Vertical Vestibulo-ocular Reflex Research Articles

Evidence for the differential efficacy of yaw and pitch gaze stabilization mechanisms in people with multiple sclerosis.

People with multiple sclerosis (PwMS) who report dizziness often have gaze instability due to vestibulo-ocular reflex (VOR) deficiencies and compensatory saccade (CS) abnormalities. Herein, we aimed to describe and compare the gaze stabilization mechanisms for yaw and pitch head movements in PwMS. Thirty-seven PwMS (27 female, mean ± SD age = 53.4 ± 12.4 years old, median [IQR] Expanded Disability Status Scale Score = 3.5, [1.0]. We analyzed video head impulse test results for VOR gain, CS frequency, CS latency, gaze position error (GPE) at impulse end, and GPE at 400 ms after impulse start. Discrepancies were found for median [IQR] VOR gain in yaw (0.92 [0.14]) versus pitch-up (0.71 [0.44], p < 0.001) and pitch-down (0.81 [0.44], p = 0.014]), CS latency in yaw (258.13 [76.8]) ms versus pitch-up (208.78 [65.97]) ms, p = 0.001] and pitch-down (132.17 [97.56] ms, p = 0.006), GPE at impulse end in yaw (1.15 [1.85] degs versus pitch-up (2.71 [3.9] degs, p < 0.001), and GPE at 400 ms in yaw (-0.25 [0.98] degs) versus pitch-up (1.53 [1.07] degs, p < 0.001) and pitch-down (1.12 [1.82] degs, p = 0.001). Compared with yaw (0.91 [0.75]), CS frequency was similar for pitch-up (1.03 [0.93], p = 0.999) but lower for pitch-down (0.65 [0.64], p = 0.023). GPE at 400 ms was similar for yaw and pitch-down (1.88 [2.76] degs, p = 0.400). We postulate that MS may have preferentially damaged the vertical VOR and saccade pathways in this cohort.

An Exploratory Analysis of Physical Examination Subtypes in Pediatric Athletes With Concussion.

Pediatric athletes with concussion present with a variety of impairments on clinical assessment and require individualized treatment. The Buffalo Concussion Physical Examination is a brief, pertinent clinical assessment for individuals with concussion. The purpose of this study was to identify physical examination subtypes in pediatric athletes with concussion within 2 weeks of injury that are relevant to diagnosis and treatment. Secondary analysis of a published cohort study and clinician consensus. Three university-affiliated sports medicine centers. Two hundred seventy children (14.9 ± 1.9 years). Orthostatic intolerance, horizontal and vertical saccades, smooth pursuits, vestibulo-ocular reflex, near-point convergence, complex tandem gait, neck range of motion, neck tenderness, and neck spasm. Correlations between independent variables were calculated, and network graphs were made. k-means and hierarchical clustering were used to identify clusters of impairments. Optimal number of clusters was assessed. Results were reviewed by experienced clinicians and consensus was reached on proposed subtypes. Physical examination clusters overlapped with each other, and no optimal number of clusters was identified. Clinician consensus suggested 3 possible subtypes: (1) visio-vestibular (horizontal and vertical saccades, smooth pursuits, and vestibulo-ocular reflex), (2) cervicogenic (neck range of motion and spasm), and (3) autonomic/balance (orthostatic intolerance and complex tandem gait). Although we identified 3 physical examination subtypes, it seemed that physical examination findings alone are not enough to define subtypes that are both statistically supported and clinically relevant, likely because they do not include symptoms, assessment of mood or cognitive problems, or graded exertion testing.

Importance of head movements in gaze tracking during table tennis forehand stroke

The purpose of this study was to clarify the properties of gaze and head movements during forehand stroke in table tennis. Collegiate table tennis players (n = 12) conducted forehand strokes toward a ball launched by a skilled experimenter. A total of ten trials were conducted for the experimental task. Horizontal and vertical movements of the ball, gaze, head and eye were analyzed from the image recorded by an eye tracking device. The results showed that participants did not always keep their gaze and head position on the ball throughout the entire ball path. Our results indicate that table tennis players tend to gaze at the ball in the initial ball-tracking phase. Furthermore, there was a significant negative correlation between eye and head position especially in the vertical direction. This result suggests that horizontal VOR is suppressed more than vertical VOR in ball-tracking during table tennis forehand stroke. Finally, multiple regression analysis showed that the effect of head position to gaze position was significantly higher than that of eye position. This result indicates that gaze position during forehand stroke could be associated with head position rather than eye position. Taken together, head movements may play an important role in maintaining the ball in a constant egocentric direction in table tennis forehand stroke.

