Evaluation of the Effects of Optokinetic Stimuli and Dual-Task Performance on Vestibulo-Ocular Reflex Function in Children With Attention Deficit and Hyperactivity Disorder.

OBJECTIVES: This study investigated the effects of optokinetic stimuli and dual-task performance on vestibulo-ocular reflex (VOR) function. The study primarily focused on understanding the effects of attention deficit and hyperactivity disorder (ADHD) and its subtypes. STUDY DESIGN: A case-control study. SETTING: Tertiary medical centre. METHODS: Thirty-eight children diagnosed with ADHD and 40 typically developing (TD) children aged 8-18 were included in the study. According to their diagnostic reports, children diagnosed with ADHD were also examined in three subtypes: predominantly inattentive (ADHD-PI), predominantly hyperactive-impulsive (ADHD-HI) and the combined type. Functional head impulse test (fHIT) was applied to all participants in three conditions-with no additional stimulus, optokinetic stimulation and dual-task. Correct responses (CR) were determined for each group, and the conditions were compared. For the dual-task test performance, children were given a counting task. RESULTS: The findings of the study are significant. The CR values obtained from the fHIT tests applied under three different conditions were lower in the ADHD group compared to the control group. CR values for all fHIT conditions and all semicircular canals were lower in the ADHD-PI subtype and higher in the ADHD-HI subtype compared to other subgroups. CONCLUSION: This study has significant practical implications underscoring its relevance. fHIT, when applied with different protocols, can provide valuable information about the vestibular and cognitive states of children with ADHD. These results are particularly significant as the diagnosis of ADHD often relies on subjective interpretations, and fHIT offers a more objective and reliable method of evaluation.

Recurrent Vestibulopathy: Comparison of Vestibular Test Results with Ménière's Disease and Vestibular Migraine.

INTRODUCTION: Recurrent and episodic vestibular symptoms not fulfilling criteria for known episodic vestibular syndromes are named as recurrent vestibulopathy (RV). We aimed to compare the vestibular test results of RV patients with vestibular migraine (VM) and Ménière's disease (MD). METHODS: Twenty patients with MD, 20 patients with VM, 18 patients with RV, and 20 healthy volunteers (HC) were evaluated. Pure-tone hearing thresholds (PTHTs), video head impulse test (vHIT), functional head impulse test (fHIT), and cervical vestibular evoked myogenic potentials (cVEMPs) were studied. RESULTS: PTHT of the MD-affected ears were significantly high, and cVEMP-corrected amplitudes were low when compared with the VM, RV, and HC (p < 0.001 for all). Amplitude asymmetry ratio was significantly high in MD-affected ears when compared with the HC (p = 0.014), VM (p = 0.038), and RV (p = 0.045). VEMP latencies and lateral canal vHIT gain were not different between groups (p > 0.05). The percentage of correctly identified optotypes on fHIT of the MD (p > 0.001), VM (p = 0.004), and RV (p = 0.001) patients were low in comparison with the HC. CONCLUSION: Apart from hearing loss, low cVEMP amplitudes on the affected side were the main feature in MD differentiating it from VM and RV. Vestibular test results of patients with RV and VM were similar. Low fHIT results in all groups indicate a functional deficit in gaze stabilization. Disabling vertigo attacks disturbing attention may be the cause of this functional impairment. MD, VM, and RV may be parts of a broad-spectrum disorder, RV patients representing milder forms not associated with cochlear or migrainous features.

Evaluation of effects of optokinetic and rotational stimuli with functional head impulse test (fHIT) in individuals with motion sickness.

