88 results found
Saman Y, Sharif M, Lee A, et al., 2023, Sex-disease dimorphism underpins enhanced motion sickness susceptibility in primary adrenal insufficiency: a cross-sectional observational study., Exp Brain Res, Vol: 241, Pages: 1199-1206
Environmental motion can induce physiological stress and trigger motion sickness. In these situations, lower-than-normal levels of adrenocorticotropic hormone (ACTH) have been linked with increased susceptibility to motion sickness in healthy individuals. However, whether patients with primary adrenal insufficiency, who typically have altered ACTH levels compared to the normal population, exhibit alterations in sickness susceptibility remains unknown. To address this, we recruited 78 patients with primary adrenal insufficiency and compared changes in the motion sickness susceptibility scores from 10 years prior to diagnosis (i.e. retrospective sickness rating) with the current sickness measures (post-diagnosis), using the validated motion sickness susceptibility questionnaire (MSSQ). Group analysis revealed that motion sickness susceptibility pre-diagnosis did not differ between controls and patients. We observed that following treatment, current measures of motion sickness were significantly increased in patients and subsequent analysis revealed that this increase was primarily in female patients with primary adrenal insufficiency. These observations corroborate the role of stress hormones in modulating sickness susceptibility and support the notion of a sexually dimorphic adrenal cortex as we only observed selective enhancement in females. A potential mechanism to account for our novel observation remains obscure, but we speculate that it may reflect a complex sex-disease-drug interaction.
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
Patel P, Castro P, Koohi N, et al., 2022, Head shaking does not alter vestibulo ocular reflex gain in vestibular migraine, FRONTIERS IN NEUROLOGY, Vol: 13, ISSN: 1664-2295
Bonsu AN, Britton Z, Asif Z, et al., 2022, Migraine phenotype differentially modulates the attentional network: a cross-sectional observation study, Cephalalgia: an international journal of headache, ISSN: 0333-1024
Background: Signs of distinct brain dysfunction in patients where migraine intersects with vertigo (i.e. vestibular migraine (VM)), remains elusive. As migraine and vertigo can both independently modulate attentional processes, here we seek the utility of the attentional network to functionally differentiate patients. Methods: We used the Attentional Network Task (ANT) to elucidate 3 separate functional networks: alerting, orienting and resolving conflict. 120 participants had to attend to the direction of a target visual stimulus, whilst other parameters were simultaneously manipulated. Reaction times across the networks were assessed in, (i) 30 healthy-controls, (ii) 30 VM patients, (iii) 30 patients with migraine without vertigo, and, (iv) 30 patients with benign paroxysmal positional vertigo (BPPV) but no migraine. Results: Patients with VM (mean= 737.1ms, SEM= 28), migraine (mean= 735.3ms, SEM= 36.4), and BPPV (mean= 720.3ms SEM= 24.3) all exhibited significantly delayed ANT reaction times compared to healthy-controls (mean= 661.3ms, SEM= 23.4). Specific attentional network deficits were observed for resolving conflict in VM, alerting in migraine and orienting in BPPV. Conclusion: VM patients displayed deficits in executive function characterised by an inability to focus attentional resources and suppress peripheral distractors, whereas migraineurs without vertigo exhibited changes in the alerting network that reflects hypervigilance.
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, Bancroft MJ, Arshad Q, et al., 2022, Persistent Postural-Perceptual Dizziness (PPPD) from Brain Imaging to Behaviour and Perception, BRAIN SCIENCES, Vol: 12
- Author Web Link
- Citations: 1
Rashid SMU, Sumaria S, Koohi N, et al., 2022, Patient Experience of Flunarizine for Vestibular Migraine: Single Centre Observational Study, BRAIN SCIENCES, Vol: 12
- Author Web Link
- Citations: 1
Castro P, Hussain S, Mohamed OG, et al., 2022, Visuospatial orientation: Differential effects of head and body positions, NEUROSCIENCE LETTERS, Vol: 775, ISSN: 0304-3940
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
- Author Web Link
- Citations: 1
Arshad Q, Saman Y, Kaski D, et al., 2022, Magnitude estimates construct hierarchal maps for vestibular space and time: implications for functional dizziness, Frontiers in Neuroscience, Vol: 15, ISSN: 1662-453X
Maintaining balance necessitate an accurate perceptual map of the external world. Neuro-physiological mechanisms of locomotor control, sensory perception and anxiety systems, have been viewed as separate entities that can on occasion affect each other (i.e. walking on ice). Emerging models are more integrated, that envision sensory perception and threat assessment as a fundamental component of balance. Here we present the empirically based theoretical argument, that vestibular cortical areas construct magnitude estimates of the external world via neural integration of incoming sensory signals. In-turn these cortically derived magnitude estimates, construct context-dependent vestibulo-spatial and vestibulo-temporal representational maps of the external world, and, ensure an appropriate online scaling factor for associated action-perceptual risk. Thus, threat signals exert a continuous influence on planning movements, predicting outcomes of motion of self and surrounding objects, and adjusting tolerances for discrepancies between predicted and actual estimates. Such a process affects the degree of conscious attention directed to spatial and temporal aspects of motion stimuli, implying that maintaining balance may follow a Bayesian approach in which the relative weighting of vestibulo-spatial and vestibulo-temporal signals and tolerance for discrepancies are adjusted in accordance with the level of threat assessment. Here, we seek to mechanistically explain this process with our novel empirical concept of a Brainstem Cortical Scaling Metric (BCSM), which we developed from a series of neurophysiological studies illustrating the central role of interhemispheric vestibulo-cortical asymmetries for balance control. We conclude by using the BCSM to derive theoretical predictions of how a dysfunctional BCSM can mechanistically-account for functional dizziness.
