Revisiting benign paroxysmal positional vertigo pathophysiology

Gene expression analysis in recurrent benign paroxysmal positional vertigo: a preliminary study

Objectives

This study aimed to determine the pathophysiology of recurrent benign paroxysmal positional vertigo (BPPV) in young patients using gene expression profiling combined with bioinformatics analysis.

Methods

Total RNA was extracted from the whole blood of four young patients with recurrent BPPV and four controls. The differentially expressed genes (DEGs) between the groups were screened using a microarray analysis based on the cutoff criteria of |log₂ fold change| > 1 and an adjusted p-value of < 0.05. Functional enrichment analysis of DEGs was performed using Gene Ontology analysis, and the protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of the Interacting Genes database.

Results

A total of 39 DEGs were detected between the BPPV and control samples, comprising 33 upregulated DEGs and six downregulated DEGs in the BPPV group. Functional enrichment analysis indicated that the upregulated DEGs were significantly enriched in terms related to metabolic processes and the immune system. Two main pathways were extracted from the PPI network: one was associated with oxidative phosphorylation and stress and the other with the adaptive immune system and extracellular matrix degradation.

Conclusion

The findings of our bioinformatics analysis indicated that oxidative stress or extracellular matrix degradation due to immune-mediated inflammatory responses may contribute to the development of recurrent BPPV in young patients.

Negative Impact of Vestibular Suppressant Drugs on Provocative Positional Tests of BPPV: A Study from the Western Part of India

Aims:

To study the impact of vestibular suppressant drugs (VSD) on provocative positional tests (PPT) in patients with benign paroxysmal positional vertigo (BPPV).

Settings and Design:

A prospective case-control observational study.

Materials and Methods:

Patients with a history suggestive of BPPV were tested for PPT. Patients with vertiginous symptoms and with nystagmus on PPT were classified as objective BPPV (O-BPPV, control group), while those without nystagmus with no alternate diagnosis were classified as subjective BPPV (S-BPPV, case group). Details of VSD treatment were noted in all the patients. In both groups, patients were instructed to discontinue VSD and were further assigned as the VSD and non-VSD subgroups. Patients were followed for 2 months with PPT every week. PPT positive patients were treated by vestibular rehabilitation maneuvers.

Statistics:

Student t-test with two-tailed, unpaired, was used for continuous scale and Chi-square test for categorical differences between the two groups.

Results:

295 consecutive BPPV patients were enrolled in the study, 55 in the S-BPPV group and 240 in the O-BPPV group. Significantly higher proportion of patients in the S-BPPV group were on VSD at presentation, 80.00% vs. 53.75% (OR 2.52; 95% CI: 1.30–4.86), P = 0.006. In an unadjusted analysis of the S-BPPV group following discontinuation of VSD, PPT became positive in 79.54% of patients as compared to 18.19% in the non-VSD group (OR 35.0; 95% CI: 6.2–197.3), P < 0.001.

Conclusion:

A higher proportion of S-BPPV patients were receiving VSD in comparison to O-BPPV at the initial visit. The PPT converted positive four times higher after ceasing the VSD in S-BPPV patients.

Study Design:

Prospective case-control observational study.

Short Term Efficacy of Modified Epley’s Maneuvre Assisted by Visual Aid Dynamic Device Versus Unassisted Maneuvre for the Treatment of Posterior Canal BPPV

Introduction:

Modified Epley’s maneuver is the recommended treatment for the Posterior Canal (PC) BPPV. To enhance the efficacy of this maneuver, an easy to perform visual aid device (DizzyFIX) guided modified Epley’s maneuver was studied.

Material and Methods:

This prospective, double-blind, randomized study included consecutive patients with PC-BPPV based on clinical history, neuro-otological examination, and positive Dix- Hallpike (DHP) test from January 2018 to March 2019 at a neurology clinic of western India. Patients were randomly assigned treatment with either visual aid device assisted modified Epley’s maneuver, which constituted the case group or by a placebo device guided modified Epley’s maneuver, which constituted the control group. DizzyFIX was used as a visual aid device in the case group. Patients were followed up at one hour and 24 hours with DHP by the blinded examiners to observe for remission.

