Mental body transformation deficits in patients with chronic balance disorders

Spatial anxiety contributes to the dizziness-related handicap of adults with peripheral vestibular disease

In subjects with peripheral vestibular disease and controls, we assessed: 1. The relationship between spatial anxiety and perceived stress, and 2. The combined contribution of spatial anxiety, spatial perspective-taking, and individual cofactors to dizziness-related handicap. 309 adults participated in the study (153 with and 156 without peripheral vestibular disease), including patients with bilateral vestibular deficiency, unilateral deficiency (evolution <3 or ≥3 months), Meniere's disease, and Benign Paroxysmal Positional Vertigo. Assessments included: general health, personal habits, spatial anxiety (3-domains), perceived stress, spatial perspective-taking, dizziness-related handicap (3-domains), unsteadiness, sleep quality, motion sickness susceptibility, trait anxiety/depression, state anxiety, depersonalization/derealization. After bivariate analyses, analysis of covariance was performed (p ≤ 0.05). Spatial anxiety was related to unsteadiness and perceived stress, with an inverse relationship with trait anxiety (ANCoVA, adjusted R2 = 0.27-0.30, F = 17.945-20.086, p < 0.00001). Variability on perspective-taking was related to vestibular disease, trait and state anxiety, motion sickness susceptibility, and age (ANCoVA, adjusted R2 = 0.18, F = 5.834, p < 0.00001). All domains of spatial anxiety contributed to the Physical domain of dizziness-related handicap, while the Navigation domain contributed to the Functional domain of handicap. Handicap variability was also related to unsteadiness, spatial perspective-taking, quality of sleep, and trait anxiety/depression (ANCoVA, adjusted R2 = 0.66, F = 39.07, p < 0.00001). Spatial anxiety is related to perceived stress in adults both with and without vestibular disease, subjects with trait anxiety rated lower on spatial anxiety. State anxiety and acute stress could be helpful for recovery after peripheral vestibular lesion. Spatial anxiety and perspective-taking contribute to the Physical and Functional domains of dizziness-related handicap, possibly because it discourages behavior beneficial to adaptation.

Decrease in head sway as a measure of sensory integration following vestibular rehabilitation: A randomized controlled trial

OBJECTIVE

The purpose of this study was to determine the extent to which sensory integration strategies via head sway, derived from a Head-Mounted Display (HMD), change in people with vestibular disorders following vestibular rehabilitation.

DESIGN

Randomized Controlled TrialSetting:Vestibular Rehabilitation ClinicParticipants:Thirty participants with vestibular dysfunction and 21 age-matched controls.

MAIN OUTCOME MEASURES

Participants experienced two levels of visual surround (static or moving 'stars', front to back at 0.2 Hz, 32 mm) and white noise (none or rhythmic) while their head sway was recorded via the HTC Vive. We quantified head sway via Directional Path (DP) and Root Mean Square Velocity (RMSV) in 5 directions: anterior-posterior, medio-lateral, pitch, yaw, and roll and Power Spectral Density in low (PSD 1), medium (PSD 2) and high (PSD 3) frequencies in the anterior-posterior direction.

INTERVENTIONS

Participants performed the assessment prior to being randomized into 8-weeks of contextual sensory integration training in virtual reality or traditional vestibular rehabilitation and once again following completion of the intervention. Controls performed the assessment once. Twelve participants dropped out, half due to covid lock-down. We applied an intention to treat analysis.

RESULTS

We observed significant increases in AP DP, RMSV and all PSDs with change in visual level. Both intervention groups significantly decreased medio-lateral, pitch and roll DP and RMSV and anterior-posterior PSD 2 with no group differences. Vestibular participants were significantly higher than controls on all outcomes pre rehabilitation. Post rehabilitation they were only significantly higher on PSD 2. Sound was not a significant predictor of head sway in this protocol.

CONCLUSIONS

Head sway decreased following vestibular rehabilitation regardless of visual load or type of intervention applied. This change was measured via head kinematics derived from a portable HMD which can serve as a sensitive in-clinic assessment for tracking improvement over time.

