Vestibular-autonomic interactions: beyond orthostatic dizziness

The impact of vestibular-autonomic blood pressure responses derived from the head-up Tilt test on benign paroxysmal positional vertigo recurrence

The autonomic nervous system maintains homeostasis, with the vestibulosympathetic reflex playing a key role in regulating blood pressure during postural changes. Benign paroxysmal positional vertigo (BPPV), a common vestibular disorder, has been linked to autonomic dysfunction, but the impact of vestibular-autonomic interactions on BPPV recurrence remains unclear. This prospective study investigated whether changes in diastolic blood pressure (DBP) responses during head-up tilt tests before and after treatment are associated with BPPV recurrence in 370 patients with idiopathic BPPV. DBP responses were recorded at 1 and 2 min after tilting, and patients were categorized into three groups based on DBP changes. At 6 months, the high-response group in the 1-minute DBP category had a 1.98-fold higher recurrence rate than the low-response group (p = 0.029). At 12 months, this group showed a 9.8-fold higher multiple recurrence rate (p = 0.033), while the high-response group in the 2-minute category had a 14.3-fold higher rate (p = 0.012). These results suggest that elevated DBP responses during vestibulosympathetic reflex activation are significantly associated with BPPV recurrence. Monitoring DBP through head-up tilt tests could provide valuable insights into recurrence risk, highlighting the role of vestibular-autonomic interactions in BPPV.

Update on Clinical Physiology and Pathomechanisms for Vestibulo-Autonomic Interplay

The vestibulo-autonomic interaction refers to the neural interplay between the vestibular and autonomic systems. In particular, the vestibular system plays an active role in adjusting blood distribution during movement and changes in posture, thereby complementing the baroreflex. This review summarizes recent clinical evidence highlighting the interaction between the vestibular and autonomic systems, including altered vestibular-evoked myogenic potentials in patients with postural orthostatic tachycardia syndrome, orthostatic hypotension, and neurodegenerative disorders. Additionally, the review introduces a model-based explanation of vestibular modulation of the autonomic system via the velocity storage mechanism. Specifically, the model demonstrates how vertigo attacks influence cardiovascular autonomic outflow by altering the estimation of gravity and inertia under pathological conditions.

Effects of two kinds of vestibular function training on reducing motion sickness in college students

Introduction

To explore the advantages and disadvantages of different vestibular function training to improve Motion sickness (MS) can be associated with significant symptoms, including fatigue, dizziness, headaches, nausea, and vomiting. Vestibular function training has increasingly replaced MS medications over the past few years and has almost no side effects.

Methods

We selected 109 students with MS from a university in Tangshan, China, and randomly assigned them to either an electric rotating chair group or a visual-motion cage rotating chair group. Both training groups underwent vestibular function training for 90 seconds a day for seven consecutive days.

Results

After training, both groups' Graybiel scores, blood pressure, high-frequency power (HF), and root mean square of successive differences (rMSSD) between adjacent normal heartbeats significantly decreased. In the visual-motion cage rotating chair group, in addition to a reduction in the percentage of adjacent normal-to-normal intervals which differed by more than 50 ms (pNN50), as well as decreases in low-frequency power (LF), an increase in LF/HF was observed. Between-group comparisons showed that the Graybiel scores in the electric rotating chair group were better than those in the visual-motion cage rotating chair group. When the two groups were stratified into high and low-susceptibility subgroups, the low-susceptibility subgroup of the electric rotating chair group had lower Graybiel scores and diastolic blood pressures than the low-susceptibility visual-motion cage rotating chair subgroup, whereas in the high susceptibility subgroup, LF, rMSSD, and pNN50 were significantly higher in the visual-motion cage rotating chair group than in the electric rotating chair group.

Discussion

This study compared the effects of two types of vestibular function training on Graybiel scores and heart rate variability (HRV). we found that seven days of training with both the electric rotating chair and the visual-motion cage rotating chair relieved MS symptoms and enhanced sympathetic regulation. In terms of improving the subjective degree of MS, the electric rotating chair was superior to the visual-motion cage rotating chair. Subgroup analysis results showed that low-susceptibility MS patients' symptoms were better relieved with electric rotating chair training, while high-susceptibility patients' symptoms were better relieved with visual-motion cage rotating chair training.

