Linking Vestibular Function and Subcortical Gray Matter Volume Changes in a Longitudinal Study of Aging Adults

Emerging evidence suggests a relationship between impairments of the vestibular (inner ear balance) system and alterations in the function and the structure of the central nervous system (CNS) in older adults. However, it is unclear whether age-related vestibular loss is associated with volume loss in brain regions known to receive vestibular input. To address this gap, we investigated the association between vestibular function and the volumes of four structures that process vestibular information (the hippocampus, entorhinal cortex, thalamus, and basal ganglia) in a longitudinal study of 97 healthy, older participants from the Baltimore Longitudinal Study of Aging. Vestibular testing included cervical vestibular-evoked myogenic potentials (cVEMP) to measure saccular function, ocular VEMP (oVEMP) to measure utricular function, and video head impulse tests to measure the horizontal semicircular canal vestibulo-ocular reflex (VOR). Participants in the sample had vestibular and brain MRI data for a total of one (18.6%), two (49.5%), and three (32.0%) visits. Linear mixed-effects regression was used to model regional volume over time as a function of vestibular physiological function, correcting for age, sex, intracranial volume, and intersubject random variation in the baseline levels and rates of change of volume over time. We found that poorer saccular function, characterized by lower cVEMP amplitude, is associated with reduced bilateral volumes of the basal ganglia and thalamus at each time point, demonstrated by a 0.0714 cm3 ± 0.0344 (unadjusted p = 0.038; 95% CI: 0.00397–0.139) lower bilateral-mean volume of the basal ganglia and a 0.0440 cm3 ± 0.0221 (unadjusted p = 0.046; 95% CI: 0.000727–0.0873) lower bilateral-mean volume of the thalamus for each 1-unit lower cVEMP amplitude. We also found a relationship between a lower mean VOR gain and lower left hippocampal volume (β = 0.121, unadjusted p = 0.018, 95% CI: 0.0212–0.222). There were no significant associations between volume and oVEMP. These findings provide insight into the specific brain structures that undergo atrophy in the context of age-related loss of peripheral vestibular function.

Nystagmus Parameters of Supine Roll Test Correlates With Prognosis After Repositioning Maneuver in Horizontal Semicircular Canal Benign Paroxysmal Positional Vertigo

Background: Positional nystagmus induced by supine roll test is characteristic for diagnosing horizontal semicircular canal benign paroxysmal positional vertigo (HC-BPPV). In this study, we aimed to explore the value of nystagmus parameters in by supine roll test (SRT) as prognostic factors in HC-BPPV.Methods: We retrospectively analyzed the nystagmus parameters of 813 patients diagnosed with HC-BPPV by the SRT model in the SRM-IV system through video nystagmography. Then we used the computer-controlled canalith repositioning procedure (CCRP) mode for treatment. Based on the outcomes, patients were divided into either the cured group or the resistant group. The 1:1 propensity score matching (PSM) was applied to minimize potential selection bias. Then univariable and multivariable analyses were performed to identify the association of nystagmus parameters and the efficacy of CCRP.Results: Among the 813 patients, 99 (12.2%) were classified in the resistant group. The right side of HC-BPPV patients was twice the number of the left side patients (537 vs. 276). PSM is used to pair resistant patients to the cured patients, in which 99 pairs were successfully matched. Results of univariate and multivariate analyses showed that patients in the resistant group have longer latency in the affected side [odds ratio (OR) = 1.231 (1.110–1.366); P < 0.001] and slower slow phase velocity (SPV) in the healthy side [OR = 0.957 (0.917–0.999); P = 0.045].Conclusion: Nystagmus parameters may represent the characteristics of canalith. HC-BPPV patients with a longer latency in the affected side and slower SPV on the healthy side during SRT have a higher risk of HC-BPPV persisting after a single CCRP.

A Young Patient with Horizontal Semicircular Cupulolithiasis with Immediate Response to the Therapeutic Head-Shaking Maneuver (HSM)

The apogeotropic variant of horizontal semicircular canal benign paroxysmal positional vertigo is attributed to either short anterior ampullary arm canalolithiasis or to the cupulolithiasis with the otoconial debris adhering to the cupula on utricular (Cup-U) or canal side (Cup-C), rendering it heavy and gravity sensitive. The treatment options for horizontal semicircular cupulolithiasis are not very well defined. A 25-year-old female patient with 8 days history of vertigo on rolling to either of the lateral recumbent position presented in the first week of November 2019. The supine roll test (SRT) on yawing head maximally to the right as well as to the left elicited an apogeotropic horizontal positional nystagmus lasting more than 1 minute, which was stronger on the right side and indicated a diagnosis of left horizontal semicircular cupulolithiasis. Two short-term follow-ups at 1 and 24 hours after head-shaking maneuver (HSM), with verifying SRT, were undertaken. During either of the two follow-ups, neither the previously elicited horizontal positional nystagmus was observed, nor did the patient have vertigo on rolling to lateral recumbent positions. She was telephonically questioned weekly regarding the recurrence of rotational vertigo for the next 4 weeks, and it was confirmed that she remained symptom free till then. The therapeutic HSM, owing to the inertial forces generated, can detach the otoconial debris from the cupula that renders it heavy and gravity sensitive. Successful offloading of cupula by HSM brings immediate cure in the Cup-U variant of the horizontal semicircular cupulolithiasis.