Results:

Out of 280 patients (140 patients in each group), 6 from the case, and 2 from the controls were lost from the follow-up. Overall, 134 cases were compared to 138 controls. The success rate of remission in the case and the control group at one-hour was 79.19% vs. 48.30%, respectively, with a p-value of 0.003. Similarly, the success rate in the case and control group at 24 hours was 95.27% vs. 80.62%, respectively, with a p-value of 0.011. At 1 hour, unadjusted Odd Ratio (OR) was 4.13, (C.I. 95% 2.02- 8.46) and at 24 hours, it was 4.37, (C.I. 95% 1.39-13.77), which was significant even after adjustment of co-variables (OR 4.02, C.I. 95% 2.34- 8.26) and (OR 4.11, C.I. 95% 2.30- 14.26), respectively.

Conclusion:

For short term treatment of PC-BPPV, DizzyFIX assisted modified Epley’s maneuver is more efficacious than unassisted modified Epley’s maneuver.

Functional Integrity of the Inferior Vestibular Nerve and Posterior Canal BPPV

The functional integrity of the inferior vestibular nerve (IVN) may be evaluated by the cervical vestibular evoked myogenic potential (cVEMP) response, which requires signal transmission via the nerve. As functional integrity of the IVN innervating the posterior semicircular canal is required to produce the typical positioning vertigo and nystagmus characterizing posterior canal benign paroxysmal positional vertigo (PCBPPV), we hypothesized that normal cVEMPs would be found in most PCBPPV patients. Twenty-four PCBPPV patients participated in a prospective cohort study. All were treated by canal repositioning maneuver and had air-conduction cVEMP and videonystagmography (VNG). Follow-up evaluations including history and otoneurological bedside examination were carried out 1, 3, 6, and 12 months after the initial treatment. At the last follow-up, the patients filled the Dizziness Handicap Inventory (DHI) questionnaire. Normal cVEMPs were recorded in 19 (79%) and were absent in 5 (21%) of the subjects. The average DHI in the patients with normal cVEMP was 16.42 ± 17.99 vs. 0.4 ± 0.89 among those with pathological cVEMP (p < 0.04, Mann-Whitney test). Thirteen (54%) patients experienced recurrent PCBPPV (rPCBPPV). The average DHI score was significantly higher among patients having recurrence (22.15 ± 18.61) when compared to those with complete cure (2.36 ± 5.98; p < 0.003, Mann-Whitney test). Ten (77%) of the subjects with rPCBPPV had normal and 3 (23%) had pathological cVEMP as compared to 9 (82%) and 2 (18%) subjects in the non-recurrent (nrPCBPPV) group (Fisher's exact test-not significant). cVEMP p13 and n23 wave latencies and amplitudes, inter-aural differences in p13-n23 peak-to-peak amplitudes, and response thresholds did not differ between the groups. No differences were found between the rPCBBPV and nrPCBBPV groups in VNG caloric lateralization and directional preponderance values. We have found that in most cases, PCBPPV symptoms and signs are associated with normal cVEMP response supporting the role of IVN functional integrity. The absent cVEMPs in the minority of patients, although having similar clinical presentation, raise the possibility that the ipsilateral saccule is affected by the same pathology causing degeneration of the utricle macula. Alternatively, lacking inhibitory stimuli from the involved ipsilateral utricle or partial degeneration of the IVN and ganglion could explain the diminished cVEMP response. Clinical Trial Registration: The study was registered in ClinicalTrials.gov Internet site (study ID-NCT01004913; https://clinicaltrials.gov/ct2/show/NCT01004913?cond=BPPV&cntry=IL&draw=2&rank=3).

Serum levels of superoxide dismutases in patients with benign paroxysmal positional vertigo

Objective: To investigate the possible role of superoxide dismutases (SODs) in the development of benign paroxysmal positional vertigo (BPPV) and recurrence events in a 1-year follow-up study.

Methods: This was a prospective one-center study. A total of 204 patients with BPPV and 120 age-and sex matched healthy subjects were included. The levels of SOD between patients and control cases were compared. The levels of SOD between posterior semicircular canal (PSC) and horizontal semicircular canal (HSC) were also compared. In the 1-year follow-up, recurrence events were confirmed. The influence of SOD levels on BPPV and recurrent BPPV were performed by binary logistic regression analysis.