OBJECTIVES: To evaluate effects of optokinetic and rotational stimulus in individuals with and without motion sickness (MS) using fHIT. METHODS: The study included subjects aged 18-40; 35 subjects with MS for MS group and 35 subjects without vertigo for control group. Percentage of the correct answer (% CA) with and without optokinetic stimulus (o-fHIT) in the frontal plane in the fHIT test was compared in both groups. In addition, both group subjects were seated on an ordinary rotating office chair. % CA was compared between groups by applying rotational fHIT (r-fHIT) test after the subjects were rotated randomly to the right and left and also simultaneously moved their heads in the vertical plane. RESULTS: There was no significant difference in % CA in fHIT o-fHIT and r-fHIT in the control group. Both groups showed a significant difference in % CA for fHIT, o-fHIT, and r-fHIT for all SCCs (p < 0.05). CONCLUSIONS: Since individuals with MS are affected by optokinetic and rotational stimuli, fHIT performed after these stimuli can be used as an objective confirming test for diagnosing MS.

Role of the functional head impulse test in evaluating vestibulo-ocular reflex abnormalities in individuals with Parkinson's disease.

PURPOSE: To assess vestibular-ocular reflex (VOR) function in patients with Parkinson's disease (PD) using a new method called functional head impulse test (fHIT). STUDY DESIGN: Case-control study. SETTING: Tertiary medical center. PARTICIPANTS: Twenty individuals with PD were recruited for PD group, and twenty healthy individuals for the control group. Ages of both groups ranged from 47 to 76 years. MAIN OUTCOME MEASURES: According to the modified Hoehn-Yahr score, PD group was classified as an early stage with a range of 1-2.5 and a mid-late stage with a range of 3-5. Percentage of correct answers (%CA) was calculated using fHIT for lateral, anterior and posterior semicircular canal (SCC) planes. RESULTS: PD group had statistically lower fHIT %CA in the right lateral, left lateral, and left posterior SCC planes compared to control group (p < .05). There was no statistical difference between two PD severity groups and functional VOR abnormality. CONCLUSION: It was concluded that the functional VOR in the right lateral and left lateral and left posterior SCC plane was affected in individuals with PD. Our results show that impaired VOR and reduced dynamic visual acuity should be considered in individuals with PD for vestibular rehabilitation exercises.

Alcohol binge-drinking damage on the vestibulo-oculomotor reflex.

PURPOSE: Binge drinking is associated with several adverse effects in multiple organs. This study aimed at evaluating the effects of a binge-like-drinking on the vestibulo-oculomotor reflex (VOR) using the video Head Impulse Test (vHIT) and the functional Head Impulse Test (fHIT). METHODS: Eleven healthy men (age range 32-35 years) with moderate drinking habits and no history of vestibular dysfunction were enrolled. A preliminary assessment of breath alcohol concentration (BrAC) to check for zero alcohol value and a pre-intake evaluation of VOR using the vHIT and the fHIT were carried on. Then, the subjects were asked to take drinks with different alcohol content (8-40% ethanol by volume) according to their choice, consuming at least 5 standard drinks. Volunteers stopped drinking after 3 h. After a further 30 min, post-intake BrAC measurements and VOR analysis were repeated. RESULTS: After alcohol intake, vHIT recorded an overall significant reduction of VOR gain (0.82 ± 0.07 on both sides) although the outcomes were below the normal range only in the four subjects with the highest blood alcohol levels. The post-intake fHIT outcomes were substandard in 9 participants, with a significant deterioration in performance (% of exact answers = 84.54 ± 11.05% on the left, 83.18 ± 14.53 on the right). CONCLUSIONS: Binge drinking severely affects VOR; fHIT seems more sensitive than vHIT in the assessment of VOR function for complex vestibular lesions, such as those determined by ethanol, suggesting that fHIT could support vHIT in vestibular dysfunction assessment.

Restoring the High-Frequency Dynamic Visual Acuity with a Vestibular Implant Prototype in Humans.