Treatment Efficacy of Forced Prolonged Position After Cupulolith Repositioning Maneuver in Apogeotropic HSCC BPPV

Objectives: To evaluate the therapeutic efficacy of the forced prolonged position (FPP) in patients with horizontal semicircular canal (HSCC) cupulolithiasis in whom the cupulolith repositioning maneuver (CuRM) failed. Methods: Fifty-four consecutive patients with HSCC cupulolithiasis were included, and immediate treatment efficacy of CuRM and short-term treatment efficacy of FPP were investigated. Results: We performed the CuRM in HSCC cupulolithiasis, and, if the CuRM did not show immediate success, instructed the patients to perform the FPP or the sham position (by random allocation) at home. The immediate therapeutic success of the CuRM was assessed by the absence of nystagmus and vertigo on positional testing after 30 minutes of the maneuver, which was 14.8% on the first visit day. And the resolution rate of HSCC cupulolithiasis was higher in the FPP group than in the sham position group at the second (78.3% vs 55.6%), third (75.0% vs 42.9%), and fourth visits (100% vs 25.0%). Conclusion: Although the CuRM has been considered to be a good therapeutic option for HSCC cupulolithiasis because it theoretically aims to detach otoconial particles attached both on the utricle and canal sides of the cupula, the immediate success rate was only 14.8% at the first visit. The FPP can be additionally recommended to improve the resolution rate in HSCC cupulolithiasis patients in whom the CuRM fails.

Cholesteatoma Causing a Horizontal Semicircular Canal Fistula

Horizontal canal fistulas are not uncommon in patients with cholesteatoma. Patients with canal wall down cavities and exposed horizontal canal fistulas develop significant dizziness with wind or suction exposure. Obliteration of mastoid cavities in patients with exposed fistulas can be challenging. We describe a patient with horizontal canal fistula and chronic dizziness from wind exposure who underwent successful mastoid cavity obliteration with preservation of hearing. Patients with horizontal canal fistulas in a canal wall down cavity can be managed with mastoid obliteration for relief of dizziness.

Skull Vibration-Induced Nystagmus Test in a Human Model of Horizontal Canal Plugging

Background/Aim: the aim of this study was to assess the skull vibration-induced nystagmus test (SVINT) results and vestibular residual function after horizontal semicircular canal (HSCC) plugging. Methods: In this retrospective chart review performed in a tertiary referral center, 11 patients who underwent unilateral horizontal semicircular canal plugging (uHSCCP) for disabling Menière’s disease (MD) were included. The skull vibration-induced nystagmus (SVIN) slow-phase velocity (SPV) was compared with the results of the caloric test (CaT), video head impulse test (VHIT), and cervical vestibular-evoked myogenic potentials (cVEMP) performed on the same day. Results: Overall, 10 patients had a strong SVIN beating toward the intact side (Horizontal SVIN-SPV: 8.8°/s ± 5.6°/s), 10 had a significant or severe ipsilateral CaT hypofunction, 10 had an ipsilateral horizontal VHIT gain impairment, and 3 had altered cVEMP on the operated side. Five had sensorineural hearing worsening. SVIN-positive results were correlated with CaT and horizontal VHIT (HVHIT) results (p < 0.05) but not with cVEMP. SVIN-SPV was correlated with CaT hypofunction in % (p < 0.05). Comparison of pre- and postoperative CaT % hypofunction showed a significant worsening (p = 0.028). Conclusion: SVINT results in a human model of horizontal canal plugging are well correlated with vestibular tests exploring horizontal canal function, but not with cVEMP. SVINT always showed a strong lesional nystagmus beating away from the lesion side. SVIN acts as a good marker of HSCC function. This surgical technique showed invasiveness regarding horizontal canal vestibular function.