Results: The serum levels of SOD in patients with BPPV were lower than in those control cases (P<0.001). Levels of SOD did not differ in patients with PSC and HSC (P=0.42). As a categorical variable, for per interquartile range (IQR) increment of serum level of SOD, the unadjusted and adjusted risks of BPPV would be decreased by 72% (with the odds ratio [OR] of 0.28 [95% confidence interval (CI): 0.21–0.37], P<0.001) and 43% (0.57 [0.42–0.69], P<0.001), respectively. Recurrent attacks of BPPV were reported in 50 patients (24.5%). Patients with recurrent BPPV had lower levels of SOD than in patients without (P<0.001). For per IQR increment of serum level of SOD, the unadjusted and adjusted risks of BPPV would be decreased by 51% (with the OR of 0.49 [95% CI: 0.36–0.68], P<0.001) and 24% (0.76 [0.60–0.83], P<0.001), respectively.

Conclusion: Reduced serum levels of SOD were associated with higher risk of BPPV and BPPV recurrence events.

Hypovitaminosis D, Low Bone Mineral Density, and Diabetes Mellitus as Probable Risk Factors for Benign Paroxysmal Positional Vertigo in the Elderly

Introduction  Studies have found that elderly patients with benign paroxysmal positional vertigo (BPPV) may present low levels of vitamin D (25 (OH) D), changes in bone mineral density, and diabetes mellitus (DM).

Objective : To investigate the possible association between BPPV, bone mineral density, hypovitaminosis D, 25 (OH) D and DM.

Methods  The sample consisted of 109 elderly subjects. The BPPV was verified by a standardized questionnaire and the Dix-Hallpike maneuver. Blood samples were collected for the investigation of 25 (OH) D serum levels. The bone mineral density was evaluated by means of a densitometer. Diabetes mellitus verification was performed using a self-reported questionnaire.

Results  Of the 109 participants, 17 had BPPV. There was a statistically significant difference between BPPV and gender ( p  = 0.027, phi = 0.222), with female representing 88.2% of those with BPPV. In the group with BPPV, there was a statistically significant difference for the amount of vitamin D found ( p  = 0.001) and for age ( p  = 0.001). In the elderly group with DM and BPPV, a difference was found for the standard deviation of the femur ( p  = 0.022) with posthoc Dunn, identifying the difference between diabetics with and without BPPV ( p  = 0.047).

Conclusion  Although no association was found (25 (OH) D levels) with BPPV in the general population of this study, it was observed that there was an association with bone mineral density in the elderly group with DM and BPPV, and, in the group with BPPV, there was an association between the amount of vitamin D and age.

Subclinical vestibular dysfunction in migraineurs without vertigo: A Clinical study

OBJECTIVES

This observational study aimed to investigate the presence of potential vestibular system subclinical dysfunction among migraineurs without a history of vertigo and dizziness compared with healthy controls.

METHODS

Patients diagnosed with episodic migraine with and without aura were enrolled. All patients and healthy controls underwent vestibular examination using the following conventional tests: sitting position, Pagnini-McClure's, Dix-Hallpike's, head hanging, video head impulse, subjective visual vertical, Romberg, Fukuda, and caloric vestibular stimulation by Fitzgerald-Hallpike's tests. Nystagmus and angular velocity of the slow phase during culmination phase was analyzed by video-nystagmography.

RESULTS

Overall, 33 patients (76% female, 7 with aura and 26 without aura; mean age (mean ± SD): 29.1 ± 4.3 years) and 22 controls (33% female, mean age: 30.8 ± 9.4 years) were enrolled. There were no statistically significant differences in demographic features between patients and controls. Caloric vestibular stimulation test results were found to differ among patients and controls. In particular, right and left angular velocity (AV) were highly correlated one another (r = 0.88, P < .001). Right AV (53.0 ± 6.7 vs 44.0 ± 9.6) and left AV (54.3 ± 5.3 vs 43.3 ± 9.0) were statistically higher in migraineurs as compared to controls (P < .001). Also right V-HIT (1.1 ± 0.1 vs 0.8 ± 0.4) and left V-HIT (1.1 ± 0.1 vs 0.7 ± 0.2) were statistically higher in migraineurs compared to controls (P < .001).

CONCLUSION

Our findings suggest a subclinical alteration of vestibular pathway in migraineurs who have never complained vertigo or postural imbalance. This finding supports the hypothesis of a vestibular-cerebellar dysfunction in migraineurs, particularly among those with aura.

