Network changes in patients with phobic postural vertigo

Optokinetic stimulation in the rehabilitation of visually induced dizziness in people with vestibular disorders: A systematic review

OBJECTIVE

This systematic review and meta-analysis investigates the effects optokinetic stimulation in people with vestibular disorders, with a specific focus on people with visually induced dizziness.

DATA SOURCES

A systematic review was conducted using three electronic databases, CINAHL, PubMed and Physiotherapy Evidence Database (PEDro), from 2000 up to February 2024.

REVIEW METHODS

Randomised controlled trials were included, which compared: (a) adults above 18 years old with vestibular disorders, (b) the study evaluated interventions using optokinetic stimulation, (c) the intervention was compared with usual care; placebo or to no intervention, (d) the study included at least one outcome measure evaluating vestibular symptoms and (e) published in English. The methodological quality of the included studies was assessed using the PEDro scale and PROSPERO's registration number ID: CRD42021273382).

RESULTS

Eleven randomised control trials, reported in 12 records, fulfilled the inclusion criteria. All of the studies were considered to have 'good' methodological quality according to the PEDro scale. All studies showed significant improvement in vestibular symptoms in both the intervention and control groups. A meta-analysis performed on six of the records found a preference towards the addition of OKS to conventional vestibular rehabilitation helped to further reduce dizziness symptoms for patients, but the results were not statistically significant.

CONCLUSION

No optimal duration or frequency for OKS has been determined. The addition of OKS to conventional vestibular rehabilitation may be beneficial in further improving vestibular symptoms in patients with dizziness. OKS could help to improve enjoyment and adherence to vestibular rehabilitation.

Central vestibular networking for sensorimotor control, cognition, and emotion

PURPOSE OF REVIEW

The aim of this study was to illuminate the extent of the bilateral central vestibular network from brainstem and cerebellum to subcortical and cortical areas and its interrelation to higher cortical functions such as spatial cognition and anxiety.

RECENT FINDINGS

The conventional view that the main function of the vestibular system is the perception of self-motion and body orientation in space and the sensorimotor control of gaze and posture had to be developed further by a hierarchical organisation with bottom-up and top-down interconnections. Even the vestibulo-ocular and vestibulo-spinal reflexes are modified by perceptual cortical processes, assigned to higher vestibulo-cortical functions. A first comparative fMRI meta-analysis of vestibular stimulation and fear-conditioning studies in healthy participants disclosed widely distributed clusters of concordance, including the prefrontal cortex, anterior insula, temporal and inferior parietal lobe, thalamus, brainstem and cerebellum. In contrast, the cortical vestibular core region around the posterior insula was activated during vestibular stimulation but deactivated during fear conditioning. In recent years, there has been increasing evidence from studies in animals and humans that the central vestibular system has numerous connections related to spatial sensorimotor performance, memory, and emotion. The clinical implication of the complex interaction within various networks makes it difficult to assign some higher multisensory disorders to one particular modality, for example in spatial hemineglect or room-tilt illusion.

SUMMARY

Our understanding of higher cortical vestibular functions is still in its infancy. Different brain imaging techniques in animals and humans are one of the most promising methodological approaches for further structural and functional decoding of the vestibular and other intimately interconnected networks. The multisensory networking including cognition and emotion determines human behaviour in space.

Altered brain function in patients with vestibular migraine: a study on resting state functional connectivity

PURPOSE

To characterize the altered brain function in patients with vestibular migraine (VM) using resting-state functional magnetic resonance imaging (fMRI).

METHODS

In this prospective study, fMRI images as well as clinical characteristics and behavioral scales were collected from 40 VM patients and 40 healthy controls (HC). All patients received neurological, neuro-otological, and conventional MRI examinations to exclude peripheral vestibular lesions, focal lesions, and other neurological diseases. Seed-based (bilateral parietal operculum cortex 2, OP2) functional connectivity (FC) and independent component analysis (ICA)-based functional network connectivity (FNC) were performed to investigate the brain functional changes in patients with VM. Additionally, the correlations between the altered FC/FNC and behavioral results were analyzed.