Clinical Characteristics of Patients With Dizziness/Vertigo Accompanied by Posterior Semicircular Canal Hypofunction

Objective: To investigate the clinical characteristics of patients with dizziness/vertigo accompanied by loss of the posterior canal(s) (LPC).Methods: Clinical data of 23 patients with LPC were collected. We determined video-head-impulse test (vHIT) gains of all six semicircular canals and correlated vHIT findings with other vestibulo-cochlear tests, including caloric test, ocular and cervical vestibular-evoked myogenic potentials (oVEMP, cVEMP), pure tone audiometry (PTA), and analyzed the differences in clinical manifestations of patients with LPC with different etiologies.Results: LPC was identified in 23 patients. At the time of disease onset, most patients presented with dizziness (47.8%) and vertigo (30.4%) only, and some patients (21.7%) complained of unsteadiness. Among these 23 patients with LPC, there were 14 (60.9%) patients of isolated LPC (ILPC), 21 (91.3%) patients of unilateral LPC (ULPC), and 2 (8.7%) patients of bilateral LPC (BLPC). (1) Among 14 patients with ILPC, 13 (92.9%) patients had unilateral ILPC, the rate of ipsilesional impairment on caloric test, or oVEMP/cVEMP test or PTA ipsilesionally was 53.8% (7/13) in patients with unilateral ILPC. The causes of unilateral ILPC were vertigo/dizziness of unclear origin (38.5%), labyrinthine infarction (15.4%), vestibular migraine (15.4%), and other diseases (30.8%); (2) among 21 patients with ULPC, 7 patients (33.3%) were accompanied with horizontal semicircular canal hypofunction ipsilesionally, the abnormal rate of caloric test, or oVEMP/cVEMP tests or PTA ipsilesionally was 57.1%. The causes of ULPC were vertigo/dizziness of unclear origin (33.3%), autoimmune inner ear disease (14.3%), labyrinthine infarction (14.3%), vestibular neuritis (9.5%), vestibular migraine (9.5%), and other diseases (19.0%); (3) among two patients with BLPC, one patient presented with unsteadiness, the causes of BLPC were vestibular paroxysmia and autoimmune inner ear disease.Conclusion: vHIT is a fast and effective method for assessing LPC, which can be used to detect isolated PC dysfunction. The causes of ILPC were peripheral origin or central origin. Patients with ILPC and ULPC mostly presented with dizziness/vertigo, and ULPC was often accompanied by ipsilateral vestibulo-cochlear impairment.

Reversible Canalith Jam of the Horizontal Semicircular Canal Mimicking Cupulolithiasis

Objective: To describe a case of benign paroxysmal positional vertigo (BPPV) resulting in reversible horizontal semicircular canalith jam successfully treated with horizontal canal occlusion. A brief literature review of similar cases was performed. Methods: Case report and literature review. Results: A 68-year-old female presented with apogeotropic positional nystagmus, attributed to reversible horizontal canalith jam mimicking cupulolithiasis that was refractory to tailored repositioning maneuvers across months. She was unable to work due to the severity of her symptoms. She underwent surgical occlusion of the affected canal with immediate resolution of her symptoms. A literature review revealed similar cases of canalith jam mimicking cupulolithiasis. Conclusions: Reversible canalith jam, in which particles moving with horizontal head position alternate between obstructing the semicircular canal and resting on the cupula, can mimic signs of cupulolithiasis. This variant of BPPV can be effectively managed with surgical canal occlusion should symptoms fail to resolve after tailored repositioning maneuvers.

Significance of Pseudo-conductive Hearing Loss and Positional Nystagmus on Perilymphatic Fistula: Are they related to third window effects?

Objectives. Clinical presentation is critical to identify suspected perilymphatic fistula (PLF). To explain characteristic of PLF, it was hypothesized that a third window lesion might be involved in the pathomechanism. The purpose of this study is to investigate clinical features in PLF and figure out the relationship of third window effect and PLF. Methods. Sixty patients underwent surgical exploration under suspicion of PLF and reinforecmenet of oval window and round window was performed. Clinical features including demographics, pure tone audiometry (PTA), and videonystagmography (VNG) were evaluated preoperatively and 1 month after operation. Surgical outcomes were analyzed according to the improvement of hearing and vestibular symptoms and signs. The conductive components of PTA (air-bone gap (ABG)) were measured, and the relationship between ABG closure after surgery and hearing improvement was analyzed. In addition, the postoperative subjective dizziness was assessed by interview in clinic. The change of positional nystagmus was analyzed according to ABG closure and hearing improvement.Results. ABG at lower frequencies (LFABG, 250 Hz, 500 Hz, 1,000 Hz) was present in 27 patients (45%). Postoperatively, the PTA was significantly improved after surgical repair. Among the patients with preoperative LFABG (n=27), 15 (55.5%) showed postoperative ABG closure and significant improvement in PTA at all frequencies compared with the patients without ABG closure (P=0.012). The subjective dizziness improved in 56 patients (91.8%). Positional nystagmus was found in 45 of 49 patients. Multiple canal involvement was more common than single canal (67% vs. 33%). The horizontal semicircular canal was most commonly involved, followed by the posterior and anterior canals. Postoperatively, the positional nystagmus disappeared, or the number of involved canals decreased in 22 of 34 (64.7%) patients. Conclusions. Pseudo-conductive hearing loss at the lower frequencies and positional nystagmus originating from multiple semicircular canals were common findings in PLF. Surgical reinforcement of the RW and OW improved hearing threshold accompanied by closure of ABG. The third window lesion might explain these clinical features that indicate PLF.