Mental imagery of whole-body motion along the sagittal-anteroposterior axis

Whole-body motor imagery is conceptualised as a mental symbolisation directly and indirectly associated with neural oscillations similar to whole-body motor execution. Motor and somatosensory activity, including vestibular activity, is a typical corticocortical substrate of body motion. Yet, it is not clear how this neural substrate is organised when participants are instructed to imagine moving their body forward or backward along the sagittal-anteroposterior axis. It is the aim of the current study to identify the fingerprint of the neural substrate by recording the cortical activity of 39 participants via a 32 electroencephalography (EEG) device. The participants were instructed to imagine moving their body forward or backward from a first-person perspective. Principal Component Analysis (i.e. PCA) applied to the neural activity of whole-body motor imagery revealed neural interconnections mirroring between forward and backward conditions: beta pre-motor and motor oscillations in the left and right hemisphere overshadowed beta parietal oscillations in forward condition, and beta parietal oscillations in the left and right hemisphere overshadowed beta pre-motor and motor oscillations in backward condition. Although functional significance needs to be discerned, beta pre-motor, motor and somatosensory oscillations might represent specific settings within the corticocortical network and provide meaningful information regarding the neural dynamics of continuous whole-body motion. It was concluded that the evoked multimodal fronto-parietal neural activity would correspond to the neural activity that could be expected if the participants were physically enacting movement of the whole-body in sagittal-anteroposterior plane as they would in their everyday environment.

Evidence for cognitive impairment in patients with vestibular disorders

OBJECTIVE

 Extensive animal research has shown that vestibular damage can be associated with cognitive deficits. More recently, new evidence has emerged linking vestibular disorders to cognitive impairment in humans. Herein, we review contemporary research on the pathophysiology of cognitive-vestibular interactions and discuss its emerging clinical relevance.

DATA SOURCES

PubMed, Embase, and Cochrane databases.

REVIEW METHODS

A systematic literature search was performed with combinations of search terms: "cognition," "cognitive impairment," "chronic fatigue," "brain fog," "spatial navigation," "attention," "memory," "executive function," "processing speed," and "vestibular hypofunction." Relevant articles were considered for inclusion, including basic and clinical studies, case series, and major reviews.

CONCLUSIONS

Patients with vestibular disorders can demonstrate long-term deficits in both spatial and nonspatial cognitive domains. The underlying mechanism(s) linking the vestibular system to cognitive function is not well characterized, but several neuro-biologic correlates have been identified. Additional screening tools are required to identify individuals at risk for cognitive impairment, and further research is needed to determine whether treatment of vestibular dysfunction has the capacity to improve cognitive function.

IMPLICATIONS FOR PRACTICE

Physicians should be aware of emerging data supporting the presence of cognitive deficits in patients with vestibular disorders. Prevention and treatment of long-term cognitive deficits may be possible through screening and rehabilitation.

Hearing loss versus vestibular loss as contributors to cognitive dysfunction

In the last 5 years, there has been a surge in evidence that hearing loss (HL) may be a risk factor for cognitive dysfunction, including dementia. At the same time, there has been an increase in the number of studies implicating vestibular loss in cognitive dysfunction. Due to the fact that vestibular disorders often present with HL and other auditory disorders such as tinnitus, it has been suggested that, in many cases, what appears to be vestibular-related cognitive dysfunction may be due to HL (e.g., Dobbels et al. Front Neurol 11:710, 2020). This review analyses the studies of vestibular-related cognitive dysfunction which have controlled HL. It is suggested that despite the fact that many studies in the area have not controlled HL, many other studies have (~ 19/44 studies or 43%). Therefore, although there is certainly a need for further studies controlling HL, there is evidence to suggest that vestibular loss is associated with cognitive dysfunction, especially related to spatial memory. This is consistent with the overwhelming evidence from animal studies that the vestibular system transmits specific types of information about self-motion to structures such as the hippocampus.

