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Pastras CJ, Curthoys IS, Rabbitt RD, Brown DJ. Using macular velocity measurements to relate parameters of bone conduction to vestibular compound action potential responses. Sci Rep 2023; 13:10204. [PMID: 37353559 PMCID: PMC10290084 DOI: 10.1038/s41598-023-37102-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 06/15/2023] [Indexed: 06/25/2023] Open
Abstract
To examine mechanisms responsible for vestibular afferent sensitivity to transient bone conducted vibration, we performed simultaneous measurements of stimulus-evoked vestibular compound action potentials (vCAPs), utricular macula velocity, and vestibular microphonics (VMs) in anaesthetized guinea pigs. Results provide new insights into the kinematic variables of transient motion responsible for triggering mammalian vCAPs, revealing synchronized vestibular afferent responses are not universally sensitive to linear jerk as previously thought. For short duration stimuli (< 1 ms), the vCAP increases magnitude in close proportion to macular velocity and temporal bone (linear) acceleration, rather than other kinematic elements. For longer duration stimuli, the vCAP magnitude switches from temporal bone acceleration sensitive to linear jerk sensitive while maintaining macular velocity sensitivity. Frequency tuning curves evoked by tone-burst stimuli show vCAPs increase in proportion to onset macular velocity, while VMs increase in proportion to macular displacement across the entire frequency bandwidth tested between 0.1 and 2 kHz. The subset of vestibular afferent neurons responsible for synchronized firing and vCAPs have been shown previously to make calyceal synaptic contacts with type I hair cells in the striolar region of the epithelium and have irregularly spaced inter-spike intervals at rest. Present results provide new insight into mechanical and neural mechanisms underlying synchronized action potentials in these sensitive afferents, with clinical relevance for understanding the activation and tuning of neurons responsible for driving rapid compensatory reflex responses.
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Affiliation(s)
- Christopher J Pastras
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, NSW, 2109, Australia.
- School of Medical Sciences, The University of Sydney, Sydney, NSW, 2050, Australia.
| | - Ian S Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, 2050, Australia
| | - Richard D Rabbitt
- Departments of Biomedical Engineering, Otolaryngology and Neuroscience Program, University of Utah, Salt Lake City, UT, 84112, USA
| | - Daniel J Brown
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA, 6102, Australia
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Pastras CJ, Gholami N, Jennings S, Zhu H, Zhou W, Brown DJ, Curthoys IS, Rabbitt RD. A mathematical model for mechanical activation and compound action potential generation by the utricle in response to sound and vibration. Front Neurol 2023; 14:1109506. [PMID: 37051057 PMCID: PMC10083375 DOI: 10.3389/fneur.2023.1109506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 03/01/2023] [Indexed: 03/28/2023] Open
Abstract
IntroductionCalyx bearing vestibular afferent neurons innervating type I hair cells in the striolar region of the utricle are exquisitely sensitive to auditory-frequency air conducted sound (ACS) and bone conducted vibration (BCV). Here, we present experimental data and a mathematical model of utricular mechanics and vestibular compound action potential generation (vCAP) in response to clinically relevant levels of ACS and BCV. Vibration of the otoconial layer relative to the sensory epithelium was simulated using a Newtonian two-degree-of-freedom spring-mass-damper system, action potential timing was simulated using an empirical model, and vCAPs were simulated by convolving responses of the population of sensitive neurons with an empirical extracellular voltage kernel. The model was validated by comparison to macular vibration and vCAPs recorded in the guinea pig, in vivo.ResultsTransient stimuli evoked short-latency vCAPs that scaled in magnitude and timing with hair bundle mechanical shear rate for both ACS and BCV. For pulse BCV stimuli with durations <0.8 ms, the vCAP magnitude increased in proportion to temporal bone acceleration, but for pulse durations >0.9 ms the magnitude increased in proportion to temporal bone jerk. Once validated using ACS and BCV data, the model was applied to predict blast-induced hair bundle shear, with results predicting acute mechanical damage to bundles immediately upon exposure.DiscussionResults demonstrate the switch from linear acceleration to linear jerk as the adequate stimulus arises entirely from mechanical factors controlling the dynamics of sensory hair bundle deflection. The model describes the switch in terms of the mechanical natural frequencies of vibration, which vary between species based on morphology and mechanical factors.