Unidirectional Vertical Vestibuloocular Reflex Adaptation in Humans Using 1D and 2D Scenes.

The vertical vestibuloocular reflex (VOR) in response to pitch head impulses can be optimally trained to increase in one direction using a two-dimensional (2D) visual training target with minimal effect on the horizontal VOR. We modified the incremental VOR adaptation (IVA) technique, shown to increase the horizontal VOR in patients with vestibular hypofunction, to drive vertical VOR adaptation in healthy control subjects. We measured the horizontal and vertical active (self-generated) and passive (imposed) head impulse VOR gains (eye velocity/head velocity) before and after 15 minutes of unidirectional downward IVA training. IVA training consisted of two sessions, one using a single-dot one-dimensional (1D) target, the other a grid-of-dots 2D target. The downward head impulse VOR gain significantly increased because of training by 13.3%, whereas the upward VOR gain did not change. The addition of extraretinal (2D) feedback did not result in greater adaptation, i.e., 1D and 2D gain increases were 15.5% and 10.6%, respectively. The vertical VOR gain increase resulted in a 3.2% decrease in horizontal VOR gain. This preliminary study is the first to show that physiologically relevant (high frequency) unidirectional increases in vertical VOR gain are possible with just 15 minutes of training. This study sets the basis for future clinical trials examining vertical IVA training in patients, which may provide the first practical rehabilitation treatment to functionally improve the vertical VOR.

Vestibular semicircular canal function as detected by video Head Impulse Test (vHIT) is essentially unchanged in people with Parkinson’s disease compared to healthy controls

BACKGROUND: Parkinson’s disease (PD) is a common multi-system neurodegenerative disorder with possible vestibular system dysfunction, but prior vestibular function test findings are equivocal. OBJECTIVE: To report and compare vestibulo-ocular reflex (VOR) gain as measured by the video head impulse test (vHIT) in participants with PD, including tremor dominant and postural instability/gait dysfunction phenotypes, with healthy controls (HC). METHODS: Forty participants with PD and 40 age- and gender-matched HC had their vestibular function assessed. Lateral and vertical semicircular canal VOR gains were measured with vHIT. VOR canal gains between PD participants and HC were compared with independent samples t-tests. Two distinct PD phenotypes were compared to HC using Tukey’s ANOVA. The relationship of VOR gain with PD duration, phenotype, severity and age were investigated using logistic regression. RESULTS: There were no significant differences between groups in vHIT VOR gain for lateral or vertical canals. There was no evidence of an effect of PD severity, phenotype or age on VOR gains in the PD group. CONCLUSION: The impulsive angular VOR pathways are not significantly affected by the pathophysiological changes associated with mild to moderate PD.

A-95 The Relationship between Attention Deficit Hyperactivity Disorder (ADHD) and Vestibular Impairments Following Adolescent Sports-Related Concussion (SRC)

Abstract Objective Athletes with ADHD may experience longer and/or more complicated recoveries following SRC; however, previous research has focused on neurocognitive outcomes. The objective of this study was to investigate the relationship between a history of ADHD among adolescent athletes and vestibular impairments following SRC. Method Participants included 166 athletes aged 15.9 +/− 1.5 who sustained an SRC, including 25 with a documented history of ADHD. Appropriate summary statistics were used to describe the data. ADHD and non-ADHD groups were compared using t-tests and Mann–Whitney U tests for continuous variables and Chi-square tests for categorical variables. A linear regression model analyzed the relationship between a history of ADHD and vestibular outcomes including horizontal and vertical vestibulo-ocular reflex (hVOR; vVOR), visual motion sensitivity (VMS), and Dizziness Handicap Index (DHI), while referral to vestibular therapy (VT) was analyzed using logistic regression. Results Athletes with ADHD experienced significantly higher rates of on-field dizziness, (p = 0.039) and dizziness following vVOR testing on the Vestibular/Ocular Motor Screening (VOMS; p = 0.041). Athletes with ADHD were more likely to be referred to vestibular therapy (VT) (p = 0.033) and displayed abnormal vVOR test during the initial VT visit (p = 0.040). Conclusions Adolescent athletes with a history of ADHD are more likely to report on-field dizziness following SRC and increased dizziness with vVOR testing on VOMS, thus resulting in more frequent referrals to VT, where they also display abnormal vVOR results. Additional research is needed to improve treatment strategies and recovery outcomes in athletes after SRC.