Vestibular Stimulation Modulates Neural Correlates of Own-body Mental Imagery

There is growing evidence that vestibular information is not only involved in reflexive eye movements and the control of posture but it also plays an important role in higher order cognitive processes. Previous behavioral research has shown that concomitant vestibular stimuli influence performance in tasks that involve imagined self-rotations. These results suggest that imagined and perceived body rotations share common mechanisms. However, the nature and specificity of these effects remain largely unknown. Here, we investigated the neural mechanisms underlying this vestibulocognitive interaction. Participants (n = 20) solved an imagined self-rotation task during caloric vestibular stimulation. We found robust main effects of caloric vestibular stimulation in the core region of the vestibular network, including the rolandic operculum and insula bilaterally, and of the cognitive task in parietal and frontal regions. Interestingly, we found an interaction of stimulation and task in the left inferior parietal lobe, suggesting that this region represents the modulation of imagined body rotations by vestibular input. This result provides evidence that the inferior parietal lobe plays a crucial role in the neural integration of mental and physical body rotation.

Unilateral vestibular deafferentation impairs embodied spatial cognition

A growing number of studies indicate that cognitive complaints are common in patients with peripheral vestibular disorders. A better understanding of how vestibular disorders influence cognition in these patients requires a clear delineation of the cognitive domains affected by vestibular disorders. Here, we compared the consequences of left and right vestibular neurectomy on third-person perspective taking-a visuo-spatial task requiring mainly own-body mental imagery, and on 3D objects mental rotation imagery-requiring object-based mental imagery, but no perspective taking. Patients tested 1 week after a unilateral vestibular neurectomy and a group of age- and gender-matched healthy participants played a virtual ball-tossing game from their own first-person perspective (1PP) and from the perspective of a distant avatar (third-person perspective, 3PP). Results showed larger response times in the patients with respect to their controls for the 3PP taking task, but not for the 1PP task and the 3D objects mental imagery. In addition, we found that only patients with left vestibular neurectomy presented altered 3PP taking abilities when compared to their controls. This study suggests that unilateral vestibular loss affects mainly own-body mental transformation and that only left vestibular loss seems to impair this cognitive process. Our study also brings further evidence that vestibular signals contribute to the sensorimotor bases of social cognition and strengthens the connections between the so far distinct fields of social neuroscience and human vestibular physiology.

Effects of a program of cognitive-behavioural group therapy, vestibular rehabilitation, and psychoeducational explanations on patients with dizziness and no quantified balance deficit, compared to patients with dizziness and a quantified balance deficit

BACKGROUND

We examined whether a program combining cognitive-behavioural therapy (CBT), vestibular rehabilitation (VR) and psychoeducation is equally effective in improving psychometric measures in patients with dizziness independent of a balance deficit. Measures of patients with dizziness only (DO) were compared to those of patients also having a quantified balance deficit (QBD).

METHODS

32 patients (23 female, 9 male) with persistent dizziness were analysed as 2 groups based on stance and gait balance control: those with QBD (pathological balance) or DO (normal balance). Dizziness Handicap Inventory (DHI) and Brief Symptom Inventory (BSI) questionnaires were used pre- and post-therapy to assess psychometric measures. Patients then received the same combination therapy in a group setting.

RESULTS

The QBD group mean age was 60.6, SD 8.3, and DO group mean age 44.8, SD 12.1, years. Pre-therapy, questionnaire scores were pathological but not different between groups. Balance improved significantly for the QBD group (p=0.003) but not for the DO group. DHI and BSI scores improved significantly in the DO group (0.001<p<0.045), some BSI sub-scores reaching normal levels. These scores were unchanged for the QBD group. Phobic anxiety scores changed most for both groups, being significantly correlated with DHI scores, higher (R=0.71 vs. 0.57) for the DO group.

CONCLUSIONS

A combination of CBT, VR, and psychoeducation improves psychological measures in DO patients but not significantly in QBD patients, despite their balance control improving to near normal. Possibly, greater focus on phobic anxiety during the group therapy program would have improved psychological measures of QBD patient.