Publications
429 results found
Bronstein AM, Kattah J, 2024, Vascular neuro-otology: vestibular transient ischemic attacks and chronic dizziness in the elderly., Curr Opin Neurol, Vol: 37, Pages: 59-65
PURPOSE OF REVIEW: To explore the differential diagnosis of posterior fossa transient ischemic attacks (TIA) associated with vertigo and/or imbalance.To review the contribution of cerebral small vessel (SVD) disease to balance dysfunction and dizziness in the elderly. MAIN FINDINGS: TIAs involving vestibular structures that mediate the vestibulo-ocular and vestibulospinal reflexes remain a diagnostic challenge because they overlap with causes of benign episodic vertigo. Here, we summarize the results of multidisciplinary specialty efforts to improve timely recognition and intervention of peripheral and central vestibular ischemia. More papers confirm that SVD is a major cause of gait disability, falls and cognitive disorder in the elderly. Recent work shows that early stages of SVD may also be responsible for dizziness in the elderly. The predominant location of the white matter changes, in the frontal deep white matter and genu of the corpus callosum, explains the association between cognitive and balance dysfunction in SVD related symptoms. SUMMARY: The evaluation of patients with intermittent vascular vertigo represent a major diagnostic challenge, recent reviews explore the ideal design approach for a multidisciplinary study to increase early recognition and intervention. Hemispheric white matter microvascular ischemia has been the subject of research progress - advanced stages are known to cause gait disorder and dementia but early stages are associated with "idiopathic" dizziness in the elderly.
Ibitoye RT, Castro P, Ellmers TJ, et al., 2023, Vestibular loss disrupts visual reactivity in the alpha EEG rhythm., NeuroImage: Clinical, Vol: 39, Pages: 1-14, ISSN: 2213-1582
The alpha rhythm is a dominant electroencephalographic oscillation relevant to sensory-motor and cognitive function. Alpha oscillations are reactive, being for example enhanced by eye closure, and suppressed following eye opening. The determinants of inter-individual variability in reactivity in the alpha rhythm (e.g. changes with amplitude following eye closure) are not fully understood despite the physiological and clinical applicability of this phenomenon, as indicated by the fact that ageing and neurodegeneration reduce reactivity. Strong interactions between visual and vestibular systems raise the theoretical possibility that the vestibular system plays a role in alpha reactivity. To test this hypothesis, we applied electroencephalography in sitting and standing postures in 15 participants with reduced vestibular function (bilateral vestibulopathy, median age = 70 years, interquartile range = 51-77 years) and 15 age-matched controls. We found participants with reduced vestibular function showed less enhancement of alpha electroencephalography power on eye closure in frontoparietal areas, compared to controls. In participants with reduced vestibular function, video head impulse test gain - as a measure of residual vestibulo-ocular reflex function - correlated with reactivity in alpha power across most of the head. Greater reliance on visual input for spatial orientation ('visual dependence', measured with the rod-and-disc test) correlated with less alpha enhancement on eye closure only in participants with reduced vestibular function, and this was partially moderated by video head impulse test gain. Our results demonstrate for the first time that vestibular function influences alpha reactivity. The results are partly explained by the lack of ascending peripheral vestibular input but also by central reorganisation of processing relevant to visuo-vestibular judgements.
Zachou A, Bronstein AM, 2023, Vestibulo-spatial navigation: pathways and sense of direction, Journal of Neurophysiology, Vol: 129, Pages: 672-684, ISSN: 0022-3077
Aims of the present article are: 1) assessing vestibular contribution to spatial navigation, 2) exploring how age, global positioning systems (GPS) use and vestibular navigation contribute to subjective sense of direction (SOD), 3) evaluating vestibular navigation in patients with lesions of the vestibular-cerebellum (downbeat nystagmus patients, DBN) which could inform on the signals carried by vestibulo-cerebellar-cortical pathways. We applied two navigation tasks on a rotating chair in the dark: return-to-start(RTS), where subjects drive the chair back to the origin after discrete angular displacement stimuli (path reversal), and complete-the-circle(CTC) where subjects drive the chair on, all the way round to origin (path completion). We examined 24 normal controls (20-83 year old), 5 DBN patients (62-77 year old) and, as proof of principle, 2 patients with early dementia (84 and 76 year old). We found a relationship between SOD, assessed by Santa-Barbara-Sense-Of-Direction-scale, and subject's age (positive), GPS use (negative) and CTC-vestibular-navigation-task (positive). Age-related decline in vestibular navigation was observed with the RTS-task but not with the complex CTC-task. Vestibular navigation was normal in vestibulo-cerebellar patients but abnormal, particularly CTC, in the demented patients. We conclude that vestibular navigation skills contribute to the build-up of our SOD. Unexpectedly, perceived SOD in the elderly is not inferior, possibly explained by increased GPS use by the young. Preserved vestibular navigation in cerebellar patients suggests that ascending vestibular-cerebellar projections carry velocity (not position) signals. The abnormalities in the cognitively impaired patients suggest that their vestibulo-spatial navigation is disrupted.
