Vestibulo-ocular Function Research Articles

Neurocognitive Performance, Vestibulo-Ocular Function and Postural Control in Youth Male Soccer and Basketball Players of Different Ages

Neurocognitive Performance, Vestibulo-Ocular Function and Postural Control in Youth Male Soccer and Basketball Players of Different Ages

Altered Oculomotor and Vestibulo-ocular Function in Children and Adolescents Postconcussion.

To document (1) oculomotor (OM) and vestibulo-ocular (VO) function in children with concussion who were symptomatic at the time of assessment and to compare it with that in children with concussion who were clinically recovered (asymptomatic) and in children with no concussive injury, and (2) the extent to which OM and VO function relates to postconcussion symptom severity in injured children. Participants were recruited from a concussion clinic or the community. A total of 108 youth with concussion (72 symptomatic; 36 recovered) and 79 healthy youth (aged 9-18 years). Youth with concussion were included if aged 9 to 18 years, had no previous concussion within the last 12 months, less than 90 days since injury, and no known existing visual disorders or learning disabilities. A prospective cross-sectional study. All participants were tested for OM and VO function with a commercial virtual reality (VR) eye-tracking system (Neuroflex ® , Montreal,Québec, Canada). Participants in the concussion group who completed the postconcussion symptoms were scored with the Post-Concussion Symptom Inventory. There was a significant group effect for vergence during smooth pursuit ( F2,176 = 10.90; P < .05), mean latency during saccades ( F2,171 = 5.99; P = .003), and mean response delay during antisaccades ( F2,177 = 9.07; P < .05), where children with symptomatic concussion showed poorer performance than clinically recovered and healthy children. Similar results were found in VO for average vestibular ocular reflex gain in the horizontal leftward ( F2,168 = 7; P = .001) and rightward directions ( F2,163 = 13.08; P < .05) and vertical upward ( F2,147 = 7.60; P = .001) and downward directions ( F2,144 = 13.70; P < .05). Mean saccade error was positively correlated to total Post-Concussion Symptom Inventory scores in younger clinically recovered children. VR eye tracking may be an effective tool for identifying OM and VO deficits in the subacute phase (<90 days) postconcussion.

Longitudinal Assessment of Postconcussion Driving: Evidence of Acute Driving Impairment.

Current medical practices and recommendations largely ignore the safety of postconcussion driving, even though commonly used measures of neurocognition, balance, and vestibulo-ocular function show impairment. To compare simulated driving between patients with concussion and controls throughout concussion recovery using a case-control design. Cohort study; Level of evidence, 2. A total of 26 concussed and 23 control Division I collegiate athletes completed a driving simulation assessment at 3 time points (within 72 hours, asymptomatic, and return to sport). Cumulative driving simulation outcome variables included total number of collisions, speed exceedances, stop signs missed, lane excursions, total drive time, percentage of time over the speed limit, and percentage of time out of the lane. The mean speed, standard deviation of speed (SDS), lateral lane position, and standard deviation of lateral lane position (SDLP) were examined for each of the 11 drive segments. Outcomes were compared using generalized linear mixed models with random intercepts by participant with Poisson or normal distributions. Within 72 hours of injury, the concussion group committed more lane excursions (median difference, 2; P = .003), exhibited greater SDS while avoiding a child pedestrian crossing the road (Cohen d = 0.73; P = .011), drove ~7 inches (~18 cm) closer to the centerline during a residential left curve (d = 0.90; P = .015), and had greater SDLP while navigating around a car crash compared with controls (d = 0.72; P = .016). When asymptomatic, the concussion group committed fewer speed exceedances (median difference, 2; P = .002) and had lower SDLP while navigating through a traffic light compared with controls (d = 0.60; P = .045). No differences were evident at return to sport. Groups did not differ in total collisions at any time point. The concussion group showed more impaired driving patterns within 72 hours of injury, drove more conservatively once asymptomatic, and had similar driving performance at the time they returned fully to sport. Clinicians should consider these findings when discussing driving with patients acutely after concussion. Further research is needed to determine whether on-road collision risk is elevated after concussion.

Risk of falls, vestibular multimodal processing, and multisensory integration decline in the elderly-Predictive role of the functional head impulse test.