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Affiliation(s)
- Christopher J. Pastras
- Faculty of Science and Engineering, School of Engineering, Macquarie University, Sydney, NSW, Australia
| | - Nastaran Gholami
- Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Skyler Jennings
- Communication Sciences and Neuroscience Program, University of Utah, Salt Lake City, UT, United States
| | - Hong Zhu
- University of Mississippi Medical Center, Jackson, MS, United States
| | - Wu Zhou
- University of Mississippi Medical Center, Jackson, MS, United States
| | - Daniel J. Brown
- School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA, Australia
| | - Ian S. Curthoys
- Vestibular Research Laboratory, School of Psychology, The University of Sydney, Sydney, NSW, Australia
| | - Richard D. Rabbitt
- Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Otolaryngology and Neuroscience Program, University of Utah, Salt Lake City, UT, United States
- *Correspondence: Richard D. Rabbitt,
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Rosengren SM, Young AS, Taylor RL, Welgampola MS. Vestibular function testing in the 21st century: video head impulse test, vestibular evoked myogenic potential, video nystagmography; which tests will provide answers? Curr Opin Neurol 2022; 35:64-74. [PMID: 34889807 DOI: 10.1097/wco.0000000000001023] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW To most neurologists, assessing the patient with vertigo is an unpleasant and worrisome task. A structured history and focused examination can be complemented by carefully selected laboratory tests, to reach an early and accurate diagnosis. We provide evidence-based recommendations for vestibular test selection. RECENT FINDINGS The video head impulse test (vHIT), cervical and ocular vestibular evoked myogenic potential (VEMP) and home-video nystagmography are four modern, noninvasive methods of assessing vestibular function, which are equally applicable in the hospital and office-practice. Collectively, they enable assessment of all five vestibular end-organs. The prevalence and patterns of test abnormalities are distinct for each vestibular disorder. We summarize typical abnormalities encountered in four common vestibular syndromes. SUMMARY In the context of acute vestibular syndrome, an abnormal vHIT with low gain and large amplitude refixation saccades and an asymmetric oVEMP separates innocuous vestibular neuritis from stroke. In episodic spontaneous vertigo, high-velocity ictal nystagmus and asymmetric cVEMP help separate Ménière's disease from vestibular migraine. In chronic imbalance, all three tests help detect unilateral or bilateral vestibular loss as the root cause. Recurrent positional vertigo requires no laboratory test and can be diagnosed and treated at the bedside, guided by video nystagmography.
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Affiliation(s)
- Sally M Rosengren
- Central Clinical School, Faculty of Medicine and Health, University of Sydney
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, Australia
| | - Allison S Young
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, Australia
| | - Rachael L Taylor
- Department of Physiology and Centre for Brain Research, The University of Auckland, Auckland, New Zealand
| | - Miriam S Welgampola
- Central Clinical School, Faculty of Medicine and Health, University of Sydney
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, Australia
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Dlugaiczyk J. Rare Disorders of the Vestibular Labyrinth: of Zebras, Chameleons and Wolves in Sheep's Clothing. Laryngorhinootologie 2021; 100:S1-S40. [PMID: 34352900 PMCID: PMC8363216 DOI: 10.1055/a-1349-7475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The differential diagnosis of vertigo syndromes is a challenging issue, as many - and in particular - rare disorders of the vestibular labyrinth can hide behind the very common symptoms of "vertigo" and "dizziness". The following article presents an overview of those rare disorders of the balance organ that are of special interest for the otorhinolaryngologist dealing with vertigo disorders. For a better orientation, these disorders are categorized as acute (AVS), episodic (EVS) and chronic vestibular syndromes (CVS) according to their clinical presentation. The main focus lies on EVS sorted by their duration and the presence/absence of triggering factors (seconds, no triggers: vestibular paroxysmia, Tumarkin attacks; seconds, sound and pressure induced: "third window" syndromes; seconds to minutes, positional: rare variants and differential diagnoses of benign paroxysmal positional vertigo; hours to days, spontaneous: intralabyrinthine schwannomas, endolymphatic sac tumors, autoimmune disorders of the inner ear). Furthermore, rare causes of AVS (inferior vestibular neuritis, otolith organ specific dysfunction, vascular labyrinthine disorders, acute bilateral vestibulopathy) and CVS (chronic bilateral vestibulopathy) are covered. In each case, special emphasis is laid on the decisive diagnostic test for the identification of the rare disease and "red flags" for potentially dangerous disorders (e. g. labyrinthine infarction/hemorrhage). Thus, this chapter may serve as a clinical companion for the otorhinolaryngologist aiding in the efficient diagnosis and treatment of rare disorders of the vestibular labyrinth.