Arshad Q, Cousins S, Golding JF, et al., 2023, Factors influencing clinical outcome in vestibular neuritis – A focussed review and reanalysis of prospective data, Journal of the Neurological Sciences, Vol: 446, Pages: 1-7, ISSN: 0022-510X
Following vestibular neuritis (VN), long term prognosis is not dependent on the magnitude of the residual peripheral function as measured with either caloric or the video head-impulse test. Rather, recovery is determined by a combination of visuo-vestibular (visual dependence), psychological (anxiety) and vestibular perceptual factors. Our recent research in healthy individuals has also revealed a strong association between the degree of lateralisation of vestibulo-cortical processing and gating of vestibular signals, anxiety and visual dependence. In the context of several functional brain changes occurring in the interaction between visual, vestibular and emotional cortices, which underpin the aforementioned psycho-physiological features in patients with VN, we re-examined our previously published findings focusing on additional factors impacting long term clinical outcome and function. These included: (i) the role of concomitant neuro-otological dysfunction (i.e. migraine and benign paroxysmal positional vertigo (BPPV)) and (ii) the degree to which brain lateralisation of vestibulo-cortical processing influences gating of vestibular function in the acute stage. We found that migraine and BPPV interfere with symptomatic recovery following VN. That is, dizziness handicap at short-term recovery stage was significantly predicted by migraine (r = 0.523, n = 28, p = .002), BPPV (r = 0.658, n = 31, p < .001) and acute visual dependency (r = 0.504, n = 28, p = .003). Moreover, dizziness handicap in the long-term recovery stage continued to be predicted by migraine (r = 0.640, n = 22, p = .001), BPPV (r = 0.626, n = 24, p = .001) and acute visual dependency (r = 0.667, n = 22, p < .001). Furthermore, surrogate measures of vestibulo-cortical lateralisation were predictive of the amount of cortical suppression exerted over vestibular thresholds. That is, in right-sided VN patients, we observed a positive correlation between visual dependence and acute ipsilesional ocu
Cooke JI, Guven O, Castro Abarca P, et al., 2022, Electroencephalographic response to transient adaptation of vestibular perception, JOURNAL OF PHYSIOLOGY-LONDON, Vol: 600, Pages: 3517-3535, ISSN: 0022-3751
Ibitoye RT, Castro P, Cooke J, et al., 2022, A link between frontal white matter integrity and dizziness in cerebral small vessel disease, NeuroImage: Clinical, Vol: 35, Pages: 1-12, ISSN: 2213-1582
One in three older people (>60 years) complain of dizziness which often remains unexplained despite specialist assessment. We investigated if dizziness was associated with vascular injury to white matter tracts relevant to balance or vestibular self-motion perception in sporadic cerebral small vessel disease (age-related microangiopathy). We prospectively recruited 38 vestibular clinic patients with idiopathic (unexplained) dizziness and 36 age-matched asymptomatic controls who underwent clinical, cognitive, balance, gait and vestibular assessments, and structural and diffusion brain MRI. Patients had more vascular risk factors, worse balance, worse executive cognitive function, and worse ankle vibration thresholds in association with greater white matter hyperintensity in frontal deep white matter, and lower fractional anisotropy in the genu of the corpus callosum and the right inferior longitudinal fasciculus. A large bihemispheric white matter network had less structural connectivity in patients. Reflex and perceptual vestibular function was similar in patients and controls. Our results suggest cerebral small vessel disease is involved in the genesis of dizziness through its effect on balance.