Age-related degeneration of the vestibular system, also known as presbyastasis, leads to unstable gait and higher risk of falls. These conditions affect lifestyle and may have non-negligible social repercussions due to fear-related states of anxiety and depression. In order to develop a model for predicting risk of falls, we assessed vestibulo-ocular function by video and functional Head Impulse Tests (vHIT and fHIT) and their possible correlations with Tinetti Balance Test score. Thirty-one patients over 65 years of age admitted with trauma due to falls were recruited. Vestibular evaluation (complete otoneurological assessment, vHIT, fHIT), cognitive tests (Mini Mental State Examination), anxiety and depression evaluation and Tinetti Balance Test were performed. The possibility of a correlation between the head impulse tests (vHIT, fHIT) and the Tinetti Balance Test was investigated by logistic regression analysis (Nagelkerke r 2 and Wald test). A linear correlation was found between the Tinetti Balance Test score and fHIT, whereas no correlation was found for vHIT. Functional HIT is an effective test for predicting the risk of falls in elderly patients.

Characterizing the evolution of oculomotor and vestibulo-ocular function over time in children and adolescents after a mild traumatic brain injury.

BackgroundImpairments to oculomotor (OM) and vestibulo-ocular reflex (VOR) function following pediatric mTBI have been demonstrated but are poorly understood. Such impairments can be associated with more negative prognosis, affecting physical and mental wellbeing, emphasizing the need to more fully understand how these evolve.Objectivesto determine i) the extent to which performance on clinical and computerized tests of OM and VOR function varies over time in children and adolescents at 21 days, 3-, and 6-months post-mTBI; ii) the proportion of children and adolescents with mTBI presenting with abnormal scores on these tests at each timepoint.DesignProspective longitudinal design.SettingTertiary care pediatric hospital.Participants36 participants with mTBI aged 6 to18.ProceduresParticipants were assessed on a battery of OM and VOR tests within 21 days, at 3- and 6-months post injury.Outcome measuresClinical measures: Vestibular/ocular motor screening tool (VOMS) (symptom provocation and performance); Computerized measures: reflexive saccade test (response latency), video head impulse test (VOR gain), and dynamic visual acuity test (LogMAR change).AnalysisGeneralized estimating equations (parameter estimates and odd ratios) estimated the effect of time. Proportions above and below normal cut-off values were determined.ResultsOur sample consisted of 52.8% females [mean age 13.98 (2.4) years, assessed on average 19.07 (8–33) days post-injury]. Older children performed better on visual motion sensitivity (OR 1.43, p = 0.03) and female participants worse on near point of convergence (OR 0.19, p = 0.03). Change over time (toward recovery) was demonstrated by VOMS overall symptom provocation (OR 9.90, p = 0.012), vertical smooth pursuit (OR 4.04, p = 0.03), voluntary saccade performance (OR 6.06, p = 0.005) and right VOR gain (0.068, p = 0.013). Version performance and VOR symptom provocation showed high abnormal proportions at initial assessment.DiscussionResults indicate impairments to the VOR pathway may be present and driving symptom provocation. Vertical smooth pursuit and saccade findings underline the need to include these tasks in test batteries to comprehensively assess the integrity of OM and vestibular systems post-mTBI.ImplicationsFindings demonstrate 1) added value in including symptom and performance-based measures in when OM and VOR assessments; 2) the relative stability of constructs measured beyond 3 months post mTBI.

Vestibular and oculomotor function in male combat sport athletes

ObjectivesTo investigate for differences in vestibulo-ocular function between active male combat sport athletes and a healthy control group. In addition, to explore the relationship between symptom-based outcome measures with vestibulo-ocular function. DesignCross-sectional. Methods40 male adult combat sport athletes and 40 active male control participants were recruited from 4 martial arts schools and a University campus in Queensland, Australia. All participants completed a standardised protocol which was used to assess vestibulo-ocular function. The protocol included 3 components: 1) oculomotor function, 2) benign paroxysmal positional vertigo screening, and 3) vestibulo-ocular reflex function. The Post-Concussion Symptom Scale, Vestibular/Ocular Motor Screening tool and Dizziness Handicap Inventory were used as symptom-based outcome measures. ResultsMore combat sport athletes had oculomotor abnormalities than control group participants. There were no between group differences in benign paroxysmal positional vertigo, vestibulo-ocular reflex function and the video-head impulse test gain (ms). Combat sport athletes had higher symptom-based outcome scores. The Vestibular/Ocular Motor Screening tool and Dizziness Handicap Inventory were found to have moderate positive relationships with the total number of abnormalities detected in the combat sport group. ConclusionsVestibulo-ocular function is imperative for combat sport athletes to perform evasive manoeuvres and land their own strikes. The present study findings may aid clinicians in the identification of combat sport athletes with underlying vestibulo-ocular dysfunction, prompting further investigation.