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Affiliation(s)
- Julia Dlugaiczyk
- Klinik für Ohren-, Nasen-, Hals- und Gesichtschirurgie
& Interdisziplinäres Zentrum für Schwindel und
neurologische Sehstörungen, Universitätsspital Zürich
(USZ), Universität Zürich (UZH), Zürich,
Schweiz
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Hawkins KE, Chiarovano E, Paul SS, MacDougall HG, Curthoys IS. Static and dynamic otolith reflex function in people with Parkinson's disease. Eur Arch Otorhinolaryngol 2020; 278:2057-2065. [PMID: 33112983 DOI: 10.1007/s00405-020-06446-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 10/14/2020] [Indexed: 12/24/2022]
Abstract
PURPOSE Parkinson's disease (PD) is a neurodegenerative disorder with possible vestibular system dysfunction. This study reports the transient and sustained functions of the otoliths and their reflex pathways in PD compared to healthy controls (HC) and determines if otolith function relates to previous fall history. METHODS Forty participants with PD and 40 HC had their otolith function assessed. Transient saccular and utricular-mediated reflexes were assessed by cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs, respectively) elicited by air-conducted stimulus (clicks) and bone-conducted vibration (light tendon hammer taps). Static otolith function was assessed by the Curator Subjective Visual Vertical (SVV) test. RESULTS Compared to HC, the PD group had significantly more absent cVEMP responses to both clicks (47.5% vs. 30%, respectively, p = 0.03) and taps (21.8% vs. 5%, respectively, p = 0.002). Only the PD group had bilaterally absent tap cVEMPs, this was related to previous falls history (p < 0. 001). In both groups, click oVEMPs were predominantly absent, and tap oVEMPs were predominantly present. The PD group had smaller tap oVEMP amplitudes (p = 0.03) and recorded more abnormal SVV responses (p = 0.01) and greater error on SVV compared to HC, p < 0.001. SVV had no relationship with VEMP responses (p = 0.14). CONCLUSIONS PD impacts on cVEMP reflex pathways but not tap oVEMP reflex pathways. Bone-conducted otolith stimuli (taps) are more robust than air-conducted sound stimuli (clicks) for both o and cVEMPs. A lack of association between SVV and VEMP responses suggest that static and dynamic otolith functions are differentially affected in PD.
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Affiliation(s)
- Kim E Hawkins
- Vestibular Research Laboratory, School of Psychology, Faculty of Science, University of Sydney, Sydney, Australia.
| | - Elodie Chiarovano
- Sydney Human Factors Research, School of Psychology, Faculty of Science, University of Sydney, Sydney, Australia
| | - Serene S Paul
- Discipline of Physiotherapy, Faculty of Medicine and Health, Sydney School of Health Sciences, University of Sydney, Sydney, Australia
| | - Hamish G MacDougall
- Sydney Human Factors Research, School of Psychology, Faculty of Science, University of Sydney, Sydney, Australia
| | - Ian S Curthoys
- Vestibular Research Laboratory, School of Psychology, Faculty of Science, University of Sydney, Sydney, Australia
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Abstract
BACKGROUND Vestibular evoked myogenic potentials (VEMPs) are increasingly being used for testing otolith organ function. OBJECTIVE This article provides an overview of the anatomical, biomechanical and neurophysiological principles underlying the evidence-based clinical application of ocular and cervical VEMPs (oVEMPs and cVEMPs). MATERIAL AND METHODS Systematic literature search in PubMed until April 2019. RESULTS Sound and vibration at a frequency of 500 Hz represent selective vestibular stimuli for the otolith organs. The predominant specificity of oVEMPs for contralateral utricular function and of cVEMPs for ipsilateral saccular function is defined by the different central projections of utricular and saccular afferents. VEMPs are particularly useful in the diagnosis of superior canal dehiscence and otolith organ specific vestibular dysfunction and as an alternative diagnostic approach in situations when video oculography is not possible or useful. CONCLUSION The use of VEMPs is a simple, safe, reliable and selective test of dynamic function of otolith organs.
