Ocular vestibular-evoked myogenic potential assists in differentiation of multiple system atrophy from Parkinson's disease.

Vestibular-evoked myogenic potentials (VEMPs) can help assess otolithic neural pathway in the brainstem that may also participate in cardiovascular autonomic function. Parkinson's disease (PD) is associated with altered VEMP responses; however, the association between VEMP abnormalities and multiple system atrophy (MSA) remains unknown. Therefore, we compared the extent of otolith dysfunction using ocular (oVEMP) and cervical VEMP (cVEMP) between MSA and PD. We analyzed the clinical features and VEMP and head-up tilt table test (HUT) findings using the Finometer in 24 patients with MSA and 52 with de-novo PD, who had undergone neurotologic evaluation in a referral-based university hospital in South Korea from January 2021 to March 2023. MSA was associated with bilateral oVEMP abnormality (odds ratio [95% confidence interval] = 9.19 [1.77-47.76], p=0.008). n1-p1 amplitude was negatively correlated with Unified Multiple System Atrophy Rating Scale I-II scores in patients with MSA (r=-0.571, p=0.033), whereas it did not correlate with Movement Disorder Society-Unified Parkinson's Disease Rating Scale-III scores in patients with PD (r=-0.051, p=0.687). n1 latency was negatively correlated with maximum changes in systolic blood pressure within 15 s during HUT in patients with PD (r=-0.335, p=0.040) but not in those with MSA (r=0.277, p=0.299). In conclusion, bilaterally abnormal oVEMP responses may indicate the extent of brainstem dysfunction in MSA. oVEMP reflects the integrity of otolith-autonomic interplay, reliably assists in differentiating between MSA and PD, and helps infer clinical decline.

Relationship Between Motion Sickness Susceptibility and Vestibular Test Results.

Objective: There is no test parameter with high sensitivity and specificity for the diagnosis of motion sickness. The aim of this study was to demonstrate a correlation between vestibular function tests and motion sickness. In addition, our secondary aim is to evaluate the sensitivity of the skull vibration-induced nystagmus test (SVINT) in the diagnosis of motion sickness. Methods: A total of 44 young adults aged 19-25 who had no hearing loss, complaints of dizziness/vertigo, or any diagnosed neurological disease were included. According to the motion sickness susceptibility questionnaire-short form (MSSQ-SF), participants were divided into the motion sickness group (21±1.38 years) and control group (20.5±1.18 years). Mean MSSQ-SF score for the motion sickness group is 78.18±12.2 and for control group 19.09±17.08. Ocular and cervical vestibular evoked myogenic potential tests, SVINT, video head impulse test, and oculomotor tests were performed. Results: The only significant difference between the groups was in n1-p1 amplitudes in the left ocular vestibular evoked myogenic potential test (p=0.014). None of the other parameters differed between the two groups (p>0.05). Conclusions: There was no significant relationship between motion sickness susceptibility and the results of any vestibular function test. Performing diagnostic tests for motion sickness in an environment that creates significant sensory conflict may yield different results. This study contributes to the literature in terms of evaluating the vestibular system using a comprehensive test battery and is the first to use the SVINT test in motion sickness.

Investigation of Pathogenesis and Otolithic Organ Responses in Sailors with Seasickness Using cVEMP.

There are different theories cited as the cause of Motion Sickness. Asymmetrical otolithic organ function is one of the etiology theories of motion sickness. In our study, the aim was to reveal whether there is a cause originating from the sacculocolic reflex pathway in the physiopathology of seasickness. The patient group included 15 man sailors with diagnosis of seasickness and the control group included 15 man sailors without seasickness in our study. Cervical evoked myogenic vestibular potential (cVEMP) findings were compared between the groups. In the right and left ears of sailors with seasickness, the mean latencies of the p13 and n23 waves at 100, 95, and 90 dB normal hearing level (nHL) levels were found significantly shorter than in the control group (p < 0.05, for all). In the seasickness group, cVEMP interaural wave amplitude asymmetry ratio at 100 nHL level were found significantly higher than the control group (p = 0.001). The findings of our study indicated that there may be reasons arising rom the sacculocolic reflex pathway in the pathophysiology of seasickness.

The role of cochlear and vestibular afferents in long-latency cervical vestibular evoked myogenic potentials.

