Electrical Vestibular Stimulation Research Articles

Vestibular control of standing balance following 24h of sleep deprivation.

Sleep deprivation alters cognitive and sensorimotor function, but its effects on the control of standing balance are inconclusive. The vestibular system is critical for standing balance, and is modified by sleep deprivation; however, how sleep deprivation affects vestibular-evoked balance responses is unknown. Thus, this study aimed to examine the effect of 24h of sleep deprivation on the vestibular control of standing balance. During both a well-rested (i.e., control) and sleep deprivation condition, nine females completed two 90-s trials of bilateral, binaural stochastic electrical vestibular stimulation (EVS) and two 120-s trials of quiet stance on a force plate. Quiet stance performance was assessed by center of pressure displacement parameters. Mediolateral ground reaction force (ML force) and surface electromyography (EMG) of the right medial gastrocnemius (MG) were sampled simultaneously with the EVS signal to quantify vestibular control of balance within the frequency (gain and coherence) and time (cumulant density) domains. Twenty-four hours of sleep deprivation did not affect quiet stance performance. Sleep deprivation also had limited effect on EVS-MG EMG and EVS-ML Force coherence (less than control at 8-10.5Hz, greater at ~ 16Hz); however, gain of EVS-MG EMG (< 8, 11-24Hz) and EVS-ML force (0.5-9Hz) was greater for sleep deprivation than control. Sleep deprivation did not alter peak-to-peak amplitude of EVS-MG EMG (p = 0.51) or EVS-ML force (p = 0.06) cumulant density function responses. Despite no effect on quiet stance parameters, the observed increase in vestibular-evoked balance response gain suggests 24-h sleep deprivation may lead to greater sensitivity of the central nervous system when transforming vestibular-driven signals for standing balance control.

The effects of four hours of normobaric hypoxia on the vestibular control of balance.

Whole-body vestibular-evoked balance responses decrease following ~ 55min of normobaric hypoxia. It is unclear how longer durations of hypoxia affect the vestibular control of balance at the muscle and whole-body levels. This study examined how four hours of normobaric hypoxia influenced the vestibular control of balance. Fifteen participants (4 females; 11 males) stood on a force plate with vision occluded and head rotated rightward while subjected to three blocks of binaural, bipolar stochastic electrical vestibular stimulation (EVS; 0-25Hz, root mean square amplitude = 1.1mA) consisting of two, 90-s trials. The relationship between EVS and anteroposterior (AP) forces or medial gastrocnemius (MG) electromyography (EMG) was estimated in the time and frequency domains at baseline (BL; 0.21 fraction of inspired oxygen-FIO2) and following two (H2) and four (H4) hours of normobaric hypoxia (0.11 FIO2). The EVS-MG EMG short-latency peak and peak-to-peak amplitudes were smaller than BL at H2 and H4, but the medium-latency peak amplitude was only lower at H4. The EVS-AP force medium-latency peak amplitude was lower than BL at H4, but the short-latency peak and peak-to-amplitudes were unchanged. The EVS-MG EMG coherence and gain were reduced compared to BL at H2 and H4 across multiple frequencies ≥ 7Hz, whereas EVS-AP force coherence was blunted at H4 (≤ 4Hz), but gain was unaffected. Overall, the central nervous system's response to vestibular-driven signals during quiet standing wasdecreased forup to four hours of normobaric hypoxia, and vestibular-evoked responses recorded within postural muscles may be more sensitive than the whole-body response.

In vivo and dosimetric investigation on electrical vestibular stimulation with frequency- and amplitude-modulated currents