Blood Pressure Variability and Ocular Vestibular-Evoked Myogenic Potentials Are Independently Associated With Orthostatic Hypotension

BACKGROUND AND PURPOSE

We delineated the association between otolithic dysfunction and blood pressure (BP) variability.

METHODS

We prospectively recruited 145 consecutive patients (age=71 [59-79] years, median [interquartile range]; 76 females) with orthostatic intolerance between December 2021 and December 2023 at a tertiary hospital in South Korea. Each patient underwent evaluations of cervical and ocular vestibular-evoked myogenic potentials (oVEMPs), 24-h noninvasive ambulatory BP monitoring (ABPM), and a head-up tilt-table test using the Finometer device. As measures of BP variability, the standard deviations (SDs) of the systolic BP (SBPSD) and the diastolic BP were calculated based on serial ABPM recordings. Patients were divided into those with orthostatic hypotension (OH, n=68) and those with a normal head-up tilt-table test despite orthostatic intolerance (NOI, n=77) groups.

RESULTS

A multivariable logistic regression analysis showed that OH was associated with bilateral oVEMP abnormalities (p=0.021), SBPSD (p=0.012), and female sex (p=0.004). SBPSD was higher in patients with OH than in those with NOI (p<0.001), and was not correlated with n1-p1 amplitude (p=0.491) or normalized p13-n23 amplitude (p=0.193) in patients with OH. The sensitivity and specificity for differentiating OH from NOI were 72.1% and 67.5%, respectively, at a cutoff value of 12.7 mm Hg for SBPSD, with an area under the receiver operating characteristic curve of 0.73.

CONCLUSIONS

Bilaterally deficient oVEMP responses may be associated with OH regardless of 24-h BP variability, reflecting the integrity of the otolith-autonomic reflex during orthostasis. Alternatively, 24-h BP variability is predominantly regulated by the baroreflex, which also participates in securing orthostatic tolerance complementary to the vestibulo-autonomic reflex.

Ocular Vestibular-Evoked Myogenic Potential Assists in the Differentiation of Multiple System Atrophy From Parkinson's Disease

OBJECTIVE

Vestibular-evoked myogenic potentials (VEMPs) can help in assessing otolithic neural pathway in the brainstem, which may also contribute to the cardiovascular autonomic function. Parkinson's disease (PD) is associated with altered VEMP responses; however, the associations between VEMP abnormalities and multiple system atrophy (MSA) remain unknown. Therefore, we compared the extent of otolith dysfunction using ocular (oVEMP) and cervical VEMPs between patients with MSA and PD.

METHODS

We analyzed the clinical features, 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 at a referral-based university hospital in South Korea from January 2021 to March 2023.

RESULTS

MSA was associated with bilateral oVEMP abnormalities (odds ratio [95% confidence interval] = 9.19 [1.77-47.76], p = 0.008). The n1-p1 amplitude was negatively correlated with the Unified Multiple System Atrophy Rating Scale I-II score in patients with MSA (r = -0.571, p = 0.033), whereas it did not correlate with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale-III score in patients with PD (r = -0.051, p = 0.687). The 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).

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.

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.

The Degree of Cardiovascular Autonomic Dysfunction is not Different in GBA-Related and Idiopathic Parkinson's Disease Patients: A Case-Control Instrumental Evaluation

Background

Increased prevalence of cardiovascular autonomic failure might play a key role on Parkinson's disease (PD) progression of glucocerebrosidase gene (GBA)-mutated patients, determining a malignant phenotype of disease in these patients.

Objective

To objectively characterize, for the first time, the cardiovascular autonomic profile of GBA-mutated patients compared to idiopathic PD patients by means of cardiovascular reflex tests (CRTs).

Methods

This is a case-control (1 : 2) study on PD patients belonging to well-characterized prospective cohorts. For each PD patient carrying GBA variants, two idiopathic PD patients, matched for sex and disease duration at CRTs, were selected. Patients recruited in these cohorts underwent a complete clinical and instrumental evaluation including specific autonomic questionnaires, CRTs and extensive genetic analysis.