OBJECTIVE: To examine the origin of cervical vestibular evoked myogenic potential (cVEMP) late waves (n34-p44) elicited with air-conducted click stimuli. DESIGN: Using a retrospective design, cVEMPs from normal volunteers were compared to those obtained from patients with vestibular and auditory pathologies. STUDY SAMPLE: (1) Normal volunteers (n = 56); (2) severe-to-profound sensorineural hearing loss (SNHL) with normal vestibular function (n = 21); (3) peripheral vestibular impairment with preserved hearing (n = 16); (4) total vestibulocochlear deficit (n = 23). RESULTS: All normal volunteers had ipsilateral-dominant early p13-n23 peaks. Late peaks were present bilaterally in 78%. The p13-n23 response was present in all patients with SNHL but normal vestibular function, and 43% had late waves. Statistical comparison of these patients to a subset of age-matched controls showed no significant difference in the frequencies, amplitudes or latencies of their ipsilateral early and late peaks. cVEMPs were absent in all patients with vestibular impairment. CONCLUSION: The presence of long-latency cVEMP waves was not dependent on the integrity of sensorineural hearing pathways, but instead correlated with intact vestibular function. This finding conflicts with the view that these late waves are cochlear in origin, and suggests that vestibular afferents may assume a more prominent role in their generation.

[Update on diagnostic procedures in third window syndromes. German version]. / Update zur Diagnostik der Drittfenstersyndrome.

BACKGROUND: The diagnosis of third window syndromes often poses a challenge in clinical practice. OBJECTIVE: This paper provides an up-to-date overview of diagnostic procedures in third window syndromes, with special emphasis on superior canal dehiscence syndrome (SCDS), large vestibular aqueduct syndrome (LVAS), and X-chromosomal malformation of the cochlea. MATERIALS AND METHODS: A literature search was performed in PubMed up to December 2023. Furthermore, a selection of the authors' own cases is presented. RESULTS: Audiovestibular tests for the diagnosis of third window syndromes are most often reported for patients with SCDS in the literature. In this context, cut-off values with different sensitivities and specificities have been defined for different outcome parameters of vestibular evoked myogenic potentials. Current developments include the application of electrocochleography, broadband tympanometry, video head impulse testing, and vibration-induced nystagmus. Genetic analyses are increasingly applied in LVAS. CONCLUSION: The diagnosis of third window syndromes is always based on the synthesis of patients' symptoms, clinical signs, audiovestibular test results, and imaging.

Otolithic functions in patients with residual dizziness after successful repositioning manoeuvres for unilateral posterior canal BPPV.

OBJECTIVE: To evaluate otolithic functions in patients with residual dizziness after successful canalith repositioning procedures (CRPs) for unilateral posterior canal benign paroxysmal positional vertigo (BPPV), and to investigate possible risk factors. METHODS: This case-control observational study included healthy controls and patients with residual dizziness after improvement following CRP for BPPV. All participants were subjected to full history taking, otoscopy, audiological basic evaluation, Dix-Hallpike test to search for posterior canal BPPV, residual dizziness screening, and vestibular evoked myogenic potential (VEMP) testing. Between-group differences were assessed and possible factors associated with residual dizziness were identified by univariate analysis. RESULTS: A total of 50 patients with residual dizziness (mean age, 56.53 ± 7.46 years [29 female: 21 male]) and 50 healthy controls (mean age, 58.13 ± 7.57 years [20 female: 30 male]) were included. A significant difference in VEMP latencies was found between the patient and control group (delayed in the patient group), with no significant between-group difference in amplitude in both ears. Aging, female sex, long duration of BPPV, number of CRPs, cervical VEMP and ocular VEMP abnormalities, and winter onset, were significantly associated with the risk of residual dizziness. CONCLUSIONS: Residual dizziness is a frequent sequel of BPPV that may relate to otolithic dysfunction. VEMP changes were revealed in the form of delayed latencies.

Posterior Semicircular Canal Dehiscence with Vestibulo-Ocular Reflex Reduction for the Affected Canal at the Video-Head Impulse Test: Considerations to Pathomechanisms.