Objective. Normal function of the vestibular system can be disturbed using a noninvasive technique called electrical vestibular stimulation (EVS), which alters a person's sense of balance and causes false sensations of movement. EVS has been widely used to study the function of the vestibular system, and it has recently gained interest as a therapeutic tool to improve postural stability and help those suffering from vestibular dysfunction. Yet, understanding of how EVS stimulates the vestibular system, the current intensity needed to produce an effect and the frequencies at which it occurs have remained unclear.Approach. The effect of EVS on postural sway was examined in five participants using sinusoidal alternating current with time-varying amplitude from 0 to 1.5 mA and frequency from 0.1 to 10 Hz for three electrode configurations. Dosimetry of the current flow inside the head was conducted using anatomically realistic computational models created individually for each subject based on magnetic resonance imaging data. An estimate for the minimal field strength capable of affecting the vestibular system was calculated with the finite element method.Main results. Bipolar EVS at frequencies up to 10 Hz caused harmonic full-body swaying, and the frequency of the sway was the same as that of the stimulation current. The size of the sway was amplified by increasing the current intensity. Dosimetry modeling indicated that, for 0.2 mA current, the average electric field strength in the vestibular system was approximately 10-30 mV m-1, depending on the electrode montage. The size of the measured postural sway was proportional to the montage-specific electric field strength in the vestibular system.Significance. The results provide insight to EVS's working mechanisms and improve its potential as a tool to study the sense of balance.

Repeated electrical vestibular nerve stimulation (VeNS) reduces severity in moderate to severe insomnia; a randomised, sham-controlled trial; the modius sleep study

BackgroundInsomnia is a prevalent health concern in the general population associated with a range of adverse health effects. New, effective, safe and low-cost treatments, suitable for long-term use, are urgently required. Previous studies have shown the potential of electrical vestibular nerve stimulation (VeNS) in improving insomnia symptoms, however only one sham-controlled trial has been conducted on people with chronic insomnia. Objectives/HypothesisRepeated VeNS delivered by the Modius Sleep device prior to sleep onset will show superior improvement in Insomnia Severity Index (ISI) scores over a 4-week period compared to sham stimulation. MethodsIn this double-blinded, multi-site, randomised, sham-controlled study, 147 participants with moderate to severe insomnia (ISI≥15) were recruited and allocated a VeNS or a sham device (1:1 ratio) which they were asked to use at home for 30 min daily (minimum 5 days per week) for 4 weeks. ResultsAfter 4 weeks, mean ISI score reduction was 2.26 greater in the VeNS treatment group than the sham group (p = 0.002). In the per protocol analysis, the treatment group had a mean ISI score decrease of 5.8 (95 % CI [-6.8, −4.81], approaching the clinically meaningful threshold of a 6-point reduction, with over half achieving a clinically significant decrease. Furthermore, the treatment group showed superior improvement to the sham group in the SF-36 (Quality of Life) energy/fatigue component (PP p = 0.004, effect size 0.26; ITT p = 0.006, effect size 0.22). ConclusionsModius sleep has the potential to provide a viable, non-invasive and safe clinically meaningful alternative treatment option for insomnia.

Bed rest impairs the vestibular control of balance.

Prolonged bed rest impairs standing balance but the underlying mechanisms are uncertain. Previous research suggests strength loss is not the cause, leaving impaired sensorimotor control as an alternative. Here we examine vestibular control of posture in 18male volunteers before and after 60days of bed rest. Stochastic vestibular stimulation (SVS) was used to evoke sway responses before, 1 and 6days after bed rest under different head yaw orientations. The directional accuracy and precision of these responses were calculated from ground reaction force vectors. Bed rest caused up to 63% increases in spontaneous standing sway and 31% reductions in leg strength, changes which were uncorrelated. The increase in sway was exacerbated when the eyes were closed. Mean directions of SVS-evoked sway responses were unaffected, being directed towards the anodal ear and rotating in line with head orientation in the same way before and after bed rest. However, individual trial analysis revealed 25%-30% increases in directional variability, which were significantly correlated with the increase in spontaneous sway (r=0.48-0.71; P≤0.044) and were still elevated on day 6 post-bed rest. This reveals that individual sway responses may be inappropriately oriented, a finding masked by the averaging process. Our results confirm that impaired balance following prolonged bedrest is not related to loss of strength. Rather, they demonstrate that the sensorimotor transformation process which converts vestibular feedback into appropriately directed balance responses is impaired. KEY POINTS: Prolonged inactivity impairs balance but previous research suggests this is not caused by loss of strength. Here we investigated vestibular control of balance before and after 60days of bed rest using electrical vestibular stimulation (EVS) to evoke sway responses. Spontaneous sway significantly increased and muscle strength reduced following bed rest, but, in keeping with previous research, these two effects were not correlated. While the overall accuracy of EVS-evoked sway responses was unaffected, their directional variability significantly increased following bed rest, and this was correlated with the increases in spontaneous sway. We have shown that the ability to transform head-centred vestibular feedback into an appropriately directed body sway response is negatively affected by prolonged inactivity; this may contribute to the impaired balance commonly observed following bed rest.

