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Recovery of Vestibular Ocular Reflex Function and Balance Control after a Unilateral Peripheral Vestibular Deficit  [PDF]
J. H. J. Allum
Frontiers in Neurology , 2012, DOI: 10.3389/fneur.2012.00083
Abstract: This review describes the effect of unilateral peripheral vestibular deficit (UPVD) on balance control for stance and gait tests. Because a UPVD is normally defined based on vestibular ocular reflex (VOR) tests, we compared recovery observed in balance control with patterns of recovery in VOR function. Two general types of UPVD are considered; acute vestibular neuritis (AVN) and vestibular neurectomy. The latter was subdivided into vestibular loss after cerebellar pontine angle tumor surgery during which a vestibular neurectomy was performed, and vestibular loss following neurectomy to eliminate disabling Ménière’s disease. To measure balance control, body-worn gyroscopes, mounted near the body’s center of mass (CoM), were used. Measurement variables were the pitch (anterior–posterior) and roll (lateral) sway angles and angular velocities of the lower trunk/pelvis. Both patient groups showed balance deficits during stance tasks on foam, especially with eyes closed when stable balance control is normally highly dependent on vestibular inputs. Deficits during gait were also present and were more profound for complex gait tasks such as tandem gait than simple gait tasks. Major differences emerged between the groups concerning the severity of the deficit and its recovery. Generally, the effects of acute neuritis on balance control were more severe but recovered rapidly. Deficits due to vestibular neurectomy were less severe, but longer lasting. These results mostly paralleled recovery of deficits in VOR function. However, questions need to be raised about the effect on balance control of the two modes of neural plasticity occurring in the vestibular system following vestibular loss due to neuritis: one mode being the limited central compensation for the loss, and the second mode being some restoration of peripheral vestibular function. Future work will need to correlate deficits in balance control during stance and gait more exactly with VOR deficits and carefully consider the differences between insufficient central compensation compared to inadequate peripheral restoration of function.
Sensorintegrative dysfunction underlying vestibular disorders after traumatic brain injury: A review  [PDF]
Laura M. Franke, PhD,William C. Walker, MD,David X. Cifu, MD,Alfred L. Ochs, PhD
Journal of Rehabilitation Research and Development , 2012, DOI: 10.1682/jrrd.2011.12.0250
Abstract: Vestibular symptoms are persistent and problematic sequelae of blast exposure. Several lines of evidence suggest that these symptoms often stem from injury to the central nervous system. Current methods of assessing the vestibular system have described vestibular deficits that follow traumatic brain injury and differentiate blunt and blast trauma but have not examined the full range of vestibular functions that depend on the cerebral structures above the midbrain. Damage to the central vestibular circuits can lead to deficits in vital processes of spatial perception and navigation, in addition to dizziness and disequilibrium, and may also affect emotional functioning, particularly noradrenergically modulated states of anxiety. Perceptual functions can be assessed to determine the extent of central nervous system involvement in vestibular symptoms and to provide greater confidence when vestibular dysfunction is to be excluded. The ability to detect central vestibular dysfunction will significantly enhance our response to the dizziness and balance symptoms that are a common source of distress for Veterans.
Vergence and Standing Balance in Subjects with Idiopathic Bilateral Loss of Vestibular Function  [PDF]
Zo? Kapoula, Chrystal Gaertner, Qing Yang, Pierre Denise, Michel Toupet
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0066652
Abstract: There is a natural symbiosis between vergence and vestibular responses. Deficits in vergence can lead to vertigo, disequilibrium, and postural instability. This study examines both vergence eye movements in patients with idiopathic bilateral vestibular loss, and their standing balance in relation to vergence. Eleven patients participated in the study and 16 controls. Bilateral loss of vestibular function was objectified with many tests; only patients without significant response to caloric tests, to video head impulse tests and without vestibular evoked myogenic potentials were included in the study. Vergence testing (from 8 patients and 15 controls) A LED display with targets at 20, 40, and 100 cm along the median plane was used to elicit vergence eye movements, recorded with the IRIS device. Standing balance (11 patients and 16 controls) Four conditions were run, each lasting 1 min: fixation of a LED at 40 cm (convergence of 9°), at 150 cm (convergence of 2.3°); this last condition was repeated with eyes closed. Comparison of the eyes closed-eyes open conditions at 150 cm allowed evaluation of the Romberg Quotient. In the forth condition, two LEDS, at 20 and at 100 cm, were light on, one after the other for 1 sec, causing the eyes to converge then diverge. Standing balance was recorded with an accelerometer placed at the back near the center of mass (McRoberts, Dynaport). Results Vergence Relative to controls, convergence eye movements in patients showed significantly lower accuracy, lower mean velocity, and saccade intrusions of significantly higher amplitude. Balance The normalized 90% area of body sway was significantly higher for patients than for controls for all conditions. Yet, similarly to controls, postural stability was better while fixating at near (sustained convergence) than at far, or while making active vergence movements. We argue that vestibular loss deteriorates convergence, but even deficient, convergence can be helpful for postural control.