INTRODUCTION: The vestibular implant could become a clinically useful device in the near future. This study investigated the feasibility of restoring the high-frequency dynamic visual acuity (DVA) with a vestibular implant, using the functional Head Impulse Test (fHIT). METHODS: A 72-year-old female, with bilateral vestibulopathy and fitted with a modified cochlear implant incorporating three vestibular electrodes (MED-EL, Innsbruck, Austria), was available for this study. Electrical stimulation was delivered with the electrode close to the lateral ampullary nerve in the left ear. The high-frequency DVA in the horizontal plane was tested with the fHIT. After training, the patient underwent six trials of fHIT, each with a different setting of the vestibular implant: (1) System OFF before stimulation; (2) System ON, baseline stimulation; (3) System ON, reversed stimulation; (4) System ON, positive stimulation; (5) System OFF, without delay after stimulation offset; and (6) System OFF, 25 min delay after stimulation offset. The percentage of correct fHIT scores for right and left head impulses were compared between trials. RESULTS: Vestibular implant stimulation improved the high-frequency DVA compared to no stimulation. This improvement was significant for "System ON, baseline stimulation" (p = 0.02) and "System ON, positive stimulation" (p < 0.001). fHIT scores changed from 19 to 44% (no stimulation) to maximum 75-94% (System ON, positive stimulation). CONCLUSION: The vestibular implant seems capable of improving the high-frequency DVA. This functional benefit of the vestibular implant illustrates again the feasibility of this device for clinical use in the near future.

Customized Vestibular Rehabilitation for Vestibular Schwannoma Excision via Translabyrinthine Approach: A Single-Center Experience.

Objectives: To evaluate the effectiveness of intensive customized vestibular rehabilitation after vestibular schwannoma (VS) excision. Methods: 52 patients who underwent VS removal via a translabyrinthine approach from 2020 to 2022 were involved in this study. Bedside examination, video head impulse test (vHIT), functional head impulse test (fHIT), and the dizziness handicap inventory (DHI) were performed before and after the rehabilitation, which consisted of 10 sessions of specifically designed vestibular, visual, and physical integrated training. Results: After rehabilitation, the vHIT showed overall unchanged values on the affected and healthy side. In contrast, the scores of fHIT, which explores the higher connection of the vestibular system with visual and cerebellar pathways, improved on both the pathological and healthy sides after training (p-value 0.004 and 0.000, respectively). The effectiveness of the rehabilitation was reinforced by the DHI scores, which were considerably lower after training. Conclusions: To our knowledge, this is the first study to explore fHIT outcomes after removal of VS, estimating the impact of rehabilitation on the overall compensation process. The outcomes support the role of extensive postsurgical rehabilitation in the compensatory process, even just a few days after surgery.

vHIT and fHIT in Patients With Migraine, Vestibular Migraine, and Persistent Postural-Perceptual Dizziness.

OBJECTIVE: Impairment in the integration of different vestibular stimuli is the proposed mechanisms in vestibular migraine (VM). In this study, it was aimed to assess the vestibulo-ocular reflex (VOR) and dynamic visual acuity (DVA) in patients with VM and to compare the results with migraine without vestibular symptoms (MwoV), and persistent postural-perceptual dizziness (PPPD) to find out if there are discriminative differences and search for a correlation with the levels of anxiety. METHODS: Twenty-two patients with MwoV, 23 patients with VM, 22 patients with PPPD, and 23 healthy controls (HC) were studied. Video head impulse test (vHIT) and functional head impulse test (fHIT) without and with an optokinetic background (OB) were performed. Percentage of correctly identified optotypes (CA%) was considered for the fHIT test. Beck anxiety inventory (BAI) was used to assess anxiety. RESULTS: Lateral canal vHIT gain of the patient groups were not different from the healthy controls (p > 0.05). fHIT and fHIT/OB CA% results of all patient groups were lower than the HC (p < 0.005), and VM patients had the lowest scores for both tests. BAI scores of the PPPD patients were the highest and a correlation between anxiety levels, and fHIT results could not be identified (p > 0.05). CONCLUSION: Prominent CA% drop by the use of an OB was the main finding in patients with VM. This discriminative feature was not correlated with anxiety scores. Difficulty in resolving the conflict between visual and vestibular inputs seem to be the underlying mechanism. LEVEL OF EVIDENCE: 3 Laryngoscope, 2024.

Evaluation of vestibulo-ocular reflex with functional head impulse test in healthy individuals: normative values.