Castro P, Papoutselou E, Mahmoud S, et al., 2022, Priming overconfidence in belief systems reveals negative return on postural control mechanisms, GAIT & POSTURE, Vol: 94, Pages: 1-8, ISSN: 0966-6362
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- Citations: 2
Arshad Q, Bronstein A, 2021, Motion perception in vestibular migraine, EUROPEAN JOURNAL OF NEUROLOGY, Vol: 28, Pages: E93-E94, ISSN: 1351-5101
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- Citations: 1
Ibitoye RT, Desowska A, Guven O, et al., 2021, Small vessel disease disrupts EEG postural brain networks in ‘unexplained dizziness in the elderly’, Clinical Neurophysiology, Vol: 132, Pages: 2751-2762, ISSN: 1388-2457
ObjectiveTo examine the hypothesis that small vessel disease disrupts postural networks in older adults with unexplained dizziness in the elderly (UDE).MethodsSimultaneous electroencephalography and postural sway measurements were undertaken in upright, eyes closed standing, and sitting postures (as baseline) in 19 younger adults, 33 older controls and 36 older patients with UDE. Older adults underwent magnetic resonance imaging to determine whole brain white matter hyperintensity volumes, a measure of small vessel disease. Linear regression was used to estimate the effect of instability on electroencephalographic power and connectivity.ResultsAgeing increased theta and alpha desynchronisation on standing. In older controls, delta and gamma power increased, and theta and alpha power reduced with instability. Dizzy older patients had higher white matter hyperintensity volumes and more theta desynchronisation during periods of instability. White matter hyperintensity volume and delta power during periods of instability were correlated, positively in controls but negatively in dizzy older patients. Delta power correlated with subjective dizziness and instability.ConclusionsNeural resource demands of postural control increase with age, particularly in patients with UDE, driven by small vessel disease.SignificanceEEG correlates of postural control saturate in older adults with UDE, offering a basis to this common syndrome.
Bonsu A, Britton Z, Asif Z, et al., 2021, Attentional network dysfunction in vestibular migraine, 25th World Congress of Neurology (WCN), Publisher: ELSEVIER, ISSN: 0022-510X
Mendis S, Ealing J, Larkin J, et al., 2021, Isolated imbalance due to bilateral vestibular failure following immune checkpoint inhibitor administration: two cases, EUROPEAN JOURNAL OF CANCER, Vol: 156, Pages: 187-189, ISSN: 0959-8049
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- Citations: 1
Curro R, Salvalaggio A, Tozza S, et al., 2021, RFC1 expansions are a common cause of idiopathic sensory neuropathy, BRAIN, Vol: 144, Pages: 1542-1550, ISSN: 0006-8950
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- Citations: 2
Bonsu AN, Nousi S, Lobo R, et al., 2021, Vestibulo-perceptual influences upon the vestibulo-spinal reflex, Experimental Brain Research, Vol: 239, Pages: 2141-2149, ISSN: 0014-4819
The vestibular system facilitates gaze and postural stability via the vestibulo-ocular (VOR) and vestibulo-spinal reflexes, respectively. Cortical and perceptual mechanisms can modulate long-duration VOR responses, but little is known about whether high-order neural phenomena can modulate short-latency vestibulo-spinal responses. Here, we investigate this by assessing click-evoked cervical vestibular myogenic-evoked potentials (VEMPS) during visual roll motion that elicited an illusionary sensation of self-motion (i.e. vection). We observed that during vection, the amplitude of the VEMPs was enhanced when compared to baseline measures. This modulation in VEMP amplitude was positively correlated with the subjective reports of vection strength. That is, those subjects reporting greater subjective vection scores exhibited a greater increase in VEMP amplitude. Control experiments showed that simple arousal (cold-induced discomfort) also increased VEMP amplitude but that, unlike vection, it did not modulate VEMP amplitude linearly. In agreement, small-field visual roll motion that did not induce vection failed to increase VEMP amplitude. Taken together, our results demonstrate that vection can modify the response of vestibulo-collic reflexes. Even short-latency brainstem vestibulo-spinal reflexes are influenced by high-order mechanisms, illustrating the functional importance of perceptual mechanisms in human postural control. As VEMPs are inhibitory responses, we argue that the findings may represent a mechanism whereby high-order CNS mechanisms reduce activity levels in vestibulo-collic reflexes, necessary for instance when voluntary head movements need to be performed.
