Publications
429 results found
Bronstein AM, 2016, Multisensory integration in balance control., Handbook of Clinical Neurology, Vol: 137, Pages: 57-66, ISSN: 0072-9752
This chapter provides an introduction to the topic of multisensory integration in balance control in, both, health and disease. One of the best-studied examples is that of visuo-vestibular interaction, which is the ability of the visual system to enhance or suppress the vestibulo-ocular reflex (VOR suppression). Of clinical relevance, examination of VOR suppression is clinically useful because only central, not peripheral, lesions impair VOR suppression. Visual, somatosensory (proprioceptive), and vestibular inputs interact strongly and continuously in the control of upright balance. Experiments with visual motion stimuli show that the visual system generates visually-evoked postural responses that, at least initially, can override vestibular and proprioceptive signals. This paradigm has been useful for the study of the syndrome of visual vertigo or vision-induced dizziness, which can appear after vestibular disease. These patients typically report dizziness when exposed to optokinetic stimuli or visually charged environments, such as supermarkets. The principles of the rehabilitation treatment of these patients, which use repeated exposure to visual motion, are presented. Finally, we offer a diagnostic algorithm in approaching the patient reporting oscillopsia - the illusion of oscillation of the visual environment, which should not be confused with the syndrome mentioned earlier of visual vertigo.
Patel M, Agarwal K, Arshad Q, et al., 2016, Intratympanic steroids vs. gentamicin in unilateral Ménière's disease: a randomised double-blind comparative effectiveness trial, Lancet, ISSN: 1474-547X
Background: Ménière’s disease (MD) is characterised by severe vertigo attacks and deafness. Intratympanic gentamicin ablates vestibular function, quells vertigo and is the standard treatment for refractory MD - but it can worsen hearing. Intratympanic corticosteroids may reduce vertigo without harming hearing but no RCT comparing steroids versus gentamicin is available.Methods: In this comparative effectiveness trial, refractory unilateral MD patients, defined according to the American Academy of Otolaryngology, were double-blindly randomised (1:1 block-design) to intratympanic methylprednisolone (n=30, 62·5mg/ml) or gentamicin (n=30, 40mg/ml) and followed-up over two years at Charing Cross Hospital (Imperial NHS, London) and Leicester Royal Infirmary, Leicester, UK. Primary outcome was vertigo frequency over the final 6-months (18-24months post-injection) compared to a 6-month pre-injection baseline. Secondary outcomes were vestibular and auditory symptoms (validated questionnaires) and hearing preservation (audiometry). ClinicalTrials.gov:NCT00802529.Findings: For intention-to-treat analysis i.e., all 60 patients, number of vertigo attacks/6months (primary outcome) fell from 19·9 to 2·5 [87%] in the gentamicin arm and 16·4 to 1·6 [90%] in the steroid arm (difference in absolute number of attacks in the final 6months -0·9; 95%CI -3·4 to 1·6). Both drugs reduced the number of vertigo attacks at 2 years (P<0·0001), with equal efficacy (P=0·51). For hearing preservation (secondary outcome), there was no difference (P=0·18) between drugs for hearing thresholds (final difference -2·45decibels, 95%CI -13·4 to 8·5). Both drugs reduced auditory and vestibular symptoms equally. As protocol, patients whose vertigo did not respond post-injection (‘non-responders’) were considered for additional injections by an unblinded physician (8 patients ge
Nigmatullina Y, Siddiqui S, Khan S, et al., 2016, Lateralisation of the vestibular cortex is more pronounced in left-handers, Brain Stimulation, Vol: 9, Pages: 942-944, ISSN: 1935-861X
Murdin L, Seemungal BM, Bronstein AM, 2016, Dizziness, Medicine (United Kingdom), Vol: 44, Pages: 484-487, ISSN: 1357-3039
© 2016 Elsevier Ltd 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 stroke-protocol brain magnetic resonance imaging results, 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 the interpretation of findings requires appropriate training, but in this article we outline the basic diagnostic and therapeutic approach to patients with dizziness.