Sensorimotor system changes in adolescent rugby players post-concussion: A prospective investigation from the subacute period through to return-to-sport

BackgroundThe pathophysiology of concussion is complex. Altered sensorimotor function post-concussion may contribute to the wide range of symptoms and impairments reported. There is currently limited evidence documenting changes in sensorimotor function during the recovery period. The aim of this study was to investigate the effect of concussion on the sensorimotor system in adolescents post-concussion using a multifaceted approach. Study designProspective nested case-control study. MethodsA total of 285 male adolescent rugby players underwent assessment of sensorimotor function during preseason. Players who sustained a concussion during the season and control players, matched for age and playing position, were assessed in the subacute period (3–5 days) and after return-to-sport (3 weeks). Tests of sensorimotor function included balance, cervical spine and vestibulo-ocular function, and measurement of the size and contraction of lumbopelvic muscles (ultrasound imaging). ResultsTwenty-three players (8%) sustained a concussion. Of these, 20 players were assessed during the subacute period and 17 players following return-to-sport. The prevalence of vestibulo-ocular dysfunction increased from 38.9% to 72.2% during the subacute period and dysfunction was present in 83.3% of players after return-to-sport (p = 0.01). Changes in lumbar multifidus muscle size (p = 0.002) and thickness (p = 0.05) at the L5 vertebral level were observed. No statistically significant changes in balance, cervical spine proprioception, or contraction of lumbopelvic muscles were found (p > 0.05). ConclusionChanges in sensorimotor function were observed in the subacute period post-concussion, with some persisting after return-to-sport. Using symptom-based criteria for return-to-sport may not adequately reflect the sequelae of concussion on the sensorimotor system.

Cervical and ocular vestibular evoked myogenic potentials in epileptic patients

BackgroundVertigo and dizziness are very common complaints that may be related to epilepsy. The purpose of this study was to assess vestibulo-spinal and linear vestibulo-ocular function in epileptic patients in the inter ictal period. The current observational study was carried out in audio-vestibular unit Menoufia University. Subjects in the current study were divided into two groups: The control group included 30 normal individuals not complaining from any dizzy symptoms and the epileptic cases group included 30 epileptic patients. All subjects in the study were submitted to cervical and ocular vestibular evoked myogenic potential.ResultsThere was no significant difference between the control and epileptic group regarding the age and sex distribution. Sixty-seven percent of epileptic cases had dizzy symptoms. There was statistically significant difference in the latency and amplitude of c and o VEMP between the control and the epileptic group, 39/60 ears (65%) in the study group had cVEMP abnormalities, 32/60 ears (53%) had oVEMP abnormalities. Abnormal c and o VEMP were reported in 28/60 ears (46.7%). There was statistically significant relationship between VEMP abnormalities and duration of seizures, frequency of epileptic attacks, and type of therapy.ConclusionVestibular abnormalities were frequently reported in epileptic patients in the current study which may be related to the severity and control of epilepsy.

The Utility of Neuromotor Retraining to Augment Manual Therapy and Vestibular Rehabilitation in a Patient with Post-Concussion Syndrome: A Case Report