RESULTS

Compared with HC, patients with VM showed increased FC between the left OP2 and right precuneus and exhibited decreased FC between the left OP2 and left anterior cingulate cortex. We also observed increased FC between the right OP2 and regions of the right middle frontal gyrus and bilateral precuneus, as well as decreased FC between the bilateral OP2. Furthermore, patients with VM showed decreased FNC between visual network (VN) and networks of auditory and default mode, and exhibited increased FNC between VN and executive control network. A correlation analysis found that FC between the left OP2 and right precuneus was positively correlated with scores of dizziness handicap inventory (DHI) in patients with VM.

CONCLUSION

The present study demonstrated altered brain function in patients with VM.

Aberrant dynamic functional network connectivity in vestibular migraine patients without peripheral vestibular lesion

PURPOSE

This study aimed to investigate changes in dynamic functional network connectivity (FNC) in patients with vestibular migraine (VM) and explore their relationship with clinical manifestations.

METHODS

Resting-state functional magnetic resonance imaging (rs-fMRI) data were scanned from 35 VM patients without peripheral vestibular lesion and 40 age-, sex- and education-matched healthy controls (HC). Independent component analysis (ICA), sliding window (SW) and k-means clustering analysis were performed to explore the difference in FNC and temporal characteristics between two groups. Additionally, Pearson's partial correlation analysis was adopted to investigate the relationship between clinical manifestations and rs-fMRI results in patients with VM.

RESULTS

Compared with HC, patients with VM showed increased FNC in pairs of extrastriate visual network (eVN)-ventral attention network (VAN), eVN-default mode network (DMN) and eVN-left frontoparietal network (lFPN), and exhibited decreased FNC in pairs of VAN-auditory network (AuN). The altered FNC was correlated with clinical manifestations of patients with VM. Additionally, we found increased mean dwell time and fractional windows in state 2 in VM patients compared with HC. Mean dwell time was positively correlated with headache impact test-6 (HIT-6) scores, fractional windows was positively associated with dizziness handicap inventory (DHI) scores.

CONCLUSION

Our results indicated that patients with VM showed altered FNC primarily between sensory networks and networks related to cognitive, emotional and attention implementation, with more time spent in a state characterized by positive FNC between sensor cortex system and dorsal attention network (DAN). These findings could help reinforce the understanding on the neural mechanisms of VM.

Clinical Observation on the Treatment of Chronic Subjective Dizziness by the Herbal-Scraping Duplex Method Based on Holographic Theory

Chronic subjective dizziness (CSD) is a chronic, subjective, nonrotational dizziness and instability caused by mental or physical factors, and patients generally have no existing vestibular system diseases. Clinically, antianxiety drugs are often used for symptomatic treatment with mediocre effects. This study observed the clinical efficacy of the herbal-scraping duplex method in the treatment of CSD based on the holographic theory. 180 patients with CSD were randomly and equally divided into group A (n = 60) who received fluoxetine hydrochloride, group B (n = 60) who received fluoxetine hydrochloride combined with holographic soup, and group C (n = 60) who received fluoxetine hydrochloride, holographic soup, and holographic scraping combined with five-element music. The effects of the 3 different treatment modalities on patients’ vertigo symptoms, traditional Chinese medicine (TCM) symptoms, anxiety and depression status, sleep quality, and fatigue level were observed. The safety of medication and the recurrence after discontinuation were observed. The results showed that group C was better than group B and group A in terms of improvement in all of the above indicators, and group B was better than group A ( $P<0.05$ ). The total efficiency of Chinese and Western medicine was better in groups C and B than in group A ( $P<0.05$ ). No statistical difference was seen in the comparison of adverse reaction rates between the 3 groups ( $P>0.05$ ). After 1 month of drug discontinuation, the recurrence rates in groups C and B were lower than those in group A ( $P<0.05$ ). This suggests that the clinical efficacy and safety of applying the herbal-scraping duplex method based on holographic theory for the treatment of CSD is ideal and has the value of promotion.

