approach has been utilized in various skull base surgeries but has not been fully utilized in the management of internal auditory canal (IAC) lesions, such as vestibular schwannoma (VS). Microsurgical retrolabyrinthine approach provides limited visualization of the IAC, while endoscopic-assisted techniques allow for further lateral exposure with labyrinthine preservation. Traditional approaches to the IAC have the disadvantage of hearing sacrifice or retraction of brain tissue. With the introduction of endoscopic techniques and enhanced visualization, access to this region of complex anatomy is possible. Radiomorphometric and anatomical dissection was performed on two cadaveric temporal bones. High-resolution computed tomography was used to segment and delineate the volume of the IAC. Projected accessible IAC was compared to actual postdissection data with preservation of the posterior semicircular canal (PSCC) via the retrolabyrinthine corridor. While preserving the PSCC, the 0° and 30° endoscopes visualized 57.1% and 78.6% of the IAC for cadaver 1, and 64.0% and 76.0% of the IAC for cadaver 2, respectively. Sacrificing the PSCC, the 0° and 30° endoscopes provided visualization of 78.6% 85.7% of the IAC for cadaver 1, and 88.0% and 95.1% of the IAC for cadaver 2, respectively. Retrolabyrinthine approach to resection of VS is a potentially viable hearing-preserving alternative to traditional approaches. This approach provides access to the majority of the IAC, while angled endoscopes or sacrifice of the PSCC can provide additional access toward the fundus. Further studies are needed to determine the clinical feasibility of this approach.

Asymmetry of the Subjective Visual Vertical in Patients With Unilateral Peripheral Vestibular Deficit.

Perception of verticality is clinically assessed using the subjective visual vertical (SVV), a test of the otolith system that consists of aligning a bar on the gravitational vertical in darkness. Patients with acute unilateral vestibulopathy (AUVP) show a systematic SVV bias toward the affected side, whichever the side of line orientation. Whether SVV estimates are symmetrical has not been investigated. This study included 10 patients with AUVP (vestibular neuritis) and 10 with BPPV (posterior semicircular canal). SVV measurements were made at two preset angles of line orientation (15° and 30°) toward the ipsilateral and contralateral sides, relative to the affected side. The results showed asymmetrical SVV estimates in the AUVP group, with significantly greater SVV errors for ipsilateral than contralateral line orientation, as well as for the preset angle of 30° compared to 15°. SVV estimates were significantly lower in patients with BPPV who also exhibited SVV asymmetry. SVV estimates remained unchanged just after the maneuver and were normalized some days later or after supplementary maneuvers. SVV asymmetry should be routinely considered in the clinic. We recommend individually assessing ipsilateral and contralateral SVV and using at least two preset angles. This allows for a better assessment and diagnosis of otolith organ imbalance that can trigger chronic instability and dizziness. The contribution of neck afferents related to head position in space seems to be the main source of SVV asymmetry.

Correlation between parameters of suppression head impulse paradigm and changesin DHI score in acute vestibular neuritis

Objective:To explore the correlation between the parameters of suppression head impulse paradigm（SHIMP） and changes in dizziness handicap inventory（DHI） scores. Additionally, to evaluate the degree of vertigo and prognosis of patients with acute vestibular neuritis through SHIMP parameters. Methods:Thirty-three patients with acute vestibular neuritis were enrolled for DHI evaluation, vHIT and SHIMP. A secondary DHI score were evaluated after after two weeks, once patients no longer exhibited spontaneous nystagmus. The decrease in the second DHI score was used as the efficacy index（EI）. All patients were divided into significantly effective group, effective group and ineffective group based on EI. Differences of the VOR gain values of SHIMP and the anti-compensatory saccade were compared among the three groups. Results:There were 13 cases in the significant effective group, 11 cases in the effective group, and 9 cases in the ineffective group. ①The mean gain of the horizontal semicircular canal in the significant effective group, the effective group, and the ineffective group was（0.50±0.11）, （0.44±0.12）, and（0.34±0.08）, respectively. The difference between the significant effective group and the ineffective group was statistically significant（P<0.01）. The gain of horizontal semicircular canal was positively correlated with EI（r=0.538 5, P<0.01） 。②The occurrence rate of the anti-compensatory saccade in the significant effective group, the effective group, and the ineffective group was（51.23±19.59）, （33.64±17.68）, and（13.78±11.81）, respectively. Pairwise comparisons between each group showed statistical significance（P<0.05）. The occurrence rate of anti-compensatory saccade was positively correlated with EI（r=0.658 2, P<0.01）. Conclusion:The horizontal semicircular canal gain and the occurrence rate of the anti-compensatory saccade in SHIMP for patients with acute vestibular neuritis were closely correlated with decrease in DHI score.