Presbyastasis: a multifactorial cause of balance problems in the elderly
C Rogers
South African Family Practice , 2010,
Abstract: Presbyastasis is the result of age-related physiological changes in the three sensory systems and their central connections that contribute to balance. In all likelihood, presbyastasis is a complex condition involving many intertwined systems rather than a lesion within the vestibular system only, thus evaluation and management need to be holistic. Balance problems can have detrimental consequences and are associated with falls, loss of quality of life and psychological sequelae such as anxiety, depression and panic. Healthcare practitioners need increased awareness of the pathophysiology of presbyastasis and its possible impact.
Association between Hearing Loss and Vestibular Disorders: A Review of the Interference of Hearing in the Balance  [PDF]
Tatiana G. T. Santos, Alessandra Ramos Venosa, Andre Luiz Lopes Sampaio
International Journal of Otolaryngology and Head & Neck Surgery (IJOHNS) , 2015, DOI: 10.4236/ijohns.2015.43030
Abstract: Introduction: Dizziness is very prevalent and makes a great impact on people’s life. Because of anatomical and functional similarities of hearing and vestibular systems, it is noted that there is a big relation between hearing loss and vestibular disorders. Depending on the age onset of hearing loss, it can cause even delay on motor development. Objective: To find literature that demonstrates the relation between hearing and balance. Confirming that hearing loss or even intervention to improve quality of hearing can interfere on vestibular system. Methodology: Revision of literature was carried out, preferring recent research only in English. Conclusion: Cochlea and vestibular systems have a close relationship; changes in one of them can cause big damage in the other. So, a complete evaluation of vestibular system is recommended before ear surgeries. Video Head Impulse Test is a new procedure able to evaluate high frequency movements of the head. It was an additional exam of vestibular status and came to help detect problems that were not diagnosed before. Efforts must be directed in order to protect the balance.
Artificial Balance: Restoration of the Vestibulo-Ocular Reflex in Humans with a Prototype Vestibular Neuroprosthesis  [PDF]
Angelica Perez Fornos,Nils Guinand,Raymond Van De Berg,Robert Stokroos,Silvestro Micera,Marco Pelizzone,Jean Philippe Guyot
Frontiers in Neurology , 2014, DOI: 10.3389/fneur.2014.00066
Abstract: The vestibular system plays a crucial role in the multisensory control of balance. When vestibular function is lost, essential tasks such as postural control, gaze stabilization, and spatial orientation are limited and the quality of life of patients is significantly impaired. Currently there is no effective treatment for bilateral vestibular deficits. Research efforts both in animals and humans during the last decade set a solid background to the concept of using electrical stimulation to restore vestibular function. Still, the potential clinical benefit of a vestibular neuroprosthesis has to be demonstrated to pave the way for a translation into clinical trials. An important parameter for the assessment of vestibular function is the Vestibulo-Ocular Reflex (VOR), the primary mechanism responsible for maintaining the perception of a stable visual environment while moving. Here we show that the VOR can be artificially restored in humans using motion-controlled, amplitude modulated electrical stimulation of the ampullary branches of the vestibular nerve. Three patients received a vestibular neuroprosthesis prototype, consisting of a modified cochlear implant providing vestibular electrodes. Significantly higher VOR responses were observed when the prototype was turned ON. Furthermore, VOR responses increased significantly as the intensity of the stimulation increased, reaching on average 79% of those measured in healthy volunteers in the same experimental conditions. These results constitute a fundamental milestone and allow us to envision for the first time clinically useful rehabilitation of patients with bilateral vestibular loss.
Effects of conventional versus multimodal vestibular rehabilitation on functional capacity and balance control in older people with chronic dizziness from vestibular disorders: design of a randomized clinical trial
Ricci Natalia,Aratani Mayra,Caovilla Heloisa,Ganan?a Fernando
Trials , 2012, DOI: 10.1186/1745-6215-13-246
Abstract: Background There are several protocols designed to treat vestibular disorders that focus on habituation, substitution, adaptation, and compensation exercises. However, protocols that contemplate not only vestibular stimulation but also other components that are essential to the body balance control in older people are rare. This study aims to compare the effectiveness of two vestibular rehabilitation protocols (conventional versus multimodal) on the functional capacity and body balance control of older people with chronic dizziness due to vestibular disorders. Methods/design A randomized, single-blind, controlled clinical trial with a 3 months follow-up period will be performed. The sample will be composed of older individuals with a clinical diagnosis of chronic dizziness resulting from vestibular disorders. The subjects will be evaluated at baseline, post-treatment and follow-up. Primary outcomes will be determined in accordance with the Dizziness Handicap Inventory (functional capacity) and the Dynamic Gait Index (body balance). Secondary outcomes include dizziness features, functional records, body balance control tests, and psychological information. The older individuals (minimum sample n = 68) will be randomized to either the conventional or multimodal Cawthorne&Cooksey protocols. The protocols will be performed during individual 50-minute sessions, twice a week, for 2 months (a total of 16 sessions). The outcomes of both protocols will be compared according to the intention-to-treat analysis. Discussion Vestibular rehabilitation through the Cawthorne&Cooksey protocol has already proved to be effective. However, the addition of other components related to body balance control has been proposed to improve the rehabilitation of older people with chronic dizziness from vestibular disorders. Trial registration ACTRN12610000018011
Optimizing the vertebrate vestibular semicircular canal: could we balance any better?  [PDF]
Todd M. Squires
Physics , 2004, DOI: 10.1103/PhysRevLett.93.198106
Abstract: The fluid-filled semicircular canals (SCCs) of the vestibular system are used by all vertebrates to sense angular rotation. Despite masses spanning seven decades, all mammalian SCCs are nearly the same size. We propose that the SCC represents a sensory organ that evolution has `optimally designed'. Four geometric parameters are used to characterize the SCC, and `building materials' of given physical properties are assumed. Identifying physical and physiological constraints on SCC operation, we find that the most sensitive SCC has dimensions consistent with available data.