Martinez-Gallardo S, Miguel-Puga JA, Cooper-Bribiesca D, et al., 2021, Derealization and motion-perception related to repeated exposure to 3T Magnetic Resonance Image scanner in healthy adults, JOURNAL OF VESTIBULAR RESEARCH-EQUILIBRIUM & ORIENTATION, Vol: 31, Pages: 69-80, ISSN: 0957-4271
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- Citations: 2
Shaikh AG, Bronstein A, Carmona S, et al., 2020, Consensus on virtual management of vestibular disorders: urgent versus expedited care, The Cerebellum: an international journal from neurosciences to clinical perspectives, Pages: 1-5, ISSN: 1473-4222
The virtual practice has made major advances in the way that we care for patients in the modern era. The culture of virtual practice, consulting, and telemedicine, which had started several years ago, took an accelerated leap as humankind was challenged by the novel coronavirus pandemic (COVID19). The social distancing measures and lockdowns imposed in many countries left medical care providers with limited options in evaluating ambulatory patients, pushing the rapid transition to assessments via virtual platforms. In this novel arena of medical practice, which may form new norms beyond the current pandemic crisis, we found it critical to define guidelines on the recommended practice in neurotology, including remote methods in examining the vestibular and eye movement function. The proposed remote examination methods aim to reliably diagnose acute and subacute diseases of the inner-ear, brainstem, and the cerebellum. A key aim was to triage patients into those requiring urgent emergency room assessment versus non-urgent but expedited outpatient management. Physicians who had expertise in managing patients with vestibular disorders were invited to participate in the taskforce. The focus was on two topics: (1) an adequate eye movement and vestibular examination strategy using virtual platforms and (2) a decision pathway providing guidance about which patient should seek urgent medical care and which patient should have non-urgent but expedited outpatient management.
Lin D, Castro P, Edwards A, et al., 2020, Dissociated motor learning and de-adaptation in patients with functional gait disorders, BRAIN, Vol: 143, Pages: 2594-2606, ISSN: 0006-8950
Bednarczuk NF, Bradshaw JM, Mian SY, et al., 2020, Pathophysiological dissociation of the interaction between time pressure and trait anxiety during spatial orientation judgments, EUROPEAN JOURNAL OF NEUROSCIENCE, Vol: 52, Pages: 3215-3222, ISSN: 0953-816X
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- Citations: 6
Murdin L, Seemungal BM, Bronstein AM, 2020, Assessment of dizziness in neurology, Medicine, ISSN: 1357-3039
Dizziness and vertigo are common symptoms. Because there are effective treatments for vestibular disorders, it is always important to make an accurate diagnosis. In acute vertigo, expert clinical assessment is critically important in discerning stroke from non-stroke causes because results of stroke-protocol brain magnetic resonance imaging, including diffusion-weighted imaging, can be falsely negative in the first 24 hours. It follows that acute medical services must have access to clinicians expert in assessing acute vertigo. Expertise in clinical examination and interpretation of findings requires appropriate training, but here we outline the basic diagnostic and therapeutic approach to patients with dizziness. Appropriate early management of these conditions is part of prevention of disabling chronic functional dizziness.
Patel M, Roberts E, Arshad Q, et al., 2020, The "broken escalator" phenomenon: vestibular dizziness interferes with locomotor adaptation, Journal of Vestibular Research: Equilibrium and Orientation: an international journal of experimental and clinical vestibular science, Vol: 30, Pages: 81-94, ISSN: 0957-4271
BACKGROUND: Although vestibular lesions degrade postural control we do not know the relative contributions of the magnitude of the vestibular loss and subjective vestibular symptoms to locomotor adaptation. OBJECTIVE: To study how dizzy symptoms interfere with adaptive locomotor learning. METHODS: We examined patients with contrasting peripheral vestibular deficits, vestibular neuritis in the chronic stable phase (n = 20) and strongly symptomatic unilateral Meniere's disease (n = 15), compared to age-matched healthy controls (n = 15). We measured locomotor adaptive learning using the "broken escalator" aftereffect, simulated on a motorised moving sled. RESULTS: Patients with Meniere's disease had an enhanced "broken escalator" postural aftereffect. More generally, the size of the locomotor aftereffect was related to how symptomatic patients were across both groups. Contrastingly, the degree of peripheral vestibular loss was not correlated with symptom load or locomotor aftereffect size. During the MOVING trials, both patient groups had larger levels of instability (trunk sway) and reduced adaptation than normal controls. CONCLUSION: Dizziness symptoms influence locomotor adaptation and its subsequent expression through motor aftereffects. Given that the unsteadiness experienced during the "broken escalator" paradigm is internally driven, the enhanced aftereffect found represents a new type of self-generated postural challenge for vestibular/unsteady patients.