Objectives: This study aimed to determine the normative values of the functional head impulse test (fHIT) test in healthy young adults. Materials and methods: The study included 100 individuals, 58 females and 42 males, aged 20-25 years. Beon Solution Zero Branco (TV) fHIT test was applied to all participants. FHIT results were analyzed in terms of lateral-posterior-anterior semicircular canals (SSCs), gender, and right-left ear. Results: In the fHIT test, for the lateral SSC the mean percent correct answer (%CA) values for 4,000-6,000°/s2 and 1,000-7,000°/s2 were 88.52 ± 9.04 and 89.91 ± 6.95, respectively; for the posterior SSC, the mean %CA values for SSC 3000-6,000°/s2 and 1,000-7,000°/s2 were 90.63 ± 8.69 and 91.16 ± 7.42, respectively; for the anterior SSC, the mean %CA values for 3,000-6,000°/s2 and 1,000-7,000°/s2 were 91.21 ± 7.96 and 91.49 ± 7.13, respectively. There was no statistically significant difference between the right and left ear in %CA values at all accelerations in all SSCs (p > 0.05). There was a statistically significant difference between genders in the mean %CA values for 6,000-7,000°/s2, 4,000-6,000°/s2, and 1,000-7,000°/s2 in the lateral SSC and 3,000-6,000°/s2 in the anterior SSC (p < 0.05). Conclusion: The FHIT is a noninvasive test battery that functionally evaluates the VOR of the six semicircular canals. In clinical use, the determination of normative values at all accelerations (1,000-7,000 degrees/s2) constitutes an important database for future studies to distinguish pathologic results.

Comparison of children with and without dyslexia using functional head impulse test and pediatric balance scale.

Purpose: The aim of this study is to compare functionality of vestibulo-ocular reflex (VOR) responses to evaluate the functional properties of the vestibular system and daily balance performance in children with dyslexia and children with normal development. Method: Fifteen participants diagnosed with dyslexia were included in the study group (SG), and 15 healthy participants were included in the control group (CG). All groups underwent Functional Head Impulse Test (f-HIT) and Pediatric Balance Scale (PBS). f-HIT was performed with at least 15 head impulses at 4000-5000-6000°/s2 randomly to the right and left in the plane of the horizontal semicircular canal (SCC). Statistical analysis was performed using descriptive statistics and the Mann-Whitney U test. Results: SG percentage values were obtained lower than CG percentage values. Comparisons between the two groups showed that there was a significant difference in all parameters (4000-5000-6000°/s2 and total) in the right-side stimulation, there was significant difference for 4,000 s2 and total correct answers in the left side. In addition, although there was no significant difference between the groups in terms of the PBS score, the SG scores were lower (p = 0.062). Conclusions: As a novel test, f-HIT, revealed the difference in functionality of vestibular performance in the dyslexia group. In the dyslexia group, f-HIT may be helpful in evaluating and monitoring the vestibular system.

Vestibular test results in patients with vestibular migraine and Meniere's Disease.

BACKGROUND: Vestibular migraine (VM) and Meniere's Disease (MD) are episodic vestibular disorders, sometimes difficult to differentiate from each other on clinical grounds. OBJECTIVE: To evaluate vestibular test results of the two groups that may help in the differential diagnosis. METHODS: Twenty-two patients with VM, 21 patients with definite MD and 21 healthy volunteers (HC) were studied. Pure tone hearing thresholds (PTHT), cervical vestibular evoked myogenic potentials (cVEMPs), video head impulse test (vHIT) and functional head impulse test (fHIT) were performed. RESULTS: PTHT of the MD-affected ears were significantly higher than VM and HC groups (p < .001 for both) when cVEMP amplitudes were lower (p = .005 for HC), (p = .006 for VM). Lateral canal vHIT gain of the MD-affected ears were lower than VM patients (p = .003) and the HC (p < .001). The percentage of correctly identified optotypes (CA%) on fHIT was low for both patient groups when compared with the HC (p < .001). CONCLUSION: In addition to hearing loss, low cVEMP amplitudes on the affected side with decreased gain on vHIT indicate disturbed saccular and lateral semicircular canal functions in MD patients differentiating them from VM. A functional deficit in gaze stabilization detected by fHIT is the only abnormality found in patients with VM.