Study on the consistency between CBCT image features of sphenopalatine foramen and those seen in nasal endoscopy

Objective:To study the clinical anatomy of the sphenopalatine foramina by dissecting the sphenopalatine foramina during Vidian nerve branch neurotomy. The anatomy and CBCT images of sphenopalatine foramen were analyzed to facilitate the navigational of clinical operation using CBCT images. Methods:From October 2017 to September 2023, 84 cases（168 sides） of Vidian nerve branch neurotomy in our department were collected. The clinical summary was made according to the anatomy of sphenopalatine foramen during the operation. Preoperative CBCT imaging findings of the sphenopalatine foramina were also studied. Results:The clinical anatomy of sphenopalatine foramen could be divided into four types: middle meatus type（1.19%）, trans-meatus type（62.29%）, superior meatus type（33.33%） and double foramen type（1.19%）. The incidence of ethmoidal ridge was 98.81%. The distance from sphenopalatine foramina to posterior nasal canal were（14.63±2.66） mm to left and（14.65±2.63） mm to right, The position Angle ∠a of lower margin of sphenopalatine foramina were（62.36±10.05）° to left and（61.51±11.82）° to right, respectively. Axial CT images can be used to divide the sphenopalatine foramen into five levels: the upper edge of the sphenopalatine foramen level, the Vidian nerve level, the basal plate interaction level, the lower edge of the sphenopalatine foramen level and the pterygopalatine canal level. The agreement between endoscopic anatomy of sphenopalatine foramen and imaging navigation was 100%. Conclusion:The sphenopalatine foramina exhibit various anatomical types. The preoperative navigational CBCT reading can effectively identify the type of sphenopalatine foramina, guide the choice of surgical method, and help avoid serious complications. This has significant clinical application value.

Posterior semicircular canal involvement in sudden hearing loss

Posterior semicircular canal involvement in sudden hearing loss

An algorithm for the surgical approach to spontaneous temporal bone CSF leak

ObjectiveTo suggest a comprehensive algorithm for the surgical approach for correcting of sources of temporal bone CSF leaks. MethodsA case series for patients operated in a single academic tertiary referral center between 2011 and 4.2022. Included in the study were 46 patients, 5 of whom had a bilateral problem, resulting in 51 pathologic temporal bones. The presentation was an active CSF leak (38 patients) or bacterial otogenic meningitis (8 patients). Follow up ranged from 8 months to 5 years. ResultsOf the 42 ears operated via the default middle fossa approach, 37 were successful (88 %) in controlling CSF leak. None had intracranial complications or sensorineural hearing loss. Location, number and size of the defects, hearing status, associated superior semicircular canal dehiscence, additional intra-temporal or intra-cranial pathologies may indicate a transmastoid approach. Of the six ears that had a canal wall up mastoidectomy as a primary procedure, one required revision due to ongoing CSF leak. Five revision cases and three primary cases were effectively sealed with a subtotal petrosectomy and obliteration. One was lost to follow-up. Hearing was reconstructed with bone-anchored hearing implants in 6 out of these 8 ears. ConclusionsThe middle fossa approach could be used as a default approach for sealing TD. There are a number of indications for transmastoid approaches in both primary and revision cases. Obliteration of the ear was used in all revision cases. The suggested algorithm can help in planning surgery for temporal bone CSF leaks or a history of otogenic meningitis.

Development and Standardization of Modified Simultaneous Multifrequency (SiMFy) Stimulus for Recording oVEMP And Its Interaction with the Alternate Electrode Montages.