Background and PurposeLess than half of patients discharged from the emergency department post-concussion receive patient education or follow-up care, and 10-20% of individuals will develop symptoms that last longer than six months. Current research on interventions for post-concussion syndrome (PCS) shows inconsistent results, and recommendations for effective physical therapy treatment for patients with chronic PCS are lacking. The purpose of this case report is to highlight a successful, multi-system approach to physical therapy examination and treatment of a patient with chronic PCS.Case DescriptionThis case describes a 21-year-old male who sustained a concussion 356 days prior to evaluation. He received no follow-up treatment and reported periods of worsening symptoms since the injury. Impairments in cervical range of motion and accessory mobility, vestibular and vestibulo-ocular function, and postural stability were identified. Both cognitive and emotional symptoms were also present. The patient attended eight, sixty-minute sessions over a five-week period in an outpatient setting. Comprehensive physical therapy interventions included manual therapy, vestibular rehabilitation, and neuromotor retraining aimed at restoring proper sensory integration and midline postural orientation.OutcomesOutcomes included cervical spine goniometric measurements and accessory mobility assessments. Objective measures of postural stability included the Modified Clinical Test of Sensory Interaction in Balance (m-CTSIB) and the Fukuda Step Test. The Rivermead Post-Concussion Symptoms Questionnaire (RPQ) was used to subjectively assess symptom severity. At discharge, goniometric measurements returned to within normal limits except left cervical rotation active range of motion (ROM), and both the m-CTSIB and Fukuda Step Test were within normal ranges. The RPQ score reduced from 20 to 2 demonstrating symptom resolution in all items but “headache.”DiscussionPCS can affect multiple systems, necessitating a comprehensive approach to examination and intervention. Manual therapy was used to restore cervical spine ROM, vestibular rehabilitation was utilized to improve gaze stability and visual motion sensitivity, and neuromotor retraining was implemented to improve postural stability and sensory integration. Physical therapists have the ability to treat multiple systems impacted with PCS, with the potential to reduce the longevity and severity of impairments for patients.Level of EvidenceLevel V

Video head impulse test in epileptic patients

ObjectivesTo assess the vestibulo-ocular function in epileptic patients in the interictal period.BackgroundVertigo or dizziness are common symptoms with epileptic seizures.Patients and methodsThis is a cross-sectional study. The participants included in this study were divided into two groups. The control group consisted of 40 normal participants not complaining of any dizzy symptoms, with an age range of 20–40 years, and the study group (epileptic cases group) consisted of 40 epileptic patients, with age range of 20–40 years. All participants were subjected to vestibular assessment in the form of videonystagmography and video head impulse test (vHIT).ResultsThere was no significant statistical difference between both groups regarding age (P = 0.17, Student t test) and sex distribution (P = 0.65, χ2 test). A total of 25 (62.5%) epileptic patients had vestibular symptoms. On videonystagmography, saccadic intrusions in pursuit test were reported in four (10%) epileptic patients, and seven (17.5%) epileptic patients had abnormal velocity in the saccade test; there was a significant statistical difference between both groups regarding the velocity of the saccade test (P = 0.02, Student t test). On vHIT, there was a significant statistical difference between both groups regarding lateral canal gain (P = 0.001, Student t test). A total of 29 (72.5%) patients in the study group had an abnormal gain in at least one canal of the six semicircular canals. Eight (20%) patients in the study group had low gain, and 21/40 (52.5%) patients had high gain. There was a significant statistical relationship between vestibular abnormalities and type of epilepsy, as well as EEG findings.ConclusionVestibular system may be affected with epilepsy; high gain was the most frequently encountered abnormality in the vHIT.

Association of acute vestibular/ocular motor screening scores to prolonged recovery in collegiate athletes following sport-related concussion

ABSTRACT Introduction Researchers have yet to explore the association of acute (i.e., within 3 days) post-injury VOMS scores and length of time until clearance to return to play in collegiate athletes. Objective The purpose was to determine if individual Vestibular/Ocular Motor Screening (VOMS) component symptom scores (e.g., smooth pursuits, convergence, vestibular-ocular reflex) can predict clearance to return to activity from a sport-related concussion. Methods Pre-season demographic and medical history and post-injury VOMS testing were collected (n = 79) on collegiate student-athletes following concussion. Impaired vestibulo-ocular function post-injury scores (≥2) were compared to normal scores using survival analysis, with days to clearance to return to sport as the outcome. Results Abnormal scores on smooth pursuits (p =.026), horizontal saccades (p =.025), vertical saccades (p =.028), and convergence (p =.031) were associated with lower probability of clearance in comparison with normal scores. Any score ≥2 predicted significantly greater days to clearance for return to play (13.1 days; 95% CI: 11.9–14.3; p = .025) compared with athletes with no abnormal test scores (9.6 days; 95% CI: 7.2–12.1, P =.014). Discussion Post-injury symptoms with VOMS smooth pursuit, saccades, and convergence is associated with increased time-to-clearance for return to sport in collegiate athletes.