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.

The relationship between functional head impulse test and age in healthy individuals.

BACKGROUND: fHIT is an easily applicable test battery that indirectly evaluates the vestibulo-ocular reflex (VOR) from a functional perspective. AIMS/OBJECTIVES: The aim of this study was to Individuals determine the correlation between age and the percentage of correct answers (%CA) obtained in the functional head impulse test (fHIT) in healthy individuals. MATERIAL AND METHODS: A total of 105 volunteers, 50 males and 55 females, between the ages of 18 and 70 years, participated in the study. A Beon Solution fHIT system (Zero Branco (TV), Italy) was used in the study. RESULTS: In our study, a decrease in the mean %CA was observed in all semicircular canals (SCCs) with increasing age. Between age and mean %CA, a significant negative moderate (-0.311) correlation was observed in lateral SCCs, and a significant negative low (-0.257) correlation was observed in posterior SCCs (p < 0.05). In anterior SCCs, there was no statistically significant relationship between age and mean %CA (p > 0.05). CONCLUSIONS: The present study performed in a healthy population will be helpful in terms of making comparisons in studies to be conducted in various vestibular diseases. It will also be a guide for identifying pathological consequences in vestibular diseases.

Vestibulo-ocular reflex evaluation of the children with acquired esotropia.

OBJECTIVES: This study aims to evaluate the effects of acquired esotropia on vestibulo-ocular reflex (VOR) gain in children using video (vHIT) and functional head impulse (fHIT) tests. METHODS: A total of 62 children aged 6-18 years, with acquired esotropia and normal vision, were evaluated in the study. The patients were divided into two sub-groups: accommodative and non-accommodative. VOR gains were analyzed by performing lateral canal vHIT and fHIT with monocular and binocular recordings by a single examiner. RESULTS: Seventeen (10 male, 7 female) children with accommodative esotropia, 24 (14 male, 10 female) children with non-accommodative esotropia, and 21 (8 male and 12 female) healthy controls were included in this study. The vHIT findings did not differ between the groups (p˃.05). In the non-accommodative esotropia group, the location of the camera in both binocular and monocular vHIT recordings made a significant difference in the left VOR gain (p = .025, z = -2.243, p = .032, and z = -2.143, respectively), but no difference was observed in the right VOR gain. In the accommodative esotropia group, while the camera was on the left there was a significant difference in the right VOR gain between binocular and monocular recordings (p = .016, z = -2.413) but no difference was observed in the left VOR gain. No overt or covert saccade was detected in any group. CONCLUSIONS: The statistical differences found in vHIT and fHIT in acquired esotropia patients are thought to be sporadic and based on the results of this study no correction or change in recording technique is required for vHIT or fHIT in children with acquired esotropia.

Evaluation of Vestibular Function in Patients Affected by Obstructive Sleep Apnea Performing Functional Head Impulse Test (fHIT).

Purpose: Obstructive sleep apnoea (OSA) is a common disease with significantly related complications. Since a connection between the vestibular nucleus and sleep regulator pathways has been demonstrated, vestibular evaluation in OSA patients was partially studied and none used functional head impulse test (fHIT) for this purpose. This paper aimed at evaluating the vestibular function in patients affected by OSA using fHIT, selecting patients who did not present any other related to cardiovascular, neurological, or metabolic diseases. Patients and Methods: Patients enrolled had a diagnosis of OSA by polysomnography type III and were cataloged according to American Association of Sleep Medicine criteria. Each patient underwent fHIT. Statistical significance was set at 0.05. Results: A total of 85 patients were enrolled in the study of which 50 had a diagnosis of OSA and were included in the case group, while 35 belonged to the control group. In 88.6% of subjects of the case group was evidenced a vestibular impairment with a substantial difference between the two study groups (p<0.05). Conclusion: The results show that the incidence of vestibular lesions in patients with obstructive sleep apnoea is underestimated and that fHIT can identify these lesions early.