Vertebral level specific modulation of paraspinal muscle activity based on vestibular signals during walking.

Evoking muscle responses by electrical vestibular stimulation (EVS) may help to understand the contribution of the vestibular system to postural control. Although paraspinal muscles play a role in postural stability, the vestibulo-muscular coupling of these muscles during walking has rarely been studied. This study aimed to investigate how vestibular signals affect paraspinal muscle activity at different vertebral levels during walking with preferred and narrow step width. Sixteen healthy participants were recruited. Participants walked on a treadmill for 8min at 78steps/min and 2.8 km/h, at two different step width, either with or without EVS. Bipolar electromyography was recorded bilaterally from the paraspinal muscles at eight vertebral levels from cervical to lumbar. Coherence, gain, and delay of EVS and EMG responses were determined. Significant EVS-EMG coupling (P < 0.01) was found at ipsilateral and/or contralateral heel strikes. This coupling was mirrored between left and right relative to the midline of the trunk and between the higher and lower vertebral levels, i.e. a peak occurred at ipsilateral heel strike at lower levels, whereas it occurred at contralateral heel strike at higher levels. EVS-EMG coupling only partially coincided with peak muscle activity. EVS-EMG coherence slightly, but not significantly, increased when walking with narrow steps. No significant differences were found in gain and phase between the vertebral levels or step width conditions. In summary, vertebral level specific modulation of paraspinal muscle activity based on vestibular signals might allow a fast, synchronized, and spatially co-ordinated response along the trunk during walking. KEY POINTS: Mediolateral stabilization of gait requires an estimate of the state of the body, which is affected by vestibular afference. During gait, the heavy trunk segment is controlled by phasic paraspinal muscle activity and in rodents the medial and lateral vestibulospinal tracts activate these muscles. To gain insight in vestibulospinal connections in humans and their role in gait, we recorded paraspinal surface EMG of cervicalto lumbar paraspinal muscles, and characterized coherence, gain and delay between EMG and electrical vestibular stimulation, during slow walking. Vestibular stimulation caused phasic, vertebral level specific modulation of paraspinal muscle activity at delays of around 40ms, which was mirrored between left, lower and right, upper vertebral levels. Our results indicate that vestibular afference causesfast, synchronized, and spatially co-ordinated responses of the paraspinal muscles along the trunk, that simultaneously contribute to stabilizing the centre of mass trajectory and to keeping the head upright.

Vestibular control of deep and superficial lumbar muscles.

The active control of the lumbar musculature provides a stable platform critical for postures and goal-directed movements. Voluntary and perturbation-evoked motor commands can recruit individual lumbar muscles in a task-specific manner according to their presumed biomechanics. Here, we investigated the vestibular control of the deep and superficial lumbar musculature. Ten healthy participants were exposed to noisy electrical vestibular stimulation while balancing upright with their head facing forward, left, or right to characterize the differential modulation in the vestibular-evoked lumbar extensor responses in generating multidirectional whole body motion. We quantified the activation of the lumbar muscles on the right side using indwelling [deep multifidus, superficial multifidus, caudal longissimus (L4), and cranial longissimus (L1)] and high-density surface recordings. We characterized the vestibular-evoked responses using coherence and peak-to-peak cross-covariance amplitude between the vestibular and electromyographic signals. Participants exhibited responses in all lumbar muscles. The vestibular control of the lumbar musculature exhibited muscle-specific modulations: responses were larger in the longissimus (combined cranio-caudal) compared with the multifidus (combined deep-superficial) when participants faced forward (P < 0.001) and right (P = 0.011) but not when they faced left. The high-density surface recordings partly supported this observation: the location of the responses was more lateral when facing right compared with left (P < 0.001). The vestibular control of muscle subregions within the longissimus or the multifidus was similar. Our results demonstrate muscle-specific vestibular control of the lumbar muscles in response to perturbations of vestibular origin. The lack of differential activation of lumbar muscle subregions suggests the vestibular control of these subregions is co-regulated for standing balance.NEW & NOTEWORTHY We investigated the vestibular control of the deep and superficial lumbar extensor muscles using electrical vestibular stimuli. Vestibular stimuli elicited preferential activation of the longissimus muscle over the multifidus muscle. We did not observe clear regional activation of lumbar muscle subregions in response to the vestibular stimuli. Our findings show that the central nervous system can finely tune the vestibular control of individual lumbar muscles and suggest minimal regional variations in the activation of lumbar muscle subregions.

