Subjective Visual Vertical Perception Research Articles

Subjective visual vertical and head position in patients with idiopathic scoliosis.

Idiopathic scoliosis (IS) is a structural spinal deformity that can affect the position of the head. One of the etiological hypotheses is that it can be caused by dysfunction of the vestibular system, which can cause abnormal perception of subjective visual vertical (SVV). This study aimed to evaluate the differences in head position and its possible correlation with the perception of SVV in children with IS. We examined 37 patients with IS and 37 healthy individuals. The position of the head was evaluated from digital photographs, where we compared the coronal head tilt and the coronal shoulder angle. Measurement of SVV perception was performed using the Bucket method. Coronal head tilt values were significantly different between the groups (median 2.3° [interquartile range 1.8-4.2] vs 1.3° [0.9-2.3], p = 0.001; patients vs. controls). There was a significant difference in SVV between the groups (2.33° [1.40-3.25] vs 0.50° [0.41-1.10], p < 0.001; patients vs controls). There was a correlation between the side of head tilt and the side of SVV in patients with IS (χ2 = 5.6, p = 0.02). Patients with IS had a greater head tilt in the coronal plane and impaired SVV perception.

Visuospatial Deficits Are Associated with Pisa Syndrome and not Camptocormia in Parkinson's Disease.

Pisa syndrome (PS) and camptocormia (CC) are postural abnormalities frequently associated with Parkinson's disease (PD). Their pathophysiology remains unclear, but the role of cognitive deficits has been postulated. To identify differences in the neuropsychological functioning of patients with PD with PS or CC compared with matched patients with PD without postural abnormalities. We performed a case-control study including 57 patients with PD with PS (PS+) or CC (CC+) and 57 PD controls without postural abnormalities matched for sex, age, PD duration, phenotype, and stage. Patients were divided into four groups: PS+ (n=32), PS+ controls (PS-, n=32), CC+ (n=25), and CC+ controls (CC-, n=25). We compared PS+ versus PS- and CC+ versus CC- using a neuropsychological battery assessing memory, attention, executive functions, visuospatial abilities, and language. Subjective visual vertical (SVV) perception was assessed by the Bucket test as a sign of vestibular function; the misperception of trunk position, defined as a mismatch between the objective versus subjective evaluation of the trunk bending angle >5°, was evaluated in PS+ and CC+. PS+ showed significantly worse visuospatial performances (P = 0.025) and SVV perception (P = 0.038) than their controls, whereas CC+ did not show significant differences compared with their control group. Reduced awareness of postural abnormality was observed in >60% of patients with PS or CC. Low visuospatial performances and vestibular tone imbalance are significantly associated with PS but not with CC. These findings suggest different pathophysiology for the two main postural abnormalities associated with PD and can foster adequate therapeutic and prevention strategies.

Vestibular Extremely Low-Frequency Magnetic and Electric Stimulation Effects on Human Subjective Visual Vertical Perception.

Electric fields from both extremely low‐frequency magnetic fields (ELF‐MF) and alternating current (AC) stimulations impact human neurophysiology. As the retinal photoreceptors, vestibular hair cells are graded potential cells and are sensitive to electric fields. Electrophosphene and magnetophosphene literature suggests different impacts of AC and ELF‐MF on the vestibular hair cells. Furthermore, while AC modulates the vestibular system more globally, lateral ELF‐MF stimulations could be more utricular specific. Therefore, to further address the impact of ELF‐MF‐induced electric fields on the human vestibular system and the potential differences with AC stimulations, we investigated the effects of both stimulation modalities on the perception of verticality using a subjective visual vertical (SVV) paradigm. For similar levels of SVV precision, the ELF‐MF condition required more time to adjust SVV, and SVV variability was higher with ELF‐MF than with AC vestibular‐specific stimulations. Yet, the differences between AC and ELF‐MF stimulations were small. Overall, this study highlights small differences between AC and ELF‐MF vestibular stimulations, underlines a potential utricular contribution, and has implications for international exposure guidelines and standards. © 2022 Bioelectromagnetics Society.

Methods for Testing the Subjective Visual Vertical during the Chronic Phase of Menière's Disease.