Prevalence of Abnormalities in Vestibular Function and Balance among HIV-Seropositive and HIV-Seronegative Women and Men  [PDF]
Helen S. Cohen, Christopher Cox, Gayle Springer, Howard J. Hoffman, Mary A. Young, Joseph B. Margolick, Michael W. Plankey
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038419
Abstract: Background Most HIV-seropositive subjects in western countries receive highly active antiretroviral therapy (HAART). Although many aspects of their health have been studied, little is known about their vestibular and balance function. The goals of this study were to determine the prevalences of vestibular and balance impairments among HIV-seropositive and comparable seronegative men and women and to determine if those groups differed. Methods Standard screening tests of vestibular and balance function, including head thrusts, Dix-Hallpike maneuvers, and Romberg balance tests on compliant foam were performed during semiannual study visits of participants who were enrolled in the Baltimore and Washington, D. C. sites of the Multicenter AIDS Cohort Study and the Women's Interagency HIV Study. Results No significant differences by HIV status were found on most tests, but HIV-seropositive subjects who were using HAART had a lower frequency of abnormal Dix-Hallpike nystagmus than HIV-seronegative subjects. A significant number of nonclassical Dix-Hallpike responses were found. Age was associated with Romberg scores on foam with eyes closed. Sex was not associated with any of the test scores. Conclusion These findings suggest that HAART-treated HIV infection has no harmful association with vestibular function in community-dwelling, ambulatory men and women. The association with age was expected, but the lack of association with sex was unexpected. The presence of nonclassical Dix-Hallpike responses might be consistent with central nervous system lesions.
Effectiveness of conventional versus virtual reality based vestibular rehabilitation in the treatment of dizziness, gait and balance impairment in adults with unilateral peripheral vestibular loss: a randomised controlled trial
Meldrum Dara, Herdman Susan, Moloney Roisin, Murray Deirdre, Duffy Douglas, Malone Kareena, French Helen, Hone Stephen, Conroy Ronan, McConn-Walsh Rory
BMC Ear, Nose and Throat Disorders , 2012, DOI: 10.1186/1472-6815-12-3
Abstract: In a single (assessor) blind, two centre randomised controlled superiority trial, 80 patients with unilateral peripheral vestibular loss will be randomised to either conventional or virtual reality based (NWFP) vestibular rehabilitation for 6 weeks. The primary outcome measure is gait speed (measured with three dimensional gait analysis). Secondary outcomes include computerised posturography, dynamic visual acuity, and validated questionnaires on dizziness, confidence and anxiety/depression. Outcome will be assessed post treatment (8 weeks) and at 6 months.Advances in the gaming industry have allowed mass production of highly sophisticated low cost virtual reality systems that incorporate technology previously not accessible to most therapists and patients. Importantly, they are not confined to rehabilitation departments, can be used at home and provide an accurate record of adherence to exercise. The benefits of providing augmented feedback, increasing intensity of exercise and accurately measuring adherence may improve conventional vestibular rehabilitation but efficacy must first be demonstrated.Clinical trials.gov identifier: NCT01442623Unilateral peripheral vestibular loss (UVL) results in disabling problems including vertigo, dizziness, oscillopsia, and impaired balance and gait [1,2]. In the acute phase most patients are managed at primary care level and recover through a process known as vestibular compensation [3]. Pharmacological treatments are recommended only in the acute phase [4] and the mainstay for treatment thereafter in those who do not recover, is specialised rehabilitation known as vestibular rehabilitation. Vestibular rehabilitation is a safe, effective and non-invasive treatment for the sequelae of UVL [5,6]. Subjectively, balance impairment is rated as more problematic than dizziness or vertigo [7] and while meta-analysis has demonstrated a clear benefit for the reduction in dizziness and vertigo symptoms, a less convincing effect has been sho
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