Posterior semicircular canal dehiscence (PSCD) has been demonstrated to result in a third mobile window mechanism (TMWM) in the inner ear similar to superior semicircular canal dehiscence (SSCD). Typical clinical and instrumental features of TMWM, including low-frequency conductive hearing loss (CHL), autophony, pulsatile tinnitus, sound/pressure-induced vertigo and enhanced vestibular-evoked myogenic potentials, have been widely described in cases with PSCD. Nevertheless, video-head impulse test (vHIT) results have been poorly investigated. Here, we present six patients with PSCD presenting with a clinical scenario consistent with a TMWM and an impaired vestibulo-ocular reflex (VOR) for the affected canal on vHIT. In two cases, an additional dehiscence between the facial nerve and the horizontal semicircular canal (HSC) was detected, leading to a concurrent VOR impairment for the HSC. While in SSCD, a VOR gain reduction could be ascribed to a spontaneous "auto-plugging" process due to a dural prolapse into the canal, the same pathomechanism is difficult to conceive in PSCD due to a different anatomical position, making a dural herniation less likely. Alternative putative pathomechanisms are discussed, including an endolymphatic flow dissipation during head impulses as already hypothesized in SSCD. The association of symptoms/signs consistent with TMWM and a reduced VOR gain for the posterior canal might address the diagnosis toward PSCD.

Efficacy of vestibular rehabilitation program in children with balance disorders and sensorineural hearing loss.

OBJECTIVE: Asses the efficacy of a Vestibular-balance rehabilitation program to minimize or reverse balance disability in children with sensorineural hearing loss. METHOD: Forty-five hearing-impaired children with balance deficits (i.e., variable degrees of sensorineural hearing loss or auditory neuropathy). Thirty-five were rehabilitated with cochlear implants, and ten with hearing aids. Their age ranged from 4 to 10 years old. A Pre-rehab evaluation was done using questionnaires, neuromuscular evaluation, vestibular and balance office testing, and vestibular lab testing (using cVEMP and caloric test). Customized balances, as well as vestibular rehabilitation exercises, have been applied for three months. That was followed by post-rehab assessment, including the Arabic DHI questionnaire, PBS, BESS, HTT, and DVA test. RESULTS: There was a statistically significant difference in all measured parameters (including the Arabic DHI questionnaire, PBS, BESS, HTT, and DVA test) after rehabilitation. CONCLUSIONS: Vestibular-balance rehabilitation intervention positively impacts vestibular and balance functions in hearing-impaired children.

Impaired vestibular function associated with orthostatic hypotension in patients with multiple system atrophy.

BACKGROUND: Orthostatic hypotension (OH) is one of the most common symptoms in patients with multiple system atrophy (MSA). Vestibular system plays an important role in blood pressure regulation during orthostatic challenges through vestibular-sympathetic reflex. The current study aimed to investigate the relationship between vestibular function and OH in patients with MSA. METHODS: Participants with MSA, including 20 with OH (mean age, 57.55 ± 8.44 years; 7 females) and 15 without OH (mean age, 59.00 ± 8.12 years; 2 females) and 18 healthy controls (mean age, 59.03 ± 6.44 years; 8 females) were enrolled. Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) tests were conducted to evaluate vestibular function. RESULTS: Patients with MSA presented with significantly higher rate of absent cVEMPs (57.1% vs 11.1%, p = 0.001) and oVEMPs (25.7% vs 0, p = 0.021) than controls. MSA patients with OH showed more absent cVEMPs (75.0% vs 11.1%, Bonferroni corrected p < 0.001) and oVEMPs (40.0% vs 0, Bonferroni corrected p = 0.003) than controls. Patients with OH also showed higher rate of absent cVEMPs than those without OH (33.3%, Bonferroni corrected p = 0.014). CONCLUSIONS: Our results demonstrated that impairment of vestibular function was associated with MSA, particularly in those with OH. Absent VEMPs may be a potential marker for MSA severity. Our findings suggest that impaired vestibular function is involved in OH development and may serve as an intervention target.

Vestibular function in cases of posterior semicircular canal canalolithiasis and cupulolithiasis.

Objective: To analyze and compare the vestibular function of posterior canal cupulolithiasis and canalolithiasis. Methods: The results of posterior cupulolithiasis in 45 cases, posterior canalolithiasis in 122 cases and 19 healthy controls were analyzed retrospectively. Results: The abnormal rates of vHIT in the canalolithiasis group and the cupulolithiasis group were 42.6 and 37.8%, respectively, both higher than those in the control group (both p < 0.05); there was no statistically significant difference between two BPPV groups (p = 0.573). The abnormal vHIT in 76.9% of the canalolithiasis cases and 82.4% of the cupulolithiasis cases showed normal gain with saccades, with no difference between the groups (p = 0.859). The lesion location of vHIT in the two groups did not show a correlation with the affected side of BPPV (both p > 0.05). 84.4% of canalolithiasis and 65.0% of cupulolithiasis had abnormal VEMP results, with no significant differences in abnormality rates or sides (both p > 0.05). Abnormal results of VEMPs did not show any correlation with side (p > 0.05). The results of pc-ca and pc-cu were both abnormal in 14 cases and 7 cases, and there was no correlation between the site and side of the injury (all p > 0.05). Conclusion: The results of vHIT and VEMP in pc-cu and pc-ca were partially abnormal, but they did not show any correlation with side of BPPV. It can be considered that there are scattered vestibular peripheral organ damage in both groups.