Characterizing gaze and postural stability deficits in people with multiple sclerosis

BackgroundPeople with Multiple Sclerosis (PwMS) experience a wide range of symptoms that can alter function and limit activity and community participation. Symptoms including sensory changes, weakness, fatigue and others have been well documented. However, symptoms related to changes in vestibular related function, including gaze and postural stability have not been fully explored. While some recent studies have begun to provide insight into these deficits in PwMS and have explored the use of rehabilitation paradigms for their management, much remains unknown about the full extent of these deficits. Therefore, this study aimed to characterize the presence of gaze and postural stability deficits in measures across the World Health Organization International Classification of Functioning, Disability, and Health (WHO ICF) and to examine how deficits in domains of body structure and function and activity contribute to participation level limitations. MethodsBaseline data from 41 PwMS (mean(SD) age = 53.9(11.2), 78% female) enrolled as part of a randomized clinical trial were used in this analysis. Measures of gaze and postural stability from the ICF domains of body structure and function (Vestibular ocular reflex [VOR] gain and postural sway area), activity (computerized dynamic visual acuity [cDVA] and MiniBEST test), and participation (Dizziness handicap inventory [DHI] and Activities Balance Confidence [ABC] scale) along with demographic data were used to characterize the sample. To explore relationships between ICF domains for gaze and postural stability, univariate correlations were performed between measures from each domain using Pearson's correlations. Separate multivariate regression models examined how measures from the body structure and function and activity domains contributed to the variance in the participation level outcomes. Variance explained by the models was quantified using R-squared statistic and contribution of the independent variables were quantified using the beta coefficient (p < 0.05). ResultsCorrelation analysis demonstrated significant relationships in the postural stability measures across domains. Specifically, between postural sway area on a firm surface and MiniBEST test score (r = -.48;p < 0.01) and MiniBEST test score and ABC score (r = 0.5;p < 0.01). Significant correlations were also found between the gaze stability measures of horizontal and vertical VOR gain (r = .68;p < 0.001), horizontal VOR gain and dynamic visual acuity (r = .38;p = 0.02), and vertical VOR gain and dynamic visual acuity (r = .54;p < 0.001). Regression models assessing postural stability, found that only the MiniBEST score significantly contributed to the variance in ABC score (p = 0.01) and the full model explained 34% of the variance in ABC score. Regression modeling of gaze stability outcomes did not produce any variable that significantly contributed to the variance in DHI score and the full model explained 18% of the variance in DHI score. ConclusionsPwMS in this sample demonstrated deficits in gaze and postural stability across the domains of the WHO ICF compared to past samples of PwMS and healthy cohorts. Correlation between measures in the different domains were present, but no strong relationship between measures of body structure and function, activity and participation level outcomes were observed. This lack of relationship across the domains is likely contributed to the relatively small sample size, the high level of variability observed in the outcomes, and the diverse presentation often seen in PwMS.

Vestibular/Ocular Motor Screening Assessment Outcomes After Sport-Related Concussion in High School and Collegiate Athletes.

Vestibular and ocular motor assessment is an emerging clinical assessment for patients with sport-related concussion (SRC). The increased use of these assessments by clinicians calls for the examination of outcomes that may affect clinical practice. To compare vestibular and ocular motor impairments in high school and collegiate athletes within 72 hours of SRC and examine the distribution of impairments in these populations based on pre-established clinical cutoff scores. Cross-sectional study. High school and collegiate athletics. Data were collected from 110 athletes (high school: n = 47, age = 15.40 ± 1.35 years; college: n = 63, age = 19.46 ± 1.28 years) within 72 hours of sustaining an SRC. Total and change scores were calculated for the Vestibular/Ocular Motor Screening (VOMS) tool, along with average near point of convergence (NPC) distance. Separate Mann-Whitney U tests were used to compare group differences, and χ2 analyses were used to examine the proportion of athletes with scores greater than clinical cutoff scores for all VOMS outputs. The α level was set a priori at .05. No differences were found between high school and collegiate athletes for VOMS total and change scores and NPC distance. A larger proportion of the sample had scores greater than the cutoff for all total scores (P < .001) and change scores in horizontal vestibulo-ocular reflex (59.01%; P < .001), vertical vestibulo-ocular reflex (60.91%; P < .001), and visual motion sensitivity (60.91%; P < .001). However, a larger proportion demonstrated smooth pursuit change scores (85.45%; P < .001) and NPC distances (73.64%; P = .01) that were less than the cutoff scores. During the acute phase of SRC, high school and collegiate athletes presented with similar vestibular and ocular motor impairments as measured using the VOMS, but vestibular tasks appeared to cause greater symptom provocation. Lastly, VOMS change scores may offer more clinical utility compared with total scores in assessing specific impairments after SRC.