Results

A total of 23 GBA-PD patients (19 males, disease duration 7.7 years) were included and matched with 46 non-mutated PD controls. GBA-mutated patients were younger than controls (59.9±8.1 vs. 64.3±7.2 years, p = 0.0257) and showed a more severe phenotype. Despite GBA-mutated patients reported more frequently symptoms suggestive of orthostatic hypotension (OH) than non-mutated patients (39.1% vs 6.5%, p = 0.001), the degree of cardiovascular autonomic dysfunction, when instrumentally assessed, did not differ between the two groups, showing the same prevalence of neurogenic OH, delayed OH and cardiovascular reflex impairment (pathological Valsalva maneuver).

Conclusion

GBA-PD patients did not show different instrumental cardiovascular autonomic pattern than non-mutated PD. Our findings suggested that symptoms suggestive of OH should be promptly investigated by clinicians to confirm their nature and improve patient care and management.

Appropriate Vestibular Stimulation in Children and Adolescents-A Prerequisite for Normal Cognitive, Motor Development and Bodily Homeostasis-A Review

The structural development of the vestibular part of the inner ear is completed by birth but its central connections continue to develop until adolescence. Their development is dependent on vestibular stimulation-vestibular experience. Studies have shown that vestibular function, modulated by experience and epigenetic factors, is not solely an instrument for body position regulation, navigation, and stabilization of the head and images but also influences cognition, emotion, the autonomous nervous system and hormones. To emphasize the importance of appropriate vestibular stimulation, we present a literature review of its effect on bodily homeostasis, cognition and emotion.

A study of otolith function in patients with orthostatic dizziness

BACKGROUND

Orthostatic dizziness (OD) is the dizziness that occurs when moving from a sitting or a supine to a standing position. It is typically thought to be connected to orthostatic hypotension (OH). The otolithic control of respiratory and cardiovascular system through vestibulosympathetic reflex has been the focus of considerable recent interest. This study aimed to evaluate the relationship between the orthostatic dizziness and otolith organ function.

METHODS

This study was carried on 50 adults aged from 18 to 50 years with normal peripheral hearing. Subjects were divided into two groups: controls (GI): 20 healthy adults and study group (GII): 30 patients who were complaining of OD. Patients were submitted to; blood pressure measurement in sitting and standing positions, combined vestibular-evoked myogenic potentials (VEMPs) and subjective visual vertical and horizontal tests (SVV) and (SVH).

RESULTS

The study group showed abnormal absent cVEMP, oVEMP. There were also statistically significant differences of P13 and N23 latencies and (P13N23) amplitudes between the two groups in the left ears. Both groups differed significantly in SVH values deviated to the left side. Study group were further subdivided into ten patients with OH and 20 patients with OD without OH. The both study subgroups showed abnormal absent cVEMP, oVEMP and abnormal SVH. OH patients showed statistically significant differences of cVEMP waves P13, N23 latencies in the left ears when compared with the control.

CONCLUSIONS

Otolith malfunction may be the cause of orthostatic dizziness (OD) in patients with and without orthostatic hypotension.

Virtual Reality Sickness Reduces Attention During Immersive Experiences

In this paper, we show that Virtual Reality (VR) sickness is associated with a reduction in attention, which was detected with the P3b Event-Related Potential (ERP) component from electroencephalography (EEG) measurements collected in a dual-task paradigm. We hypothesized that sickness symptoms such as nausea, eyestrain, and fatigue would reduce the users' capacity to pay attention to tasks completed in a virtual environment, and that this reduction in attention would be dynamically reflected in a decrease of the P3b amplitude while VR sickness was experienced. In a user study, participants were taken on a tour through a museum in VR along paths with varying amounts of rotation, shown previously to cause different levels of VR sickness. While paying attention to the virtual museum (the primary task), participants were asked to silently count tones of a different frequency (the secondary task). Control measurements for comparison against the VR sickness conditions were taken when the users were not wearing the Head-Mounted Display (HMD) and while they were immersed in VR but not moving through the environment. This exploratory study shows, across multiple analyses, that the effect mean amplitude of the P3b collected during the task is associated with both sickness severity measured after the task with a questionnaire (SSQ) and with the number of counting errors on the secondary task. Thus, VR sickness may impair attention and task performance, and these changes in attention can be tracked with ERP measures as they happen, without asking participants to assess their sickness symptoms in the moment.