Real-world characterization of vestibular contributions during locomotion.

The vestibular system, which encodes our head movement in space, plays an important role in maintaining our balance as we navigate the environment. While in-laboratory research demonstrates that the vestibular system exerts a context-dependent influence on the control of balance during locomotion, differences in whole-body and head kinematics between indoor treadmill and real-world locomotion challenge the generalizability of these findings. Thus, the goal of this study was to characterize vestibular-evoked balance responses in the real world using a fully portable system. While experiencing stochastic electrical vestibular stimulation (0-20 Hz, amplitude peak ± 4.5 mA, root mean square 1.25 mA) and wearing inertial measurement units (IMUs) on the head, low back, and ankles, 10 participants walked outside at 52 steps/minute (∼0.4 m/s) and 78 steps/minute (∼0.8 m/s). We calculated time-dependent coherence (a measure of correlation in the frequency domain) between the applied stimulus and the mediolateral back, right ankle, and left ankle linear accelerations to infer the vestibular control of balance during locomotion. In all participants, we observed vestibular-evoked balance responses. These responses exhibited phasic modulation across the stride cycle, peaking during the middle of the single-leg stance in the back and during the stance phase for the ankles. Coherence decreased with increasing locomotor cadence and speed, as observed in both bootstrapped coherence differences (p < 0.01) and peak coherence (low back: 0.23 ± 0.07 vs. 0.16 ± 0.14, p = 0.021; right ankle: 0.38 ± 0.12 vs. 0.25 ± 0.10, p < 0.001; left ankle: 0.33 ± 0.09 vs. 0.21 ± 0.09, p < 0.001). These results replicate previous in-laboratory studies, thus providing further insight into the vestibular control of balance during naturalistic movements and validating the use of this portable system as a method to characterize real-world vestibular responses. This study will help support future work that seeks to better understand how the vestibular system contributes to balance in variable real-world environments.

Effects of a short period of postural training on postural stability and vestibulospinal reflexes.

The effects of postural training on postural stability and vestibulospinal reflexes (VSRs) were investigated in normal subjects. A period (23 minutes) of repeated episodes (n = 10, 50 seconds) of unipedal stance elicited a progressive reduction of the area covered by centre of pressure (CoP) displacement, of average CoP displacement along the X and Y axes and of CoP velocity observed in this challenging postural task. All these changes were correlated to each other with the only exception of those in X and Y CoP displacement. Moreover, they were larger in the subjects showing higher initial instability in unipedal stance, suggesting that they were triggered by the modulation of sensory afferents signalling body sway. No changes in bipedal stance occurred soon and 1 hour after this period of postural training, while a reduction of CoP displacement was apparent after 24 hours, possibly due to a beneficial effect of overnight sleep on postural learning. The same period of postural training also reduced the CoP displacement elicited by electrical vestibular stimulation (EVS) along the X axis up to 24 hours following the training end. No significant changes in postural parameters of bipedal stance and VSRs could be observed in control experiments where subjects were tested at identical time points without performing the postural training. Therefore, postural training led to a stricter control of CoP displacement, possibly acting through the cerebellum by enhancing feedforward mechanisms of postural stability and by depressing the VSR, the most important reflex mechanism involved in balance maintenance under challenging conditions.