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
Chan Y, Wong Y, Khalid N, et al., 2021, Acute dizziness and vertigo in cortical stroke: Bias of subjective recall, 25th World Congress of Neurology (WCN), Publisher: ELSEVIER, Pages: 3-3, ISSN: 0022-510X
Ibitoye R, Castro P, Desowska A, et al., 2021, Small vessel disease disrupts EEG postural brain networks in 'unexplained dizziness in the elderly', 25th World Congress of Neurology (WCN), Publisher: ELSEVIER, ISSN: 0022-510X
Arshad Q, Bronstein A, 2021, Motion perception in vestibular migraine, EUROPEAN JOURNAL OF NEUROLOGY, Vol: 28, Pages: E93-E94, ISSN: 1351-5101
- Author Web Link
- Citations: 1
Man Chan Y, Wong Y, Khalid N, et al., 2021, Prevalence of acute dizziness and vertigo in cortical stroke, EUROPEAN JOURNAL OF NEUROLOGY, Vol: 28, Pages: 3177-3181, ISSN: 1351-5101
- Author Web Link
- Citations: 6
Kamourieh S, Sokolska M, Akram H, et al., 2021, Miners' Nystagmus Following Visual Deprivation: A Case Report, ANNALS OF INTERNAL MEDICINE, Vol: 174, Pages: 1021-+, ISSN: 0003-4819
Bonsu A, Walker P, Edey J, et al., 2021, Time to consider the role of rationalisation in health psychology, PUBLIC HEALTH, Vol: 196, Pages: 59-61, ISSN: 0033-3506
McCarthy J, Castro P, Cottier R, et al., 2021, Multisensory contribution in visuospatial orientation: an interaction between neck and trunk proprioception, EXPERIMENTAL BRAIN RESEARCH, Vol: 239, Pages: 2501-2508, ISSN: 0014-4819
- Author Web Link
- 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.
Calzolari E, Chepisheva M, Smith RM, et al., 2021, Vestibular agnosia in traumatic brain injury and its link to imbalance, Brain, Vol: 144, Pages: 128-143, ISSN: 0006-8950
Vestibular dysfunction, causing dizziness and imbalance, is a common yet poorly understoodfeature in traumatic brain injury patients. Damage to the inner ear, nerve, brainstem, cerebellumand cerebral hemispheres may all affect vestibular functioning, hence, a multi-level assessment– from reflex to perception – is required. In a previous report, postural instability was thecommonest neurological feature in ambulating acute traumatic brain injury patients. We alsofrequently observe, during ward assessment of acute traumatic brain injury patients withcommon inner ear conditions and a related vigorous vestibular-ocular reflex nystagmus, a lossof vertigo sensation, suggesting a “vestibular agnosia”. Vestibular agnosia patients were alsomore unbalanced, however the link between vestibular agnosia and imbalance was confoundedby the presence of inner ear conditions. We investigated the brain mechanisms of imbalance inacute traumatic brain injury, its link with vestibular agnosia, and potential clinical impact, byprospective laboratory assessment of vestibular function, from reflex to perception, in patientswith preserved peripheral vestibular function. Assessment included vestibular-reflex function;vestibular-perception by participants’ report of their passive yaw rotations in the dark;objective balance via posturography; subjective symptoms via questionnaires; and structuralneuroimaging. We prospectively screened 918 acute admissions, assessed 146 and recruited37. Compared to 37 matched controls, patients showed elevated vestibular-perceptualthresholds (patients 12.92°/s vs. 3.87°/s) but normal vestibular-ocular reflex thresholds(patients 2.52°/s vs. 1.78°/s). Patients with elevated vestibular-perceptual thresholds (3standard deviations above controls’ average), were designated as having vestibular agnosia,and displayed worse posturography than non-vestibular-agnosia patients, despite no differencein vestibular symptom sc
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.