Masseter Vestibular evoked myogenic potentials: A new tool to assess the vestibulomasseteric reflex pathway.

Purpose: This review article provides the readers with an in-depth insight in understanding and interpreting various research literatures on the masseter vestibular evoked myogenic potentials (mVEMP). The article also reviews the contemporary researches involving the clinical applications of the mVEMP. Conclusions: Masseter VEMP is an evolving yet clinically promising neuro-otology test tool that has recently gained more research interest and is considered an additional tool to diagnose various vestibular disorders. Masseter VEMP assesses the functional integrity of the acoustic-masseteric and vestibulo-masseteric reflex pathways. The mVEMP could be used as a complementary test to evaluate the same peripheral generator as the cervical VEMP but a different central pathway i.e., vestibulo-trigeminal pathway. Various research studies that have experimented on parameters such as the effect of different electrode montages (zygomatic vs mandibular configurations), stimulation rates, filter settings and stimuli used to evoke mVEMP have been discussed in this article that could assist in the optimization of a comprehensive clinical protocol. The latency and the amplitude of mVEMP waveforms serve as significant parameters in differentiating normals from those of the clinical populations. Along with the cVEMPs and oVEMPs, mVEMP might help diagnose brainstem lesions in REM Sleep behaviour disorders, Multiple Sclerosis and Parkinson's disease. However, further studies are required to probe in this area of research.

Effects of valproic acid and levetiracetam monotherapy on balance functions in patients with generalized epilepsy.

BACKGROUND: It is reported that antiepileptic drugs have an effect on balance functions. The aim of the study was to evaluate and compare the effects of valproic acid and levetiracetam monotherapy on balance functions in patients with generalized epilepsy using objective test methods. METHODS: The study included 43 generalized epilepsy patients aged 18-60 years, including 20 patients receiving valproic acid monotherapy, 23 patients receiving levetiracetam monotherapy, and 25 healthy individuals as controls, in the Neurology Clinic of a university hospital in eastern Turkey. The demographic data form was filled out and the Video Head Impulse Test and Vestibular Evoked Myogenic Potentials test were performed. RESULTS: Statistically significant differences were obtained between the groups in lateral, posterior, and anterior semicircular canal gains and RALP and LARP asymmetry values in the V-HIT test (p < 0.05). Statistically significant differences were obtained between the groups in P1, N1 latency and asymmetry values in the C-VEMP test and in N1, P1 latency, amplitude, and asymmetry values in the o-VEMP test (p < 0.05). CONCLUSION: Valproic acid and levetiracetam may affect the vestibulocular and vestibulocolic reflex pathways negatively. In this cohort, valproic acid had more pronounced adverse effects on balance functions as compared to levetiracetam.

Diagnostic value of vestibular evoked myogenic potentials in benign paroxysmal positional vertigo.

OBJECTIVES: Vestibular evoked myogenic potentials (VEMPs) are useful for studying the disturbances along nerve pathways implicated in the transmission of neurological information from otolithic organs related to vestibular function. This study aims to determine the differences in VEMPs in patients affected with benign paroxysmal positional vertigo (BPPV). METHODS: We recruited 36 patients, 9 diagnosed with recurrent BPPV (rBPPV), 9 with only one episode of vertigo (iBPPV), and 18 as a control group. We performed cervical and ocular VEMPs (cVEMPs and oVEMPs). RESULTS: We observed differences in asymmetry ratio, which was 41.82% in cVEMPs in iBPPV and 68.27% in oVEMPs in rBPPV, while no asymmetry was found in control cases. Also, there was a lack of both VEMP responses in 22.2% of cases and an absence of cVEMP in 11.1% in iBPPV; in rBPPV, 11.1 % presented no responses in cVEMPs or oVEMPs, 22.2% showed no oVEMP, and 11.1% showed no cVEMP. These values were normal in the control group. CONCLUSION: The value of VEMPs in BPPV demonstrates the implication of vestibular damage, mainly utricle damage. For better sensitivity in detecting otolith abnormalities, we should perform oVEMPs and cVEMPs in recurrent BPPV and early stages of BPPV.