Arshad Q, Nigmatullina Y, Roberts RE, et al., 2016, Perceived state of self during motion can differentially modulate numerical magnitude allocation., European Journal of Neuroscience, Vol: 44, Pages: 2369-2374, ISSN: 1460-9568
Although a direct relationship between numerical-allocation and spatial-attention has been proposed, recent research suggests these processes are not directly coupled. In keeping with this, spatial attention shifts induced either via visual or vestibular motion can modulate numerical allocation in some circumstances but not in others. In addition to shifting spatial attention, visual or vestibular motion-paradigms also (i) elicit compensatory eye-movements which themselves can influence numerical-processing and (ii) alter the perceptual-state of-"self", inducing changes in bodily self-consciousness impacting upon cognitive mechanisms. Thus, the precise mechanism by which motion modulates numerical-allocation remains unknown. We sought to investigate the influence that different perceptual experiences of motion have upon numerical magnitude allocation whilst controlling for both eye-movements and task-related effects. We first used optokinetic visual-motion stimulation (OKS) to elicit the perceptual experience of either "visual world" or "self"-motion during which eye movements were identical. In a second experiment we used a vestibular protocol examining the effects of perceived and subliminal angular rotations in darkness, which also provoked identical eye movements. We observed that during the perceptual experience of "visual-world" motion, rightward OKS biased judgments towards smaller numbers, whereas leftward OKS biased judgments towards larger numbers. During the perceptual experience of "self-motion", judgments were biased towards larger numbers irrespective of the OKS direction. Contrastingly, vestibular motion perception was found not to modulate numerical magnitude allocation, nor was there any differential modulation when comparing "perceived" versus "subliminal" rotations. We provide a novel demonstration that magnitude-allocation can be differentially modulated by the perceptual state
Kaski D, Bronstein AM, 2016, Functional (psychogenic) saccadic oscillations and oculogyric crises - author's reply, Lancet Neurology, Vol: 15, Pages: 791-792, ISSN: 1474-4465
Arshad Q, Bonsu A, Malhotra PA, et al., 2016, Influence of lateralised hemispheric asymmetries upon numerical cognition and its influence upon pro-social decision making in Parkinson's disease, Publisher: WILEY, Pages: 97-97, ISSN: 1351-5101
Arshad Q, Bronstein A, 2016, Interhemispheric asymmetry and its role in higher-order vestibular function, Publisher: WILEY, Pages: 451-451, ISSN: 1351-5101
Arshad Q, Bronstein A, 2016, Bidirectional modulation of numerical magnitude, Cerebral Cortex, Vol: 26, Pages: 2311-2324, ISSN: 1460-2199
Numerical cognition is critical for modern life; however, the precise neural mechanisms underpinning numerical magnitude allocation in humans remain obscure. Based upon previous reports demonstrating the close behavioral and neuro-anatomical relationship between number allocation and spatial attention, we hypothesized that these systems would be subject to similar control mechanisms, namely dynamic interhemispheric competition. We employed a physiological paradigm, combining visual and vestibular stimulation, to induce interhemispheric conflict and subsequent unihemispheric inhibition, as confirmed by transcranial direct current stimulation (tDCS). This allowed us to demonstrate the first systematic bidirectional modulation of numerical magnitude toward either higher or lower numbers, independently of either eye movements or spatial attention mediated biases. We incorporated both our findings and those from the most widely accepted theoretical framework for numerical cognition to present a novel unifying computational model that describes how numerical magnitude allocation is subject to dynamic interhemispheric competition. That is, numerical allocation is continually updated in a contextual manner based upon relative magnitude, with the right hemisphere responsible for smaller magnitudes and the left hemisphere for larger magnitudes.
Patel M, Arshad Q, Roberts RE, et al., 2016, Chronic Symptoms After Vestibular Neuritis and the High-Velocity Vestibulo-Ocular Reflex, OTOLOGY & NEUROTOLOGY, Vol: 37, Pages: 179-184, ISSN: 1531-7129
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- Citations: 43
Kaski D, Bronstein AM, 2016, Patients with Vestibular Loss, Tullio Phenomenon, and Pressure-induced Nystagmus: Vestibular Atelectasis?, Otology & Neurotology, Vol: 37, Pages: 115-116, ISSN: 1537-4505
Kaski D, Quadir S, Nigmatullina Y, et al., 2015, Temporoparietal encoding of space and time during vestibular-guided orientation, Brain, Vol: 139, Pages: 392-403, ISSN: 0006-8950