Simultaneous Multifrequency (SiMFy) is a time-saving and reliable stimulus to determine the frequency tuning of ocular vestibular-evoked myogenic potential (oVEMP); however, the absence of 4000 Hz in SiMFy potentially makes it a less potent tool for the diagnosis of Superior semicircular canal dehiscence, a pathology with an ever-increasing prevalence. Further, SiMFy was validated using only the infra-orbital (IO) electrode montage. However, the recordings obtained using the IO montage might be susceptible to reference contamination introduced by a small separation between the recording electrodes, and also susceptible to reflex impurity due to the spatially displaced reference electrode from the inferior oblique muscle (IOM), rendering it vulnerable to picking up responses from other muscles. Nonetheless, little is known about the similarities/differences between the SiMFy-induced oVEMPs using alternate montages [belly-tendon (BT), chin-reference (CR), and sternum-reference (SR)] and the non-simultaneous multifrequency oVEMPs (NSM-oVEMPs) using the IO montage. To develop a modified SiMFy stimulus and investigate its effects on frequency tuning of oVEMP using various electrode montages. Within-subject experimental design. Thirty-three healthy adults aged 20-30 years. Tone bursts of octave and mid-octave frequencies from 250 Hz to 4000 Hz were generated and concatenated to create the modified SiMFy stimulus. All participants underwent non-simultaneous multifrequency oVEMPs and modified SiMFy oVEMPs using BT, CR, SR, and IO montages simultaneously. The response rate, peak-to-peak amplitude, and frequency tuning were compared between NSM-oVEMP and modified SiMFy oVEMP and also between the electrode montages. BT montage recorded the largest amplitude among the montages in non-simultaneous multifrequency stimulation and modified SiMFy stimulation. Although the response rates were comparable, the modified SiMFy produced significantly lower oVEMP amplitudes than the non-simultaneous multifrequency stimulation within each electrode montage (p < 0.05). A moderate-to-strong agreement on frequency tuning existed between the non-simultaneous multifrequency stimuli and modified SiMFy stimulus for all the montages, except for the SR montage. Although the modified SiMFy produces smaller amplitude oVEMPs than the non-simultaneous multifrequency stimulation for the respective montages, its use in combination with the BT montage yields higher response rates and larger peak-to-peak amplitudes than the non-simultaneous multifrequency recording using IO montage.

The Role of Asymmetry Values, Gain, and Pathological Saccades of the Video Head Impulse Test (vHIT) in Sudden Sensorineural Hearing Loss.

The purpose of this study was to evaluate the value of asymmetry values, gain, and pathological saccades of the video head impulse test (vHIT) in sudden sensorineural hearing loss (SSNHL). Retrospective study. Tertiary referral center. A total of 226 individuals diagnosed with unilateral definite SSNHL were hospitalized. The assessment included a comprehensive evaluation of medical history, pure-tone test, acoustic impedance, positional test, video nystagmography (VNG), vHIT, vestibular evoked myogenic potentials (VEMPs) and magnetic resonance. vHIT, VNG, cVEMP, oVEMP. Statistical analysis was performed with SPSS version 22.0 for Windows. The asymmetry values, gain, and pathological saccades of the vHIT. The abnormal gain of vHIT in anterior, horizontal, and posterior canal in SSNHL patients with vertigo were revealed in 20 of 112 (17.9%), 24 of 112 (21.4%), and 60 of 112 (53.6%), respectively. The vHIT pathological saccades (overt + covert) of anterior, horizontal, and posterior canal in SSNHL patients with vertigo were observed in 5 of 112 (4.6%), 52 of 112 (46.4%), and 58 of 112 (51.8%), respectively. Multivariate analysis indicated that the prognosis of patients with vertigo was correlated with vHIT gain of posterior canal, pathological saccade in horizontal canal, asymmetric ratio of horizontal canal gain, asymmetric ratio of posterior canal gain, Canal paresis (%) on caloric test and spontaneous nystagmus. In the vHIT of patients with SSNHL with vertigo, the posterior canal is most easily affected. Reduced gain of posterior canal, pathological saccade of horizontal canal, and larger asymmetric gain of posterior canal and horizontal canal may be negative prognostic factors.

Morphometric evaluation of the anatomical relationships between the superior orbital fissure and the orbital structures based on computed tomography images with clinical implications.

To assist in surgical planning in endoscopic approaches, we analyzed the morphometric measurements of the superior orbital fissure (SOF) and optic canal (OC) by three-dimensional multislice computed tomography (3D MDCT) and evaluated them according to age, gender, and lateralization. The study analyzed 219 MDCT images (114 women, 105 men) from individuals aged 18-90. Measurements of SOF and OC were performed on 3D MDCT images in the axial plane and with 3D-Slicer software. The distance between the infraorbital foramen and the anterior entrance of the maxillary sinus (CBW) (p < 0.001), the distance between the CBW and the lateral point of the SOF (p = 0.001), and the Angle 1 (p = 0.028) were higher in women than in men. While the SOF length and on 3D the SOF width were higher in women than men (p < 0.001 and (p = 0.001, respectively), the lateral wall length OC was higher in men than women (p = 0.045). According to SOF classification, SOF length was highest in type II and lowest in type VIII (p = 0.025), SOF width was highest in type I and lowest in type VI (p < 0.001). No significant difference was found based on age groups and lateralization in all parameters. We found that as the SOF width increased, the SOF length also increased, and there was a statistically strong positive correlation. These findings can contribute to a more effective and safe operation by improving and updating surgeons' knowledge about safe distances to SOF in endoscopic procedures from a 3D MDCT perspective.