Neuroimaging Systematic Review in Persistent Postural-Perceptual Dizziness: The Elaborate Alterations in the Delicate Network to Remain Balanced

OBJECTIVES

Persistent postural-perceptual dizziness (PPPD) is a chronic functional vestibular disorder that may have normal physical examination, clinical laboratory testing and vestibular evaluation. However, advances in neuroimaging have provided new insights in brain functional connectivity and structure in patients with PPPD. This systematic review was aimed at identifying significant structural or alterations in functional connectivity in patients with PPPD.

DATABASES REVIEWED

Science Direct, Pubmed, Embase via Ovid databases, and Cochrane library.

METHODS

This review following the guidelines of PRISMA, systematically and independently examined papers published up to March 2021 which fulfilled the predetermined criteria. PROSPERO Registration (CRD42020222334).

RESULTS

A total of 15 studies were included (MRI = 4, SPECT = 1, resting state fMRI = 4, task-based fMRI = 5, task-based fMRI + MRI = 1). Significant changes in the gray matter volume, cortical folding, blood flow, and connectivity were seen at different brain regions involved in vestibular, visual, emotion, and motor processing.

CONCLUSION

There is a multisensory dimension to the impairment resulting in chronic compensatory changes in PPPD that is evident by the significant alterations in multiple networks involved in maintaining balance. These changes observed offer some explanation for the symptoms that a PPPD patient may experience.Systematic Review Registration: This study is registered with PROSPERO (CRD42020222334).

The impact of disease duration in persistent postural-perceptual dizziness (PPPD) on the quality of life, dizziness handicap and mental health

BACKGROUND

Persistent Postural-Perceptual Dizziness (PPPD) is a chronic functional disorder which interferes with the way individuals experience their personal, social and work life.

OBJECTIVE

To study the impact of disease duration in PPPD on the quality of life (QOL), dizziness handicap and mental health on the patients.

METHODS

A prospective study comparing the EQ-5D for QOL, Dizziness Handicap Inventory (DHI) and DASS-21 between 27 patients with PPPD and 27 of those who have recovered from an acute vestibular event. Similar parameters between PPPD patients with symptoms less than one year and more than a year were compared.

RESULTS

The PPPD patients were predominantly females and middle-aged with significantly higher DHI scores (mean 48.3 + 25.7, p = 0.00002), higher total mean scores in the DASS-21 (mean 21.6 + 13.7, p = 0.009) and poorer QOL with mean EQ-5D VAS of 67.9 + 17.3 (p <  0.00001). PPPD patients with symptoms for more than a year had significant increase in physical handicap (p = 0.041) as well as anxiety levels (p = 0.008).

CONCLUSIONS

PPPD is predominantly seen in females and middle-aged which significantly reduces the QOL, increases dizziness handicap and increases depression, anxiety and stress levels. The increase in duration of illness further increases the anxiety levels and physical handicap.

The Neuropsychology of Dizziness and Related Disorders

There is a reciprocal relationship between vestibular and neuropsychological disorders. People with vertigo and dizziness are at higher risk of various psychiatric disorders, particularly anxiety, depression, and panic disorder. On the other hand, people with mood disorders are at higher risk of experiencing vertigo and dizziness. Vestibular information plays a crucial role in cognitive processes, especially visuo-spatial abilities. Consequently, vestibular disorders (both peripheral and central) often result in visuo-spatial deficits. In addition, lesions of the cortical and subcortical components of the vestibular system result in disorders of higher vestibular function, such as hemispatial neglect, pusher syndrome, and topographagnosia.

