Numerical Simulations of the Epley Maneuver With Clinical Implications

OBJECTIVES

Canalith repositioning procedures to treat benign paroxysmal positional vertigo are often applied following standardized criteria, without considering the possible anatomical singularities of the membranous labyrinth for each individual. As a result, certain patients may become refractory to the treatment due to significant deviations from the ideal membranous labyrinth, that was considered when the maneuvers were designed. This study aims to understand the dynamics of the endolymphatic fluid and otoconia, within the membranous labyrinth geometry, which may contribute to the ineffectiveness of the Epley maneuver. Simultaneously, the study seeks to explore methods to avoid or reduce treatment failure.

DESIGN

We conducted a study on the Epley maneuver using numerical simulations based on a three-dimensional medical image reconstruction of the human left membranous labyrinth. A high-quality micro-computed tomography of a human temporal bone specimen was utilized for the image reconstruction, and a mathematical model for the endolymphatic fluid was developed and coupled with a spherical particle model representing otoconia inside the fluid. This allowed us to measure the position and time of each particle throughout all the steps of the maneuver, using equations that describe the physics behind benign paroxysmal positional vertigo.

RESULTS

Numerical simulations of the standard Epley maneuver applied to this membranous labyrinth model yielded unsatisfactory results, as otoconia do not reach the frontside of the utricle, which in this study is used as the measure of success. The resting times between subsequent steps indicated that longer intervals are required for smaller otoconia. Using different angles of rotation can prevent otoconia from entering the superior semicircular canal or the posterior ampulla. Steps 3, 4, and 5 exhibited a heightened susceptibility to failure, as otoconia could be accidentally displaced into these regions.

CONCLUSIONS

We demonstrate that modifying the Epley maneuver based on the numerical results obtained in the membranous labyrinth of the human specimen under study can have a significant effect on the success or failure of the treatment. The use of numerical simulations appears to be a useful tool for future canalith repositioning procedures that aim to personalize the treatment by modifying the rotation planes currently defined as the standard criteria.

Neurotological emergencies: a narrative review

INTRODUCTION

Vestibular symptoms, including vertigo, dizziness, and gait unsteadiness, are a frequent reason of urgent medical assistance. Their causes are numerous and diverse, including neurological, otorhinolaryngological, and systemic diseases. Therefore, following a systematic approach is essential to differentiate striking but benign conditions from others that can compromise the patient's life. This study is intended to review vestibular disorders from a practical perspective and provide guidance to physicians involved in the emergency care of patients with vestibular symptoms.

MATERIALS AND METHODS

A narrative review was performed, revisiting the main causes of vestibular disorders.

RESULTS

Based on the speed of onset, duration, and history of similar episodes in the past, vestibular disorders can be categorized into three syndromic entities (acute, recurrent, and chronic vestibular syndromes). The most representative conditions pertaining to each group were reviewed (including their diagnosis and treatment) and a practical algorithm was proposed for their correct management in the acute care setting.

CONCLUSIONS

Carrying out a correct categorization of the vestibular disorders is essential to avoid diagnostic pitfalls. This review provides useful tools for clinicians to approach their patients with vestibular symptoms at the emergency room.

Numerical simulations to determine the stimulation of the crista ampullaris during the Head Impulse Test

The Head Impulse Test, the most widely accept test to assess the vestibular function, comprises rotations of the head based on idealized orientations of the semicircular canals, instead of their individual arrangement specific for each patient. In this study, we show how computational modelling can help personalize the diagnosis of vestibular diseases. Based on a micro-computed tomography reconstruction of the human membranous labyrinth and their simulation using Computational Fluid Dynamics and Fluid-Solid Interaction techniques, we evaluated the stimulus experienced by the six cristae ampullaris under different rotational conditions mimicking the Head Impulse Test. The results show that the maximum stimulation of the crista ampullaris occurs for directions of rotation that are more aligned with the orientation of the cupulae (average deviation from alignment of 4.7°, 9.8°, and 19.4° for the horizontal, posterior, and superior maxima, respectively) than with the planes of the semicircular canals (average deviation from alignment of 32.4°, 70.5°, and 67.8° for the horizontal, posterior, and superior maxima, respectively). A plausible explanation is that when rotations are applied with respect to the center of the head, the inertial forces acting directly over the cupula become dominant over the endolymphatic fluid forces generated in the semicircular canals. Our results indicate that it is necessary to consider cupulae orientation to ensure optimal conditions for testing the vestibular function.

Individualized Vibrotactile Neurofeedback Training in Patients with Chronic Bilateral Vestibulopathy

Patients with bilateral vestibulopathy (BVP) suffer from postural imbalance during daily life conditions, which in turn leads to a high frequency of falls. Unfortunately, vestibular rehabilitation has only modest and somewhat inconsistent effects in this patient group. Approximately 50% of BVP patients show an improved postural control after conventional vestibular rehabilitation training. New and more promising approaches are required. The individualized vibrotactile neurofeedback training (IVNT) in stance and gait conditions has already been described as highly effective in patients with various vestibular disorders. The purpose of the present multicenter study was to determine the efficacy of the IVNT in improving balance, reducing self-perceived disability, and improving gait in patients with confirmed BVP. In total, 22 patients performed the IVNT with the Vertiguard® system for 10 daily sessions. The dizziness handicap inventory (DHI), the stance stability score of the sensory organization test (SOT) and the score for everyday life mobility in stance and gait tasks (SBDT) were obtained immediately before and after the rehabilitation training period, as well as 3 and 12 months later. All measures improved significantly after the IVNT. Between 77.3% and 94.4% of patients showed an individual benefit (depending on outcome measure). The effect was not significantly reduced within the follow-up period of 12 months. The results demonstrate a high efficacy of the IVNT for vestibular rehabilitation in BVP patients.