Cortese A, Tozza S, Yau WY, et al., 2020, Cerebellar ataxia, neuropathy, vestibular areflexia syndrome due to RFC1 repeat expansion., Brain, Vol: 143, Pages: 480-490
Ataxia, causing imbalance, dizziness and falls, is a leading cause of neurological disability. We have recently identified a biallelic intronic AAGGG repeat expansion in replication factor complex subunit 1 (RFC1) as the cause of cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS) and a major cause of late onset ataxia. Here we describe the full spectrum of the disease phenotype in our first 100 genetically confirmed carriers of biallelic repeat expansions in RFC1 and identify the sensory neuropathy as a common feature in all cases to date. All patients were Caucasian and half were sporadic. Patients typically reported progressive unsteadiness starting in the sixth decade. A dry spasmodic cough was also frequently associated and often preceded by decades the onset of walking difficulty. Sensory symptoms, oscillopsia, dysautonomia and dysarthria were also variably associated. The disease seems to follow a pattern of spatial progression from the early involvement of sensory neurons, to the later appearance of vestibular and cerebellar dysfunction. Half of the patients needed walking aids after 10 years of disease duration and a quarter were wheelchair dependent after 15 years. Overall, two-thirds of cases had full CANVAS. Sensory neuropathy was the only manifestation in 15 patients. Sixteen patients additionally showed cerebellar involvement, and six showed vestibular involvement. The disease is very likely to be underdiagnosed. Repeat expansion in RFC1 should be considered in all cases of sensory ataxic neuropathy, particularly, but not only, if cerebellar dysfunction, vestibular involvement and cough coexist.
Bronstein AM, Golding JF, Gresty MA, 2020, Visual Vertigo, Motion Sickness, and Disorientation in Vehicles, SEMINARS IN NEUROLOGY, Vol: 40, Pages: 116-129, ISSN: 0271-8235
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- Citations: 16
Anastasopoulos D, Ziavra N, Bronstein A, 2019, Large gaze shift generation whilst standing up - the role of the vestibular system, Journal of Neurophysiology, Vol: 122, Pages: 1928-1936, ISSN: 0022-3077
The functional significance of vestibular information for the generation of gaze shifts is controversial and less well established than the vestibular contribution to gaze stability. Here, we asked seven bilaterally avestibular patients to execute voluntary, whole-body pivot turns to visual targets up to 180° whilst standing. In these conditions not only the demands imposed on gaze transfer mechanisms are more challenging but also neck-proprioceptive input represents an inadequate source of head-in-space motion information. Patients' body segments motion was slower and jerky. In the absence of visual feedback, gaze advanced in small steps, closely resembling normal multiple-step gaze shift patterns but, as a consequence of the slow head motion, target acquisition was delayed. In approximately 25% of trials, however, patients moved faster but the velocity of prematurely emerging slow-phase compensatory eye movements remained lower than head-in-space velocity due to vestibulo-ocular failure. During these trials, therefore, gaze advanced towards the target without interruption but taking again longer than when normal controls use single-step gaze transfers. That is, even when patients attempted faster gaze shifts, exposing themselves to gaze instability they acquired distant targets significantly later than controls. Thus, whilst upright, loss of vestibular information not only disrupts gaze stability but also gaze transfers. The slow and ataxic head and trunk movements introduce significant foveation delays. These deficits explain patients' symptoms during upright activities and show, for the first time, the clinical significance of losing the so called "anti-compensatory" (gaze shifting) function of the vestibulo-ocular reflex.