When we walk in our environment, we readily determine our travelled distance and location using visual cues. In the dark, estimating travelled distance uses a combination of somatosensory and vestibular (i.e. inertial) cues. The observed inability of patients with complete peripheral vestibular failure to update their angular travelled distance during active or passive turns in the dark implies a privileged role for vestibular cues during human angular orientation. As vestibular signals only provide inertial cues of self-motion (e.g. velocity, °/s), the brain must convert motion information to distance information (a process called ‘path integration’) to maintain our spatial orientation during self-motion in the dark. It is unknown, however, what brain areas are involved in converting vestibular-motion signals to those that enable such vestibular-spatial orientation. Hence, using voxel-based lesion–symptom mapping techniques, we explored the effect of acute right hemisphere lesions in 18 patients on perceived angular position, velocity and motion duration during whole-body angular rotations in the dark. First, compared to healthy controls’ spatial orientation performance, we found that of the 18 acute stroke patients tested, only the four patients with damage to the temporoparietal junction showed impaired spatial orientation performance for leftward (contralesional) compared to rightward (ipsilesional) rotations. Second, only patients with temporoparietal junction damage showed a congruent underestimation in both their travelled distance (perceived as shorter) and motion duration (perceived as briefer) for leftward compared to rightward rotations. All 18 lesion patients tested showed normal self-motion perception. These data suggest that the cerebral cortical regions mediating vestibular-motion (‘am I moving?’) and vestibular-spatial perception (‘where am I?’) are distinct. Furthermore, the congruent contralesiona
Kaski D, Bronstein AM, Edwards MJ, et al., 2015, Cranial functional (psychogenic) movement disorders, LANCET NEUROLOGY, Vol: 14, Pages: 1196-1205, ISSN: 1474-4422
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- Citations: 41
Ahmad H, Cerchiai N, Mancuso M, et al., 2015, ARE WHITE MATTER ABNORMALITIES A CAUSE OF 'UNEXPLAINED DIZZINESS'? A RETROSPECTIVE BICENTRE STUDY, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050
Kaski D, Bronstein A, Cutfield N, et al., 2015, HEAD JOLTING NYSTAGMUS: HEAD-SHAKING-INDUCED OCCLUSION OF THE HORIZONTAL SEMICIRCULAR CANAL, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050
Ahmad H, Roberts R, Arshad QA, et al., 2015, USING TRANSCRANIAL MAGNETIC STIMULATION (TMS) TO PROBE EFFECTS OF VISUAL MOTION ADAPTATION ON PRIMARY VISUAL CORTEX (V1) EXCITABILITY IN BILATERAL VESTIBULAR FAILURE (BVF) PATIENTS, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050
Ahmad H, Arshad Q, Patel M, et al., 2015, ACQUIRED PENDULAR NYSTAGMUS IN STARGARDT'S SYNDROME SUPPRESSED BY ALCOHOL, Annual Meeting of the Association-of-British-Neurologists (ABN), Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050
Bronstein AM, Arshad Q, Siddiqui S, et al., 2015, Right hemisphere dominance directly predicts both baseline V1 cortical excitability and the degree of top-down modulation exerted over low-level brain structures, Neuroscience, Vol: 311, Pages: 484-489, ISSN: 0306-4522
Right hemisphere dominance for visuo-spatial attention is characteristically observed in most right-handed individuals. This dominance has been attributed to both an anatomically larger right fronto-parietal network and the existence of asymmetric parietal interhemispheric connections. Previously it has been demonstrated that interhemispheric conflict, which induces left hemisphere inhibition, results in the modulation of both (i) the excitability of the early visual cortex (V1) and (ii) the brainstem-mediated vestibular–ocular reflex (VOR) via top-down control mechanisms. However to date, it remains unknown whether the degree of an individual’s right hemisphere dominance for visuospatial function can influence, (i) the baseline excitability of the visual cortex and (ii) the extent to which the right hemisphere can exert top-down modulation. We directly tested this by correlating line bisection error (or pseudoneglect), taken as a measure of right hemisphere dominance, with both (i) visual cortical excitability measured using phosphene perception elicited via single-pulse occipital trans-cranial magnetic stimulation (TMS) and (ii) the degree of trans-cranial direct current stimulation (tDCS)-mediated VOR suppression, following left hemisphere inhibition. We found that those individuals with greater right hemisphere dominance had a less excitable early visual cortex at baseline and demonstrated a greater degree of vestibular nystagmus suppression following left hemisphere cathodal tDCS. To conclude, our results provide the first demonstration that individual differences in right hemisphere dominance can directly predict both the baseline excitability of low-level brain structures and the degree of top-down modulation exerted over them.
