Double-Blind Sham-Controlled Crossover Trial of Repetitive Transcranial Magnetic Stimulation for Mal de Debarquement Syndrome

Vestibular dysfunction in Parkinson's disease: a neglected topic

Dizziness and postural instability are frequently observed symptoms in patient with Parkinson's disease (PD), potentially linked to vestibular dysfunction. Despite their significant impact on quality of life, these symptoms are often overlooked and undertreated in clinical practice. This review aims to summarize symptoms associated with vestibular dysfunction in patients with PD and discusses vestibular-targeted therapies for managing non-specific dizziness and related symptoms. We conducted searches in PubMed and Web of Science using keywords related to vestibular dysfunction, Parkinson's disease, dizziness, and postural instability, alongside the reference lists of relevant articles. The available evidence suggests the prevalence of vestibular dysfunction-related symptoms in patients with PD and supports the idea that vestibular-targeted therapies may be effective in improving PD symptoms.

Assessing the synergistic effectiveness of intermittent theta burst stimulation and the vestibular ocular reflex rehabilitation protocol in the treatment of Mal de Debarquement Syndrome: a randomised controlled trial

INTRODUCTION

Mal de Debarquement Syndrome (MdDS) is a rare central vestibular disorder characterised by a constant sensation of motion (rocking, swaying, bobbing), which typically arises after motion experiences (e.g. sea, air, and road travel), though can be triggered by non-motion events. The current standard of care is non-specific medications and interventions that only result in mild-to-moderate improvements. The vestibular ocular reflex (VOR) rehabilitation protocol, a specialised form of rehabilitation, has shown promising results in reducing symptoms amongst people with MdDS. Accumulating evidence suggests that it may be possible to augment the effects of VOR rehabilitation via non-invasive brain stimulation protocols, such as theta burst stimulation (TBS).

METHODS

The aim of this randomised controlled trial was to evaluate the effectiveness of intermittent TBS (iTBS) over the dorsolateral prefrontal cortex in enhancing the effectiveness of a subsequently delivered VOR rehabilitation protocol in people with MdDS. Participants were allocated randomly to receive either Sham (n = 10) or Active (n = 10) iTBS, followed by the VOR rehabilitation protocol. Subjective outcome measures (symptom ratings and mental health scores) were collected 1 week pre-treatment and for 16 weeks post-treatment. Posturography (objective outcome) was recorded each day of the treatment week.

RESULTS

Significant improvements in subjective and objective outcomes were reported across both treatment groups over time, but no between-group differences were observed.

DISCUSSION

These findings support the effectiveness of the VOR rehabilitation protocol in reducing MdDS symptoms. Further research into iTBS is required to elucidate whether the treatment has a role in the management of MdDS. TRN: ACTRN12619001519145 (Date registered: 04 November 2019).

Symptom reduction in mal de débarquement syndrome with attenuation of the velocity storage contribution in the central vestibular pathways

Background

The velocity storage mechanism of the central vestibular system is closely associated with the vestibulo-ocular reflex (VOR), but also contributes to the sense of orientation in space and the perception of self-motion. We postulate that mal de débarquement syndrome (MdDS) is a consequence of inappropriate sensory adaptation of velocity storage. The premise that a maladapted velocity storage may be corrected by spatial readaptation of the VOR has recently been translated into the development of the first effective treatment for MdDS. However, this treatment's initial impact may be reversed by subsequent re-triggering events. Presently, we hypothesized that MdDS symptoms could alternatively be reduced by attenuating the velocity storage contribution in the central vestibular pathways.

Methods

Forty-three patients with MdDS (aged 47 ± 14 yo; 36 women) were randomly assigned to two treatment groups and followed for 6 months. The horizontal VOR was tested with chair rotation during laboratory visits, and the strength of velocity storage was quantified with model-based parameters-the time constant (Tc) and the gain of coupling from the vestibular primary afferent signals (g0). To attenuate velocity storage, Group 1 underwent a progressively intensifying series of low-frequency earth-vertical oscillatory rotation coupled to conflicting visual stimuli. Group 2 underwent an established protocol combining head tilts and visual stimulation, designed to correct maladapted spatial orientation but not change the velocity storage strength. The symptom severity was self-rated on an 11-point scale and reported before and up to 6 months after the treatment.