What could posturography tell us about balance in essential tremor?

BACKGROUND

Essential tremor (ET) is a neurological disorder characterized primarily by action tremor. Balance impairments in ET patients were formerly considered to be uncommon and simply age-related. However quantitative assessment with posturography has revealed impairments in control of both static and dynamic balance.

RESEARCH QUESTION

The aim of the present study is to assess postural stability with different posturographic techniques in ET patients.

METHODS

A prospective cross-sectional study conducted in two University Hospitals. Eleven patients diagnosed with essential tremor and twelve healthy controls were included. Balance assessment were performed with: sensory organization test (SOT) and limits of stability (LOS) of the computer dynamic posturography (CDP), results of free-field body sway analysis with mobile posturography (Vertiguard®), modified timed up and go test (TUG), Dizziness handicap inventory (DHI) and activities-specific balance confidence scale (ABC).

RESULTS

Patients with ET showed poorer scores in the SOT than controls for composite balance and somatosensory input. They also performed worse in LOS tests and Vertiguard® device indicated a higher risk of falling. There were no differences in the modified TUG. The mean score of DHI was 15.64 and 85.16 for ABC.

SIGNIFICANCE

Posturography assessment (CDP and Vertiguard®) is more accurate in showing balance impairment in ET patients than clinical evaluation (modified TUG). Balance impairment involves deteriorated processing of somatosensory input which could be explained by cerebellar dysfunction. Balance deficits could be included into future diagnostic criteria.

Rare coding variants involving MYO7A and other genes encoding stereocilia link proteins in familial meniere disease

The MYO7A gene encodes a motor protein with a key role in the organization of stereocilia in auditory and vestibular hair cells. Rare variants in the MYO7A (myosin VIIA) gene may cause autosomal dominant (AD) or autosomal recessive (AR) sensorineural hearing loss (SNHL) accompanied by vestibular dysfunction or retinitis pigmentosa (Usher syndrome type 1B). Familial Meniere's disease (MD) is a rare inner ear syndrome mainly characterized by low-frequency sensorineural hearing loss and episodic vertigo associated with tinnitus. Familial aggregation has been found in 6-8% of sporadic cases, and most of the reported genes were involved in single families. Thus, this study aimed to search for relevant genes not previously linked to familial MD. Through exome sequencing and segregation analysis in 62 MD families, we have found a total of 1 novel and 8 rare heterozygous variants in the MYO7A gene in 9 non-related families. Carriers of rare variants in MYO7A showed autosomal dominant or autosomal recessive SNHL in familial MD. Additionally, some novel and rare variants in other genes involved in the organization of the stereocilia links such as CDH23, PCDH15 or ADGRV1 co-segregated in the same patients. Our findings reveal a co-segregation of rare variants in the MYO7A gene and other structural myosin VIIA binding proteins involved in the tip and ankle links of the hair cell stereocilia. We suggest that recessive digenic inheritance involving these genes could affect the ultrastructure of the stereocilia links in familial MD.

Burden of Rare Variants in the OTOG Gene in Familial Meniere's Disease

OBJECTIVES

Meniere's disease (MD) is a rare inner ear disorder characterized by sensorineural hearing loss, episodic vertigo, and tinnitus. Familial MD has been reported in 6 to 9% of sporadic cases, and few genes including FAM136A, DTNA, PRKCB, SEMA3D, and DPT have been involved in single families, suggesting genetic heterogeneity. In this study, the authors recruited 46 families with MD to search for relevant candidate genes for hearing loss in familial MD.

DESIGN

Exome sequencing data from MD patients were analyzed to search for rare variants in hearing loss genes in a case-control study. A total of 109 patients with MD (73 familial cases and 36 early-onset sporadic patients) diagnosed according to the diagnostic criteria defined by the Barany Society were recruited in 11 hospitals. The allelic frequencies of rare variants in hearing loss genes were calculated in individuals with familial MD. A single rare variant analysis and a gene burden analysis (GBA) were conducted in the dataset selecting 1 patient from each family. Allelic frequencies from European and Spanish reference datasets were used as controls.

RESULTS

A total of 5136 single-nucleotide variants in hearing loss genes were considered for single rare variant analysis in familial MD cases, but only 1 heterozygous likely pathogenic variant in the OTOG gene (rs552304627) was found in 2 unrelated families. The gene burden analysis found an enrichment of rare missense variants in the OTOG gene in familial MD. So, 15 of 46 families (33%) showed at least 1 rare missense variant in the OTOG gene, suggesting a key role in familial MD.

CONCLUSIONS

The authors found an enrichment of multiplex rare missense variants in the OTOG gene in familial MD. This finding supports OTOG as a relevant gene in familial MD and set the groundwork for genetic testing in MD.

Presbyvestibulopathy, Comorbidities, and Perception of Disability: A Cross-Sectional Study

Objective: To assess the perception of disability in patients with presbyvestibulopathy and to determine the factors (demographic, balance test scores, and comorbidities) that determine higher levels of disability.

Material and Methods: This was a cross-sectional study conducted in a tertiary university hospital. There were 103 patients who fulfilled the diagnostic criteria for presbyvestibulopathy and were included. Dizziness Handicap Inventory (DHI) score was the main variable used to quantify disability. Influence on DHI score, sex, age, time of evolution, equilibriometric parameters (posturographic scores and timed up and go test), history of falls, comorbidities (high blood pressure, diabetes, and dyslipidemia), psychotropic drug use, tobacco or alcohol use, living environment (urban or rural), and active lifestyle were analyzed.