Bronstein A, 2015, Diagnosis of acute vertigo, 22nd World Congress of Neurology (WCN), Publisher: ELSEVIER, Pages: E499-E499, ISSN: 0022-510X
Ahmad H, Roberts RE, Arshad Q, et al., 2015, Probing effects of visual motion adaptation on primary visual cortex (V1) excitability using Tms in Bilateral Vestibular Failure (Bvf) patients, JOURNAL OF THE NEUROLOGICAL SCIENCES, Vol: 357, Pages: E172-E172, ISSN: 0022-510X
Ahmad H, Cerchiai N, Mancuso M, et al., 2015, Are white matter abnormalities a cause of "unexplained dizziness"?: A retrospective bi-centre study, 22nd World Congress of Neurology (WCN), Publisher: ELSEVIER SCIENCE BV, Pages: E45-E45, ISSN: 0022-510X
Arshad Q, Cerchiai N, Goga U, et al., 2015, ELECTROCORTICAL THERAPY FOR MOTION SICKNESS, Neurology, Vol: 85, Pages: 1257-1259, ISSN: 0028-3878
Pavlou M, Acheson J, Nicolaou D, et al., 2015, Effect of Developmental Binocular Vision Abnormalities on Visual Vertigo Symptoms and Treatment Outcome, JOURNAL OF NEUROLOGIC PHYSICAL THERAPY, Vol: 39, Pages: 215-224, ISSN: 1557-0576
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- Citations: 17
Ahmad H, Cerchiai N, Mancuso M, et al., 2015, Are white matter abnormalities associated with “unexplained dizziness”?, Journal of the Neurological Sciences, Vol: 358, Pages: 428-431, ISSN: 0022-510X
IntroductionAlthough cerebral small vessel disease is a significant contributor to the development of imbalance and falls in the elderly, whether it causes dizziness is not known.MethodsA retrospective case analysis was conducted for 122 dizzy patients referred to two neuro-otology tertiary centres in London and Pisa. Patients were divided into ‘explained’ causes of dizziness (e.g. benign positional vertigo, vestibular neuritis, orthostatic hypotension, cerebellar ataxias) and ‘unexplained’ dizziness. White matter hyperintensities (WMH) in MRI (T2 weighted and FLAIR sequences) were blindly rated according to the Fazekas scale.Results122 patients; 58 (mean age = 72, SD=7.95 years) in the ‘unexplained’ group and 64 (mean age=72.01, SD=8.28 years) in the ‘explained’ group were recruited. The overall frequency of lesions (Fazekas 1–3) significantly differed between groups (p=0.011). The frequency of severe lesions (Fazekas 3) was significantly higher in the ‘unexplained’ group (22%) than in the ‘explained’ group (5%; p=0.003).ConclusionIncreased severity of WMH in cases of unexplained dizziness suggests that such abnormalities are likely contributory to the development of dizziness. WM lesions may induce dizziness either because patients perceive a degree of objective unsteadiness or by a disconnection syndrome involving vestibular or locomotor areas of the brain.
Patel M, Roberts RE, Riyaz MU, et al., 2015, Locomotor adaptation is modulated by observing the actions of others, Journal of Neurophysiology, Vol: 114, Pages: 1538-1544, ISSN: 1522-1598
Observing the motor actions of another person could facilitate compensatory motor behavior in the passive observer. Here we explored whether action observation alone can induce automatic locomotor adaptation in humans. To explore this possibility, we used the “broken escalator” paradigm. Conventionally this involves stepping upon a stationary sled after having previously experienced it actually moving (Moving trials). This history of motion produces a locomotor aftereffect when subsequently stepping onto a stationary sled. We found that viewing an actor perform the Moving trials was sufficient to generate a locomotor aftereffect in the observer, the size of which was significantly correlated with the size of the movement (postural sway) observed. Crucially, the effect is specific to watching the task being performed, as no motor adaptation occurs after simply viewing the sled move in isolation. These findings demonstrate that locomotor adaptation in humans can be driven purely by action observation, with the brain adapting motor plans in response to the size of the observed individual's motion. This mechanism may be mediated by a mirror neuron system that automatically adapts behavior to minimize movement errors and improve motor skills through social cues, although further neurophysiological studies are required to support this theory. These data suggest that merely observing the gait of another person in a challenging environment is sufficient to generate appropriate postural countermeasures, implying the existence of an automatic mechanism for adapting locomotor behavior.
Essery R, Kirby S, Geraghty AWA, et al., 2015, The Development of Balance Retraining: An Online Intervention for Dizziness in Adults Aged 50 Years and Older, AMERICAN JOURNAL OF AUDIOLOGY, Vol: 24, Pages: 276-279, ISSN: 1059-0889
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- Citations: 7
Saifee TA, Parees I, Kassavetis P, et al., 2015, Tremor in Charcot-Marie-Tooth disease: No evidence of cerebellar dysfunction, CLINICAL NEUROPHYSIOLOGY, Vol: 126, Pages: 1817-1824, ISSN: 1388-2457
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- Citations: 16
Patel M, Roberts RE, Arshad Q, et al., 2015, Galvanic Vestibular Stimulation Induces a Spatial Bias in Whole-body Position Estimates, Brain Stimulation, Vol: 8, Pages: 981-983, ISSN: 1935-861X
Ahmad H, Cerchiai N, Mancuso M, et al., 2015, White matter abnormalities in dizzy patients: retrospective cohort multi - centre study, 1st Congress of the European-Academy-of-Neurology, Publisher: WILEY, Pages: 365-365, ISSN: 1351-5101
Ahmad H, Roberts R, Patel M, et al., 2015, Using transcranial magnetic stimulation (TMS) to probe effects of visual motion adaptation on primary visual cortex (V1) excitability in bilateral vestibular failure patients, 1st Congress of the European-Academy-of-Neurology, Publisher: WILEY, Pages: 51-51, ISSN: 1351-5101
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- Citations: 1
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