Kim HA, Bisdorff A, Bronstein AM, et al., 2019, Hemodynamic orthostatic dizziness/vertigo: diagnostic criteria, Journal of Vestibular Research, Vol: 29, Pages: 45-56, ISSN: 0957-4271
This paper presents the diagnostic criteria for hemodynamic orthostatic dizziness/vertigo to be included in the International Classification of Vestibular Disorders (ICVD). The aim of defining diagnostic criteria of hemodynamic orthostatic dizziness/vertigo is to help the clinicians to understand the terminology related to orthostatic dizziness/vertigo and to distinguish orthostatic dizziness/vertigo due to global brain hypoperfusion from that caused by other etiologies. Diagnosis of hemodynamic orthostatic dizziness/vertigo requires: A) one or more episodes of dizziness/vertigo or unsteadiness triggered by arising or present during upright position, which subsides by sitting or lying down; B) orthostatic hypotension, postural tachycardia syndrome or syncope documented on standing or during head-up tilt test; and C) not better accounted for by another disease or disorder. Probable hemodynamic orthostatic dizziness/vertigo is defined as follows: A) at least 5 episodes of dizziness/vertigo or unsteadiness triggered by arising or present during upright position, which subsides by sitting or lying down; B) at least one of the following accompanying symptoms: generalized weakness/tiredness, difficulty of thinking/concentration, blurred vision, and tachycardia/palpitations; and C) not better accounted for by another disease or disorder. These diagnostic criteria have been derived by expert consensus from an extensive review of 90 years of research on hemodynamic orthostatic dizziness/vertigo, postural hypotension or tachycardia, and autonomic dizziness. Measurements of orthostatic blood pressure and heart rate are important for the screening and documentation of orthostatic hypotension or postural tachycardia syndrome to establish the diagnosis of hemodynamic orthostatic dizziness/vertigo.
Castro P, Kaski D, Al-Fazly H, et al., 2019, Body sway during postural perturbations is mediated by the degree of vestibulo-cortical dominance, Brain Stimulation, Vol: 12, Pages: 1098-1100, ISSN: 1935-861X
Arshad Q, Ortega MC, Goga U, et al., 2019, Interhemispheric control of sensory cue integration and self-motion perception, Neuroscience, Vol: 408, Pages: 378-387, ISSN: 0306-4522
Spatial orientation necessitates the integration of visual and vestibular sensory cues, in-turn facilitating self-motion perception. However, the neural mechanisms underpinning sensory integration remain unknown. Recently we have illustrated that spatial orientation and vestibular thresholds are influenced by interhemispheric asymmetries associated with the posterior parietal cortices (PPC) that predominantly house the vestibulo-cortical network. Given that sensory integration is a prerequisite to both spatial orientation and motion perception, we hypothesized that sensory integration is similarly subject to interhemispheric influences. Accordingly, we explored the relationship between vestibulo-cortical dominance – assessed using a biomarker, the degree of vestibular-nystagmus suppression following transcranial direct current stimulation over the PPC – with visual dependence measures obtained during performance of a sensory integration task (the rod-and-disk task). We observed that the degree of visual dependence was correlated with vestibulo-cortical dominance. Specifically, individuals with greater right hemispheric vestibulo-cortical dominance had reduced visual dependence. We proceeded to assess the significance of such dominance on behavior by correlating measures of visual dependence with self-motion perception in healthy subjects. We observed that right-handed individuals experienced illusionary self-motion (vection) quicker than left-handers and that the degree of vestibular cortical dominance was correlated with the time taken to experience vection, only during conditions that induced interhemispheric conflict. To conclude, we demonstrate that interhemispheric asymmetries associated with vestibulo-cortical processing in the PPC functionally and mechanistically link sensory integration and self-motion perception, facilitating spatial orientation. Our findings highlight the importance of dynamic interhemispheric competition upon control of vestib
Khan AN, Bronstein A, Bain P, et al., 2019, Pedunculopontine and Subthalamic Nucleus Stimulation Effect on Saccades in Parkinson Disease, WORLD NEUROSURGERY, Vol: 126, Pages: E219-E231, ISSN: 1878-8750
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- Citations: 3
Bronstein AM, 2019, A conceptual model of the visual control of posture., Prog Brain Res, Vol: 248, Pages: 285-302
In order to isolate the visual contribution to the control of postural balance, experiments in which subjects are exposed to large-field visual motion (optokinetic) stimuli are reviewed. In these situations, at motion onset, the visual stimulus signals subject self-motion but inertial (vestibulo-proprioceptive) cues do not. Visually evoked postural responses (VEPR) thus induced can be quickly suppressed by cognitive status or simple repetition of the stimulus, if the inertial self-motion cues available to the subject are reliable. In the conceptual model presented here, the process of assessing the reliability, and degree of matching, of visual and inertial signals is carried out by a General comparator; in turn able to access the Gain control mechanism of the visuo-postural system. Complexity and congruency in the visual stimulus itself are assessed by a Visual comparator, e.g., the presence of motion parallax in the visual stimulus can reverse the sway response direction. VEPR can also be re-oriented according to the position of the eyes in the head and the head on the trunk. This indicates that ocular and cervical proprioceptors must also access the gain control mechanism so that visual stimuli can recruit and silence different postural muscles appropriately. The overall gain of the visuo-postural system is also influenced by less easily defined idiosyncratic factors, such as visual dependence and psychological traits; interestingly both these factors have been found to be associated with poor long term outcome in vestibular disorders. The experimental results and model presented illustrate that the visuo-postural system is a wonderful example of interaction between physics (e.g., stimuli geometry, body dynamics), neuroscience and the border zone between neurology and psycho-somatic medicine.