Results: Most of the DHI scores showed a moderate (46 patients, 44.7%) or severe (39 participants, 37.9%) handicap. DHI scores were higher in women (59.8 vs. 36.1, p < 0.001), patients with obesity (58.92 vs. 48.68; p = 0.019), benzodiazepine (59.9 vs. 49.1, p = 0.008) or other psychotropic drug (60.7 vs. 49.2, p = 0.017) users, and fallers (57.1 vs. 47.3, p = 0.048). There was also a significant positive correlation between DHI score, time (Rho coefficient: 0.371, p < 0.001), and steps (Rho coefficient: 0.284, p = 0.004) used in the TUG and with the short FES-I questionnaire (a shortened version of the Falls Efficacy Scale-International) score (Rho coefficient: 0.695, p < 0.001). DHI scores were lower in alcohol consumers than in non-drinkers (46.6 vs. 56, p = 0.048). No significant correlation was found between DHI scores and age, time of evolution, posturographic scores, comorbidities, environment (rural or urban), or active lifestyle.

Conclusion: Most patients with presbyvestibulopathy show an important subjective perception of disability in relation to their symptoms. This perception is substantially higher in women than in men. The most influential factors are difficulties in walking, fear of falling, and obesity.

Unique Identifier: NCT03034655, www.clinicaltrials.gov.

Modified Timed Up and Go Test for Tendency to Fall and Balance Assessment in Elderly Patients With Gait Instability

Objective: To compare the results from the modified Timed Up and Go Test (TUG) with posturographic variables, the subjective perception of disability due to gait instability, and the number of falls in a sample of the elderly population with imbalance, to confirm that the TUG Test is a useful clinical instrument to assess the tendency to fall in individuals of this age group.

Materials and Methods: Cross-sectional study conducted in a tertiary university hospital, in 174 people aged 65 years or older with gait instability. Modified TUG Test was performed; time, step count and the need for support during the test were the analyzed variables. They were compared with the number of falls, Computerized Dynamic Posturography scores, and questionnaires scores (Dizziness Handicap Inventory and a shortened version of the Falls Efficacy Scale-International).

Results: The average time to complete the TUG Test was 21.24 ± 8.18 s, and the average step count was 27.36 ± 7.93. One hundred two patients (58.6%) required no support to complete the test, whereas the other 72 (41.4%) used supports. The time taken to complete the Test was significantly related with having or not having fallen in the previous year, with the scores of the questionnaires, and with various parameters of dynamic posturography. A higher percentage of patients who took more than 15 s had fallen in the previous year than those who took up to 15 s to complete the test [P = 0.012; OR = 2.378; 95% CI (1.183, 4.780)]. No significant correlation was found between the step count and the number of falls in the previous year, with falling during the test or not, or with being a single or a frequent faller. No relation was found between the need for supports and the number of falls, with having or not having fallen in the previous year, or with being a single or frequent faller.

Conclusion: The modified TUG Test is in relation with the presence or absence of falls. Time is the essential parameter for analyzing the risk of falling and the 15-s threshold is a good value to differentiate elderly patients at high risk of falling.

Unique Identifier: NCT03034655, www.clinicaltrials.gov.

Vestibular Rehabilitation Using Posturographic System in Elderly Patients with Postural Instability: Can the Number of Sessions Be Reduced?

Purpose

Vestibular rehabilitation (VR) using posturography systems has proved useful in improving balance among elderly patients with postural instability. However, its high cost hinders its use. The objective of this study is to assess whether two different protocols of VR with posturography, one of them longer (ten sessions) and the other shorter (five sessions), show significant differences in the improvement of balance among old patients with instability.

Patients and Methods

This is a prospective, experimental, single-center (Department of Otorhinolaryngology of a tertiary referral hospital), randomized (into balanced patient blocks) study with two parallel arms, in 40 people over 65 years of age, with instability and at a high risk of falling. The percentage of the average balance (composite) in the sensory organization test (SOT) of the CDP (main outcome measure), other CDP scores, time and steps in the "timed up and go" test, scores of Dizziness Handicap Inventory (DHI), short Falls Efficacy Scale - International (short FES-I), and Vertiguard were compared before and 3 weeks after VR between both intervention groups.

Results

The two treatment groups (20 patients per group) were comparable in age, sex, and pre-VR balance evaluation. In both groups, we observed a significant improvement in global balance (composite) after VR (49±11.34 vs 57±13.48, p=0.007, in the group undergoing 10 sessions; 51±12.55 vs 60±12.99, p=0.002, 5 sessions). In both groups, we also observed improvements in other posturographic parameters (in the SOT and limits of stability) but not in the timed up and go scores or in the questionnaires. Comparison of the improvement level achieved in both groups revealed no significant differences between them.

Conclusion

The protocols of vestibular rehabilitation by posturography of 5 sessions in elderly patients with postural instability are as effective as those of 10 sessions for improving balance among elderly patients with postural instability.

Trial Registration

ClinicalTrials.gov identifier: NCT03034655. Registered on 25 January 2017.

Does patient environment have any influence on balance?

BACKGROUND

Although patient environment is a factor to consider when planning a vestibular rehabilitation program, there are no studies correlating this factor to outcomes of balance assessment.

AIM

To evaluate whether there are differences in objective evaluation of balance in elderly patients at risk of falls according to the environment in which they live (urban or rural) and their lifestyle (considering cardiovascular risk factors).