Angular vestibulo ocular reflex loss with preserved saccular function in Machado-Joseph disease

ObjectiveTo provide a comprehensive evaluation of the vestibular function in Machado-Joseph Disease (MJD). Methods21 MJD patients and 19 healthy Controls underwent a detailed clinical neuro-otological evaluation including VOR gain of all six semicircular canals by video Head Impulse Test (vHIT), remaining horizontal VOR function by Suppression Head Impulse test (SHIMP), and saccular function by cervical Vestibular Evoked Myogenic Potentials (cVEMP). ResultsAll MJD had significantly lower VOR gain in all six semicircular canals (p < 0.001) with a mean ± SEM of horizontal gain of 0.52 ± 0.04 and vertical gain of 0.57 ± 0.03 versus Controls' gain of 0.95 ± 0.01 and 0.81 ± 0.02, respectively (p < 0.001). MJD showed also a significantly lower VOR gain on the SHIMP test with left gain of 0.51 ± 0.04 and right gain of 0.46 ± 0.03 versus Controls' gain of 0.79 ± 0.01 and 0.83 ± 0.03, respectively (p < 0.001). In contrast, MJD had normal saccular function reflected by the presence of cVEMP response in 18/20 patients and in 12/17 of Controls, with a non-significant difference between MJD and Controls of P13 and N23 peaks latency and normalized peak-to-peak amplitude. ROC analysis of horizontal VOR gain resulted in an area under the curve of 0.993 making the average lateral canals' VOR gain an excellent classifier of MJD vs Controls. ConclusionsHorizontal and vertical VOR impairment with preserved sacculo-collic function seems to be a distinctive feature of MJD and could be explained by selective, mostly medial and superior vestibular nuclei degeneration. This study further supports the idea that horizontal VOR gain measured by vHIT could be a potential neurophysiological biomarker of MJD.

Histochemical Characterization of the Vestibular Y-Group in Monkey

The Y-group plays an important role in the generation of upward smooth pursuit eye movements and contributes to the adaptive properties of the vertical vestibulo-ocular reflex. Malfunction of this circuitry may cause eye movement disorders, such as downbeat nystagmus. To characterize the neuron populations in the Y-group, we performed immunostainings for cellular proteins related to firing characteristics and transmitters (calretinin, GABA-related proteins and ion channels) in brainstem sections of macaque monkeys that had received tracer injections into the oculomotor nucleus. Two histochemically different populations of premotor neurons were identified: The calretinin-positive population represents the excitatory projection to contralateral upgaze motoneurons, whereas the GABAergic population represents the inhibitory projection to ipsilateral downgaze motoneurons. Both populations receive a strong supply by GABAergic nerve endings most likely originating from floccular Purkinje cells. All premotor neurons express nonphosphorylated neurofilaments and are ensheathed by strong perineuronal nets. In addition, they contain the voltage-gated potassium channels Kv1.1 and Kv3.1b which suggests biophysical similarities to high-activity premotor neurons of vestibular and oculomotor systems. The premotor neurons of Y-group form a homogenous population with histochemical characteristics compatible with fast-firing projection neurons that can also undergo plasticity and contribute to motor learning as found for the adaptation of the vestibulo-ocular reflex in response to visual-vestibular mismatch stimulation. The histochemical characterization of premotor neurons in the Y-group allows the identification of the homologue cell groups in human, including their transmitter inputs and will serve as basis for correlated anatomical-neuropathological studies of clinical cases with downbeat nystagmus.