Cortese A, Simone R, Sullivan R, et al., 2019, Author Correction: Biallelic expansion of an intronic repeat in RFC1 is a common cause of late-onset ataxia., Nat Genet, Vol: 51, Pages: 920-920
In the version of this article initially published, the name of author Wai Yan Yau was misspelled. The error has been corrected in the HTML and PDF versions of the article.
Harcourt JP, Lambert A, Wong PY, et al., 2019, Long-term follow-up of intratympanic methylprednisolone versus gentamicin in patients with unilateral Menière's disease, Otology and Neurotology, Vol: 40, Pages: 491-496, ISSN: 1531-7129
OBJECTIVES: To determine whether long term (>48 months) symptomatic vertigo control is sustained in patients with Menière's disease from a previous comparative trial of intratympanic methylprednisolone versus gentamicin, and if the two treatments remain nonsignificantly different at long-term follow-up. STUDY DESIGN: Mail survey recording vertigo frequency in the previous one and six months, further intratympanic treatment received, and validated symptom questionnaires. SETTING: Outpatient hospital clinic setting. PATIENTS: Adult patients with definite unilateral refractory Menière's disease, who previously received intratympanic treatment in a comparative trial. INTERVENTION: A survey of trial participants who received intratympanic gentamicin (40 mg/mL) or methylprednisolone (62.5 mg/mL). OUTCOME MEASURES: Primary: number of vertigo attacks in the 6 months prior to receiving this survey compared with the 6 months before the first trial injection. Secondary number of vertigo attacks over the previous 1 month; validated symptom questionnaire scores of tinnitus, dizziness, vertigo, aural fullness, and functional disability. RESULTS: Forty six of the 60 original trial patients (77%) completed the survey, 24 from the gentamicin and 22 from the methylprednisolone group. Average follow-up was 70.8 months (standard deviation 17.0) from the first treatment injection. Vertigo attacks in the 6 months prior to receiving the current survey reduced by 95% compared to baseline in both drug groups (intention-to-treat analysis, both p < 0.001). No significant difference between drugs was found for the primary and secondary outcomes. Eight participants (methylprednisolone = 5 and gentamicin = 3) required further injections for relapse after completing the original trial. CONCLUSION: Intratympanic methylprednisolone treatment provides effective long-lasting relief of vertigo, without the known inner-ear toxicity associated with gentamicin. There are no significan
Cortese A, Simone R, Sullivan R, et al., 2019, Biallelic expansion of an intronic repeat in RFC1 is a common cause of late-onset ataxia., Nature Genetics, Vol: 51, Pages: 649-658, ISSN: 1061-4036
Late-onset ataxia is common, often idiopathic, and can result from cerebellar, proprioceptive, or vestibular impairment; when in combination, it is also termed cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS). We used non-parametric linkage analysis and genome sequencing to identify a biallelic intronic AAGGG repeat expansion in the replication factor C subunit 1 (RFC1) gene as the cause of familial CANVAS and a frequent cause of late-onset ataxia, particularly if sensory neuronopathy and bilateral vestibular areflexia coexist. The expansion, which occurs in the poly(A) tail of an AluSx3 element and differs in both size and nucleotide sequence from the reference (AAAAG)11 allele, does not affect RFC1 expression in patient peripheral and brain tissue, suggesting no overt loss of function. These data, along with an expansion carrier frequency of 0.7% in Europeans, implies that biallelic AAGGG expansion in RFC1 is a frequent cause of late-onset ataxia.
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