METHODS

Cross-sectional study of a sample of 139 elderly patients with high risk of falls assessed with objective outcome measures: Computer Dynamic Posturography (CDP), and the modified Timed Up-and-Go (TUG) test; and subjective outcome measures: Dizziness Handicap Inventory (DHI) and short Falls Efficacy Scale-International (short FES-I). Rural or urban environment was defined according to administrative and legal criteria.

RESULTS

Elderly patients at risk of fall living in rural environment show better composite results in SOT with better scores in Condition 6 and fewer falls during the CDP. They also require fewer steps to perform the TUG test.

DISCUSSION

The present study provides evidence that patient environment has an influence in balance.

CONCLUSION

Patient environment should be considered when analyze tests evaluating static and dynamic balance.

Prognostic factors that modify outcomes of vestibular rehabilitation in elderly patients with falls

BACKGROUND

Our previous study has shown that vestibular rehabilitation (VR) is an effective technique to reduce falls in elderly patients. It would be interesting to establish patients' clinical characteristics in which vestibular rehabilitation is expected to be more effective.

AIMS

Evaluate factors that could modify rehabilitation outcomes in elderly patients with previous falls.

METHODS

Fifty-seven patients randomized to one of the intervention group (computerized dynamic posturography-CDP-training, optokinetic stimulus or exercise at home) and with previous falls were analyzed. Patients were assessed with objective outcome measures (sensorial organization test and limits of stability-LOS-of CDP, modified timed up and go test-TUG-and number of falls) and with subjective outcome measures (dizziness handicap inventory and Short falls efficacy scale-international-Short FES-I) during a 12-month follow-up period.

RESULTS

In the logistic regression model, a worse score in the maximum excursion (MXM), and a shorter time in the TUG significantly associated with a reduction > 50% of falls. Also, association with a higher score in the Short FES-I was close to a statistical significance. There was no statistical significance association with other covariables.

DISCUSSION

In patients with reduced limits of stability, VR seems to be more effective and they should be encouraged to perform it. But on the other hand, patients with longer time in the TUG show worse outcomes and may benefit more with gait training.

CONCLUSIONS

VR in elderly people with previous falls is effective regardless of their age and gender.

Instability in Patients with CANVAS: Can Computerized Dynamic Posturography Help in Diagnosis?

OBJECTIVE

To describe the pattern of dynamic posturography or its role in diagnosis in patients with cerebellar ataxia with neuropathy and vestibular arreflexia syndrome (CANVAS).

MATERIALS AND METHODS

We present and describe posturographic data of four patients diagnosed with the CANVAS syndrome in a tertiary hospital.

RESULTS

In all patients, the average balance score was diminished. Two patients presented a pattern of visual dependence. The other two showed misuse of three posturography sensory information (visual, vestibular and propioceptive information), specially null use of vestibular information, deterioration of somatosensory input, and poor use of strategies, particularly in conditions 5 and 6.

CONCLUSIONS

If there is misuse of somatosensory information in sensory organization test (SOT) in a patient with bilateral vestibular deficit, a possibility of CANVAS should be considered. The SOT provides valuable information, because it evaluates sensory inputs influence the maintenance of balance.

Optimising costs in reducing rate of falls in older people with the improvement of balance by means of vestibular rehabilitation (ReFOVeRe study): a randomized controlled trial comparing computerised dynamic posturography vs mobile vibrotactile posturography system

BACKGROUND

Accidental falls, especially for the elderly, are a major health issue. Balance disorders are one of their main causes. Vestibular rehabilitation (VR) has proven to be useful in improving balance of elderly patients with instability. Its major handicap is probably its cost, which has prevented its generalisation. So, we have designed a clinical trial with posturographic VR, to assess the optimum number of sessions necessary for a substantial improvement and to compare computerised dynamic posturography (CDP) (visual feedback) and mobile posturography (vibrotactile feedback).

METHODS

Design: randomized controlled trial. It is an experimental study, single-center, open, randomized (balanced blocks of patients) in four branches in parallel, in 220 elderly patients with high risk of falls; follow-up period: twelve months.

SETTING

Department of Otorhinolaryngology of a tertiary referral hospital.

PARTICIPANTS

people over 65 years, fulfilling two or more of the following requirements: a) at least one fall in the last twelve months. b) take at least 16 s or require some support in perform the "timed up and go" test. c) a percentage of average balance in the sensory organization test (SOT) of the CDP < 68%. d) at least one fall in any of the conditions in SOT-CDP. e) a score in Vertiguard's gSBDT > 60%.

INTERVENTION

Four differents protocols of vestibular rehabilitation (randomization of the patients).

MAIN OUTCOME MEASURE

The percentage of average balance in the SOT-CDP. Secondary measures: time and supports in the "timed up and go" test, scores of the CDP and Vertiguard, and rate of falls.

DISCUSSION

Posturographic VR has been proven to be useful for improving balance and reducing the number of falls among the aged. However, its elevated cost has limited its use. It is possible to implement two strategies that improve the cost-benefit of posturography. The first involves optimising the number of rehabilitation sessions; the second is based on the use of cheaper posturography systems.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03034655. Registered on 25 January 2017.

Instability Due to Drug-Induced Vestibulotoxicity

OBJECTIVE

The therapeutic use of ototoxic drugs is relatively common, particularly in patients with severe diseases. It is likely that disturbances of balance in these patients are underestimated by clinicians.

MATERIALS AND METHODS

The purpose of this study was to identify drugs involved in the vestibulotoxic origin of instability in a group of 18 patients.