Vestibular/Ocular Motor Screening is Independently Associated With Concussion Symptom Severity in Youths

To examine the independent contributions of the Vestibular/Ocular Motor Screening (VOMS) to concussion symptom severity in youths while controlling for computerized neurocognitive screening performance, demographics, and medical history. Cross-sectional. Concussion specialty clinic. A retrospective review of 278 concussed youths clinical charts resulted in a total of 158 participants (16.5 ± 2.8 years, 46.8% women, 4.3 ± 3.3 days post-injury) when exclusionary criteria (ie, neurological or substance use disorders, age >21, >14 days since injury, and missing/incomplete data) were applied. Vestibular/Ocular Motor Screening items and computerized neurocognitive test scores. Standardized postconcussion symptom scale scores. At the univariate level, all VOMS items were positively associated with concussion symptom severity at small to medium effect sizes (r range 0.26-0.42). Women and individuals with a concussion history and/or Attention Deficit Disorder/Attention Deficit Hyperactivity Disorder diagnosis reported higher VOMS item scores (Ps < 0.10). In a multiple hierarchical regression, the contribution of VOMS item scores was significant and explained 9.6% of the variance in concussion symptom severity after adjustment for sex, baseline VOMS symptom ratings, and ImPACT scores [F(6, 141) = 3.90, P = 0.001]. Vertical saccades (b = 2.22, P = 0.003) and vertical vestibulo-ocular reflex (VOR; b = -1.46, P = 0.004) VOMS items significantly contributed to concussion symptom severity in the multivariable model. Findings from this study provide support for the independent contributions of the VOMS items, particularly vertical saccades and vertical VOR, to acute concussion symptom severity in youths. Further work is warranted for a comparison of the VOMS to the full gold standard of concussion testing (ie, clinical interview, physical examination, balance testing, and neurocognitive assessment).

O3-035 Downbeat nystagmus in acute cerebellitis: Altered feed-forward inhibition by the cerebellum to the vertical vestibulo-ocular reflex

O3-035 Downbeat nystagmus in acute cerebellitis: Altered feed-forward inhibition by the cerebellum to the vertical vestibulo-ocular reflex

Vestibular impairment in Charcot-Marie-Tooth disease.

To find out if Charcot-Marie-Tooth (CMT) patients, who have peripheral vestibular as well as peripheral somatosensory impairment, have worse postural balance than those who do not. We studied 32 patients with various CMT phenotypes and genotypes. Vestibular function was measured with the video head impulse test (vHIT) which tests vestibulo-ocular reflex (VOR) gain from each of the six semicircular canals in response to rapid head rotations. Postural balance was evaluated with a battery of four postural tests with emphasis on the modified clinical test of sensory integration in balance (mCTSIB). Half of the 32 patients had some impairment of vestibular function ranging from mild, affecting only 1-2 semicircular canals, to almost total affecting all 6 semicircular canals. Their mCTSIB scores correlated with VOR gain from the vertical rather than from the lateral semicircular canals. The worse the vertical VOR gain the worse the mCTSIB score. We propose that any CMT patient could have clinically inapparent vestibular impairment that can be easily measured with the vHIT. This vestibular impairment could be contributing to their imbalance and could respond to a focused vestibular rehabilitation program.

Ictal downbeat nystagmus in Ménière disease: A cross-sectional study.

To determine the mechanism of ictal downbeat nystagmus in Ménière disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between patients with (n = 7) and without (n = 70) downbeat nystagmus during attacks of MD. We retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack. Pure or predominant downbeat nystagmus was observed in 7 patients (9%) with unilateral MD during the attacks. All 7 patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s (median 5.4, interquartile range 3.7-8.5). All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n = 4) or in the affected ear (n = 3). Cervical VEMPs were decreased in the affected (n = 2) or both ears (n = 2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p < 0.001), while the gains for other semicircular canals did not differ between the groups. Downbeat nystagmus may be observed during attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.

Effect of Gaze Angle During the Vertical Video Head Impulse Test Across Two Devices in Healthy Adults and Subjects With Vestibular Loss.

To evaluate the effect of gaze angle on vertical vestibulo-ocular reflex (VOR) gain using two different video head impulse (vHIT) devices in healthy adults and subjects with bilateral vestibular loss (BVL). Prospective study. Hospital research laboratory. Twenty-four healthy adults (mean [standard deviation {SD}] age = 32 [4.8]; 23-42; 8 men) and four subjects with previously diagnosed BVL (mean age [SD] = 32 [8.2]; 21-40; 3 men) participated. Vertical canal vHIT was administered with two different devices using three gaze angles (-45 degrees, 0 degree, +45 degrees). These devices have different gain calculation algorithms and different head and gaze angle protocols. Vertical canal gain and presence or absence of reset saccades. A significant stepwise reduction in vHIT gain was noted as gaze moved away from the plane of the canals stimulated (from -45 degrees to 0 degree, to +45 degrees) for both healthy adults and subjects with BVL. vHIT gain was able to separate the two groups using gaze angles -45 degrees and 0 degree. In spite of their differences in gain algorithm and recommended head position and gaze angle, each device was able to appropriately separate healthy adults from subjects with BVL with high sensitivity/specificity.