Results

In Group 1, velocity storage was modified through reduction of g0 (p < 0.001) but not Tc. The symptom rating was at least halved initially in 43% of Group 1 (p = 0.04), the majority of whom retained a similar level of improvement during the 6-month follow-up period. In Group 2, no systematic change was induced in the parameters of velocity storage strength, as expected. The symptom rating was at least halved initially in 80% of Group 2 (p < 0.001), but paralleling previous findings, symptoms often returned subsequently.

Conclusion

Attenuation of velocity storage shows promise as a lasting remedy for MdDS that can complement the VOR readaptation approach.

Treatment Options in Mal de Débarquement Syndrome: A Scoping Review

OBJECTIVE

The purpose of this study was to review current treatment options available for mal de debarquement syndrome (MdDS).

DATA SOURCES

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Review guidelines, we performed systematic search queries for MdDS-related texts. Documents must have been in the English language, and the time frame was all documents up until May 23, 2022.

METHODS

Studies were selected if they were published in a peer-reviewed journal and if one of the primary objectives was the assessment of treatment for MdDS. The quality and validity of all documents were assessed by two independent co-investigators. Conflicts were resolved by a third investigator.

RESULTS

One hundred ninety-four unique references were identified and underwent review. Ninety-seven were selected for full-text review, and 32 studies were ultimately included. Data were stratified by treatment methodology for MdDS. The categories used were pharmacologic, physical therapy, and neuromodulating stimulation.

CONCLUSIONS

Improvement in patient-reported outcomes is reported with several treatment modalities including specific protocols of vestibular rehabilitation, neuromodulating stimulation, and pharmacologic management with several types of neurotropic drugs.

Treatment of Mal de Debarquement Syndrome in an Audiology-Vestibular Clinic

BACKGROUND

 Mal de Debarquement Syndrome (MdDS) has a stereotypical presentation of symptoms including continuous rocking/swaying sensations described as feeling like one is "still on the boat," following travel, especially on water vessels. MdDS is even more notorious for the duration of symptoms that can persist months or years, and historically this condition has escaped effective treatments.

PURPOSE

 This case study presents a case of classic MdDS that was effectively treated in an Audiology-Vestibular clinic. Treatment consisted of three, relatively short-lived vestibular rehabilitation sessions using the "Roll Readaptation" technique that has previously been reported in Neurology journals.

STUDY SAMPLE

 The study sample includes a 48-year-old female with a history of MdDS following two separate ocean cruises. She underwent vestibular evaluation and was treated with a treatment paradigm aimed to readapt the central vestibular system and vestibular-ocular reflex.

RESULTS

 This report focuses on a brief review of current symptomology and diagnostic criteria of MdDS, underlying pathophysiology and application of a relatively new treatment technique in an audiology clinic. This patient was shown full-field, omni-directional optokinetic (OPK) stimulus while rolling her head rhythmically for up to 4 minutes at a time. After three treatment sessions, the patient had a significant reduction in subjective symptoms and returned to full-time work. She had previously been off work for nearly 3 months.

CONCLUSION

 Individuals with MdDS suffer large daily and work life disruptions due to the persistent nature of symptoms, and their physical manifestations. In addition, they have historically had minimal treatment options. This case demonstrates that audiologists with proper equipment may have the potential to readily offer treatment for a previously "untreatable" condition.

Treatment of Gravitational Pulling Sensation in Patients With Mal de Debarquement Syndrome (MdDS): A Model-Based Approach