RESULTS

Six patients showed both cochlear and vestibular damage, while 12 were affected only by posterior labyrinthine damage. Four groups of drugs were identified: antibiotics (nine patients), cytostatics (four), anti-tuberculosis medicinal products (three), and other drugs (two). Cytostatics were involved in many cases studied, a fact scarcely reported before.

CONCLUSION

It is important to ensure an early diagnosis to prevent ototoxic effects induced by drugs. We propose that patients receiving potential ototoxic drugs undergo cochlear and vestibular assessments. Further, we recommend that patients with instability undergo vestibular rehabilitation.

Extended phenotype and clinical subgroups in unilateral Meniere disease: A cross-sectional study with cluster analysis

OBJECTIVES

To define clinical subgroups by cluster analysis in patients with unilateral Meniere disease (MD) and to compare them with the clinical subgroups found in bilateral MD.

DESIGN

A cross-sectional study with a two-step cluster analysis.

SETTINGS

A tertiary referral multicenter study.

PARTICIPANTS

Nine hundred and eighty-eight adult patients with unilateral MD.

MAIN OUTCOME MEASURES

best predictors to define clinical subgroups with potential different aetiologies.

RESULTS

We established five clusters in unilateral MD. Group 1 is the most frequently found, includes 53% of patients, and it is defined as the sporadic, classic MD without migraine and without autoimmune disorder (AD). Group 2 is found in 8% of patients, and it is defined by hearing loss, which antedates the vertigo episodes by months or years (delayed MD), without migraine or AD in most of cases. Group 3 involves 13% of patients, and it is considered familial MD, while group 4, which includes 15% of patients, is linked to the presence of migraine in all cases. Group 5 is found in 11% of patients and is defined by a comorbid AD. We found significant differences in the distribution of AD in clusters 3, 4 and 5 between patients with uni- and bilateral MD.

CONCLUSIONS

Cluster analysis defines clinical subgroups in MD, and it extends the phenotype beyond audiovestibular symptoms. This classification will help to improve the phenotyping in MD and facilitate the selection of patients for randomised clinical trials.

Posturographic limits of stability can predict the increased risk of falls in elderly patients with instability?

CONCLUSIONS

There was a difference in average score of the sensory organization test (SOT) of the case group (elderly instability) compared to the control group (healthy subjects). Cases had worse scores on the limits of stability (LOS) than controls, but were only able to confirm statistically significant differences in the movement velocity.

OBJECTIVE

To study the LOS of elderly patients with instability vs healthy subjects of the same age to try to explain the increased risk of falls in elderly patients with instability.

METHODS

Fifty individuals ≥65 years, 30 cases (at least one of the next inclusion criteria: ≥1 fall in the last 12 months, >15 s or some support in the timed up and go test, composite <68 in SOT, ≥1 fall during production of the SOT) compared to 20 controls. Postural study: SOT and LOS, Smart Equitest Neurocom^® platform.

STATISTICAL ANALYSIS

t-Student test (p < 0.05).

RESULT

Mean value of overall balance: patients with instability =56% vs controls =77.1% (p < 0.001). Movement velocity: cases =2243°/s vs controls =2860°/s (p = 0.029). The reaction time (cases =1217 s vs controls =1.077 s), excursion (56.95% vs 59.35%) and directional control (56.95% vs 59.35%) differences were not statistically significant.

A novel missense variant in PRKCB segregates low-frequency hearing loss in an autosomal dominant family with Meniere's disease

Meniere's Disease (MD) is a complex disorder associated with an accumulation of endolymph in the membranous labyrinth in the inner ear. It is characterized by recurrent attacks of spontaneous vertigo associated with sensorineural hearing loss (SNHL) and tinnitus. The SNHL usually starts at low and medium frequencies with a variable progression to high frequencies. We identified a novel missense variant in the PRKCB gene in a Spanish family with MD segregating low-to-middle frequency SNHL. Confocal imaging showed strong PKCB II protein labelling in non-sensory cells, the tectal cells and inner border cells of the rat organ of Corti with a tonotopic expression gradient. The PKCB II signal was more pronounced in the apical turn of the cochlea when compared with the middle and basal turns. It was also much higher in cochlear tissue than in vestibular tissue. Taken together, our findings identify PRKCB gene as a novel candidate gene for familial MD and its expression gradient in supporting cells of the organ of Corti deserves attention, given the role of supporting cells in K⁺recycling within the endolymph, and its apical turn location may explain the onset of hearing loss at low frequencies in MD.

Balance Disorders in the Elderly: Does Instability Increase Over Time?

OBJECTIVES

To analyze the equilibriometric differences between 2 populations of elderly patients (young elderly and very elderly) with instability induced solely by age.

METHODS

Cross-sectional study, with 2 study groups classified according to patient age (cut-points in twenty-fifth and seventy-fifth percentiles of the age of the sample).

POPULATION

64 patients aged 65 years or more. Two groups of 32 subjects were established: group A (people 65 years of age or older but less than 72.6, twenty-fifth percentile) and group B (patients 82.5 years, seventh-fifth percentile, or older). Main analyzed variables: timed up-and-go test, sensory organization test of the computerized dynamic posturography, Dizziness Handicap Inventory (DHI), and Short Falls Efficacy Scale-International (FES-I) questionnaires. Student's t test or the Mann-Whitney test were used.

RESULTS

The older patients obtain poorer scores in the equilibriometric tests but not in all of them. In the sensory organization test, the older patients make poorer use of visual and vestibular information; they also require more time and steps for the timed up-and-go. With regards to the questionnaires, fear of falling is greater (higher Short FES-I scores) but not subjective perception of disability (DHI scores without differences).