The subjective visual vertical (SVV) evaluates the function of the utricle, which, in patients with Menière’s disease (MD), can be affected by endolymphatic hydrops. This study aimed to determine the SVV in MD patients during the chronic phase of illness compared to healthy participants. The second aim was to compare the SVV measurement tools: the analog bucket test, digital bucket test, and C-SVV© goggles. The SVV scores differed significantly between MD patients and the control group for the analog bucket test (p < 0.001) and the C-SVV® goggles (p = 0.028), but no significance was shown when using the digital bucket test (p = 0.062). When comparing the analog bucket test and the C-SVV® goggles applying the calculated threshold (1.125° in analog bucket test, 2.5° in C-SVV® goggles), the bucket test showed higher accuracy (bucket test 73.84%, C-SVV® goggles 69.23%). When examining the influence of betahistine on SVV scores, there were no statistically significant differences in both the analog bucket test and C-SVV© goggles. We conclude that SVV test can be used as an additional tool to evaluate utricle function during the chronic phase of MD and that the analog bucket test produces the most reliable results. The intake of betahistine does not influence the perception of SVV.

Young and Older Adults Differ in Integration of Sensory Cues for Vertical Perception.

Introduction The subjective visual vertical (SVV) measures the perception of a person's spatial orientation relative to gravity. Weighted central integration of vestibular, visual, and proprioceptive inputs is essential for SVV perception. Without any visual references and minimal proprioceptive contribution, the static SVV reflects balance of the otolith organs. Normal aging is associated with bilateral and progressive decline in otolith organ function, but age-dependent effects on SVV are inconclusive. Studies on sensory reweighting for visual vertical and multisensory integration strategies reveal age-dependent differences, but most studies have included elderly participants in comparison to younger adults. The aim of this study was to compare young adults with older adults, an age group younger than the elderly. Methods Thirty-three young and 28 older adults (50–65 years old) adjusted a tilted line accurately to their perceived vertical. The rod's final position from true vertical was recorded as tilt error in degrees. For otolithic balance, visual vertical was recorded in the dark without any visual references. The rod and frame task (RFT) with tilted disorienting visual frames was used for creating visuovestibular conflict. We adopted Nyborg's analysis method to derive the rod and frame effect (RFE) and trial-to-trial variability measures. Rod alignment times were also analyzed. Results There was no age difference in signed tilts of SVV without visual reference. There was an age effect on RFE and on overall trial-to-trial variability of rod tilt, with older adults displaying larger frame effects and greater variability in rod tilts. Alignment times were longer in the tilted-frame conditions for both groups and in the older adults compared to their younger counterparts. The association between tilt accuracy and tilt precision was significant for older adults only during visuovestibular conflict, revealing an increase in RFE with an increase in tilt variability. Correlation of σSVV, which represents vestibular input precision, with RFE yielded exactly the same contribution of σSVV to the variance in RFE for both age groups. Conclusions Older adults have balanced otolithic input in an upright position. Increased reliance on visual cues may begin at ages younger than what is considered elderly. Increased alignment times for older adults may create a broader time window for integration of relevant and irrelevant sensory information, thus enhancing their multisensory integration. In parallel with the elderly, older adults may differ from young adults in their integration of sensory cues for visual vertical perception.

Impact of Somatosensory Input Deficiency on Subjective Visual Vertical Perception in Children With Reading Disorders.

Purpose: Preliminary evidence indicated that children with a reading disorder (RD) may have deviance in their ability to perform high demanding cognitive tasks, such as reading, depending on somatosensory inputs. Until now, only anecdotical reports suggested that improving somatosensory inputs may influence their ability to maintain a stable perception of the visual world despite continuous movements of our eyes, head, and body. Here, we investigated whether changes in upright perception, the subjective visual vertical (SVV), were modulated by somatosensory inputs in a group of children with RD.Method: The SVV task was used under two distinct conditions, i.e., with or without somatosensory inputs from the foot. We enrolled a group of 20 children with reading disorders and 20 sex-, age-, IQ- matched children with neurotypical development.Results: Responses to the SVV task were found to be significantly less accurate in children with RD than in children with neurotypical development (p < 0.001). In the latter, SVV response did not depend on somatosensory inputs from the foot. In contrast, in children with RD somatosensory inputs, either improved or worsen their SVV depending on the tilt direction (p < 0.01).Conclusion: Our results suggested that SVV responses in children with RD could be related to an immaturity for heteromodal sensory integration, including somatosensory inputs.