Perception of the spatial vertical is important for maintaining and stabilizing vertical posture during body motion. The velocity storage pathway of vestibulo-ocular reflex (VOR), which integrates vestibular, optokinetic, and proprioception in the vestibular nuclei vestibular-only (VO) neurons, has spatio-temporal properties that are defined by eigenvalues and eigenvectors of its system matrix. The yaw, pitch and roll eigenvectors are normally aligned with the spatial vertical and corresponding head axes. Misalignment of the roll eigenvector with the head axes was hypothesized to be an important contributor to the oscillating vertigo during MdDS. Based on this, a treatment protocol was developed using simultaneous horizontal opto-kinetic stimulation and head roll (OKS-VOR). This protocol was not effective in alleviating the MdDS pulling sensations. A model was developed, which shows how maladaptation of the yaw eigenvector relative to the head yaw, either forward, back, or side down, could be responsible for the pulling sensation that subjects experience. The model predicted the sometimes counter-intuitive OKS directions that would be most effective in re-adapting the yaw eigenvector to alleviate the pulling sensation in MdDS. Model predictions were consistent with the treatment of 50 patients with a gravitational pulling sensation as the dominant feature. Overall, pulling symptoms in 72% of patients were immediately alleviated after the treatment and lasted for 3 years after the treatment in 58% of patients. The treatment also alleviated the pulling sensation in patients where pulling was not the dominant feature. Thus, the OKS method has a long-lasting effect comparable to that of OKS-VOR readaptation. The study elucidates how the spatio-temporal organization of velocity storage stabilizes upright posture and how maladaptation of the yaw eigenvector generates MdDS pulling sensations. Thus, this study introduces a new way to treat gravitational pull which could be used alone or in combination with previously proposed VOR readaptation techniques.

Double-blind randomized N-of-1 trial of transcranial alternating current stimulation for mal de débarquement syndrome

Background

Mal de Débarquement Syndrome (MdDS) is a medically refractory neurotological disorder characterized by persistent oscillating vertigo that follows a period of entrainment to oscillating motion such as experienced during sea or air travel. Fronto-occipital hypersynchrony may correlate with MdDS symptom severity.

Materials and methods

Individuals with treatment refractory MdDS lasting at least 6 months received single administrations of three fronto-occipital transcranial alternating current stimulation (tACS) protocols in an “n-of-1” double-blind randomized design: alpha frequency anti-phase, alpha-frequency in-phase, and gamma frequency control. Baseline assessments were made on Day 1. The treatment protocol that led to the most acute reduction in symptoms during a test session on Day 2 was administered for 10–12 stacked sessions given on Days 3 through 5 (20-minutes at 2-4mA). Pre to post symptom changes were assessed on Day 1 and Day 5. Participants who could clearly choose a preferred protocol on Day 2 did better on Day 5 than those who could not make a short-term determination on Day 2 and either chose a protocol based on minimized side effects or were randomized to one of the three protocols. In addition, weekly symptom assessments were made for four baseline and seven post stimulation points for the Dizziness Handicap Inventory (DHI), MdDS Balance Rating Scale (MBRS), and Hospital Anxiety and Depression Scale (HADS).

Results

Of 24 participants, 13 chose anti-phase, 7 chose in-phase, and 4 chose control stimulation. Compared to baseline, 10/24 completers noted ≥ 25% reduction, 5/24 ≥50% reduction, and 2/24 ≥75% reduction in oscillating vertigo intensity from Day 1 to Day 5. Stimulating at a frequency slightly higher than the individual alpha frequency (IAF) was better than stimulating at exactly the IAF, and slightly better than stimulating with a strategy of standardized stimulation at 10Hz. A one-way repeated measures ANOVA of weekly DHI, MBRS, and HADS measurements showed significant reductions immediately after treatment with improvement increasing through post-treatment week 6.

Conclusion

Fronto-occipital tACS may be effective in reducing the oscillating vertigo of MdDS and serve as a portable neuromodulation alternative for longer-term treatment. Stimulation frequency relative to the IAF may be important in determining the optimum treatment protocol [ClinicalTrials.gov study NCT02540616. https://clinicaltrials.gov/ct2/show/NCT02540616].

Perception, knowledge, and attitude of medical doctors in Saudi Arabia about the role of physiotherapists in vestibular rehabilitation: a cross-sectional survey

Objectives

There is compelling scientific evidence about the role of physiotherapists in vestibular rehabilitation. However, patients with vestibular-associated dizziness and balance disturbances are seldom referred to physiotherapists in Saudi Arabia. Therefore, this study aims to achieve insight into perceptions, knowledge, attitudes, and referral practices among Saudi Arabian medical doctors relating to the role of physiotherapists in vestibular rehabilitation.