CONCLUSIONS

There is a need to establish aged subgroups of elderly patients with instability, adapting therapeutic strategies.

Postural changes associated with ageing on the sensory organization test and the limits of stability in healthy subjects

OBJECTIVE

Acknowledgement of the age effects on postural control and balance is essential to differentiate between physiological changes and actual pathological alterations of the elderly. The aim of this study is to establish the age-related postural changes recorded by the Computerized Dynamic Posturography.

MATERIAL AND METHODS

70 healthy individuals (35 males and 35 females) with an average age of 44.9 years, evenly distributed in seven age groups. We carried out a Sensory Organization Test and Limits of Stability with the Neurocom Smart Balance Master(®) posturography platform. Statistical analysis was undertaken using ANOVA (p<0.05).

RESULTS

Increased age-related balance percentage for Condition 4 (p=0.022), reduced usage rate of ankle-strategy for Conditions 3 (p=0.027) and 4 (p=0.05) for the higher age groups were reported. Regarding limits of stability, the following were the results: age-related differences at an early stage, reaction time from 40 to 49 years, velocity of movement, excursion and directional control from 50 to 59 years.

CONCLUSIONS

Age only affects the balance rate under more complex sensory conditions. For healthy people, ankle strategy is more frequently used than hip strategy; however, the use of hip strategy increases under more difficult sensory conditions. Limits of stability get worse with age, namely after the age of 40-50 years.

Can we predict the risk of falls in elderly patients with instability?

OBJECTIVE

The aim of this study is to determine whether clinical and instrumental examination of balance can predict the risk of falls in elderly patients with instability.

METHODS

STUDY DESIGN

It is a case control study, with cases defined by falls in the last year, developed in a third level university hospital.

PATIENTS

Seventy patients aged 65 years or more who met at least one of the following inclusion criteria: (a) at least one fall in the last year; (b) spend more than 15s during the timed up and go test (TUG); (c) a score of less than 68% average balance in the sensory organisation test (SOT) of the computerised dynamic posturography (CDP); or (d) at least one fall in the CDP-SOT.

INTERVENTION

TUG test, CDP-SOT, CDP centre of gravity balancing (CG) and limits of stability (LOS), Dizziness Handicap Inventory (DHI) test and short FES-I test.

MAIN OUTCOME MEASURES

Number of steps and time (TUG), average balance and use of sensorial information (CDP-SOT), speed and directional control (CDP-CG and LOS), DHI score and short FES-I score.

RESULTS

Comparing subjects without falls (non-fallers) vs subjects with at least one fall (fallers) in the last year, fallers obtain worse scores than non-fallers in condition 2 (p=0.043) and use of somatosensory information (p=0.039). Comparing subjects with five falls or less (non-multiple-fallers) vs subjects with more than five falls (multiple-fallers), multiple-fallers obtain worse scores than non-multiple-fallers in overall balance (p=0.023), condition 6 (p=0.036), directional control (swaying (p=0.006) and LOS (p=0.023)) and short FES-I score (p=0.007).

CONCLUSION

The three most useful parameters for identifying unstable elderly patients at particularly high risk of repeated falls are mean balance in the CDP SOT, directional control of CDP LOS and short FES-I score.

Is posturography able to identify fallers in patients with Parkinson's disease?

INTRODUCTION

Parkinson' disease (PD) is one of the most prevalent neurodegenerative diseases, and more than half of patients with PD experience falls. Research for clinically useful risk factors predicting falls has yielded inconsistent findings so far. Hence the aim of the study is to validate two different posturography techniques and one modified-timed up and go test (TUG) in discriminating fallers and non-fallers among PD patients.

METHODS

32 patients diagnosed with idiopathic PD were assessed with: Dizziness handicap inventory, Activities-specific balance confidence scale, modified-TUG, sensorial organization test (SOT) and limits of stability (LOS) of computer dynamic posturography, results of free-field body sway analysis with Vertiguard device and number of falls.

RESULTS

Fallers had longer time to perform modified-TUG and required more steps. On average, fallers performed SOT and LOS significantly worse and Vertiguard device indicated a higher risk of falling. Based on the area under the curve of receiver operating characteristics analyses, the overall accuracy of directional control of LOS and steps in modified-TUG are close to 0.9 (high accuracy). Also assessment with Vertiguard device is more efficient in identifying fallers than the parameters of SOT.

DISCUSSION

Our results indicate that LOS, mobile posturography (Vertiguard), vestibular input of SOT and number of steps taken in modified-TUG are very useful to identify fallers in PD patients.

Are the three canals equally susceptible to benign paroxysmal positional vertigo?

A prospective study of patients diagnosed with 'single-canal' benign paroxysmal positional vertigo (BPPV) was performed. Demographic, etiological and prognostic differences between patients with posterior, horizontal and superior canal BPPV were studied. A total of 614 patients diagnosed in a period of 11 years and with a follow-up period of at least 1 year were included in the study. The posterior semicircular canal was affected in 543 casas (88.4%), the horizontal in 39 (6.4%) and the superior canal in 32 (5.2%). Final status at the end of the follow-up period was better in posterior canal BPPV (95% cure) than in horizontal or superior canal BPPV (87% cure in both cases). This may be explained by two facts: a poorer initial response to repositioning maneuvers in anterior canal BPPV than in BPPV involving the other two canals, and a poorer response to maneuvers in recurrences of horizontal canal BPPV.