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Affiliation(s)
- J Dlugaiczyk
- Deutsches Schwindel- und Gleichgewichtszentrum (DSGZ), Klinikum der Universität München, LMU München, Marchioninistraße 15, 81377, Munich, Germany.
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Optimization of Cervical and Ocular Vestibular Evoked Myogenic Potential Testing Using an Impulse Hammer in Adults, Adolescents, and Children. Otol Neurotol 2020; 41:817-827. [PMID: 32221109 DOI: 10.1097/mao.0000000000002632] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To characterize cervical and ocular vestibular evoked myogenic potential (c- and oVEMP) responses using an impulse hammer (IH) in adults and pediatrics at standardized force levels and evaluate: the relationship of force level on VEMP amplitude, sternocleidomastoid (SCM) contraction on cVEMP amplitude, required number of tap stimuli, and subject comfort. Using these data, optimal testing parameters were selected. STUDY DESIGN Prospective study. SETTING Tertiary referral center. PATIENTS Seventy-eight healthy adults, adolescents, and children with no hearing or vestibular deficits. INTERVENTIONS All subjects received c- and oVEMP testing using IH and 500 Hz tone burst air conduction stimuli. Adults received hard, medium, and soft force levels. Adolescents and children received medium and soft force levels. A comfort questionnaire was administered pre- and post-testing. MAIN OUTCOME MEASURES IH VEMP response parameters (response rates, latency, cVEMP pre-stimulus SCM Electromyography [EMG], and peak-to-peak amplitude) were assessed per force level. Subjective reporting for patient comfort was also assessed. RESULTS VEMP response rates ranged from 92 to 100%. Force had a linear relationship with VEMP amplitude. SCM contraction had a linear relationship with raw cVEMP amplitude; however, dissipated with amplitude normalization. Force level did not impact the number of taps needed. A minimum peak force of 15 to 20 N, accounting for SCM contraction, and using a lower EMG monitoring limit for cVEMP is recommended to elicit reliable responses. CONCLUSIONS Overall, IH VEMP is appropriate and comfortable to use in adults and pediatrics and can be useful when an air conduction stimulus is contraindicated or not preferred.
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Physiology, clinical evidence and diagnostic relevance of sound-induced and vibration-induced vestibular stimulation. Curr Opin Neurol 2020; 33:126-135. [DOI: 10.1097/wco.0000000000000770] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Dlugaiczyk J. [Evidence-based diagnostic use of VEMPs : From neurophysiological principles to clinical application. German version]. HNO 2019; 68:324-335. [PMID: 31578599 DOI: 10.1007/s00106-019-00757-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Vestibular evoked myogenic potentials (VEMPs) are increasingly being used for testing otolith organ function. OBJECTIVE This article provides an overview of the anatomical, biomechanical and neurophysiological principles of an evidence-based clinical application of ocular and cervical VEMPs (oVEMPs and cVEMPs). MATERIAL AND METHODS Systematic literature search in PubMed until April 2019. RESULTS Sound and vibration at a frequency of 500 Hz represent selective vestibular stimuli for the otolith organs. The predominant specificity of oVEMPs for contralateral utricular function and of cVEMPs for ipsilateral saccular function is defined by the different neuronal projections of the utricle and the saccule. VEMPs are particularly useful in the diagnosis of superior canal dehiscence and otolith organ-specific vestibular dysfunction and as an alternative diagnostic approach in situations when video oculography is not possible or useful. CONCLUSION The use of VEMPs is a simple, safe, reliable and selective test of dynamic function of otolith organs.