Methods

A sample of 381 medical doctors practicing in Saudi Arabia participated in this nationwide cross-sectional study. The sample was obtained from 226 hospitals across 13 provinces of Saudi Arabia by stratified sampling method. The 23-item questionnaire developed by a team of experts was emailed to medical doctors practicing in various hospitals across Saudi Arabia.

Results

Out of 1,231 medical doctors invited, 381 medical doctors responded, giving a response rate of 30.9%. One hundred ninety-three (50.6%) medical doctors reported managing patients with vestibular rehabilitation. The most preferred specialist for managing patients with vestibular disorders was an Ear Nose Throat (ENT) specialist (n = 173, 89.6%). Related Sample Cochran's Q test showed statistically significant difference between preferred specialist for managing patients with vestibular disorders (ENT specialists, physiotherapists, nurses, occupational therapists and audiologists) (χ2(4) = 482.476, p = 0.001). Out of 193 medical doctors, 153 (79.2%) reported no role of the physiotherapist in vestibular rehabilitation. One hundred forty-five (75.1%) of medical doctors reported that they were not aware of the role of physiotherapists in vestibular rehabilitation. Only 27 (15.5%) medical doctors reported referring patients with vestibular disorders to physiotherapists.

Conclusion

The study reports that physiotherapy services are underutilized in vestibular rehabilitation due to limited referral from Saudi Arabian medical doctors. Therefore, there is a need to increase the awareness among Saudi Arabian doctors about the physiotherapist's role in vestibular rehabilitation.

Neuromodulation for the treatment of functional neurological disorder and somatic symptom disorder: a systematic review

Functional neurological disorder and somatic symptom disorder are complex neuropsychiatric conditions that have been linked to circuit-based dysfunction of brain networks. Neuromodulation is a novel therapeutic strategy capable of modulating relevant brain networks, making it a promising potential candidate for the treatment of these patient populations. We conducted a systematic review of Medline, Embase and PsycINFO up to 4 March 2021. Trials investigating neuromodulation devices for the treatment of functional neurological disorder or somatic symptom disorder were selected. Extracted variables included study design, demographic and clinical characteristics, psychiatric comorbidity, neurostimulation protocols, clinical outcome measures and results. 404 studies were identified with 12 meeting inclusion criteria. 221 patients were treated in the included studies with mean study sample size of 18 (4-70). Five studies were randomised clinical trials. Functional motor symptoms (six weakness, four movement disorders) were the most studied subpopulations. Transcranial magnetic stimulation (TMS) was the most frequently used device (10 studies), followed by electroconvulsive therapy (one study) and direct-current stimulation (one study). Treatment protocols varied in intended therapeutic mechanism(s): eight studies aimed to modulate underlying network dysfunction, five aimed to demonstrate movement (one also leveraged the former) and three boosted their primary mechanism with enhanced suggestion/expectation. All but one study reported positive results; however, methodological/outcome heterogeneity, mixed study quality and small sample sizes precluded quantitative meta-analysis. Neuromodulation, particularly TMS for the treatment of functional motor symptoms, shows preliminary promise in a growing line of research. Larger, sham-controlled studies are needed to further establish efficacy and better understand therapeutic mechanisms.

Remotely Monitored Home-Based Neuromodulation With Transcranial Alternating Current Stimulation (tACS) for Mal de Débarquement Syndrome

Objective: To determine whether remotely-monitored transcranial alternating current stimulation (tACS) may be a viable and safe treatment option for Mal de Débarquement Syndrome (MdDS).

Background: Mal de Débarquement Syndrome is a neurotological disorder characterized by persistent oscillating vertigo that is triggered by entrainment to passive oscillatory motion such as occurs during water-based travel. Treatment options for MdDS are limited, variably effective, and can be undone by further travel.

Design and Methods: This was a remotely-monitored open-label optional extension phase of a double-blind randomized onsite study of tACS for medically refractory MdDS. The primary goal was to determine safety, feasibility, and blinded participant feedback. The secondary goal was to determine efficacy. Thirteen participants (all women), aged 22–67 years, experiencing a duration of illness of 11–72 months, were a subset of 24 individuals who participated in an on-site study of tACS. They had either not responded to the on-site protocol or had relapsed after travel home. Treatment accessories and a tablet controlled tACS stimulator (Pulvinar XCSITE-100) were mailed to participants. Three teaching sessions were performed via webcam followed by on-going remote monitoring of treatment logs and participants' reports through a daily on-line diary and weekly questionnaires. Treatment continued until an effective protocol was administered for 4 weeks and then tapered over 4 weeks. Participants completed a blinded feedback survey and a debriefing interview at the completion of the entire study.