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
- Author Web Link
- Citations: 6
Saman Y, Arshad Q, Dutia M, et al., 2020, Stress and the vestibular system, STRESS AND BRAIN HEALTH: IN CLINICAL CONDITIONS, Vol: 152, Pages: 221-236, ISSN: 0074-7742
- Author Web Link
- Citations: 2
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
Marcus HJ, Paine H, Sargeant M, et al., 2019, Vestibular dysfunction in acute traumatic brain injury, Journal of Neurology, Vol: 266, Pages: 2430-2433, ISSN: 0340-5354
Traumatic brain injury (TBI) is the commonest cause of disability in under-40-year-olds. Vestibular features of dizziness (illusory self-motion) or imbalance which affects 50% of TBI patients at 5 years, increases unemployment threefold in TBI survivors. Unfortunately, vestibular diagnoses are cryptogenic in 25% of chronic TBI cases, impeding therapy. We hypothesized that chronic adaptive brain mechanisms uncouple vestibular symptoms from signs. This predicts a masking of vestibular diagnoses chronically but not acutely. Hence, defining the spectrum of vestibular diagnoses in acute TBI should clarify vestibular diagnoses in chronic TBI. There are, however, no relevant acute TBI data. Of 111 Major Trauma Ward adult admissions screened (median 38-years-old), 96 patients (87%) had subjective dizziness (illusory self-motion) and/or objective imbalance were referred to the senior author (BMS). Symptoms included: feeling unbalanced (58%), headache (50%) and dizziness (40%). In the 47 cases assessed by BMS, gait ataxia was the commonest sign (62%) with half of these cases denying imbalance when asked. Diagnoses included BPPV (38%), acute peripheral unilateral vestibular loss (19%), and migraine phenotype headache (34%), another potential source of vestibular symptoms. In acute TBI, vestibular signs are common, with gait ataxia being the most frequent one. However, patients underreport symptoms. The uncoupling of symptoms from signs likely arises from TBI affecting perceptual mechanisms. Hence, the cryptogenic nature of vestibular symptoms in TBI (acute or chronic) relates to a complex interaction between injury (to peripheral and central vestibular structures and perceptual mechanisms) and brain-adaptation, emphasizing the need for acute prospective, mechanistic studies.
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
Britton Z, Arshad Q, 2019, Vestibular and multi-sensory influences upon self-motion perception and the consequences for human behavior, Frontiers in Neurology, Vol: 10, ISSN: 1664-2295
In this manuscript, we comprehensively review both the human and animal literature regarding vestibular and multi-sensory contributions to self-motion perception. This covers the anatomical basis and how and where the signals are processed at all levels from the peripheral vestibular system to the brainstem and cerebellum and finally to the cortex. Further, we consider how and where these vestibular signals are integrated with other sensory cues to facilitate self-motion perception. We conclude by demonstrating the wide-ranging influences of the vestibular system and self-motion perception upon behavior, namely eye movement, postural control, and spatial awareness as well as new discoveries that such perception can impact upon numerical cognition, human affect, and bodily self-consciousness.
Bronstein A, Bednarczuk N, Bonsu A, et al., 2019, Abnormal visuo-vestibular interactions in vestibular migraine: a cross sectional study, BRAIN, Vol: 142, Pages: 606-616, ISSN: 1460-2156
Vestibular migraine is among the commonest causes of episodic vertigo. Chronically, patients with vestibular migraine develop abnormal responsiveness to both vestibular and visual stimuli characterized by heightened self-motion sensitivity and visually-induced dizziness. Yet, the neural mechanisms mediating such symptoms remain unknown. We postulate that such symptoms are attributable to impaired visuo-vestibular cortical interactions, which in turn disrupts normal vestibular function. To assess this, we investigated whether prolonged, full-field visual motion exposure, which has been previously shown to modulate visual cortical excitability in both healthy individuals and avestibular patients, could disrupt vestibular ocular reflex and vestibular-perceptual thresholds of self-motion during rotations. Our findings reveal that vestibular migraine patients exhibited abnormally elevated reflexive and perceptual vestibular thresholds at baseline. Following visual motion exposure, both reflex and perceptual thresholds were significantly further increased in vestibular migraine patients relative to healthy controls, migraineurs without vestibular symptoms and patients with episodic vertigo due to a peripheral inner-ear disorder. Our results provide support for the notion of altered visuo-vestibular cortical interactions in vestibular migraine, as evidenced by vestibular threshold elevation following visual motion exposure.
Castro P, Kaskia D, Schieppati M, et al., 2019, Subjective stability perception is related to postural anxiety in older subjects, GAIT & POSTURE, Vol: 68, Pages: 538-544, ISSN: 0966-6362
- Author Web Link
- Citations: 13
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