Functional impact of bilateral vestibular loss and the unexplained complaint of oscillopsia.

Introduction: The vestibulo-ocular reflex (VOR) stabilizes vision during head movements. VOR disorders lead to symptoms such as imbalance, dizziness, and oscillopsia. Despite similar VOR dysfunction, patients display diverse complaints. This study analyses saccades, balance, and spatial orientation in chronic peripheral and central VOR disorders, specifically examining the impact of oscillopsia. Methods: Participants involved 15 patients with peripheral bilateral vestibular loss (pBVL), 21 patients with clinically and genetically confirmed Machado-Joseph disease (MJD) who also have bilateral vestibular deficit, and 22 healthy controls. All pBVL and MJD participants were tested at least 9 months after the onset of symptoms and underwent a detailed clinical neuro-otological evaluation at the Dizziness and Eye Movements Clinic of the Meir Medical Center. Results: Among the 15 patients with pBVL and 21 patients with MJD, only 5 patients with pBVL complained of chronic oscillopsia while none of the patients with MJD reported this complaint. Comparison between groups exhibited significant differences in vestibular, eye movements, balance, and spatial orientation. When comparing oscillopsia with no-oscillopsia subjects, significant differences were found in the dynamic visual acuity test, the saccade latency of eye movements, and the triangle completion test. Discussion: Even though there is a significant VOR gain impairment in MJD with some subjects having less VOR gain than pBVL with reported oscillopsia, no individuals with MJD reported experiencing oscillopsia. This study further supports that subjects experiencing oscillopsia present a real impairment to stabilize the image on the retina, whereas those without oscillopsia may utilize saccade strategies to cope with it and may also rely on visual information for spatial orientation. Finding objective differences will help to understand the causes of the oscillopsia experience and develop coping strategies to overcome it.

Bilateral vestibulopathy as the initial presentation of CANVAS.

Cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS) is a slowly progressing autosomal recessive ataxic disorder linked to an abnormal biallelic intronic (most commonly) AAGGG repeat expansion in the replication factor complex subunit 1 (RFC1). While the clinical diagnosis is relatively straightforward when the three components of the disorder are present, it becomes challenging when only one of the triad (cerebellar ataxia, neuropathy or vestibular areflexia) manifests. Isolated cases of Bilateral Vestibulopathy (BVP) or vestibular areflexia that later developed the other components of CANVAS have not been documented. We report four cases of patients with chronic imbalance and BVP that, after several years, developed cerebellar and neuropathic deficits with positive genetic testing for RFC1. Our report supports the concept that CANVAS should be considered in every patient with BVP of unknown etiology, even without the presence of the other triad components. This is especially important given that about 50% of cases in many BVP series are diagnosed as idiopathic, some of which may be undiagnosed CANVAS.

A novel intervention for treating adults with ADHD using peripheral visual stimulation.

Objective: Stimulation of the peripheral visual field has been previously reported as beneficial for cognitive performance in ADHD. This study assesses the safety and efficacy of a novel intervention involving peripheral visual stimuli in managing attention deficit hyperactivity disorder (ADHD). Methods: One hundred and eight adults, 18-40 years old, with ADHD, were enrolled in a two-month open-label study. The intervention (i.e., Neuro-glasses) consisted of standard eyeglasses with personalized peripheral visual stimuli embedded on the lenses. Participants were assessed at baseline and at the end of the study with self-report measures of ADHD symptoms (the Adult ADHD Self-Report Scale; ASRS), and executive functions (The Behavior Rating Inventory of Executive Function Adult Version; BRIEF-A). A computerized test of continuous performance (The Conners' Continuous Performance Test-3; CPT-3) was tested at baseline with standard eyeglasses and at the end of study using Neuro-glasses. The Clinical Global Impression-Improvement scale (CGI-I) was assessed at the intervention endpoint. Safety was monitored by documentation of adverse events. Results: The efficacy analysis included 97 participants. Significant improvements were demonstrated in self-reported measures of inattentive symptoms (ASRS inattentive index; p = 0.037) and metacognitive functions concerning self-management and performance monitoring (BRIEF-A; p = 0.029). A continuous-performance test (CPT-3) indicated significant improvement in detectability (d'; p = 0.027) and reduced commission errors (p = 0.004), suggesting that the Neuro-glasses have positive effects on response inhibition. Sixty-two percent of the participants met the response criteria assessed by a clinician (CGI-I). No major adverse events were reported. Conclusion: Neuro-glasses may offer a safe and effective approach to managing adult ADHD. Results encourage future controlled efficacy studies to confirm current findings in adults and possibly children with ADHD.Clinical trial registration: https://www.clinicaltrials.gov/, Identifier NCT05777785.