Results: Treatment duration ranged from 4 to 31 weeks followed by a 4-week taper accounting for 578 verified sessions. Of the 13 total participants, seven agreed or agreed strongly in the blinded survey that tACS treatment was beneficial; 2) Twelve were comfortable utilizing tACS on their own; 3) Eleven preferred stimulation above their individual alpha frequency; 4) Side effects were generally mild and typical of tACS. In the debriefing interview completed 2–9 months after the last stimulation, five participants reported doing “great,” with no to minimal symptoms, four reported doing “good,” with moderate symptoms, and four reported no change compared to pre-study baseline.

Conclusion: Remotely-monitored tACS may be a safe treatment option for MdDS with the potential for lasting outcomes, increased accessibility, and reduction in travel-related treatment reversal.

Brain network effects by continuous theta burst stimulation in mal de débarquement syndrome: simultaneous EEG and fMRI study

Objective. Heterogeneous clinical responses to treatment with non-invasive brain stimulation are commonly observed, making it necessary to determine personally optimized stimulation parameters. We investigated neuroimaging markers of effective brain targets of treatment with continuous theta burst stimulation (cTBS) in mal de débarquement syndrome (MdDS), a balance disorder of persistent oscillating vertigo previously shown to exhibit abnormal intrinsic functional connectivity.Approach.Twenty-four right-handed, cTBS-naive individuals with MdDS received single administrations of cTBS over one of three stimulation targets in randomized order. The optimal target was determined based on the assessment of acute changes after the administration of cTBS over each target. Repetitive cTBS sessions were delivered on three consecutive days with the optimal target chosen by the participant. Electroencephalography (EEG) was recorded at single-administration test sessions of cTBS. Simultaneous EEG and functional MRI data were acquired at baseline and after completion of 10-12 sessions. Network connectivity changes after single and repetitive stimulations of cTBS were analyzed.Main results.Using electrophysiological source imaging and a data-driven method, we identified network-level connectivity changes in EEG that correlated with symptom responses after completion of multiple sessions of cTBS. We further determined that connectivity changes demonstrated by EEG during test sessions of single administrations of cTBS were signatures that could predict optimal targets.Significance.Our findings demonstrate the effect of cTBS on resting state brain networks and suggest an imaging-based, closed-loop stimulation paradigm that can identify optimal targets during short-term test sessions of stimulation.ClinicalTrials.gov Identifier:NCT02470377.

Psychological assessment of individuals with Mal de Débarquement Syndrome

OBJECTIVE

To report on the psychological, personality, and behavioral profiles of individuals with persistent Mal de Débarquement Syndrome (MdDS).

MATERIALS AND METHODS

Individuals with MdDS who participated in neuromodulation clinical trials between May 2013 and June 2019 completed a series of standardized psychological questionnaires and underwent the Structural Clinical Interview for DSM-IV-TR (SCID) for specific psychiatric diagnoses. All data reported are from baseline assessments prior to any study interventions. Scores were compared to population norms for adult women.

RESULTS

Complete datasets were available for 55 women. Mean age of onset of MdDS was 49.0 ± 11.9 years (range 22-69 years) and median duration of illness of 22 months (6 months-20 years). SCID results were as follows: healthy (48.1%), any lifetime Major Depressive Disorder (35.2%, 7.4% current); any lifetime history of anxiety disorder (11.1%); any lifetime substance use disorders (18.5%, 0% current). Compared to population norms, the MdDS group scored significantly higher on the Patient Health Questionnaire-9 depression scale and the Generalized Anxiety Disorder 7 (GAD-7) anxiety scale, but only the GAD-7 correlated with symptom severity. The NEO-Five Factor Inventory for personality, Positive and Negative Affect Schedule, Behavioral Inhibition System/Behavioral Activation System Scale, and the Empathy Quotient metrics did not correlate with duration of illness. Disability assessed by the 12-item World Health Organization Disability Assessment Schedule 2.0 was 25.7 ± 6.7, comparable to reports for concussion. Disability correlated with severity of depression, anxiety, neuroticism, and affect but not to severity of MdDS.