Home particle repositioning maneuver to prevent the recurrence of posterior canal BPPV

OBJECTIVE

To check the value of home particle repositioning maneuver in the prevention of the recurrence of posterior canal benign paroxysmal positional vertigo (pc-BPPV).

METHODS

In this study, patients diagnosed as unilateral posterior canal BPPV were selected following an accurate evaluation using video goggle VNG system. All patients were managed by particle repositioning maneuver (PRM). Patients were instructed to do home PRM once weekly for five years. Then, they were divided into two groups (according to choice of patient to do PRM). The first group (control group) consisted of 144 patients who did not do home PRM; whereas the second group (study group) included 165 patients who performed home PRM. All patients (control & study groups) were followed up every four months for five years.

RESULTS

The study found out that the recurrence rate of pc-BPPV in control group was 33 patients in the first year (27.2%), 11 patients in second year (9%), 5 patients in third year (4%), 3 patients in fourth year (2.5%) and 3 patients in fifth year (2.5%). The recurrence of pc-BPPV in the treated side (study group) of patients was reported as 5 patients in the first year (3.5%), 3 patients in the second year (2%), 2 patients in the third year (1.4%), 2 patients in the fourth year (1.4%), and 1 patient in the fifth year (0.7%). There was statistically significant difference between the control and the study groups regarding the recurrence rates in the first year follow up which was the highest in first four months.

CONCLUSION

Home particle repositioning maneuver has the capacity to prevent the recurrence of pc-BPPV. It proved to be more successful and functional in minimizing the recurrence of the disease in the study than in the control group. Hence, home particle repositioning maneuver is highly recommended for one year at least in pc-BPPV.

Small Compartment Toxicity: CN VIII and Quality of Life: Hearing Loss, Tinnitus, and Balance Disorders

Life experiences, industrial/environmental exposures, and administration of Food and Drug Administration (FDA)-approved drugs may have unintended but detrimental effects on peripheral and central auditory pathways. Most relevant to the readership of this journal is the role that drug treatments approved by the FDA as safe and effective appear to interact with 3 independent modes of toxicity within the small compartment of the ear. What may seem to be trivial drug-induced toxicity has the potential to change important measures of quality of life and functional capacity of mid- to late-life patients. Drugs meant to treat can become the source of interference in the activities of daily living, and as a result, treatment compliance may be jeopardized. Ototoxicity has been defined as the tendency of certain therapeutic agents and other chemical substances to cause functional impairments and cellular degeneration of the tissues of the inner ear resulting in hearing loss. However, one of the largest contributors to hospitalizations is fall-related injuries in the elderly patients associated with disorders of vestibular function linked to progressive and drug-induced toxicities. Tinnitus affects 35 to 50 million adults representing approximately 25% of the US population, with 12 million seeking medical care and 2 to 3 million reporting symptoms that were severely debilitating. This review is intended to highlight these targets of neurotoxicity that threaten the usefulness of drug treatments deemed safe and effective prior to access by the general public.

Repeated canalith repositioning procedure in BPPV: Effects on recurrence and dizziness prevention

PURPOSE

To evaluate whether a repeated canalith repositioning procedure (CRP) influences the residual symptoms and the rate of recurrence of benign paroxysmal positional vertigo (BPPV) in patients with post-CRP dizziness.

MATERIALS AND METHODS

In this retrospective study, we analyzed 292 patients at the referral center for ENT diseases with a first episode of BPPV treated with a single CRP following clinical practice guidelines. In 178 patients (67.9%) who presented dizziness after BPPV recovery at the follow-up visit, 94 patients underwent CRP (treated group) and 84 did not (non-treated group). A subjective evaluation of vertigo was made by way of a questionnaire. The rates of recurrence of BPPV and residual dizziness were statistically compared between the treated and the non-treated groups; survival analysis was carried out as well.

RESULTS

In an observational period ranging from 1 to 6years, BPPV recurred in 122 subjects (46.6%) of the investigated population. Among the patients with residual dizziness, the difference in rate of recurrence of BPPV between the treated group and the non-treated group was not statistically significant (p=0.84). The treated group presented a significantly higher rate of recovery from dizziness compared to the non-treated group (p<0.001).