0394 Effect of electrical vestibular nerve stimulation on sleep quality in young adults with insomnia: a randomized controlled trial

Abstract Introduction Insomnia is a common sleep disorder among all age groups which adversely affects physical and mental health. Young adults are considered a high-risk population group due to increased use of electronic media at bedtime, stress associated with balancing educational demands and unhealthy sleep practices. Previous research suggests that electrical vestibular nerve stimulation (VeNS) may improve sleep outcomes by influencing the hypothalamus and brainstem nuclei involved in regulating the circadian rhythm and wakefulness. The present study is a randomised, double blinded, sham-controlled trial with the aim of assessing the efficacy of VeNS on the sleep quality of young adults suffering from insomnia. Methods Eighty adults aged 18-24 years who scored 15 or higher on the Insomnia Severity Index (ISI) were recruited. Participants assigned to the intervention group (n=40) received 30 minutes per day of VeNS with 5 sessions per week for 4 weeks, while the control group (n=40) received sham stimulation for the same period. ISI scores were recorded at baseline and repeated weekly. The primary outcome was between-group change in ISI from baseline to day 28. Secondary outcomes included between-group change in the emotional states of depression, anxiety and stress measured by the DASS-21 questionnaire, and quality of life (QoL) measured by the WHOQoL-BREF. Results A group-by-time interaction effect on change in ISI score from day 0 to day 28 (F3, 248 = 295.56; P&amp;lt; 0.001) was observed. The intervention group had a higher reduction in mean ISI score relative to the control group at day 28 (mean change [95% CI]: 7.23 [6.78, 7.67] vs. 0.98 [0.89, 1.06], P&amp;lt; 0.001; respectively). Furthermore, the intervention group showed improvements in depression, anxiety, and stress scores (P&amp;lt; 0.001) and QoL outcomes (P&amp;lt; 0.001) compared with the control group. Conclusion Regular VeNS usage over 4 weeks lead to a clinically meaningful decrease in ISI scores and improved general well-being in young adults with insomnia. VeNS may have potential as a drug-free and non-invasive therapy to improve sleep outcomes. Support (if any)

0396 Efficacy of electrical vestibular nerve stimulation for the management of insomnia: a randomized controlled trial

Abstract Introduction Insomnia is one of the most prevalent health concerns in the general population. Cognitive behavioural therapy (CBT) and pharmacological interventions are recommended for the treatment of insomnia. However, CBT can be expensive and difficult to access, while the use of pharmacotherapy can be limited by reports of adverse events. Due to these limitations, there is a strong need for alternative measures to manage insomnia. Preliminary research indicates the potential that electrical vestibular nerve stimulation (VeNS) has as a non-invasive method for managing insomnia. The aim of this study is to evaluate the efficacy of VeNS as a method of managing sleep quantity and quality in individuals with insomnia, as compared to a sham control. Methods The study was a two-armed, double-blind randomized controlled trial that was conducted across two research sites in the United Kingdom (UK) and Hong Kong (HK). Participants aged over 18 years with an Insomnia Severity Index (ISI) score of 15 or higher were randomly assigned to intervention and control groups. The intervention group was instructed to use the VeNS device at home for 30 minutes daily for 4 weeks, while the control group was instructed to use the sham device for the same period. ISI values were captured at baseline, at 2 weeks and at 4 weeks. Sleep quality and quality of life (QoL) were assessed at baseline and at 4 weeks using the Pittsburgh Sleep Quality Index (PSQI) and the 36-item Short Form Health Survey (SF-36), respectively. Results A total of 146 participants were recruited from the HK (n=94) and UK (n=52) research sites. The study has recently been completed with the statistical analysis ongoing. The between-group change in ISI values (primary outcome), sleep quality and QoL from baseline to week 4 will be examined. Conclusion The results of this study will help determine whether the relatively inexpensive, and non-invasive technique of VeNS is effective in the management of insomnia. The data collected will be used to support regulatory submissions, primarily to the US Food and Drug Administration. Support (if any)

A randomized controlled trial to evaluate the efficacy of electrical vestibular nerve stimulation (VeNS), compared to a sham control for the management of sleep in young adults.