Anti-glutamic acid decarboxylase associated neurologic disorders referred from Neuro-ophthalmology and Neurotology: A case series with characterization of vestibulo-ocular function (P1.9-003)

Anti-glutamic acid decarboxylase associated neurologic disorders referred from Neuro-ophthalmology and Neurotology: A case series with characterization of vestibulo-ocular function (P1.9-003)

Correlation of Head Impact Exposures With Vestibulo-Ocular Assessments.

Managing a concussion injury should involve the incorporation of a multifaceted approach, including a vision assessment. The frontoparietal circuits and subcortical nuclei are susceptible to trauma from a concussion injury, leading to dysfunction of the vestibulo-ocular system. Research investigating the effect of cumulative subconcussive impacts on neurological function is still in its infancy, but repetitive head impacts may result in vestibular system dysfunction. This dysfunction could create visual deficits, predisposing the individual to further head trauma. The purpose of this study was to investigate the cumulative effect of subconcussive impacts on minimum perception time, static visual acuity, gaze stability, and dynamic visual acuity scores. Prospective cohort. Division I university. Thirty-three Division I men's lacrosse players (age = 19.52 [1.20]y). Competitive lacrosse season. At the beginning and end of the season, the players completed a vestibulo-ocular reflex assessment, using the InVision™ system by Neurocom® to assess perception, static acuity, gaze stability, and dynamic visual acuity. Score differentials were correlated with the head impact exposure data collected via instrumented helmets. A significant correlation was found between change in perception scores and total number of head impacts (r = .54), and between changes in dynamic visual acuity loss scores on the rightside and maximum rotational acceleration (r = .36). No statistical differences were found between preseason and postseason vestibulo-ocular reflex variables. Cumulative subconcussive impacts may negatively affect vestibulo-ocular reflex scores, resulting in decreased visual performance. This decrease in vestibulo-ocular function may place the athlete at risk of sustaining additional head impacts or other injuries.

Vestibulo-ocular dysfunction in adolescent rugby union players with and without a history of concussion

ObjectivesSport-related concussions are common in adolescent contact sports. Vestibulo-ocular dysfunction has been reported in athletes post-concussion. There is a lack of research on vestibulo-ocular function in sporting adolescents, and the influence of previous concussions on the vestibular system in this population. The aim of this study was to investigate vestibulo-ocular function in a cohort of adolescent rugby players with and without a history of concussion during pre-season assessment. DesignCross-sectional cohort. Methods213 male adolescent (13–18 years old) rugby players were recruited from six schools in Queensland, Australia. Vestibulo-ocular assessments were conducted during the preseason and included clinical assessment of oculomotor function and the vestibulo-ocular reflex (VOR) using the clinical and video-Head Impulse Test (HIT). Players were allocated into two groups: no history of concussion in the last 12 months (n = 165); and concussion in the last 12 months (n = 48). ResultsThere were no between group differences in vestibulo-ocular function for players with and without a history of concussion (p = 0.65). However, vestibulo-ocular dysfunction was reported in 69 (32.7%) of the players tested, who had either abnormal oculomotor control or VOR function. ConclusionsThe high prevalence of vestibulo-ocular dysfunction in adolescent rugby players suggests that positive clinical findings post-concussion need to be interpreted carefully in the absence of baseline or pre-concussion assessments.

Vestibulo-ocular function in patients with sporadic ataxia

Objective: To identify vestibular alterations in patients with sporadic ataxia (SA).Materials and methods: A retrospective, cross-sectional study was carried out. Eleven patients, four females and seven males, 35–58 years of age (mean age, 46.6 ± 8 years) were evaluated, and they underwent the following procedures: anamnesis, otorhinolaryngological assessment to exclude any kind of middle ear impairments that may hinder exam results, and vestibular evaluation to verify the existence of vestibular disorders, kind and site of the lesion. Significance criterion by comparing the result of the vestibular screening (analysing normal and altered results) was p < .05.Results: Clinically, patients evidenced greater occurrence of gait imbalance (81.8%), dysarthria (63.8%) and dysphagia (54.5%). Dizziness was reported in 45.4% of the cases. In the vestibular testing, prevalence of alterations occurred in the caloric test (54.5%), in the rotation test (45.5%), and in the search for gaze and optokinetic nystagmus (27.3%, each). The presence of testing alteration was observed in 73% of the patients, central vestibular disorder was the greatest occurrence in 64% of the exams.Conclusions: Vestibular function disorder occurred in 73% of the patients, detected in the caloric test, central vestibular system disorder, deficit kind, was prevalent. The high number of alterations, diagnosed in the test, point to the relevance of the labyrinth screening in this rare kind of ataxia, and evidence the importance of patients’ early diagnosis and follow-up.