The Role of the Functional Head Impulse Test with and without Optokinetic Stimuli in Vestibular Migraine and Acute Unilateral Vestibulopathy: Discovering a Dynamic Visual Dependence.

(1) Background: Visually induced vertigo (i.e., vertigo provoked by moving visual scenes) can be considered a noticeable feature of vestibular migraines (VM) and can be present in patients suffering from acute unilateral vestibulopathy (AUV). Hypersensitivity to moving or conflicting visual stimulation is named visual dependence. (2) Methods: Visuo-vestibular interactions were analyzed via the functional Head Impulse Test (fHIT) with and without optokinetic stimulation (o-fHIT) in 25 patients with VM, in 20 subjects affected by AUV, and in 20 healthy subjects. We calculated the percentage of correct answers (%CA) without and with the addition of the optokinetic background (OB). (3) In VM groups, the %CA on the fHIT was 92.07% without OB and 73.66% with OB. A significant difference was found between %CA on the deficit side and that on the normal side in AUV, both without OB and with OB. (4) Conclusions: The fHIT results in terms of %CA with and without OB could be useful to identify the presence of a dynamic visual dependence, especially in patients suffering from VM. The difference in %CA with and without OB could provide instrumental support to help correctly identify subjects suffering from VM. We propose the use of the fHIT in clinical practice whenever there is a need to highlight a condition of dynamic visual dependence.

Short-Latency Covert Saccades - The Explanation for Good Dynamic Visual Performance After Unilateral Vestibular Loss?

Background: Functional head impulse test (fHIT) tests the ability of the vestibulo-ocular reflex (VOR) to allow visual perception during head movements. Our previous study showed that active head movements to the side with a vestibular lesion generated a dynamic visual performance that were as good as during movements to the intact side. Objective: To examine the differences in eye position during the head impulse test when performed with active and passive head movements, in order to better understand the role of the different saccade properties in improving visual performance. Method: We recruited 8 subjects with complete unilateral vestibular loss (4 men and 4 women, mean age 47 years) and tested them with video Head Impulse Test (vHIT) and Functional Head Impulse Test (fHIT) during passive and active movements while looking at a target. We assessed the mean absolute position error of the eye during different time frames of the head movement, the peak latency and the peak velocity of the first saccade, as well as the visual performance during the head movement. Results: Active head impulses to the lesioned side generated dynamic visual performances that were as good as when testing the intact side. Active head impulses resulted in smaller position errors during the visual perception task (p = 0.006) compared to passive head-impulses and the position error during the visual perception time frame correlated with shorter latencies of the first saccade (p < 0.001). Conclusion: Actively generated head impulses toward the side with a complete vestibular loss resulted in a position error within or close to the margin necessary to obtain visual perception for a brief period of time in patients with chronic unilateral vestibular loss. This seems to be attributed to the appearance of short-latency covert saccades, which position the eyes in a more favorable position during head movements.

Evaluation of high frequency horizontal VOR parameters in patients with chronic bilateral and unilateral peripheral vestibulopathy: a preliminary study.

BACKGROUND: Caloric test is one of the tests which evaluates the low frequency component of vestibular system for both diagnosis of the BPV and UPV. AIMS: The main objectives are to determine and increase the diagnostic value of BPV and UPV by evaluating the high frequency horizontal VOR parameters with HIMP, SHIMP and fHIT, to compare test results with healthy controls, and to evaluate correlation of these tests with vertigo dizziness imbalance (VDI) questionnaire results in these patients. MATERIAL AND METHODS: Six patients with BPV, ten patients with UPV and fifteen healthy controls were recruited. High frequency hVOR were evaluated with HIMP, SHIMP and fHIT. Vestibular symptoms and quality of life were assessed with VDI Questionnaire. RESULTS: Lower percentage of correct answers, and lower VOR gains were obtained in affected sides for BPV and UPV. HIMP elicited compensatory saccades in patients, whereas SHIMP elicited large anticompensatory saccades in controls and unaffected side of UPV, but no saccades in BPV. No correlation was found between VDI outcomes and all tests. CONCLUSIONS: The results show that all tests are complementary each other and able to identify the affected labyrinth and to show residual vestibular function. These tests are thought to be important in the vestibular rehabilitation process.