Influence of Somesthesic Input on Subjective Visual Vertical in Dyslexic Children

Purpose: We explored the perception of subjective visual vertical (SVV) in dyslexic and non-dyslexic age, sex and QImatched.Method: The SVV was evaluated with a laser and with or without foam under the feet. We performed an analysis ofvariance. Post hoc comparisons were made with the Fisher’s least significant differences test (LSD).Results: Our results showed two significant effects for groups and for tilt condition: counterclockwise or clockwisedirection and a significant interaction between group, tilt and somesthesic condition: without and with foam underthe feet. More precisely, SVV response in the tilt counterclockwise condition with foam was found to be significantlyless accurate for the dyslexic group than for the non-dyslexic group. Also, SVV response in the tilt counterclockwisedirection was found to be significantly less accurate for both groups compared to clockwise direction. Moreover, inclockwise direction SVV process was found to be significantly less accurate in dyslexic than in non-dyslexic group.Conclusion: These results suggest that the somesthesic information from foot sole affect SVV perception; such poorSVV responses could be due to an immaturity for heteromodal sensory integration needed in SVV perception.

Plantar cutaneous afferents influence the perception of Subjective Visual Vertical in quiet stance

The estimation of Subjective Visual Vertical (SVV) involves the allocentric, gravitational and egocentric references, which are built by visual, vestibular and somatosensory afferents. Our goals were to assess the influence of plantar cutaneous afferents on the perception of SVV, and to see if there is a difference according to the efficiency of plantar cutaneous afferents. We recruited 48 young and healthy subjects and assessed their SVV and postural performances in quiet stance with a force platform, at 40 or 200 cm, in four ground conditions: on firm ground, on foam, with a bilateral, or with a unilateral 3 mm arch support. We also assessed the efficiency of our subjects’ plantar afferents with the plantar quotient method and divided them in two groups: subjects with a normal use of plantar afferents and subjects with Plantar Exteroceptive Inefficiency (PEI). The results showed significant decreases in the counter clockwise SVV deviation only with the unilateral arch support, at near distance, and among the typically behaving subjects. We conclude that asymmetric foot cutaneous afferents are able to bias the egocentric vertical reference and hence influence the perception of SVV. This influence disappears among subjects with PEI, probably because of a distortion of the plantar signal.

Effect of Postural Control Demands on Early Visual Evoked Potentials during a Subjective Visual Vertical Perception Task in Adolescents with Idiopathic Scoliosis.

Subjective visual vertical (SVV) judgment and standing stability were separately investigated among patients with adolescent idiopathic scoliosis (AIS). Although, one study has investigated the central mechanism of stability control in the AIS population, the relationships between SVV, decreased standing stability, and AIS have never been investigated. Through event-related potentials (ERPs), the present study examined the effect of postural control demands (PDs) on AIS central mechanisms related to SVV judgment and standing stability to elucidate the time-serial stability control process. Thirteen AIS subjects (AIS group) and 13 age-matched adolescents (control group) aged 12–18 years were recruited. Each subject had to complete an SVV task (i.e., the modified rod-and-frame [mRAF] test) as a stimulus, with online electroencephalogram recording being performed in the following three standing postures: feet shoulder-width apart standing, feet together standing, and tandem standing. The behavioral performance in terms of postural stability (center of pressure excursion), SVV (accuracy and reaction time), and mRAF-locked ERPs (mean amplitude and peak latency of the P1, N1, and P2 components) was then compared between the AIS and control groups. In the behavioral domain, the results revealed that only the AIS group demonstrated a significantly accelerated SVV reaction time as the PDs increased. In the cerebral domain, significantly larger P2 mean amplitudes were observed during both feet shoulder-width-apart standing and feet together standing postures compared with during tandem standing. No group differences were noted in the cerebral domain. The results indicated that (1) during the dual-task paradigm, a differential behavioral strategy of accelerated SVV reaction time was observed in the AIS group only when the PDs increased and (2) the decrease in P2 mean amplitudes with the increase in the PD levels might be direct evidence of the competition for central processing attentional resources under the dual-task postural control paradigm.

Polarity-Dependent Misperception of Subjective Visual Vertical during and after Transcranial Direct Current Stimulation (tDCS).