The vestibular symptomatology of Machado-Joseph Disease.

BACKGROUND: Machado Joseph Disease (MJD) is an autosomal dominant neurodegenerative disease. In previous studies, we described significant bilateral horizontal Vestibulo-Ocular Reflex (VOR) deficit within this population without any reference to the presence of vestibular symptomatology. OBJECTIVE: To evaluate whether, beyond cerebellar ataxia complaints, MJD patients have typical vestibular symptomatology corresponding to the accepted diagnostic criteria of Bilateral Vestibulopathy (BVP) according to the definition of the International Barany Society of Neuro-Otology. METHODS: Twenty-one MJD, 12 clinically stable chronic Unilateral Vestibulopathy (UVP), 15 clinically stable chronic BVP, and 22 healthy Controls underwent the video Head Impulse Test (vHIT) evaluating VOR gain and filled out the following questionnaires related to vestibular symptomatology: The Dizziness Handicap Inventory (DHI), the Activities-specific Balance Confidence Scale (ABC), the Vertigo Visual Scale (VVS) and the Beck Anxiety Inventory (BAI). RESULTS: The MJD group demonstrated significant bilateral vestibular impairment with horizontal gain less than 0.6 in 71% of patients (0.54±0.17). Similar to UVP and BVP, MJD patients reported a significantly higher level of symptoms than Controls in the DHI, ABC, VVS, and BAI questionnaires. CONCLUSIONS: MJD demonstrated significant VOR impairment and clinical symptoms typical of BVP. We suggest that in a future version of the International Classification of Vestibular Disorders (ICVD), MJD should be categorized under a separate section of central vestibulopathy with the heading of bilateral vestibulopathy. The present findings are of importance regarding the clinical diagnosis process and possible treatment based on vestibular rehabilitation.

[THE HIDDEN VESTIBULAR FEATURES OF MACHADO JOSEPH DISEASE (SPINOCEREBELLAR ATAXIA 3)].

INTRODUCTION: Machado-Joseph disease (MJD) is an inherited neurodegenerative disease with progressive cerebellar ataxia manifested through lack of coordination and balance. MJD patients also present significant Vestibulo-Ocular Reflex (VOR) deficit but their whole vestibular features have not been previously evaluated. We aimed to evaluate whether MJD patients have vestibular features fitting the diagnostic criteria of Bilateral Vestibulopathy established by the International Society for Neuro-otology. METHODS: Sixteen MJD patients and 21 healthy controls underwent a detailed clinical neuro-otological examination including a quantitative evaluation of the VOR gain using the video Head Impulse Test (vHIT). Vestibular-related symptoms were evaluated by the Dizziness Handicap Inventory (DHI), the Activities-specific Balance Confidence Scale (ABC), the Vertigo Visual Scale (VVS). In addition, anxiety that is frequently present in vestibular disorders, was evaluated by the Beck Anxiety Inventory (BAI). RESULTS: MJD patients had significantly reduced horizontal VOR gain with significantly higher scores in all vestibular-related symptoms questionnaires. These symptoms scores were like those reported in studies evaluating patients with bilateral peripheral vestibular loss. CONCLUSIONS: Beyond the cerebellar deficits, MJD patients have vestibular signs and symptoms fitting the diagnostic criteria of Bilateral Vestibulopathy established by the International Society for Neuro-otology. These findings are of relevance not only for the diagnosis and evaluation of progressive cerebellar diseases but also for the possible beneficial effect of vestibular rehabilitation techniques on dizziness, balance and the emotional, physiological and functional aspects of MJD.