Revised criteria for suspicion of non-benign positional vertigo

Benign paroxysmal positional vertigo (BPPV) is the most commonly diagnosed vestibular vertigo. BPPV can be diagnosed by clinical examination and its treatment is based on particle repositioning manoeuvres, and specialized equipment is not required. Therefore, most patients could be diagnosed and treated by their general practitioner. Unfortunately, not all positional vertigos are benign. Symptoms similar to those of BPPV can be caused by diseases that affect the central nervous system. It must be possible to define criteria that allow us to suspect, in a patient with symptoms of positional vertigo, the possibility of a cerebral origin ('non-benign PV'). Requests for magnetic resonance imaging must be justified by the fulfillment of these criteria. That is especially relevant in primary care, because these criteria should make possible to distinguish between patients with positional vertigo that could be treated by general practitioner and patients that need to be directed to especialized units. We propose the following revised criteria for suspected non-benign PV: (i) association with signs or symptoms of neurological disorder, (ii) nystagmus without dizziness in positional diagnostic tests, (iii) atypical nystagmus direction, (iv) poor response to therapeutic manoeuvres and (v) recurrence (confirmed by positional tests) on at least three occasions.

What is the optimal number of treatment sessions of vestibular rehabilitation?

Vestibular rehabilitation is effective and safe in patients with instability. However, there is insufficient evidence for distinguishing between efficacies of different dosage of therapies. Therefore, the aim of the present study was to verify whether there were differences between two computerised dynamic posturography (CDP) therapies of different numbers of sessions, in order to establish the optimal strategy. We conducted a prospective, comparative study of two different dosage of CDP therapy (a 5-session group and another of 10-session group) in patients with instability due to chronic unilateral peripheral vestibular disorder. We used balanced block randomisation to include 13 patients in each group. Improvement was assessed using the Dizziness Handicap Inventory and the CDP with the sensorial organisation test (SOT) and limits of stability (LOS). We found a statistically significant improvement in both groups in composite score, visual and vestibular input (SOT); and in reaction time, distance and directional control (LOS). If we compare the groups regarding these improvements, we found that 10-session group showed a greater benefit in distance covered and directional control of LOS. Since significant improvement is obtained with only five sessions, we believe this to be the optimal number of treatment sessions for most patients with chronic unilateral peripheral vestibular disorder. Nevertheless, those patients with more reduced limits of stability, and consequently greater likelihood of falling as a result of their diminished base of support, are candidates for rehabilitation protocols with a greater number of sessions.

Vibrotactile neurofeedback balance training in patients with Parkinson's disease: reducing the number of falls

The aim of this study was to assess effectiveness of balance training with a vibrotactile neurofeedback system in improving overall stability in patients with Parkinson's disease (PD). Ten patients diagnosed with idiopathic PD were included. Individualization of the rehabilitation program started with a body sway analysis of stance and gait tasks (Standard Balance Deficit Test, SBDT) by using the diagnostic tool of the applied device (Vertiguard(®)-RT). Those tasks with the poorest outcome as related to age- and gender-related controls were included in the training program (not more than six tasks). Improvement of postural stability was assessed by performing SBDT, Sensory Organization Test (SOT) of Computerized Dynamic Posturography (CDP), Dizziness Handicap Inventory (DHI), activity-specific balance confidence scale and recording the number of falls over the past three months. Furthermore, scores of SOT and DHI of 10 PD patients previously trained in an earlier study (by using CDP) were compared with results of those in the present study. After neurofeedback training (NFT), there was a statistically significant improvement in body sway (calculated over all training tasks), number of falls, and scores of SOT, DHI and ABC. In comparison with CDP-training, a statistically significant higher increase of SOT score was observed for patients after NFT with the Vertiguard-RT device compared to CDP training. Our results showed that a free-field vibrotactile NFT with Vertiguard(®)-RT device can improve balance in PD patients in everyday life conditions very effectively, which might led in turn to a reduction of falls.

Correlation between bithermal caloric test results and vestibular evoked myogenic potentials (VEMPs) in normal subjects

Bithermal caloric testing and vestibular evoked myogenic potentials (VEMPs) are both diagnostic tools for the study of the vestibular system. The first tests the horizontal semicircular canal and the second evaluates the saccule and lower vestibular nerve. The results of these two tests can therefore be expected to be correlated. The aim of this study was to compare bithermal caloric test results with VEMP records in normal subjects to verify whether they are correlated.

MATERIAL AND METHOD

A prospective study was conducted in 60 healthy subjects (30 men and 30 women) who underwent otoscopy, pure tone audiometry, bithermal caloric testing and VEMPs. From the caloric test, we assessed the presence of possible vestibular hypofunction, whether there was directional preponderance and reflectivity of each ear (all based on both slow phase velocity and nystagmus frequency). The analysed VEMPs variables were: p1 and n1 latency, corrected amplitude, interaural p1 latency difference and p1 interaural amplitude asymmetry. We compared the reflectivity, hypofunction and directional preponderance of the caloric tests with the corrected amplitudes and amplitude asymmetries of the VEMPs. No correlations were found in the different comparisons between bithermal caloric testing results and VEMPs except for a weak correlation (p = 0.039) when comparing preponderance based on the number of nystagmus in the caloric test and amplitude asymmetry with 99 dB tone burst in the VEMPs test. The results indicate that the two diagnostic tests are not comparable, so one of them cannot replace the other, but the use of both increases diagnostic success in some conditions.

Comparative study of computerized dynamic posturography and the SwayStar system in healthy subjects

CONCLUSIONS

For healthy subjects, posturography and SwayStar™ results are basically comparable, when they are obtained under the same sensory stimulation conditions. However, the management of the information and the mathematical analyses in the two systems are not comparable.