Asymmetric vestibular stimulation reveals persistent disruption of motion perception in unilateral vestibular lesions.

Self-motion perception was studied in patients with unilateral vestibular lesions (UVL) due to acute vestibular neuritis at 1 wk and 4, 8, and 12 mo after the acute episode. We assessed vestibularly mediated self-motion perception by measuring the error in reproducing the position of a remembered visual target at the end of four cycles of asymmetric whole-body rotation. The oscillatory stimulus consists of a slow (0.09 Hz) and a fast (0.38 Hz) half cycle. A large error was present in UVL patients when the slow half cycle was delivered toward the lesion side, but minimal toward the healthy side. This asymmetry diminished over time, but it remained abnormally large at 12 mo. In contrast, vestibulo-ocular reflex responses showed a large direction-dependent error only initially, then they normalized. Normalization also occurred for conventional reflex vestibular measures (caloric tests, subjective visual vertical, and head shaking nystagmus) and for perceptual function during symmetric rotation. Vestibular-related handicap, measured with the Dizziness Handicap Inventory (DHI) at 12 mo correlated with self-motion perception asymmetry but not with abnormalities in vestibulo-ocular function. We conclude that 1) a persistent self-motion perceptual bias is revealed by asymmetric rotation in UVLs despite vestibulo-ocular function becoming symmetric over time, 2) this dissociation is caused by differential perceptual-reflex adaptation to high- and low-frequency rotations when these are combined as with our asymmetric stimulus, 3) the findings imply differential central compensation for vestibuloperceptual and vestibulo-ocular reflex functions, and 4) self-motion perception disruption may mediate long-term vestibular-related handicap in UVL patients.NEW & NOTEWORTHY A novel vestibular stimulus, combining asymmetric slow and fast sinusoidal half cycles, revealed persistent vestibuloperceptual dysfunction in unilateral vestibular lesion (UVL) patients. The compensation of motion perception after UVL was slower than that of vestibulo-ocular reflex. Perceptual but not vestibulo-ocular reflex deficits correlated with dizziness-related handicap.

Assessment of vestibulo-ocular function without measuring eye movements

BackgroundThe vestibulo-ocular reflex (VOR) maintains stable gaze during head motion. Deficiencies lead to apparent world motion due to incomplete stabilization of eyes in space. VOR measurement requires specialized apparatus, trained operators, and significant setup time. New methodWe present a system (VON: vestibulo-ocular nulling) for rapid vestibulo-ocular assessment without measuring eye movements per se. VON uses a head-mounted motion sensor, laptop computer with user input control, and laser target whose position is controlled by the computer. As the head moves, the target is made to move in the same manner with a gain set by the subject. When the subject sets the gain so the target appears stationary in space, it is stationary on the retinas. One can determine from this gain the extent to which the eyes move in space when the head moves, which is the amount by which the VOR is deficient. From this the gain of the compensatory eye movements is derived. ResultsVON was compared with conventional video-based VOR measures. Both methods track expected changes in gain over 20min of adaptation to minifying spectacles. VON measures are more consistent across subjects, and pre-adaptation values are closer to compensatory. Comparison with existing methodVON is a rapid means to assess vestibulo-ocular performance. As a functional perceptual measure, it accounts for gaze-stabilizing contributions that are not apparent in the standard VOR, such as pursuit and perceptual tolerance. ConclusionsVON assesses functional VOR performance. Future implementations will make VOR assessment widely available to investigators and clinicians.

Adaptation and Compensation of Vestibular Responses Following Superior Canal Dehiscence Surgery.