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Affiliation(s)
- J Dlugaiczyk
- Deutsches Schwindel- und Gleichgewichtszentrum (DSGZ), Klinikum der Universität München, LMU München, Marchioninistr. 15, 81377, München, Deutschland. .,Neurologische Klinik und Poliklinik, Klinikum der Universität München, LMU München, München, Deutschland.
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Rosengren SM, Colebatch JG, Young AS, Govender S, Welgampola MS. Vestibular evoked myogenic potentials in practice: Methods, pitfalls and clinical applications. Clin Neurophysiol Pract 2019; 4:47-68. [PMID: 30949613 PMCID: PMC6430081 DOI: 10.1016/j.cnp.2019.01.005] [Citation(s) in RCA: 155] [Impact Index Per Article: 31.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/15/2019] [Accepted: 01/19/2019] [Indexed: 02/07/2023] Open
Abstract
Vestibular evoked myogenic potentials (VEMPs) are used to test the otolith organs in patients with vertigo and imbalance. This review discusses the optimal procedures for recording VEMPs and the pitfalls commonly encountered by clinicians. Better understanding of VEMP methodology should lead to improved quality of recordings.
Vestibular evoked myogenic potentials (VEMPs) are a useful and increasingly popular component of the neuro-otology test battery. These otolith-dependent reflexes are produced by stimulating the ears with air-conducted sound or skull vibration and recorded from surface electrodes placed over the neck (cervical VEMPs) and eye muscles (ocular VEMPs). VEMP abnormalities have been reported in various diseases of the ear and vestibular system, and VEMPs have a clear role in the diagnosis of superior semicircular canal dehiscence. However there is significant variability in the methods used to stimulate the otoliths and record the reflexes. This review discusses VEMP methodology and provides a detailed theoretical background for the techniques that are typically used. The review also outlines the common pitfalls in VEMP recording and the clinical applications of VEMPs.
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Key Words
- AC, air-conducted
- AR, asymmetry ratio
- AVS, acute vestibular syndrome
- BAER, brainstem auditory evoked potential
- BC, bone-conducted
- BPV, benign positioning vertigo
- BVP, bilateral vestibulopathy
- CANVAS, cerebellar ataxia, neuropathy and vestibular areflexia syndrome
- Deg, degrees
- ECG, electrocardiographic
- EEG, electroencephalographic
- EMG, electromyographic activity/electromyogram
- FL, force level
- HL, hearing level
- IO, inferior oblique
- MD, Meniere’s disease
- Method
- NIOSH, National Institutes of Occupational Safety and Health
- Otolith
- PCS, posterior circulation stroke
- PICA, posterior inferior cerebellar artery
- PP, peak-to-peak
- RMS, root mean square
- SCC, semicircular canal
- SCD, superior canal dehiscence
- SCM, sternocleidomastoid
- SL, sensation level
- SPL, sound pressure level, being the RMS value for a sinusoid
- SVH, subjective visual horizontal
- Sound
- UW, unilateral weakness
- VEMP
- VEMP, vestibular evoked myogenic potential
- VM, vestibular migraine
- VN, vestibular neuritis
- VS, vestibular schwannoma
- Vestibular
- Vibration
- cVEMP, cervical vestibular evoked myogenic potential
- dB, decibels, the logarithm of the relative power versus a reference
- dBA, decibels, measured using an “A” weighting
- nHL, normal hearing level
- oVEMP, ocular vestibular evoked myogenic potential
- pkFL, peak force level
- pkSPL, peak sound pressure level (3 dB higher than RMS for a sinusoid)
- vHIT, video head impulse test
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Affiliation(s)
- Sally M Rosengren
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Camperdown, Australia.,Central Clinical School, University of Sydney, Sydney, Australia
| | - James G Colebatch
- Prince of Wales Hospital Clinical School and Neuroscience Research Australia, Randwick, Sydney, NSW, Australia
| | - Allison S Young
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Camperdown, Australia.,Central Clinical School, University of Sydney, Sydney, Australia
| | - Sendhil Govender
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Camperdown, Australia.,Prince of Wales Hospital Clinical School and Neuroscience Research Australia, Randwick, Sydney, NSW, Australia
| | - Miriam S Welgampola
- Neurology Department and Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Camperdown, Australia.,Central Clinical School, University of Sydney, Sydney, Australia
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