The overarching effects of vestibular deficit: Imbalance, anxiety, and spatial disorientation.

BACKGROUND: Comorbid Balance, Anxiety, and Spatial symptoms are observed in neurodevelopmental disorders and aging. Each of these symptoms was studied separately in association with vestibular hypofunction. We aimed to investigate whether such a diffuse range of symptoms has common vestibular pathophysiology. Specifically, we tested whether this Triad of dysfunctions is associated with central or peripheral vestibular hypofunction. We also assessed the possible contribution of semicircular canals (SCCs) vs. saccular function. METHODS: We tested patients with Peripheral bilateral and unilateral Vestibular Hypofunction (PVH), Machado Joseph Disease (MJD) with cerebellar and central bilateral vestibular hypofunction, and healthy controls. SCCs and sacculi functioning were evaluated by the video Head Impulse Test (vHIT) and cervical Vestibular Evoked Myogenic Potentials (cVEMP), respectively. Balance was assessed by the Activities-specific Balance Confidence scale (ABC), anxiety by the Hamilton Anxiety Rating Scale (HAM-A), and spatial orientation by the Object Perspective Taking test (OPT-t). RESULTS: PVH patients with vestibular SCCs and saccular hypofunction presented the Triad of symptoms, imbalance, anxiety, and spatial disorientation. MJD patients with SCCs-related vestibular hypofunction but preserved saccular-related vestibular function presented with a partial profile of imbalance and spatial disorientation. CONCLUSIONS: The present study provides evidence that peripheral vestibular hypofunction is associated with the Triad of dysfunctions, i.e., imbalance, anxiety, and spatial disorientation. The combination of SCCs and saccular hypofunction seems to contribute to the emergence of the Triad of symptoms.

Horizontal Vestibulo-Ocular Reflex Deficit as a Biomarker for Clinical Disease Onset, Severity, and Progression of Machado-Joseph Disease.

Because of the crucial importance of finding a useful biomarker for further clinical trials in Machado-Joseph disease (MJD), and based on our previous studies, we aimed to evaluate whether the horizontal vestibulo-ocular reflex (VOR) gain could be a reliable neurophysiological biomarker for the clinical onset, severity, and progression of the disease. Thirty-five MJD patients, 11 pre-symptomatic genetically confirmed MJD subjects, and 20 healthy controls underwent a detailed epidemiological and clinical neurological examination including the Scale for the Assessment and Rating of Ataxia (SARA). Their VOR gain was measured using the video Head Impulse Test system. Twenty of the MJD patients were re-tested after a period of 1-3 years. Horizontal VOR gain was abnormal in 92% of MJD, 54% pre-symptomatic, and 0% healthy controls. Horizontal VOR gain in the MJD group was significantly negatively correlated with SARA score in the first (r=0.66, p<0.001) and second (r=0.61, p<0.001) examinations. There was also a significant negative correlation between the percentage of change in horizontal VOR gain and the percentage of change in SARA score across both examinations (r=-0.54, p < 0.05). A regression model of the SARA score with the horizontal VOR gain and disease duration as predictors demonstrated that both the horizontal VOR gain and the disease duration had an independent contribution to the prediction of the SARA score. The horizontal VOR gain seems to be a reliable biomarker for the clinical onset, severity, and progression of MJD and could be used in further clinical studies.

"I Do Not Know How You Feel and How I Feel About That": Mentalizing Impairments in Machado-Joseph Disease.

Machado Joseph disease (MJD), also known as spinocerebellar ataxia type 3 (SCA3), is an autosomal dominant neurodegenerative disease. Mentalizing is the ability to think and understand the mental state of the other and of the self in terms of thoughts, feelings, and intentions. The aim of this study is to fill the gap in our understanding of mentalizing in MJD since there is currently very little and inconsistent research on MJD and mentalizing. A total of 18 Jews of Yemenite origin with clinically and genetically confirmed MJD, 5 pre-symptomatic MJD with a positive genetic test, and 17 Jews of Yemenite origin healthy controls, underwent a battery of tests consisting of reading the mind in the eyes (RME), Toronto Alexithymia Scale (TAS-20), and false belief test (FBt). The MJD group scored lower on the RME and FBt, and higher on TAS-20 test compared to control. A significant negative correlation was found between disease duration and RME score. All the pre-symptomatic participants scored within the normal clinical range in all tests. MJD patients demonstrated a widespread deficiency in the ability to mentalizing on a clinical level with autistic characteristics. These impairments may impact the patient's interpsychic experience and daily life interactions and have important clinical implication. Pre-symptomatic participants demonstrated normal mentalizing in all tests, suggesting that the mentalizing impairments do not precede the symptoms of ataxia and are part of the clinical picture of MJD.