To describe vestibulo-ocular function and compensatory mechanisms in the immediate postoperative period after superior canal dehiscence surgery. Prospective longitudinal study. Tertiary medical center. Five patients who underwent plugging of superior semicircular canal via middle cranial fossa approach. Bedside quantitative video head impulse testing (vHIT). Dynamic measures of vestibulo-ocular reflex (VOR) function including VOR gain and compensatory saccades during vHIT. Mean VOR gain of the ipsilateral superior semicircular canal (SC) decreased from 0.71 ± 0.1 preoperatively to 0.28 ± 0.07 on postoperative day (POD) 2-4 (p = 0.0031), consistent with plugging. There was also a significant immediate postoperative decrease of VOR gain for the other ipsilateral canals (posterior canal (PC) from gain 0.91 ± 0.33 down to 0.55 ± 0.14, p = 0.040; horizontal canal (HC) from 0.81 ± 0.08 down to 0.54 ± 0.19, p = 0.038). On PODs 1-2, compensatory saccades after testing the plugged SC occurred exclusively after the head stopped moving (overt) with latency of 186.2 ms ± 19.9 ms. By POD 7 saccade latency decreased to 141.0 ± 17.5 ms (p = 0.032), and saccades were occurring during the vertical head rotation (covert saccades). Follow-up >40 days was consistent with previous findings in that mean SC gain remained low. HC gain recovered fully, but some cases did not have full recovery of PC gain. When the SC is plugged surgically, early quantitative vHIT demonstrates significantly reduced VOR gain for all of the ipsilateral canals. Possible mechanisms include labyrinthine inflammation and loss of perilymph at the time of surgery. Full recovery is typical for the horizontal canal but not always for the PC. Evidence of central compensation occurred by the elicitation of compensatory saccades and by reducing their latencies within the first week after surgery.

Traumatic brain injury and vestibulo-ocular function: current challenges and future prospects.

Normal function of the vestibulo-ocular reflex (VOR) coordinates eye movement with head movement, in order to provide clear vision during motion and maintain balance. VOR is generated within the semicircular canals of the inner ear to elicit compensatory eye movements, which maintain stability of images on the fovea during brief, rapid head motion, otherwise known as gaze stability. Normal VOR function is necessary in carrying out activities of daily living (eg, walking and riding in a car) and is of particular importance in higher demand activities (eg, sports-related activities). Disruption or damage in the VOR can result in symptoms such as movement-related dizziness, blurry vision, difficulty maintaining balance with head movements, and even nausea. Dizziness is one of the most common symptoms following traumatic brain injury (TBI) and is considered a risk factor for a prolonged recovery. Assessment of the vestibular system is of particular importance following TBI, in conjunction with oculomotor control, due to the intrinsic neural circuitry that exists between the ocular and vestibular systems. The purpose of this article is to review the physiology of the VOR and the visual-vestibular symptoms associated with TBI and to discuss assessment and treatment guidelines for TBI. Current challenges and future prospects will also be addressed.

Early Adaptation and Compensation of Clinical Vestibular Responses After Unilateral Vestibular Deafferentation Surgery

To describe vestibulo-ocular function in the immediate postoperative period after unilateral vestibular deafferentation from vestibular schwannoma resection. Prospective longitudinal study. Tertiary medical center. Five patients who underwent vestibular schwannoma resection via retrosigmoid approach. Bedside video-oculography and video head impulse testing (HIT). Static and dynamic measures of vestibulo-ocular reflex (VOR) function including spontaneous nystagmus, skew deviation, VOR gain during HIT, and presence of saccades related to HIT. Mean ipsilesional horizontal VOR gain decreased from 0.88 ± 0.09 preoperatively to 0.27 ± 0.20 on POD 2 (p = 0.004). Mean contralesional VOR gain declined from 0.95 ± 0.1 preoperatively to 0.79 ± 0.17 on POD 2 (p = 0.032). By POD 4, ipsilesional VOR gain remained low, whereas contralesional VOR gain returned to baseline. Initially on POD 1 to 3, compensatory saccades occurred exclusively after the head stopped moving (overt) with latency of 192.8 ± 36.1 ms; by POD 5, saccade latency decreased to 134.5 ± 23.5 ms (p = 0.026), and saccades were occurring during the head rotation. Skew deviation was present and remained abnormal through POD 5 in 3 of the 5 patients. In the postoperative period, gaze stability seems to improve from contralesional VOR gain restoration and reduced latency of compensatory saccades.