[The "difficult" patient-pearls and pitfalls of vestibular diagnostic tests: Part 2 : Difficult aspects of vestibular laboratory testing]. / "Schwierige" Patient:innen ­ Vestibularisdiagnostik unter erschwerten Bedingungen: Teil 2 : Schwierige Aspekte der apparativen Vestibularisprüfung.

Patients with the cardinal symptoms "vertigo" or "dizziness" may be a real challenge for the treating otorhinolaryngologist. While the first part of this educational series was focused on history taking and bedside neurotological examination, the present paper is devoted to difficult aspects of vestibular laboratory testing, including getting the indication right, what to do if my patient is not able to fully cooperate during the tests, how to choose the adequate diagnostic procedure depending on the patient's comorbidities, how to interpret discordant results of various tests. Finally the paper addresses which conclusions can be drawn (and cannot be drawn) from normal findings in vestibular testing and how to communicate this result to the dizzy patient.

Analysis of postural stability using foam posturography in patients with persistent postural-perceptual dizziness.

BACKGROUND/OBJECTIVE: Persistent postural-perceptual dizziness (PPPD) is worsened in a standing posture, or by body movement, or visual stimulation. We aimed to evaluate postural stability in PPPD patients using foam posturography and to investigate the dependence on visual and somatosensory input in the standing posture. METHODS: Foam posturography was performed on 53 PPPD patients, and data from the PPPD patients were compared with the data from an age- and sex-matched healthy controls. The PPPD patients were divided into four groups based on the findings of vestibular function tests and the effect of vestibular function on posturographic data was examined. RESULTS: Romberg's ratios were significantly higher in PPPD patients than in controls. The median Romberg's ratios in PPPD patients with normal vestibular function were also higher than those in controls. However, foam ratio was significantly lower in PPPD patients than in controls. The median foam ratios in PPPD patients with vestibular dysfunction were also lower than those in controls. CONCLUSIONS: In a standing posture, PPPD patients may be more dependent on visual input and less dependent on somatosensory input than healthy subjects. Higher dependence on visual and lower dependence on somatosensory input in PPPD may be a feature unaffected by vestibular function.

Vestibular function in children with vestibulocochlear nerve aplasia/hypoplasia.

BACKGROUND: Infants and young children with vestibulocochlear nerve (VCN) hypoplasia/aplasia present with severe hearing loss and are candidates for cochlear implantation (CI). It is unknown whether vestibular function is related to CI outcome and if vestibular tests can guide the operation decision. AIMS/OBJECTIVES: Our aim was to describe the vestibular function in patients with VCN hypoplasia/aplasia before a possible CI. MATERIALS AND METHODS: Forty-two ears in 23 patients were tested between 2019 and 2022 with bone-conducted cervical vestibular evoked myogenic potentials (BCcVEMP), video head impulse test (vHIT) and miniice-water caloric test (mIWC). RESULTS: All ears could be tested with at least one vestibular test and 83% could be tested with more than one method. Twenty-nine ears (61%) showed normal function with at least one method. The presence of a normal response to any test doubled the likelihood of a measured hearing threshold after CI, the best predictors being the BCcVEMP and vHIT (p < 0.05). CONCLUSION: Canal function may represent a predictor of auditive pathway integrity with a possible favourable audiological outcome after CI operation. SIGNIFICANCE: Our results demonstrate high vestibular response rates suggesting a functioning pathway despite the radiological diagnosis.

Comparative study of vestibular function preservation in manual versus robotic-assisted cochlear implantation.

OBJECTIVE: To compare vestibular outcomes in cochlear implant (CI) surgery, between robotic-assisted insertion of the electrodes versus manual insertion. METHODS: We performed a monocentric retrospective study. From March 2021, the robotic system RobOtol© was used for all CI cases. We compared this robotic-assisted insertion group with a manual insertion group of patients who received a CI between July 2020 and March 2021. Primary objective was vestibular outcome. We used objective vestibular function tests: caloric testing, Vestibular Evoked Myogenic Potential (VEMP), and Video Head Impulse Test (VHIT). Secondary objectives were postoperative complications including patient-reported postoperative vertigo. RESULTS: We found no statistically significant difference between the two groups in terms of caloric testing, VEMP or VHIT outcomes. In patient-reported outcomes, there was significantly more vertigo in the manual insertion group compared with robotic-assisted insertion. CONCLUSION: It is hypothesized that a non-traumatic insertion would cause less vestibular dysfunction postoperatively. Larger prospective studies are required to determine whether robotic-assisted CI insertion has a significant impact on vestibular outcomes in CI surgery.