Preliminary research suggests that electrical vestibular nerve stimulation (VeNS) may improve sleep outcomes by influencing the hypothalamus and brainstem nuclei involved in regulating the circadian rhythm and wakefulness. This randomised, sham-controlled trial aimed to assess the effectiveness of VeNS on insomnia in young adults. Eighty adults aged 18-24 years were randomly allocated to the intervention (n=40) and control groups (n=40). The intervention group was provided with 30min per day of VeNS with five sessions weekly for four weeks, while the control group received sham stimulation for the same period. Baseline Insomnia Sleep Index (ISI) scores were recorded weekly. At baseline and at day 28, questionnaires to evaluate emotional states of depression, anxiety and stress, and quality of life (QoL) were completed. The primary outcome was change in ISI with comparison between baseline and day 28. The VeNS group significantly reduced their mean ISI score after 7days usage (p<0.001). At day 28 it was found that mean ISI scores had reduced from 19 to 11 in the VeNS group, and from 19 to 18 in the sham group, and the difference between the groups was significant (p<0.001). Moreover, application of VeNS appeared to significantly improve emotional state and QoL outcomes. This trial demonstrates that regular VeNS usage over four weeks leads to a clinically meaningful decrease in ISI scores in young adults with insomnia. VeNS may have potential as a drug-free and non-invasive therapy to improve sleep outcomes by positively influencing the hypothalamic and brainstem nuclei.

The effects of acute normobaric hypoxia on vestibular-evoked balance responses in humans.

Hypoxia influences standing balance and vestibular function. The purpose here was to investigate the effect of hypoxia on the vestibular control of balance. Twenty participants (10 males; 10 females) were tested over two days (normobaric hypoxia and normoxia). Participants stood on a force plate (head rotated leftward) and experienced random, continuous electrical vestibular stimulation (EVS) during trials of eyes open (EO) and closed (EC) at baseline (BL), after 5 (H1), 30 (H2) and 55-min (H3) of hypoxia, and 10-min into normoxic recovery (NR). Vestibular-evoked balance responses were quantified using cumulant density, coherence, and gain functions between EVS and anteroposterior forces. Oxyhemoglobin saturation, end-tidal oxygen and carbon dioxide decreased for H1-3 compared to BL; however, end-tidal carbon dioxide remained reduced at NR with EC (p≤0.003). EVS-AP force peak-to-peak amplitude was lower at H3 and NR than at BL (p≤0.01). At multiple frequencies, EVS-AP force coherence and gain estimates were lower at H3 and NR than BL for females; however, this was only observed for coherence for males. Overall, vestibular-evoked balance responses are blunted following normobaric hypoxia >30 min, which persists into NR and may contribute to the reported increases in postural sway.

Evaluating the Efficacy of Electrical Vestibular Stimulation (VeNS) on Insomnia Adults: Study Protocol of a Double-Blinded, Randomized, Sham-Controlled Trial.

Insomnia is a common health problem in the general population. There are different ways to improve sleeping habits and quality of sleep; however, there is no clinical trial using transdermal neurostimulation to treat individuals with symptoms of insomnia in Asia. This gives us the impetus to execute the first study in Asia which aims to evaluate the efficacy of Electrical Vestibular Stimulation (VeNS) on individuals with insomnia in Hong Kong. This study proposes a two-armed, double-blinded, randomized, sham-controlled trial including the active VeNS and sham VeNS group. Both groups will be measured at baseline (T1), immediately after the intervention (T2), and at the 1-month (T3) and 3-month follow-up (T4). A total of 60 community-dwelling adults aged 18 to 60 years, with insomnia symptoms will be recruited in this study. All subjects will be computer randomized into either the active VeNS group or the sham VeNS group on a 1:1 ratio. All subjects in each group will receive twenty 30-min VeNS sessions during weekdays, which will be completed in a 4-week period. Baseline measurements and post-VeNS evaluation of the psychological outcomes (i.e., insomnia severity, sleep quality and quality of life) will also be conducted on all participants. The 1-month and 3-month follow-up period will be used to assess the short-and long-term sustainability of the VeNS intervention. For statistical analysis, a mixed model will be used to analyze the repeated measures data. Missing data will be managed by multiple imputations. The level of significance will be set to p < 0.05. Significance of the study: The results of this study will be used to determine whether this VeNS device can be considered as a self-help technological device to reduce the severity of insomnia in the community setting. We registered this clinical trial with the Clinical trial government, identifier: NCT04452981.