Unstable Gaze in Functional Dizziness: A Contribution to Understanding the Pathophysiology of Functional Disorders

Objective: We are still lacking a pathophysiological mechanism for functional disorders explaining the emergence and manifestation of characteristic, severely impairing bodily symptoms like chest pain or dizziness. A recent hypothesis based on the predictive coding theory of brain function suggests that in functional disorders, internal expectations do not match the actual sensory body states, leading to perceptual dysregulation and symptom perception. To test this hypothesis, we investigated the account of internal expectations and sensory input on gaze stabilization, a physiologically relevant parameter of gaze shifts, in functional dizziness.

Methods: We assessed gaze stabilization in eight functional dizziness patients and 11 healthy controls during two distinct epochs of large gaze shifts: during a counter-rotation epoch (CR epoch), where the brain can use internal models, motor planning, and resulting internal expectations to achieve internally driven gaze stabilization; and during an oscillation epoch (OSC epoch), where, due to terminated motor planning, no movement expectations are present, and gaze is stabilized by sensory input alone.

Results: Gaze stabilization differed between functional patients and healthy controls only when internal movement expectations were involved [F(1,17) = 14.63, p = 0.001, and partial η² = 0.463]: functional dizziness patients showed reduced gaze stabilization during the CR (p = 0.036) but not OSC epoch (p = 0.26).

Conclusion: While sensory-driven gaze stabilization is intact, there are marked, well-measurable deficits in internally-driven gaze stabilization in functional dizziness pointing at internal expectations that do not match actual body states. This experimental evidence supports the perceptual dysregulation hypothesis of functional disorders and is an important step toward understanding the underlying pathophysiology.

Neuroimaging studies in persistent postural-perceptual dizziness and related disease: a systematic review

BACKGROUND

Persistent Postural-Perceptual Dizziness (PPPD) is one of the most common types of chronic dizziness. The pathogenesis remains unclear.

OBJECTIVE

This study aimed to systematically review neuroimaging literature for investigating the central mechanism of PPPD and related disorders.

METHODS

PubMed, EMBASE, Medline, Cochrane, and Web of Science were searched by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The articles analyzing structural and functional neuroimaging features of PPPD and related disorders were selected according to eligibility criteria.

RESULTS

Fifteen articles, including 4 structural, 10 functional, and 1 multimodal imaging, were eligible for inclusion in this review. The whiter matter alterations in PPPD are not entirely consistent. The changes of grey matter mainly in multisensory vestibular cortices, visual cortex, cerebellum, as well as anxiety-related network. Consistent with structural imaging, functional imaging conducted during the specific tasks or in the resting state has both found abnormal functional activation and connectivity in the vestibular cortex, especially in the parieto-insular vestibular cortex (PIVC), visual cortex, cerebellum, and anxiety-related network in PPPD and related disorder.

CONCLUSIONS

The current review provides up-to-date knowledge and summarizes the possible central mechanism for PPPD and related disorders, and it is helpful to understanding the mechanism of PPPD.

Network changes in patients with phobic postural vertigo

INTRODUCTION

Functional dizziness comprises a class of dizziness disorders, including phobic postural vertigo (PPV), that cause vestibular symptoms in the absence of a structural organic origin. For this reason, functional brain mechanisms have been implicated in these disorders.

METHODS

Here, functional network organization was investigated in 17 PPV patients and 18 healthy controls (HCs) during functional magnetic resonance imaging with a visual motion stimulus, data initially collected and described by Popp et al. (2018). Graph theoretical measures (degree centrality [DC], clustering coefficient [CC], and eccentricity) of 160 nodes within six functional networks were compared between HC and PPV patients during visual motion and static visual patterns.

RESULTS

Graph theoretical measures analyzed during the static condition revealed significantly different DC in the default-mode, sensorimotor, and cerebellar networks. Furthermore, significantly different group differences in network organization changes between static visual and visual motion stimulation were observed. In PPV, DC and CC showed a significantly stronger increase in the sensorimotor network during visual stimulation, whereas cerebellar network showed a significantly stronger decrease in DC.

CONCLUSION

These results suggest that the altered visual motion processing seen in PPV patients may arise from a modified state of sensory and cerebellar network connectivity.