Pathologic tilt of subjective visual vertical (SVV) frequently has adverse functional consequences for patients with stroke and vestibular disorders. Repetitive transcranial magnetic stimulation (rTMS) of the supramarginal gyrus can produce a transitory tilt on SVV in healthy subjects. However, the effect of transcranial direct current stimulation (tDCS) on SVV has never been systematically studied. We investigated whether bilateral tDCS over the temporal-parietal region could result in both online and offline SVV misperception in healthy subjects. In a randomized, sham-controlled, single-blind crossover pilot study, thirteen healthy subjects performed tests of SVV before, during and after the tDCS applied over the temporal-parietal region in three conditions used on different days: right anode/left cathode; right cathode/left anode; and sham. Subjects were blind to the tDCS conditions. Montage-specific current flow patterns were investigated using computational models. SVV was significantly displaced towards the anode during both active stimulation conditions when compared to sham condition. Immediately after both active conditions, there were rebound effects. Longer lasting after-effects towards the anode occurred only in the right cathode/left anode condition. Current flow models predicted the stimulation of temporal-parietal regions under the electrodes and deep clusters in the posterior limb of the internal capsule. The present findings indicate that tDCS over the temporal-parietal region can significantly alter human SVV perception. This tDCS approach may be a potential clinical tool for the treatment of SVV misperception in neurological patients.

Subjective visual and haptic vertical in young and elderly.

Perception of verticality can be assessed in two different ways: measuring of subjective visual vertical (SVV) and subjective haptic vertical (SHV). The evidence on aging of SVV and SVH is not conclusive and there is just little knowledge focused on this issue. The aim of this study was to compare accuracy of perception of SVV and SHV between groups of young and elderly healthy subjects. SVV examination was performed using the bucket test. An experimental tactile device was used to assess perceived SHV. Measurements of SVV and SHV were made in 27 young healthy and 30 elderly healthy subjects, both groups were right-handed due to self-report. SHV estimated position was significantly different (p< 0.01) in young and elderly (counterclockwise shift of 0.72 ± 3.70° and 3.51 ± 3.99°, respectively) and the SHV range (4.17 ± 5.40° and 9.64 ± 7.42°, respectively) was also different (p< 0.01). The differences were caused by significant difference in the supination maneuver (clockwise rod rotation, p< 0.001) which resulted in counterclockwise shift of 2.80 ± 4.90° and 8.33 ± 4.62° in young and elderly respectively. Pronation part of the SHV task (counterclockwise rod rotation) did not significantly differ between groups. SVV estimated position and range were not statistically different between young and elderly. These results provide evidence that the ability to detect SVV is not impaired, SHV seems also not to be affected by aging but there may be methodologic issues in SHV testing in elderly which should be controlled for in future studies. Results of both pronation and supination maneuvers should be provided along with SHV position.

Vestibular compensation following vestibular neurotomy

ObjectivesFour studies assessing vestibular compensation in Menière's disease patients undergoing unilateral vestibular neurotomy, using different analysis methods, are reviewed, with a focus on the different strategies used by patients according to their preoperative sensory preference. Material and methodsFour prospective studies performed in a university tertiary referral center were reviewed, measuring the pattern of vestibular compensation in Menière's disease patients before and after unilateral vestibular neurotomy on various assessment protocols: postural syndrome assessed on static posturography and gait analysis; perceptual syndrome assessed on subjective visual vertical perception; and oculomotor syndrome assessed on ocular cyclotorsion. ResultsVestibular compensation occurred at variable intervals depending on the parameter investigated. Open-eye postural control and gait/walking returned to normal one month after neurotomy. Fine balance analysis found that visual perception of the vertical and ocular cyclotorsion impairment persisted at long-term follow-up. Clinical postural disturbance persisted only when visual afferents were cut off (eyes closed). These impairments were the expression of a postoperative change in postural strategy related to the new use of visual and non-visual references. ConclusionsUnderstanding pre-operative interindividual variation in balance strategy is critical to screening for postural instability and tailoring vestibular rehabilitation.

The first attack of Ménière's disease: a study through SVV perception, clinical and pathogenetic implications.