Impaired Vestibulo-Ocular Reflex on Video Head Impulse Test in Superior Canal Dehiscence: "Spontaneous Plugging" or Endolymphatic Flow Dissipation?

Surgical plugging of the superior semicircular canal (SSC) represents an effective procedure to treat disabling symptoms in superior canal dehiscence (SCD), despite resulting in an impaired vestibulo-ocular reflex (VOR) gain for the SSC. On the other hand, SSC hypofunction on video head impulse test (vHIT) represents a common finding in patients with SCD exhibiting sound/pressure-induced vertigo, a low-frequency air-bone gap (ABG), and enhanced vestibular-evoked myogenic potentials (VEMPs). "Spontaneous canal plugging" has been assumed as the underlying process. Nevertheless, missing/mitigated symptoms and/or near-normal instrumental findings would be expected. An endolymphatic flow dissipation has been recently proposed as an alternative pathomechanism for SSC VOR gain reduction in SCD. We aimed to shed light on this debate by comparing instrumental findings from 46 ears of 44 patients with SCD exhibiting SSC hypofunction with post-operative data from 10 ears of 10 patients with SCD who underwent surgical plugging. While no difference in SSC VOR gain values was found between the two groups (p = 0.199), operated ears developed a posterior canal hypofunction (p = 0.002). Moreover, both ABG values (p = 0.012) and cervical/ocular VEMP amplitudes (p < 0.001) were significantly higher and VEMP thresholds were significantly lower (p < 0.001) in ears with SCD compared to operated ears. According to our data, canal VOR gain reduction in SCD should be considered as an additional sign of a third window mechanism, likely due to an endolymphatic flow dissipation.

Bone Conduction Cervical Vestibular Evoked Myogenic Potentials as an Alternative in Children with Middle Ear Effusion.

OBJECTIVE: To compare the amplitude ratio and P-wave latency of cervical vestibular evoked myogenic potentials (c-VEMPs) for bone conduction (BC) and air conduction (AC) stimulation in children with otitis media with effusion (OME). MATERIAL AND METHODS: This is an observational study of a cohort of 27 children and 46 ears with OME. The c-VEMP amplitude ratio and P-wave latency were compared between BC and AC in children with OME and healthy age-matched children. RESULTS: The c-VEMP response rate in children with OME was 100% when using BC stimulation and 11% when using AC stimulation. The amplitude ratio for BC was significantly higher in the OME group than the age-matched healthy control group (p = 0.004). When focusing on ears with an AC c-VEMP response (n = 5), there was a significant difference in the amplitude ratio between the AC and BC stimulation modes, but there was no significant difference in the AC results between the OME group and the age-matched control group. CONCLUSIONS: BC stimulation allows for reliable vestibular otolith testing in children with middle ear effusion. Given the high prevalence of OME in children, clinicians should be aware that recording c-VEMPs with AC stimulation may lead to misinterpretation of otolith dysfunction in pediatric settings.

Evaluation of vestibular functions in patients with obstructive sleep apnea syndrome.

BACKGROUND: To determine the anatomical proximity of the vestibular nuclei to the respiratory nuclei and the effect of susceptibility of the posterior labyrinth to a hypoxic state on the vestibular system. OBJECTIVE: It was aimed to evaluate the possible effects of periodic hypoxia on vestibular reflexes and proprioceptive perception in patients with obstructive sleep apnea syndrome (OSAS). MATERIAL AND METHODS: The study was conducted with 40 patients diagnosed with moderate and severe OSAS and 21 healthy individuals. All individuals were evaluated with Dizziness Handicap Inventory, ocular vestibular evoked myogenic potential (oVEMP), cervical vestibular evoked myogenic potential (cVEMP), video head impulse test (vHIT), videonystagmography (VNG) and sportKAT 3000. RESULTS: In the vHIT, a statistically significant difference was found between the groups in terms of anterior and posterior semicircular canal vestibulo-ocular reflex gains (p < .05). A negative correlation was found between the lateral gain asymmetry and RALP gain asymmetry and the awake blood oxygen level in the OSAS groups. There was a statistically significant difference between the groups in terms of wave response rates cVEMP 100 dB nHL and oVEMP 100-110 dB nHL (p < .05). CONCLUSION AND SIGNIFICANCE: It was concluded that vestibular reflexes and proprioceptive perception were affected due to periodic/chronic hypoxia in patients with moderate and severe OSAS.