How vestibular dysfunction transforms into symptoms of depersonalization and derealization?

BACKGROUND: Psychiatric Depersonalization/Derealization (DPDR) symptoms were demonstrated in patients with peripheral vestibular disorders. However, only semicircular canals (SCCs) dysfunction was evaluated, therefore, otoliths' contribution to DPDR is unknown. Also, DPDR symptoms in patients with central vestibular dysfunction are presently unknown. DPDR was also studied in the context of spatial disorientation and anxiety, but the relation of these cognitive and emotional functions to vestibular dysfunction requires clarification. METHODS: We tested patients with peripheral Bilateral Vestibular Hypofunction (pBVH), Machado Joseph Disease (MJD) with cerebellar and central bilateral vestibular hypofunction, and healthy controls. Participants completed the video Head Impulse Test (vHIT) for SCCs function, cervical Vestibular Evoked Myogenic Potentials test (cVEMPt) for sacculi function, Body Sensation Questionnaire (BSQ) for panic anxiety, Object Perspective-Taking test (OPTt) for spatial orientation and Cox & Swinson DPDR inventory for DPDR symptoms. RESULTS: pBVH patients showed significant SCCs and sacculi dysfunction, spatial disorientation, elevated panic anxiety, and DPDR symptoms. MJD patients showed significant SCCs hypofunction but preserved sacculi function, spatial disorientation but normal levels of panic anxiety and DPDR symptoms. Only pBVH patients demonstrated a positive correlation between the severity of the DPDR and spatial disorientation and panic anxiety. CONCLUSIONS: DPDR develops in association with sacculi dysfunction, either with or without SSCs dysfunction. Spatial disorientation and anxiety seem to mediate the transformation of vestibular dysfunction into DPDR symptoms. DPDR does not develop in MJD with central vestibular hypofunction but a normal saccular response. We propose a three-step model that describes the development of DPDR symptoms in vestibular patients.

Angular vestibulo ocular reflex loss with preserved saccular function in Machado-Joseph disease.

OBJECTIVE: To provide a comprehensive evaluation of the vestibular function in Machado-Joseph Disease (MJD). METHODS: 21 MJD patients and 19 healthy Controls underwent a detailed clinical neuro-otological evaluation including VOR gain of all six semicircular canals by video Head Impulse Test (vHIT), remaining horizontal VOR function by Suppression Head Impulse test (SHIMP), and saccular function by cervical Vestibular Evoked Myogenic Potentials (cVEMP). RESULTS: All MJD had significantly lower VOR gain in all six semicircular canals (p < 0.001) with a mean ± SEM of horizontal gain of 0.52 ± 0.04 and vertical gain of 0.57 ± 0.03 versus Controls' gain of 0.95 ± 0.01 and 0.81 ± 0.02, respectively (p < 0.001). MJD showed also a significantly lower VOR gain on the SHIMP test with left gain of 0.51 ± 0.04 and right gain of 0.46 ± 0.03 versus Controls' gain of 0.79 ± 0.01 and 0.83 ± 0.03, respectively (p < 0.001). In contrast, MJD had normal saccular function reflected by the presence of cVEMP response in 18/20 patients and in 12/17 of Controls, with a non-significant difference between MJD and Controls of P13 and N23 peaks latency and normalized peak-to-peak amplitude. ROC analysis of horizontal VOR gain resulted in an area under the curve of 0.993 making the average lateral canals' VOR gain an excellent classifier of MJD vs Controls. CONCLUSIONS: Horizontal and vertical VOR impairment with preserved sacculo-collic function seems to be a distinctive feature of MJD and could be explained by selective, mostly medial and superior vestibular nuclei degeneration. This study further supports the idea that horizontal VOR gain measured by vHIT could be a potential neurophysiological biomarker of MJD.