CONCLUSIONS

A repeated CRP in patients with post-CRP dizziness increased the rate of recovery from dizziness but had no influence on BBPV recurrence.

Cases requiring increased number of repositioning maneuvers in benign paroxysmal positional vertigo

Introduction

Benign paroxysmal positional vertigo (BPPV) is a clinical syndrome that is proposed to be caused by dislocated utricular debris into semicircular canals. Although the majority of patients are treated by one or two repositioning maneuvers, some of the patients need repeated maneuvers for relief.

Objective

The goal of this study was to investigate the factors associated with patients with benign paroxysmal positional vertigo who required multiple repositioning procedures for treatment.

Methods

Data were obtained from the clinical records of 153 patients diagnosed with benign paroxysmal positional vertigo. Patients were treated by repositioning maneuvers. Demographic data and the factors including age, sex, canal type, duration of symptoms, comorbidities and number of repositioning maneuvers for relief were documented for statistical analysis.

Results

Age, sex, canal type and the duration of symptoms had no impact on the number of maneuvers. The most common comorbidity was spine problems. Hypertension was the only comorbidity that significantly associated with increased number of maneuvers.

Conclusion

The presence of hypertension is a risk factor for repeated maneuvers in benign paroxysmal positional vertigo treatment. Physicians should be aware of the increased probability of repeated repositioning maneuvers in these group of patients. The role of comorbidities and vascular factors need to be further clarified in the course of benign paroxysmal positional vertigo.

Vertiginous Symptoms and Objective Measures of Postural Balance in Elderly People with Benign Paroxysmal Positional Vertigo Submitted to the Epley Maneuver

Introduction Benign Paroxysmal Positional Vertigo (BPPV) is one of the most common and treatable causes of peripheral vestibular vertigo in adults. Its incidence increases with age, eventually leading to disability and a decreased quality of life. Objective The research aims to assess short-term effects of Otolith Repositioning Maneuver (ORM) on dizziness symptoms, quality of life, and postural balance in elderly people with Benign Paroxysmal Positional Vertigo. Methods A quasi-experimental study, which evaluated 14 elderly people that underwent the Otolith Repositioning Maneuver and reevaluation after one week. The authors performed statistical analysis by descriptive analysis of central tendency and dispersion; for pre- and post-treatment conditions, the authors used the Wilcoxon test. Results All aspects of the Dizziness Handicap Inventory (physical, functional, emotional, and total scores) as well as the Visual Analogue Scale (VAS) decreased after therapy (p < 0.05 and p = 0.001, respectively). However, more than half of the elderly participants did not achieve negative Dix-Hallpike. Regarding static and dynamic balance, there were significant differences in some parameters of the modified Clinical Test of Sensory Interaction and Balance, Limits of Stability and gait assessment measured by the Dizziness Gait Index (p < 0.05). Conclusion Results reveal clinical and functional benefits in elderly people with Benign Paroxysmal Positional Vertigo submitted to Otolith Repositioning Maneuver. However, most of the participants did not overcome Benign Paroxysmal Positional Vertigo and not all aspects of postural balance improved. Therefore, a longer follow-up period and a multidisciplinary team are required to establish comprehensive care for elderly patients with dizziness complaints.

Horizontal canal benign paroxysmal positional vertigo: diagnosis and treatment of 37 patients

Benign paroxysmal positional vertigo (BPPV), the most frequent cause of vertigo is associated with high morbidity in the elderly population. The most common form is linked to debris in the posterior semicircular canal. However, there has been an increasing number of reported BPPV cases involving the horizontal canals. The purpose of this article is to highlight the clinical features, diagnosis, and treatment in 37 patients with horizontal canal BPPV; twenty-six with geotropic nystagmus, and eleven with the apogeotropic form. Treatment consisted of the Gufoni manoeuver in eighteen patients (48.6%), the barbecue 360° maneuver in twelve patients (32.4%), both manoeuvers in four patients (10.8%), both manoeuvers plus head shaking in one patient (2.7%), and the Gufoni maneuver plus head shaking in two patients. Cupulolithiasis patients were asked to sleep in a forced prolonged position. We obtained a complete resolution of vertigo and nystagmus in 30 patients (81.0%) on the initial visit.