Effects of Vestibular Training on Postural Control of Healthy Adults

Background: Postural stability depends on the integration of multisensory inputs to drive motor outputs. When visual and somatosensory input is available and reliable, this reduces the postural control system’s reliance on the vestibular system. Despite this, vestibular loss can still cause severe postural dysfunction (1,2). Training one or more of the three sensory systems can alter sensory weighting and change postural behavior. Vestibular activation exercises, including horizontal and vertical headshaking, influence vestibular-ocular and -motor responses and have been showed to be effective in vestibular rehabilitation (3–8). &#x0D; Purpose/Hypothesis: To assess sensory reweighting of postural control processing and vestibular-ocular and -motor responses after concurrent vestibular activation with postural training. It was hypothesized that the effect of this training would significantly alter the pattern of sensory weighting by changing the ratio of visual, somatosensory and vestibular dependence needed to maintain postural stability, and significantly decrease vestibular responses.&#x0D; Methods: Forty-two young healthy individuals (22 females; 23.0+3.9 years; 1.6+0.1 meters) were randomly assigned into four groups: 1) visual feedback weight shift training (WST) coupled with an active horizontal headshake (HHS), 2) same WST with vertical headshake (VHS), 3) WST with no headshake (NHS) and 4) no training/headshake control (CTL) groups. The headshake groups performed an intensive body WST together with horizontal or vertical rhythmic headshake at 80 to 120 beats/minute. The NHS group performed the WST with no headshake while the controls did not perform any training. Five 15-minute training sessions were performed on consecutive days for one week with the weight shift exercises involving upright limits of stability activities on a flat surface, foam or rocker board (Fig. 1). All groups performed baseline- and post-assessments including sensory organization test (SOT) and force platform ramp perturbations, coupled with electromyographic (EMG) recordings. A video head impulse test was also used to record horizontal vestibulo-ocular reflex (VOR) gain. A between- and within-group repeated measures ANOVA was used to analyze five COP sway variables, the equilibrium and composite scores and sensory ratios of the SOT as well as EMG signals and horizontal VOR gain. Similarly, COP variables, EMG, as well as vestibular reflex data (vertical VOR, vestibulo-collic reflex [VCR] and vestibulo-spinal [VSR] gains) during ramp perturbations were analyzed. Alpha level was set at p&lt;.05.&#x0D; Results: The training showed a significant somatosensory downweighting (p=.050) in the headshake groups compared to the other groups. Training also showed significant decreased horizontal VOR gain (p=.040), faster automatic postural response (p=.003) (Figs. 2-4) with improved flexibility (p=.010) in the headshake groups. Muscle activation pattern in medial gastrocnemius (p=.033) was significantly decreased in the headshake.&#x0D; Conclusion: The concurrent vestibular activation and weight shift training modifies vestibular-dependent responses after the training intervention as evidenced in somatosensory downweighting, decreased VOR gain, better postural flexibility and faster automatic postural response. Findings suggest this is predominantly due to vestibular adaptation and habituation of VOR, VCR and VSR which induced sensory reweighting.&#x0D; Clinical relevance: Findings may be used to guide the development of a vestibular-postural rehabilitation intervention in impaired neurological populations, such as with vestibular disorders or sensory integration problems.

Influence of Pre-Morbid Migraine History on Baseline Vestibular/Ocular Motor Screening and King-Devick Test Performance