Impact of reduction of tinnitus intensity on patients' quality of life.

OBJECTIVE: Assess the impact of a reduction of tinnitus intensity achieved through sound stimulation during sleep on the improvement in the patients' quality of life. DESIGN: Acoustic stimuli consisted of a highly customized sound that reproduced the spectral and intensity characteristics of the tinnitus in each patient. This stimulus was uploaded into a portable electronic device and delivered through customized ear buds during sleep, every night for three months. STUDY SAMPLE: Twelve patients with subjective idiopathic chronic tinnitus were studied. RESULTS: Results were assessed through: (1) the measurement in dB SPL of tinnitus intensity reduction over time; (2) the results of three psychometric tests: Tinnitus handicap inventory (THI), Tinnitus reaction questionnaire (TRQ), Tinnitus functional index (TFI); and (3) a Visual analog scale (VAS) for tinnitus annoyance. After three months of treatment, we observed an average decrease in tinnitus intensity of 14.1 dB SPL (p < 0.001), implying a 62% reduction of the perceived sound. This improvement was followed by a statistically significant decrease of TRQ (78%), THI (65%), and TFI (77%). CONCLUSIONS: These results suggested that the intensity reduction achieved through the protocol used in this study had a direct impact on the improvement in the patients' quality of life.

Chronic balance disorders after acoustic neuroma surgery: assessment of gravitational vertical perception.

CONCLUSION: The head tilt response (HTR) test performed in a group of patients with chronic dizziness after acoustic neuroma surgery showed alterations in the gravitational vertical perception (GV). OBJECTIVE: The assessment of the accuracy in the GV through the HTR test in patients with long-term balance disorders after acoustic neuroma surgery. METHODS: The HTR was performed in two groups of patients that had undergone acoustic neuroma surgery: six uncompensated patients (UPs) who maintained vestibular symptoms 1 year after surgery and two compensated patients (CPs) without vestibular symptoms. Twelve healthy control adults were also tested (control group, CG). Three parameters were measured in the HTR test: steady-state error (SSE), rise time (TRS), and mean energy of the error signal per step (MEE). RESULTS: The UP group showed higher values for the TRS and MEE parameters compared with the CG (p < 0.05) when performing the HTR test to the side of the lesion and to the contralateral side, while the SSE only showed significant higher values when the patient estimated the GV towards the side of the lesion. The two patients in the CP group did not have differences in the three parameters assessed when compared with the CG.

Effects of balance training using a virtual-reality system in older fallers.

Poor balance is considered a challenging risk factor for falls in older adults. Therefore, innovative interventions for balance improvement in this population are greatly needed. The aim of this study was to evaluate the effect of a new virtual-reality system (the Balance Rehabilitation Unit [BRU]) on balance, falls, and fear of falling in a population of community-dwelling older subjects with a known history of falls. In this study, 60 community-dwelling older subjects were recruited after being diagnosed with poor balance at the Falls and Fractures Clinic, Nepean Hospital (Penrith, NSW, Australia). Subjects were randomly assigned to either the BRU-training or control groups. Both groups received the usual falls prevention care. The BRU-training group attended balance training (two sessions/week for 6 weeks) using an established protocol. Change in balance parameters was assessed in the BRU-training group at the end of their 6-week training program. Both groups were assessed 9 months after their initial assessment (month 0). Adherence to the BRU-training program was 97%. Balance parameters were significantly improved in the BRU-training group (P < 0.01). This effect was also associated with a significant reduction in falls and lower levels of fear of falling (P < 0.01). Some components of balance that were improved by BRU training showed a decline after 9 months post-training. In conclusion, BRU training is an effective and well-accepted intervention to improve balance, increase confidence, and prevent falls in the elderly.

Postural response characterization in elderly patients with bilateral vestibular hypofunction.