OBJECTIVES

Postural control represents man's ability to maintain the center of pressures inside the limits of stability. Posturography is a set of techniques that objectively studies and quantifies the postural control. The present study analyzed the different parameters of the dynamic computerized posturography and SwayStar systems related to balance, to determine whether the results of the two systems in the same healthy subject are equivalent.

METHODS

Seventy healthy individuals, with a mean age of 44.9 years, were homogeneously divided into seven age groups. Postural studies with a Neurocom(®) Smart Balance Master posturography platform (sensorial organization test), with the SwayStar(®) system (14 tests), and another sensorial organization test were recorded simultaneously with the two posturographs. The Pearson correlation test was used for the statistical study (p < 0.05).

RESULTS

Comparison of the independent records showed correlation only in the Romberg position with eyes closed on a normal surface and in the Romberg position with open eyes on moving/foam surface. We found correlation for all conditions when simultaneously recorded.

[Influence of gender on the sensory organisation test and the limits of stability in healthy subjects]

INTRODUCTION

The sensory organization test and the limits of stability are the gold standard for dynamic posturography. It is postulated that these measurements vary depending on age, activity of the subject and musculoskeletal system, emotional condition or other factors. The aim of this study was to determine the influence of gender on the above-mentioned analyses.

MATERIAL AND METHODS

70 healthy subjects (35 males and 35 females); mean age: 44.9 years. A clinical history was taken and a physical and otoneurological exploration was performed for each subject, along with a posturography study using the Neurocom SMART Balance Master platform model. The statistical study was carried out with the ANOVA test (p<0.05).

RESULTS

Condition 5 presented the lowest percentage of balance in both sexes (64.36%). The highest percentage of balance in males was in Condition 1 (p<0.001) and the lowest in 3 (p=0.030). There were no differences in the sensory analysis. The lowest employment of ankle strategy was in Condition 5 for both sexes (88.61%); women used the ankle strategy in Condition 4 more efficiently (p=0.0129). There were also differences in the time of reaction towards the right (p=0.022) and the mean (p=0.011) (higher in females), and in the speed of movement backwards (p=0.001) and towards the right (p=0.04) (higher in males). In path length and directional control, there were no differences.

CONCLUSIONS

Gender differences should be taken into consideration for vestibular rehabilitation. Greater speed in conducting the tests does not lead to better balance control.

What is the most effective vestibular rehabilitation technique in patients with unilateral peripheral vestibular disorders?

Vestibular rehabilitation has been found to be effective and safe in patients with instability. There is insufficient evidence, however, for distinguishing between the efficacies of different rehabilitation techniques. The objective of this study is to verify whether there are differences between two instrumental vestibular rehabilitation techniques, computerised dynamic posturography (CDP) and optokinetic stimulation (OKN), in order to establish the optimal strategy for each patient. We conducted a prospective, comparative study of the two techniques (CDP and OKN) in patients with instability due to chronic unilateral peripheral vestibular disorder. We randomly included 12 patients in each group, performing the evaluation with the Dizziness Handicap Inventory and the CDP with the sensorial organisation test (SOT), rhythmic weight shift and limits of stability (LOS). We found a statistically significant improvement in both groups in average balance score according to the SOT. In the OKN group, however, improvement was greater in visual preference. The CDP group showed greater benefits in the visual and vestibular input and LOS. Patients with poor vestibular and visual input or with reduced LOS will benefit more from an exercise protocol with CDP. Patients with poor visual preference, however, are ideal candidates for rehabilitation with OKN.

Polymorphisms of CD16A and CD32 Fcγ receptors and circulating immune complexes in Ménière's disease: a case-control study

BACKGROUND

Autoimmune diseases with elevated circulating autoantibodies drive tissue damage and the onset of disease. The Fcγ receptors bind IgG subtypes modulating the clearance of circulating immune complexes (CIC). The inner ear damage in Ménière's disease (MD) could be mediated by an immune response driven by CIC. We examined single-nucleotide polymorphism (SNPs) in the CD16A and CD32 genes in patients with MD which may determine a Fcγ receptor with lower binding to CIC.

METHODS

The functional CD16A (FcγRIIIa*559A > C, rs396991) and CD32A (FcγRIIa*519A > G, rs1801274) SNPs were analyzed using PCR-based TaqMan Genotyping Assay in two cohorts of 156 mediterranean and 112 Galicia patients in a case-control study. Data were analyzed by χ2 with Fisher's exact test and Cochran-Armitage trend test (CATT). CIC were measured by ELISA for C1q-binding CIC.

RESULTS

Elevated CIC were found in 7% of patients with MD during the intercrisis period. No differences were found in the allelic frequency for rs396991 or rs1801274 in controls subjects when they were compared with patients with MD from the same geographic area. However, the frequency of AA and AC genotypes of CD16A (rs396991) differed among mediterranean and Galicia controls (Fisher's test, corrected p = 6.9 × 10-4 for AA; corrected p = 0.02 for AC). Although genotype AC of the CD16A receptor was significantly more frequent in mediterranean controls than in patients, [Fisher's test corrected p = 0.02; OR = 0.63 (0.44-0.91)], a genetic additive effect for the allele C was not observed (CATT, p = 0.23). Moreover, no differences were found in genotype frequencies for rs396991 between patients with MD and controls from Galicia (CATT, p = 0.14). The allelic frequency of CD32 (rs1801274) was not different between patients and controls either in mediterranean (p = 0.51) or Galicia population (p = 0.11).

CONCLUSIONS

Elevated CIC are not found in most of patients with MD. Functional polymorphisms of CD16A and CD32 genes are not associated with onset of MD.