Benign paroxysmal positional vertigo--a review of 101 cases

INTRODUCTION AND OBJECTIVE

Benign paroxysmal positional vertigo is one of the most common vestibular disorders, with a lifetime prevalence of 2.4%. This study aimed to assess age, gender, lesion type and site, association with other vestibular diseases, progression and recurrence in a Portuguese population.

METHODS

This was a retrospective observational study of 101 patients diagnosed with benign paroxysmal positional vertigo by the same senior doctor, in a tertiary academic hospital, between January 2009 and May 2011.

RESULTS

A total of 101 cases were pooled, with a mean age of 56.57±15.33 years (15-90 years). From these, 72.3% were women. The posterior canal was affected in 72.3%, the lateral in 24.7%, the anterior in 2% and multiple canals in 1%. Unilateral canal and left labyrinth involvement were more frequent. The therapeutic maneuver used most was Epley's. Recurrence was observed in 10.9% of the cases. It was idiopathic in 83.2% of cases. No association was found between the number of maneuvers necessary to treat benign paroxysmal positional vertigo and etiology.

CONCLUSION

Benign paroxysmal positional vertigo is more frequent in female subjects, in the 6th decade and involves preferably the posterior semicircular canal of the right labyrinth. In most cases it is idiopathic and treatment with repositioning maneuvers has a mean success of 90%. Our results were in accordance with the literature; nevertheless, in this study the left labyrinth was most affected and the follow-up period was variable.

Prevalence of benign paroxysmal positional vertigo in the young adult population

OBJECTIVE

To evaluate the prevalence of benign paroxysmal positional vertigo (BPPV), defined as positionally induced nystagmus (PIN) with associated symptoms on provocative testing, in the young healthy adult population.

DESIGN

A prospective, cohort, screening study.

SETTING

A community-based hospital located in a small midwestern city with a greater metropolitan population of approximately 125,000.

PARTICIPANTS

One hundred ninety-eight young adults (99 men and 99 women), ages 18-34 years and not being treated for dizziness or balance problems, were recruited from November 2009 to April 2010.

METHODS

The participants completed questionnaires that detailed demographics, medical and surgical history, sports and/or activity participation history, and baseline symptoms commonly associated with BPPV. The participants were screened for inclusion with an ocular motor assessment in room light, followed by a vestibular positional assessment for BPPV with infrared camera-equipped goggles recorded on digital video disk.

MAIN OUTCOME MEASUREMENT

The prevalence of BPPV, defined as PIN, along with symptoms in study participants.

RESULTS

The prevalence of BPPV was 9% in this young adult population. Symptoms during testing were reported in 14% of all subjects (22% of women, 5% of men). Of 22 women who reported symptoms, 12 had PIN (P = .519), whereas the 5 men who reported symptoms all had PIN (P = .001). PIN, characteristic of that seen in BPPV (with or without associated symptoms), was identified in 53% of subjects, with 43% of subjects having posterior canal involvement, 10% having anterior canal involvement, and 8% having horizontal canal involvement. Eleven percent of subjects had bilateral semicircular canal involvement.

CONCLUSION

Nine percent of our young adult subjects were diagnosed with previously unrecognized BPPV, with provoked symptoms of dizziness, headache, nausea, or imbalance, symptoms that may cause significant physical and psychosocial limitations if left untreated. This is an important finding because BPPV is an often-overlooked diagnosis that has a known, very effective treatment.

Divergent roles for Wnt/β-catenin signaling in epithelial maintenance and breakdown during semicircular canal formation

The morphogenetic program that shapes the three semicircular canals (SSCs) must be executed with extreme precision to satisfy their complex vestibular function. The SSCs emerge from epithelial outgrowths of the dorsal otocyst, the central regions of which fuse and resorb to leave three fluid-filled canals. The Wnt/β-catenin signaling pathway is active at multiple stages of otic development, including during vestibular morphogenesis. How Wnt/β-catenin functionally integrates with other signaling pathways to sculpt the SSCs and their sensory patches is unknown. We used a genetic strategy to spatiotemporally modulate canonical Wnt signaling activity during SSC development in mice. Our findings demonstrate that Wnt/β-catenin signaling functions in a multifaceted manner during SSC formation. In the early phase, Wnt/β-catenin signaling is required to preserve the epithelial integrity of the vertical canal pouch perimeter (presumptive anterior and posterior SSCs) by establishing a sensory-dependent signaling relay that maintains expression of Dlx5 and opposes expression of the fusion plate marker netrin 1. Without this Wnt signaling activity the sensory to non-sensory signaling cascade fails to be activated, resulting in loss of vestibular hair and support cells and the anterior and posterior SSCs. In the later phase, Wnt/β-catenin signaling becomes restricted to the fusion plate where it facilitates the timely resorption of this tissue. Mosaic recombination of β-catenin in small clusters of canal pouch cells prevents their resorption, causing instead the formation of ectopic SSCs. Together, these disparate functions of the Wnt/β-catenin pathway in epithelial maintenance and resorption help regulate the size, shape and number of SSCs.