CONCLUSIONS: The measurement of the energy consumption (EC) of the body's center of pressure (COP) to maintain the upright stance position was higher in elderly patients with bilateral vestibular hypofunction (BVH) compared with a control group and may be a valid parameter in the assessment of balance disorders. OBJECTIVE: The aim of the study was to evaluate the energy consumption of the COP in elderly patients with BVH. METHODS: The COP was recorded on a force platform (FP) for eight elderly patients with BVH related to aging and eight normal control group subjects. The EC of the COP was calculated using the discrete wavelet transform. The two groups were tested in standing position on the FP in three sensory conditions:1, eyes open; 2, eyes closed; and 3, standing on a foam pad placed on the force platform. Wilcoxon's rank test and multi-factor analysis of variance were used, with the level of significance set at 0.05. RESULTS: BVH patients showed higher values of EC of the COP signal measured in arbitrary units compared with the control group (conditions 1 and 2). None of the BVH patients could perform the test in condition 3. BVH patients had increased EC in the frequency band between 0.1 and 0.78 Hz when the visual information was canceled (condition 2).

Visual gravitational vertical perception in peripheral vestibular hypofunction.

CONCLUSIONS: Rise time in the estimation of the gravitational vertical in the head tilt response (HTR) test is increased in patients with peripheral vestibular lesions and residual chronic dizziness. OBJECTIVE: Assessment of the perception of the gravitational vertical in patients with peripheral vestibular lesions through the HTR. METHODS: HTR was studied in 12 patients with peripheral vestibular lesion, 8 clinically with chronic dizziness and 4 without it; 23 normal subjects were studied as control group. Two parameters of the HTR were assessed, rise time and steady-state error to characterize a dynamical system step response. The Kolmogorov-Smirnov test (alpha = 5%) was used to verify normal distribution (steady-state error, p = 0.53; rise time, p = 0.88). The three sigma ellipse was calculated for the control group. ROC curves were used to measure the sensitivity and specificity of these parameters. RESULTS: Rise time showed increased values in peripheral vestibular lesion patients with chronic dizziness. Two-dimensional analysis (rise time vs steady-state error) allows a better discrimination between patients with peripheral vestibular hypofunction with chronic dizziness and the rest of the studied population.

Balance in Parkinson's disease patients changing the visual input.

The description of the postural responses in Parkinson's disease patients when visual information changes from a stable to a moving visual field analyzing the impact on balance in these patients. METHODS (CLINICAL): Limits of Stability, Body center of pressure and balance functional reserve were measured by means of the force platform in 24 Parkinson's patients in stages 1 and 2 of the Boher classification and 19 volunteers as a control group. Both groups were stimulated with 1-Static visual field and 2-horizontal optokinetic stimulation using a virtual reality system. Postural responses were analyzed using the inverted pendulum as mathematical model. RESULTS: While the control group didn't show significant differences on the postural control between the two sensory conditions (COP p=0.0017, BFR p=0.0025), Parkinson's patients presented significant differences in the area of the center of pressure and the balance functional reserve values between static visual field and optokinetic stimulation. (COP p=0.0017, BFR p=0.0025). CONCLUSIONS: The results support the hypothesis about the influence of the changes in the visual information in triggering balance control disorders in Parkinson's patients. It is discussed the interest of these fact in the assessment and the rehabilitation programs of this disease.

Balance in Parkinson's disease patients changing the visual input / Equilíbrio na doença de Parkinson alterando as informações visuais

The description of the postural responses in Parkinson's disease patients when visual information changes from a stable to a moving visual field analyzing the impact on balance in these patients. METHODS (CLINICAL): Limits of Stability, Body center of pressure and balance functional reserve were measured by means of the force platform in 24 Parkinson´s patients in stages 1 and 2 of the Boher classification and 19 volunteers as a control group. Both groups were stimulated with 1-Static visual field and 2-horizontal optokinetic stimulation using a virtual reality system. Postural responses were analyzed using the inverted pendulum as mathematical model. RESULTS: While the control group didn't show significant differences on the postural control between the two sensory conditions (COP p=0.0017, BFR p=0.0025), Parkinson's patients presented significant differences in the area of the center of pressure and the balance functional reserve values between static visual field and optokinetic stimulation. (COP p=0.0017, BFR p=0.0025). CONCLUSIONS: The results support the hypothesis about the influence of the changes in the visual information in triggering balance control disorders in Parkinson's patients. It is discussed the interest of these fact in the assessment and the rehabilitation programs of this disease.