Rapid axial roll test outperforms alternative positional tests in identifying the affected ear in HSC-BPPV: an observational cohort study.

To evaluate the utility of supine roll test (SRT) and alternative positional tests, such as head-shaking test (HST), seated supine positioning test (SSPT), bow and lean test (BLT), and rapid axial roll test (RART) in determining the affected semicircular canal of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV). In an observational cohort study, 553 patients diagnosed with HSC-BPPV were divided into five groups in terms of different positional tests received: SRT group (n = 110), HST+ SRT (n = 112), BLT + SRT (n = 114), SSPT+SRT (n = 108) and RART+SRT (n = 109). The same method was used for the last four groups: The patients were first subjected to different alternative positional tests and then to SRT, and the nystagmus was observed separately to determine the affected side. The primary outcomes compared included the accuracy and sensitivity of these tests in the determination of the affected semicircular canal in HSC-BPPV. Patients with nystagmus elicited by positional tests accounted for 84.99% (470/553). The elicitation rate of nystagmus of SRT was lowest, being 77.27% (85/110). The elicitation rate of nystagmus were higher in the test groups than in the control group, and RART+SRT group yielded the highest elicitation rate of nystagmus (95.41%, 104/109). Among the alternative positional tests, RART attained the highest elicitation rate of nystagmus (101/109, 92.66%). Comparison between alternative positional tests and SRT, RART and SRT showed obviously better agreement in determining the affected semicircular canal (85.45%, 96/109) and eliciting nystagmus (95.41%, Kappa = 0.642), but no difference was found in curative effect when the affected side was accurately determined (χ2 = 1.618, p = 0.655). All alternative positional tests are helpful for eliciting nystagmus in patients with HSC-BPPV, and the significant advantages of RART include high-sensitivity in eliciting nystagmus and high accuracy in determining the affected semicircular canal, which provided objective support for the correct diagnosis of HSC-BPPV and the successful reduction of otolith.

Computerized Rotational Head Impulse Test: Age-Dependent Normative Data.

The objective of this study was to determine the normative vestibulo-ocular reflex gain output values of the computerized rotational head impulse test (crHIT) with stationary visual targets (earth bound) in healthy participants in each decade age band of life: 10-19, 20-29, 30-39, 40-49, 50-59, 60-69, and 70+ years. Seventy-seven community-dwelling participants (10-85 years of age) with normal lateral semicircular canal (SCC) functioning and no symptoms or history of vestibular dysfunction were recruited through convenience sampling and assessed with the crHIT using stationary targets. These participants were assessed using two standard protocols in a randomized order. Results from 77 participants (M age = 46 years; 43 women, 34 men) were analyzed. Pearson's correlation coefficient and simple linear regression indicated a statistically significant relationship between crHIT gain output and age (p > .05) for right gain, 1030°/s2, and left gain, 1005°/s2. Although a statistically significant relationship was found, the slope was minor, demonstrating that the clinical effect of age on crHIT gain output was insignificant. Furthermore, no statistically significant relationship exists between crHIT gain output and gender (p > .05). Age-dependent normative data were calculated using the 2.5th and 97.5th confidence interval (CI) percentile method. The responses of angular vestibulo-ocular reflex (aVOR) gain values for crHIT are expected to occur within the range for lower limit reference interval (RI) of 0.85-0.9 and upper limit RI of 1.11-1.18 for 1030°/s2 and lower limit RI of 0.86-0.92 and upper limit RI of 1.13-1.16 for 1005°/s2. It can be expected that 90% CI of the population with normal lateral SCC functioning will have aVOR gain values that fall within this range. Despite a statistically significant relationship that exists with aVOR gain output and age, the changes are minor, declining by 0.0088 units per 10 years, justifying the same normative data for all decade age bands.

Clinico-radiologic discordance: A case of superior semicircular canal dehiscence by superior petrosal sinus

Clinico-radiologic discordance: A case of superior semicircular canal dehiscence by superior petrosal sinus