Augmented ocular vestibular-evoked myogenic potentials in postural orthostatic tachycardia syndrome

PURPOSE

To delineate the association between otolith function and changes in mean orthostatic blood pressure (BP) and heart rate (HR) in patients with postural orthostatic tachycardia syndrome (POTS).

METHODS

Forty-nine patients with POTS were prospectively recruited. We analyzed the results of ocular vestibular-evoked myogenic potentials (oVEMPs) and cervical vestibular-evoked myogenic potentials (cVEMPs), as well as head-up tilt table tests using a Finometer. The oVEMP and cVEMP responses were obtained using tapping stimuli and 110 dB tone-burst sounds, respectively. We measured maximal changes in 5-s averaged systolic BP (SBP), diastolic BP (DBP), and heart rate (HR) within 15 s and during 10 min after tilting. We compared the results with those of 20 age- and sex-matched healthy participants.

RESULTS

The n1-p1 amplitude of oVEMPs was larger in patients with POTS than in healthy participants (p = 0.001), whereas the n1 latency (p = 0.280) and interaural difference (p = 0.199) did not differ between the two. The n1-p1 amplitude was a positive predictor for POTS (odds ratio 1.07, 95% confidence interval 1.01-1.13, p = 0.025). Body weight (p = 0.007) and n1-p1 amplitude of oVEMP (p = 0.019) were positive predictors for ΔSBP15s in POTS, whereas aging was a negative predictor (p = 0.005). These findings were not observed in healthy participants.

CONCLUSIONS

Augmented utricular inputs may be associated with a relative predominance of sympathetic over vagal control of BP and HR, especially for an early response during orthostasis in patients with POTS. Overt sympathoexcitation due to exaggerated utricular input and lack of readaptation may be associated with the pathomechanism of POTS.

Self-reported symptom burden in postural orthostatic tachycardia syndrome (POTS): A narrative review of observational and interventional studies

BACKGROUND AND OBJECTIVE

Postural Orthostatic Tachycardia Syndrome (POTS) is a chronic health condition affecting mostly women of childbearing age, and significantly impacting their health and quality of life. It is currently poorly understood with no approved licensed treatments. The aim of this systematic review was to contextualize the symptom burden of POTS, and review factors associated with this burden that may guide future treatments. The specific questions were (1) How does symptom burden in POTS compare to the burden in other long term conditions (LTCs), (2) Which factors are associated with POTS symptom burden, and (3) Which interventions show promise in reducing symptom burden in POTS.

DATABASES AND DATA TREATMENT

Electronic databases (CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, Web of Science, APA PsycArticles, OpenGrey) were searched from inception to January 2022 for observational studies reporting on the association between any biological, psychological or social factors and symptom burden, and randomized controlled trials reporting on interventions for symptom burden in adults with POTS. Two reviewers independently conducted eligibility screening, data extraction and quality assessment. A narrative synthesis was undertaken.

RESULTS/CONCLUSION

5159 entries were screened for eligibility. Twenty-nine studies were included (1372 participants with POTS of a total sample size of 2314, 17 High-, 12 Medium-quality), seventeen were observational and twelve were randomized controlled experimental and intervention trials. Overall methodological quality of the evidence was medium-high but heterogeneity was high and sample sizes modest, allowing moderately robust conclusions. Orthostatic symptom burden was higher in POTS than other LTCs. Serum activity against adrenergic α1 receptors, physical functioning, depression, catastrophizing, prolonged cognitive stress testing and anxiety were significantly associated with symptom burden in medium-high quality studies. Preliminary medium-high quality evidence from predominantly proof-of-concept (n = 11) studies and one 3-month 2 × 2 factorial design trial suggest that compression garments, propranolol, pyridostigmine, desmopressin, and bisoprolol may hold promise in reducing symptom burden. Directions for future research include investigating associated factors over time, the development of complex interventions which address both biological and psychosocial factors associated with symptom burden, and effectiveness trials of these interventions.