Abstract Purpose To examine the effects of premorbid migraine history on baseline Vestibular/Ocular Motor Screening (VOMS) and King-Devick (KD) test performance in youth athletes. Methods This study implemented a cross-sectional design and was conducted at a series of youth sport venues in a designated research area. Youth athletes between the ages of 8 and 14 years with a diagnosed history of migraine headaches (n=28) and match controls (n=28) were administered a baseline VOMS and KD test. Between-group comparisons for provocation scores on the VOMS (smooth pursuit, saccades, convergence, vestibular-ocular reflex [VOR], and visual motion sensitivity [VMS]), Near-point of convergence [NPC] average distance (cm), and KD time (seconds) were conducted. Results Individuals diagnosed with migraine headaches reported greater VOMS scores compared to match controls on smooth pursuit (0.43±1.1 vs. 0.00±0.0; p=.02), convergence (0.46±1.2 vs. 0.04±0.1; p=.04), horizontal VOR (0.89±1.4 vs. 0.07±0.2; p&lt;.001), vertical VOR (0.61±1.1 vs. 0.11±0.3; p=.04), and VMS (0.86±1.5 vs. 0.04±0.1; p=.01). Differences were also observed on the KD test with worse times in the diagnosed migraine group (54.33±11.8s) compared to match controls (47.17±8.9s; p=.02). No differences were reported on NPC distance between the migraine (2.22±3.1cm) and control group (0.83±1.2; p=.06). Conclusion Youth athletes with diagnosed migraine history reported higher baseline VOMS scores and worse KD time compared to match controls, further illustrating the influence of premorbid migraine headaches as a risk factor for elevated baseline concussion assessment. Special consideration may be warranted for post-concussion assessment in athletes with diagnosed migraine headaches.

Congenital monocular elevation deficiency associated with a novel TUBB3 gene variant

BackgroundThe genetic basis of monocular elevation deficiency (MED) is unclear. It has previously been considered to arise due to a supranuclear abnormality.MethodsTwo brothers with MED were referred to Leicester Royal...

Selective suppression of the vestibulo-ocular reflex during human locomotion.

In lower vertebrates, gaze stabilization during locomotion is at least partially driven by a direct coupling of spinal locomotor commands with extraocular motor signals. To what extent locomotor feed-forward mechanisms contribute to gaze stabilization during human locomotion is yet unknown. In principle, the feasibility of a feed-forward regulation of gaze during locomotion should critically depend on the spatiotemporal coupling between body and head kinematics and hence the internal predictability of head movements (HMP). The present study thus investigated whether changes in eye-head coordination during human locomotion can be explained by concurrent changes in HMP. Eye and head movements were recorded at different locomotor speeds in light and darkness to obtain the gain and phase of the horizontal and vertical angular VOR (aVOR). Potential correlations between aVOR performance and HMP were analyzed in dependence of locomotor speed and gait cycle phase. Horizontal aVOR responses persisted independent of locomotor speed. In contrast, with increasing locomotor speed vertical eye-head coordination switched from a VOR-driven compensatory mode to a synergistic behavior where head and eyes move in phase. Concurrently, vertical HMP increased with faster locomotion. Furthermore, modulations in vertical aVOR gain across the gait cycle corresponded to simultaneous alterations in vertical HMP. The vertical aVOR appears to be suppressed during faster walking and running, whereas at the same time, the predictability of resultant head movements increases. This suggests that during stereotyped human locomotion, internal feed-forward commands supplement or even suppress sensory feedback to mediate gaze stabilization in the vertical plane.

Reference ranges and stability of auditory and vestibular measures in a comprehensive assessment battery for traumatic brain injury

Audiology clinics have many tools available to evaluate auditory and vestibular complaints. However, many tools lack established normative ranges across the life span. We conducted this study to establish reference ranges across the life span for audiology/vestibular measures commonly used to evaluate patients with traumatic brain injury. In this repeated measures study, 75 adults, ages 18-65 years, without a history of traumatic brain injury, underwent robust auditory/vestibular evaluations three times over six months, including rotational chair, videonystagmography, computerized dynamic posturography, vestibular evoked myogenic potentials, and retinal fundoscopy. Age effect was notable for transient evoked otoacoustic emissions, pure-tone audiometry, auditory brainstem response, auditory middle latency response, and auditory-steady state response at 4000 hertz (Hz). Older participants (50-65 years) were more likely to have delayed latency horizontal saccades, positional nystagmus, slowed lower-extremity motor control responses, and delayed latency ocular vestibular evoked myogenic potentials. Low to mid-frequency horizontal (0.003-4 Hz) and mid-frequency vertical (1-3 Hz) vestibulo-ocular reflex, otolith-mediated reflexes, dynamic visual acuity and balance measures were generally not influenced by age. Females had larger static subjective visual testing offset angles, longer cervical vestibular evoked myogenic potential P1 latency, faster velocity horizontal saccades, and quicker motor control latency for large backward translations than age-matched males. These reference ranges can be used to discern impairment within the auditory and vestibular pathway following traumatic brain injury in young to middle-aged adults. TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01925963.