This is a study of Subjective Visual Vertical (SVV) perception during acute attacks of Ménière's disease (MD) with comparative evaluation of concurrent nystagmus. We studied 21 patients with unilateral MD during the acute phase and 7 days later. Of the nine patients with an initial attack of MD, seven had an alteration of SVV perception and of these, three indicated a match with canal functional signs, while four patients showed an opposite trend of SVV perception relative to the spontaneous nystagmus. Nine of the 12 patients with definite MD had a pathological SVV perception always in correspondence with the same type of canal event. At 1-week control, no patient with an initial MD attack had alteration of SVV perception, whereas 5 patients with definite MD presented a pathological SVV perception toward the affected side. In the course of acute attacks of unilateral MD, clinical manifestations may include otolithic involvement and this may have an opposite trend compared to concomitant canal signs, especially during initial attacks. This behavior allows us to distinguish clinical signs of maculo-canal "correspondence" and "dissociation" with a significant prevalence of the second indication in those subjects with an initial MD attack.

Augmented asymmetrical visual field dependence in asymptomatic diabetics: Evidence of subclinical asymmetrical bilateral vestibular dysfunction

BackgroundDiabetes negatively affects the vestibular system in many ways, with vestibular dysfunction (VD), a co-morbidity with a high prevalence in diabetics. ProceduresThe ability to perceive subjective visual vertical (SVV), as a sign of vestibular dysfunction, and visual field dependence was measured using a computerized rod and frame test (CRAF). Alignment errors recorded from 47 asymptomatic Type II diabetics (no vertigo or falls, without peripheral neuropathy or retinopathy) were compared to 29 healthy age matched (46–69years) controls. FindingsVisual field dependence was significantly larger and more asymmetrical in the diabetics than controls. In the absence of any visual references, or when a vertical reference frame was provided, SVV perception was accurate in both groups, with no significant difference between the controls and diabetics. During tilted frame presentations, the proportion of subjects with either SVV deviations, or an asymmetry index, larger than an upper limit derived from the control data was significantly greater in diabetics than controls. ConclusionThese results suggest that the decreased ability to resolve visuo-vestibular conflict in asymptomatic diabetic patients (free of retinopathy and peripheral neuropathy) compared to controls may be related to diabetic complications affecting vestibular structures and thus causing a decompensation of subclinical vestibular asymmetries.

Effects of botulinum toxin treatment on subjective visual vertical perception in cervical dystonia

Effects of botulinum toxin treatment on subjective visual vertical perception in cervical dystonia

The effects of support-proprioceptive deprivation on visual-manual tracking and vestibular function

To determine the effects of support and proprioceptive afferentation on characteristics of the visual-manual tracking (VMT) we used a model of weightlessness - horizontal "dry" immersion. Altogether 30 subjects who stayed in immersion bath from 5 to 7 days were examined to evaluate the accuracy of VMT in tasks to pursue the jerky (saccadically) and smooth (linear, pendular and circular) movement of a point visual stimulus. Examinations were performed before, during and after immersion using electrooculography (to record eye movements) and a joystick (to record hand movements) with a biological visual feedback - one of the two visible stimuli on the screen matched the current angle of the joystick handle. Computerized visual stimulation programs were presented to subject using a virtual reality glasses. We analyzed time, amplitude and velocity characteristics of the visual and manual tracking (VT and MT), including efficiency ratio (eVT and eMT) and gain (gVT and gMT) as ratios of respectively amplitudes and velocities of eyes/hand movements to the stimulus movement. eVT was significantly decreased in comparison with baseline all the time while subject lied in the immersion bath and until R+4 day after immersion, eMT was significantly decreased only on I-1 and I-3 days in immersion. gVT significantly differed from baseline only on I-3 and I-6 days in immersion and R + 1 day after immersion. We found no significant changes in gMT. Evaluations of the vestibular function (VF) were performed before and after immersion using videooculography approach. We analyzed statical torsional otolith-cervical-ocular reflex (OCOR), dynamical vestibular-cervical-ocular reactions (VCOR), spontaneous eye movements (SpEM), the accuracy of perception of subjective visual vertical (SVV). After immersion 47% of subjects had significant decrease of OCOR with a simultaneous significant increase of VCOR on 37% of subjects as well as significant changes in accuracy of perception of SVV which correlated with changes in OCOR. We found correlation between characteristics of the VT and MT, between characteristics of the VF and VT and found no correlation between VF and MT. It was found that removal of the support and minimization of the proprioceptive afferentation has a greater impact upon accuracy of the VT then accuracy of the MT.