Descrição das respostas posturais em pacientes com doença de Parkinson quando a informação visual muda de um campo visual estável para um móvel, analisando o impacto do equilíbrio nesses pacientes. MÉTODOS (CLÍNICO): Limites de estabilidade, centro de pressão corporal e reserva funcional do equilíbrio foram medidos em uma plataforma de força em 24 pacientes com doença de Parkinson nos estágios 1 e 2 da classificação de Boher e em 19 voluntários de um grupo controle. Ambos os grupos foram estimulados a partir de um campo visual estático e dois estímulos optocinéticos horizontais, usando-se um sistema de realidade virtual. As respostas posturais foram analisadas usando-se o pêndulo invertido como modelo matemático. RESULTADOS: Enquanto o grupo controle não demonstrou diferenças significativas no controle postural entre as duas condições sensoriais (COP p=0,0017, BFR p=0,0025), os pacientes com doença de Parkinson apresentaram diferenças significativas na área do centro de pressão e nos valores de reserva do equilíbrio funcional entre o campo visual estático e a estimulação optocinética (COP p=0,0017, BFR p=0,0025). CONCLUSÕES: Os resultados corroboram a hipótese sobre a influência das mudanças na informação visual deflagrando distúrbios no controle do equilíbrio em pacientes com doença de Parkinson. Discutimos esse fato com relação à avaliação e programas de reabilitação associados a essa doença.

Clinical characteristics of positional vertigo after mild head trauma.

CONCLUSION: This study showed that a population with benign paroxysmal positional vertigo related to mild head trauma (BPPVAT) was younger and more frequently presented with bilateral canalithiasis than another population with idiopathic etiology (IBPPV). In both groups, females presented a higher risk of BPPV. OBJECTIVE: To compare the clinical features of a population with BPPVAT and another with IBBPV. METHODS: We carried out statistical analysis of a population of 51 subjects with BPPVAT and another of 325 subjects with IBPPV, comparing age, gender, recurrence of symptoms, associated chronic dizziness (CD), and clinical presentation. Kolmogorov Smirnov test, Student's t test, Mann-Whitney test, 95% binomial confidence interval for proportions, chi-squared, and Fisher's test were used as statistical tools. A significance level of p < 0.05 was considered in all cases. RESULTS: The population affected with BPPVAT was younger and bilateral canalithiasis was also more frequent. No differences were found in gender distribution, semicircular canals involved in the symptoms, recurrence after repositioning maneuvers, or associated CD.

Dynamic modeling and experimental results for a head tilt response.

The estimation of the vertical in humans is important in everyday life although the mechanisms involved are not completely understood yet. This paper presents two sets of experiments with normal subjects, using the same virtual reality setup, aiming to help in this understanding. First, a steady state experiment is presented, which is used to determine the gravitational vertical precision while the second, a dynamical transient response experiment, is used to find dynamic models of each subject response. Results show that the dynamic models are able to reproduce the results of the steady state experiment while having the benefits that a dynamic model brings to evaluate subjects performance.

Head tilt response: A complementary test to the Subjective Visual Vertical.

This paper studies the phenomenon of the perceived vertical by means of a novel dynamic experiment. This task is inspired in the Subjective Visual Vertical test and can be regarded as complementary in terms of how the information involved varies (visual, otolithic and neck proprioception). The experiment consists in presenting a white stripe in a pair of virtual reality goggles and adjusting the roll angle of the head until the stripe is aligned with the gravitational vertical. The roll angle of the head is measured and recorded along each trial where the white stripe changes position four times, after a specific amount of time. The task was run on a group of 28 normal subjects and a small sample of 5 patients with vestibular hypofunction. Six parameters derived from Control Theory were extracted from the data to characterize the subject transient response. All parameters for normal subjects were found to be normally distributed. Experimental results show that discrimination is possible between normal subjects and patients using just one or two of the parameters studied.