A randomized controlled clinical trial to evaluate the efficacy of electrical vestibular stimulation, compared to a sham control for the modulation of neurotransmitters in patients with Parkinson’s disease

Background: The existing treatments for PD were associated with side effects and does not offer complete cure. Hence there is a need of alternative therapy which can prevent or delay the onset of PD with less or no side effects. Aim and objective: The overall objective of the present study was to assess the effectiveness of electrical vestibular nerve stimulation in the management of Parkinson’s disease. Materials and methods: 60 cases with PD, including both males and females, were recruited in the study by convenient sampling after obtaining written and informed consent. They were randomly grouped with 30 participants in each group. Control group received sham stimulation and the intervention group received electrical vestibular nerve stimulation for 12 weeks. After recording the baseline biochemical parameters, post intervention assessment was performed after 6 weeks and 12 weeks of intervention and compared. Results: Demographic variables were not statistically significant among the control and intervention groups. There was a significant increase in the dopamine and GABA levels followed by the intervention. Conclusion: The present study results support the positive impact of non-invasive electrical vestibular nerve stimulation in modulating neurotransmitters in patients with Parkinson’s disease. A further detailed translational study is required in this area with a larger sample size to generalize the results.

Effects of vestibular stimulation on gait stability when walking at different step widths.

Vestibular information modulates muscle activity during gait, presumably to contribute to stability. If this is the case, stronger effects of perturbing vestibular information on local dynamic stability of gait, a measure of the locomotor system's response to small, naturally occurring perturbations, can be expected for narrow-base walking (which needs more control) than for normal walking and smaller effects for wide-base walking (which needs less control). An important mechanism to stabilize gait is to coordinate foot placement to center of mass (CoM) state. Vestibular information most likely contributes to sensing this CoM state. We, therefore, expected that stochastic electrical vestibular stimulation (EVS) would decrease the correlation between foot placement and CoM state during the preceding swing phase. In 14 healthy participants, we measured the kinematics of the trunk (as a proxy of the CoM), and feet, while they walked on a treadmill in six conditions: control (usual step width), narrow-base, and wide-base, each with and without stochastic EVS (peak amplitude of 5mA; RMS of ~ 1.2mA; frequency band from 0 to 25Hz). Stochastic EVS decreased local dynamic stability irrespective of step width. Foot placement correlated stronger with trunk motion during walking with EVS than without in the control condition. However, residual variance in foot placement was increased when walking with EVS, indicating less precise foot placement. Thus, a vestibular error signal leads to a decrease in gait stability and precision of foot placement, but these effects are not consistently modulated by step width.

Effectiveness of 12 weeks of electrical vestibular nerve stimulation in the management of obesity: A pilot study

Background: It was hypothesized that electrical vestibular nerve stimulation (VeNs) was an effective therapy in the management of obesity. Aims and Objectives: The present pilot study was undertaken to observe the efficacy of 12-week electrical VeNs in the management of obesity. Materials and Methods: As this is a pilot study, a total of ten obese male and female participants were recruited after obtaining written, informed consent. After recording the baseline values, electrical VeNs was administered as an intervention for 12 weeks. The post-interventional assessment was done after 12 weeks. Results: There was a significant decrease in the serum cholesterol, VLDL, and HbA1C followed by the vestibular stimulation for 12 weeks. Although the body weight was decreased, it was not statistically significant. Conclusion: The present pilot study results support the positive impact of electrical VeNs in the management of obesity. Further, detailed studies with higher sample size were recommended to provide adequate scientific evidence to adopt electrical VeNs as an alternative therapy for the management of obesity.