Subjective visual vertical perception in patients with vestibular neuritis and sudden sensorineural hearing loss

To determine the subjective visual vertical (SVV) perception in patients with vestibular neuritis (VN) and sudden sensorineural hearing loss (SSHL) using the SVV test and other neuro-otological examinations, namely, the vestibular evoked myogenic potential (VEMP) and caloric tests, and to clarify which vestibular nerve function is associated with an SVV shift. We performed the SVV test in 36 VN patients and 80 SSHL patients. Thereafter, we investigated directional changes in the SVV in the VN and SSHL patients, and compared the results of the SVV test with those of the VEMP and caloric tests. Abnormal SVV (> 2° was found at a rate of 69.4% in the VN patients and 26.3% in the SSHL patients. In all except 1 VN patient, the SVV tilted to the lesion side. The rate of abnormal SVV was significantly higher in patients with complete canal paresis (CP) than in patients with partial CP. There was no significant relationship between the rates of abnormal SVV and VEMP. In the SSHL patients, neither the SVV nor the VEMP affected the hearing outcome and patients with abnormal VEMP tended to show abnormal SVV. VN patients showed a higher rate of abnormal SVV than SSHL patients. From the results, it is speculated that the superior vestibular nerve function mainly affects the SVV tilt, although the inferior vestibular nerve function may also have an effect.

Subjective visual vertical perception and sense of smell in Parkinson disease

This article describes an open cross-sectional observational study involving 47 participants with Parkinson disease (PD) and 47 (age- and sex-matched) nondisabled controls without PD. The aim was to determine the profiles of subjective visual vertical (SVV) perception and sense of smell perception in both groups. There was a statistically significant difference (p < 0.001) between patients and controls on their smell test performance. Controls were more likely to correctly identify odors, with a median score of 10 out of 12 compared with 6.5 out of 12 for patients with PD. The median SVV error for the PD group when the frame was untilted was 0.75 degrees compared with 0.50 degrees for controls. This difference was statistically significant (p = 0.02). When the frame was tilted, the median SVV error for the PD group was 2.31 degrees compared with 2.00 degrees for controls (not statistically significant), with both groups showing similar distribution pattern of errors. There was no statistical correlation between number of correctly identified odors and an individual's SVV error. However, a statistically significant negative correlation (r = -0.45, p = 0.01) was found between Mini-Mental State Examination score and mean time taken to complete each rod and frame test in patients with PD, suggesting that SVV errors might be more correlated with cognitive function than with loss of sense of smell.

Influence of subjective visual vertical misperception on balance recovery after stroke

Background: Subjective visual vertical (SVV) perception can be perturbed after stroke, but its effect on balance recovery is not yet known. Aim: To evaluate the influence of SVV perturbations on...

Subjective Visual Vertical Perception Relates to Balance in Acute Stroke

Bonan IV, Guettard E, Leman MC, Colle FM, Yelnik AP. Subjective visual vertical perception relates to balance in acute stroke. Objective To determine whether misperception of the subjective visual vertical (SVV) underlies balance difficulties in hemiplegic patients. Design Descriptive study, using a convenience sample. Setting Department of physical medicine of a university hospital. Participants Thirty inpatients with hemiplegia after a hemispheric stroke during the 3 previous months. Interventions Not applicable. Main Outcome Measures The SVV was tested while subjects sat in a dark room and were asked to adjust a luminous line to the vertical position. Mean SVV deviation and uncertainty, defined as the standard deviation, were calculated for 8 trials. Balance was assessed by the Postural Assessment Scale for Stroke (PASS) and while patients sat on a laterally rocking platform placed on a Satel force platform. The mean body position and the instability score (Lx), calculated as the length of the course of the center of pressure, were recorded. Functional outcome was also evaluated by the FIM instrument. Results An abnormal SVV was recorded for 20 of 30 patients. Balance (ie, PASS, Lx) and FIM correlated significantly with SVV tilt ( P<.001, P=.01, and P<.001, respectively) and with uncertainty (PASS, P=.006; FIM, P=.003). Conclusions Verticality misperception was related to poor balance and might be an important element in the assessment of contributing factors to balance disorders after stroke. It should probably be taken into account when establishing balance rehabilitation programs for patients with hemiplegia.