Association between gout and vertigo in a Taiwanese population

There are reports of an association between benign paroxysmal positional vertigo and hyperuricemia. We sought to determine the risk of vertigo among patients with gout compared with the general population, using a nationwide Taiwanese population-based claims database. Our study cohort consisted of patients with a diagnosis of gout disorders in 2004 (N = 18773). Four age- and gender-matched controls for every patient in the study cohort were selected using random sampling as the comparison cohort (N = 75092). All subjects were followed from the date of cohort entry until they developed vertigo or to the end of 2006. Cox proportional hazard regressions were performed to evaluate the 3-year vertigo-free survival rates. Of the total sample, 2563 (incidence, 10.09 per 1000 person-years) had vertigo during the 3-year follow-up period: 570 (incidence, 11.78 per 1000 person-years) from the study cohort and 1993 (incidence, 9.69 per 1000 person-years) from the comparison cohort. The adjusted hazard ratios (HR) of peripheral and central vertigo in patients with gout compared with controls during the 2-3-year follow-up were 1.17 (95% confidence interval [CI] = 1.05-1.29, p = 0.003) and 1.08 (95% CI = 0.86-1.36, p = 0.53), respectively. This is the first population-based study performed to suggest that patients with gout may have an increased risk of peripheral vertigo but not central vertigo. Benign paroxysmal positional vertigo may be the reason for the observed association; however, future studies are required to further ascertain the relationship between gout and the various causes of peripheral vertigo.

Nystagmus parameters and subtypes of benign paroxysmal positional vertigo

CONCLUSION

Although computational models suggest the existence of canalithiasis and cupulolithiasis subtypes of benign paroxysmal positional vertigo (BPPV), these subtypes cannot be distinguished from each other based on characteristics of nystagmus. Therefore, although the subtypes probably exist more information is needed from each patient than is available without invasive procedures. Also, some patients may have clinical syndromes that include both canalithiasis and cupulolithiasis subtypes.

OBJECTIVE

To determine if the parameters of nystagmus provide sufficient information to determine the subtype of nystagmus in a patient with BPPV.

METHODS

Patients (n = 118) had unilateral BPPV of the posterior canal; 15 patients also had BPPV of the lateral canal. The main outcome measures were parameters of nystagmus in response to the Dix-Hallpike maneuver: latency to onset of nystagmus, maximum slow phase velocity, and maximum duration.

RESULTS

Correlations between pairs of variables showed minimal or no relationships. Also, cluster analyses showed no significant subtypes. The contralateral eye moved significantly faster than the ipsilateral eye.

Regulation of cellular calcium in vestibular supporting cells by otopetrin 1

Otopetrin 1 (OTOP1) is a multitransmembrane domain protein, which is essential for mineralization of otoconia, the calcium carbonate biominerals required for vestibular function, and the normal sensation of gravity. The mechanism driving mineralization of otoconia is poorly understood, but it has been proposed that supporting cells and a mechanism to maintain high concentrations of calcium are critical. Using Otop1 knockout mice and a utricular epithelial organ culture system, we show that OTOP1 is expressed at the apex of supporting cells and functions to increase cytosolic calcium in response to purinergic agonists, such as adenosine 5'-triphosphate (ATP). This is achieved by blocking mobilization of calcium from intracellular stores in an extracellular calcium-dependent manner and by mediating influx of extracellular calcium. These data support a model in which OTOP1 acts as a sensor of the extracellular calcium concentration near supporting cells and responds to ATP in the endolymph to increase intracellular calcium levels during otoconia mineralization.