A randomized, controlled, and clinical trial to evaluate the efficacy of electrical vestibular stimulation, compared to a sham control for the management of sleep and autonomic parameters in patients with Parkinson’s disease

Background: Electrical vestibular nerve stimulation (VeNs) was simple, non-invasive, and can administer the stimulus in a controlled manner. The studies related to the application of electrical VeNs in the management of sleep and autonomic parameters were sparse in the Indian population. Aims and Objectives: The present study was undertaken to observe the effectiveness of electrical VeNs in the management of sleep and autonomic parameters in patients with Parkinson’s disease (PD). Materials and Methods: Thirty cases of PD, both the genders, were recruited in the study by convenient sampling after obtaining written informed consent. After recording baseline parameters of Insomnia Severity Index (ISI), systolic and diastolic blood pressure (DBP), and pulse rate, electrical VeNs was administered to the intervention group and placebo stimulation was administered to the control group for 12 weeks. Post-intervention parameters were recorded after 6 weeks and after 12 weeks after the intervention in both control and intervention groups. Results: There was a significant decrease in the ISI scores, pulse rate, and systolic blood pressure after the intervention in the participants of the intervention group. DBP was decreased but was not statistically significant. There was no significant difference in the ISI scores, pulse rate, and systolic and DBP before and after the intervention in the participants of the control group. Conclusion: The present study results support the improvement of sleep followed by electrical VeNs. The study recommends detailed studies in this area to support the incorporation of electrical VeNs in the management strategy of PD.

The influence of reduced foot dorsum cutaneous sensitivity on the vestibular control of balance.

Foot sole cooling increases vestibular-evoked balance responses, but less is known about foot dorsum temperature alterations. The purpose was to determine whether decreasing cutaneous receptor sensitivity via foot dorsum cooling modulates the vestibular control of balance. Eighteen participants (9 males; 9 females) stood quietly on a force plate with feet together, eyes closed, and head rotated leftward during 4, 90-s trials (2 control; 2 cooled) of continuous electrical vestibular stimulation (EVS). Icepacks placed on the dorsum of both feet for 15min induced cooling and remained throughout the EVS trials. Monofilament testing was performed at multiple locations before and after cooling to determine tactile detection thresholds. T-type thermocouples monitored skin temperature over the tibialis anterior, soleus, foot dorsum and arch of the right leg. Vestibular-evoked balance responses were characterized using time (cumulant density) and frequency (coherence and gain) domain analyses to determine the relationship between the EVS input and motor output (anteroposterior force-AP force; right medial gastrocnemius electromyography-MG EMG). Skin temperature of the foot dorsum and arch decreased ~ 70 and 15%, respectively during cooling (p < 0.05), but was unaltered at other locations (p ≥ 0.10). Detection thresholds for the foot dorsum increased following cooling (p < 0.05). Surprisingly, cooling reduced EVS-AP force and EVS-MG EMG coherence and gain at multiple frequencies, and peak-to-peak amplitude compared to control (p < 0.05). Our results indicate that vestibular-driven balance responses are reduced following foot dorsum cooling, likely owing to alterations in cutaneous mechanoreceptor sensitivity and subsequent alterations in the transformation of vestibular cues for balance control.

Effectiveness of electrical vestibular nerve stimulation as adjunctive therapy to improve the cognitive functions in patients with Parkinson's disease.

The present study was undertaken to observe the effectiveness of electrical vestibular stimulation in improving cognitive functions in patients with Parkinson's disease. Randomized controlled trial (ClinicalTrials.gov Identifier: NCT04450550). 30 cases of PD, including both males and females were recruited in the study by convenient sampling after obtaining written informed consent. After recruiting, the participants were randomly assigned into two groups. The control group (n=15) received placebo stimulation whereas the intervention group (n=15) received electrical vestibular stimulation administered for 12weeks. Auditory, visual reaction time and spatial and verbal memory were recorded before and after 6weeks and after 12weeks of intervention and compared. There was a significant improvement in both auditory and visual reaction time of right and left-hand responses. Also, significant improvement was observed in both the spatial and verbal memory of the patients. There was a significant improvement in the auditory and visual reaction time and spatial and verbal memory in the participants after the electrical vestibular nerve stimulation administration. No side effects were reported by the study participants and they have expressed willingness to continue the intervention after the study period also. The study recommends further detailed studies with a higher sample size to adopt electrical vestibular nerve stimulation as adjunctive therapy in the management of Parkinson's disease.