SIGNIFICANCE

POTS symptom burden is high, particularly in relation to orthostatic intolerance when compared to other long-term conditions (LTCs). Despite this burden, there are no effectiveness randomized controlled trials of treatment to reduce symptoms in POTS. This review provides a starting point to understanding researched biological and psychosocial factors associated with this burden. There was however inconsistency in the measurement of symptom burden, lowering the confidence of cross-study inferences. A coherent definition of POTS symptom range, severity and impact along with a validated and reliable POTS-specific instrument is currently lacking. A standardized questionnaire to assess POTS symptom burden as a core outcome measure will help clarify future research and clinical practice.

Utricular dysfunction in patients with orthostatic hypotension

PURPOSE

To delineate the association between otolithic dysfunction and orthostatic hypotension (OH).

METHODS

We retrospectively reviewed the medical records of 382 patients who presented with orthostatic dizziness at a tertiary dizziness center between July 2017 and December 2021. Patients were included for analyses when they had completed ocular (oVEMP) and/or cervical vestibular-evoked myogenic potentials (cVEMP), and head-up tilt table test with a Finometer (n = 155). We compared the results between the patients with OH (n = 38) and those with NOI (normal head-up tilt table test despite orthostatic intolerance, n = 117).

RESULTS

Thirty-eight patients with OH were further categorized as either classic (n = 30), delayed (n = 7), or initial (n = 1) types. Multivariable logistic regression showed that OH was associated with high baseline systolic BP (p = 0.046), presence of heart failure (p = 0.016), and unilateral oVEMP abnormalities (p = 0.016). n1 latency of oVEMP were negatively correlated with the maximal changes of systolic blood pressure (BP) in 15 s ([Formula: see text]SBP_15s, p = 0.013), 3 min ([Formula: see text]SBP_3min, p = 0.005) and 10 min ([Formula: see text]SBP_10min, p = 0.002). In contrast, the n1-p1 amplitude was positively correlated with [Formula: see text]SBP_15s (p = 0.029). Meanwhile, p13 latency of cVEMP was negatively correlated with [Formula: see text]SBP_10min (p = 0.018).

CONCLUSIONS

Our study provides evidence of utricular dysfunction related to OH.

Vestibular syncope: clinical characteristics and mechanism

Background and Objectives

Vestibular syncope is a condition in which vertigo‐induced hemodynamic changes cause syncope. This study investigated the clinical and laboratory findings of vestibular syncope and tried to refine our knowledge of the mechanism underlying this newly recognized entity.

Methods

This study retrospectively analyzed 53 patients (33 women, median age = 63 years [interquartile range = 54–71 years]) with vestibular syncope from January 2017 to December 2021. To explain the mechanism of vestibular syncope, we incorporated a velocity‐storage model into the dual reflex pathways comprising the vestibulo‐sympathetic reflex and baroreflex and predicted the cardiovascular responses.

Results

Twenty (37.7%) patients had multiple episodes of vestibular syncope, and seven (13.2%) had potentially life‐threatening injuries. Meniere's disease (20.8%) and benign paroxysmal positional vertigo (9.4%) were the most common underlying vestibular disorders. Abnormal vestibular function tests included impaired cervical vestibular‐evoked myogenic potentials (57.5%) and positive head impulse tests (31.0%). Orthostatic hypotension was found in 19.5% of patients. Dyslipidemia (30.2%) and hypertension (28.3%) were common medical comorbidities. The dual reflex pathways incorporating the function of the velocity‐storage circuit in the brainstem and cerebellum suggest that vestibular syncope is a neurally mediated reflex syncope associated with a sudden hemodynamic change during vertigo. This change can be arterial hypertension triggered by a false downward inertial cue, as suggested previously, or hypotension driven by a false upward inertial cue.

Conclusions

Vestibular syncope is associated with various vestibular disorders and requires careful evaluation and intervention to prevent recurrent falls and significant injuries.