The integration of multisensory motion stimuli is impaired in vestibular migraine patients.

BACKGROUND: Vestibular migraine (VM) is a relatively recently acknowledged vestibular syndrome with a very relevant prevalence of about 10% among patients complaining of vertigo. The diagnostic criteria for VM have been recently published by the Bárány Society, and they are now included in the latest version of the International Classification of Headache Disorders, yet there is no instrumental test that supports the diagnosis of VM. OBJECTIVE: In the hypothesis that the integration of different vestibular stimuli is functionally impaired in VM, we tested whether the combination of abrupt vestibular stimuli and full-field, moving visual stimuli would challenge vestibular migraine patients more than controls and other non-vestibular migraineurs. METHODS: In three clinical centers, we compared the performance in the functional head impulse test (fHIT) without and with an optokinetic stimulus rotating in the frontal plane in a group of 44 controls (Ctrl), a group of 42 patients with migraine (not vestibular migraine, MnoV), a group of 39 patients with vestibular migraine (VM) and a group of 15 patients with vestibular neuritis (VN). RESULTS: The optokinetic stimulation reduced the percentage of correct answers (%CA) in all groups, and in about 33% of the patients with migraine, in as many as 87% of VM patients and 60% of VN patients, this reduction was larger than expected from controls' data. CONCLUSIONS: The comparison of the fHIT results without and with optokinetic stimulation unveils a functional vestibular impairment in VM that is not as large as the one detectable in VN, and that, in contrast with all the other patient groups, mainly impairs the capability to integrate different vestibular stimuli.

The Functional Head Impulse Test to Assess Oscillopsia in Bilateral Vestibulopathy.

Introduction: Bilateral vestibulopathy (BV) is a chronic condition in which vestibular function is severely impaired or absent on both ears. Oscillopsia is one of the main symptoms of BV. Oscillopsia can be quantified objectively by functional vestibular tests, and subjectively by questionnaires. Recently, a new technique for testing functionally effective gaze stabilization was developed: the functional Head Impulse Test (fHIT). This study compared the fHIT with the Dynamic Visual Acuity assessed on a treadmill (DVAtreadmill) and Oscillopsia Severity Questionnaire (OSQ) in the context of objectifying the experience of oscillopsia in patients with BV. Methods: Inclusion criteria comprised: (1) summated slow phase velocity of nystagmus of <20°/s during bithermal caloric tests, (2) torsion swing tests gain of <30% and/or phase <168°, and (3) complaints of oscillopsia and/or imbalance. During the fHIT (Beon Solutions srl, Italy) patients were seated in front of a computer screen. During a passive horizontal head impulse a Landolt C optotype was shortly displayed. Patients reported the seen optotype by pressing the corresponding button on a keyboard. The percentage correct answers was registered for leftwards and rightwards head impulses separately. During DVAtreadmill patients were positioned on a treadmill in front of a computer screen that showed Sloan optotypes. Patients were tested in static condition and in dynamic conditions (while walking on the treadmill at 2, 4, and 6 km/h). The decline in LogMAR between static and dynamic conditions was registered for each speed. Every patient completed the Oscillopsia Severity Questionnaire (OSQ). Results: In total 23 patients were included. This study showed a moderate correlation between OSQ outcomes and the fHIT [rightwards head rotations (r s = -0.559; p = 0.006) leftwards head rotations (r s = -0.396; p = 0.061)]. No correlation was found between OSQ outcomes and DVAtreadmill, or between DVAtreadmill and fHIT. All patients completed the fHIT, 52% of the patients completed the DVAtreadmill on all speeds. Conclusion: The fHIT seems to be a feasible test to quantify oscillopsia in BV since, unlike DVAtreadmill, it correlates with the experienced oscillopsia measured by the OSQ, and more BV patients are able to complete the fHIT than DVAtreadmill.