CONCLUSIONS

Psychological profiles of MdDS relate to disability but not to duration of illness.

Chronic Dizziness

PURPOSE OF REVIEW

Determining the etiology of disorders that manifest with chronic dizziness can seem a daunting task, but extracting some basic elements of the patient's history can reduce the differential diagnosis significantly. This includes determining initial triggers, timing of symptoms, associated features, and exacerbating factors. This article covers distinct causes of chronic dizziness including persistent postural perceptual dizziness, mal de débarquement syndrome, motion sickness and visually induced motion sickness, bilateral vestibulopathy, and persistent dizziness after mild concussion.

RECENT FINDINGS

To date, none of the disorders above has a cure but are considered chronic syndromes with fluctuations that are both innate and driven by environmental stressors. As such, the mainstay of therapy for chronic disorders of dizziness involves managing factors that exacerbate symptoms and adding vestibular rehabilitation or cognitive-behavioral therapy alone or in combination, as appropriate. These therapies are supplemented by serotonergic antidepressants that modulate sensory gating and reduce anxiety. Besides expectation management, ruling out concurrent disorders and recognizing behavioral and lifestyle factors that affect symptom severity are critical issues in reducing morbidity for each disorder.

SUMMARY

Many syndromes of chronic dizziness can be diagnosed by recognition of key features, although many symptoms overlap between these groups. Symptoms may be manageable and improve with time, but they are often incompletely relieved.

Transcranial Alternating Current Stimulation Reduces Network Hypersynchrony and Persistent Vertigo

OBJECTIVES

Persistent oscillating vertigo that occurs after entrainment to periodic motion is known as Mal de Débarquement Syndrome (MdDS). Down-modulation of this oscillating vertigo is associated with reduction in long-range resting-state functional connectivity between fronto-parieto-occipital regions. In order to determine the association between this oscillating vertigo and hypersynchrony as measured by the auditory steady-state response (ASSR), we investigated the differences in ASSR between individuals with MdDS and healthy controls as well as the change in ASSR in individuals with MdDS before and after treatment with transcranial alternating current stimulation (tACS).

MATERIALS AND METHODS

Individuals with treatment refractory MdDS lasting at least six months received single administrations of fronto-parieto-occipital tACS in an "n-of-1" double-blind randomized design: alpha-frequency in-phase, alpha-frequency antiphase, and gamma frequency antiphase control. The treatment protocol that led to the most acute reduction in symptoms and improved balance was administered for 10-12 sessions given over three days (each session 20-min at 2-4 mA).

RESULTS

Twenty-four individuals with MdDS participated (mean age 53.0 ± 11.8 years [range: 22-66 years, median: 57.0 years]; mean duration of illness 38.6 ± 53.4 months [range: 6-240 months, median: 18.0 months]). Individuals with MdDS had elevated ASSR compared to healthy controls at baseline (t₁₁  = 5.95, p < 0.001). There was a significant decrease in the 40 Hz-ASSR response between responders compared to nonresponders to tACS (t-test, t₁₅  = -2.26, p = 0.04). Both in-phase and anti-phase alpha tACS lead to symptom improvement but only antiphase alpha-tACS led to a significant decrease of 40 Hz-ASSR (t-test, t₁₂  = -9.6, p < 0.001).

CONCLUSIONS

Our findings suggest that tACS has the potential to reduce network-level hypersynchrony and pathological susceptibility to entrainment by sensory input. To the best of our knowledge, this is the first successful demonstration of desynchronization by noninvasive brain stimulation leading to reduced vertigo. Other disease states associated with pathological functional coupling of neuronal networks may similarly benefit from this novel approach.

Occipital and Cerebellar Theta Burst Stimulation for Mal De Debarquement Syndrome

BACKGROUND

Individuals with Mal de Debarquement syndrome (MdDS) experience persistent oscillating vertigo lasting for months or years. Transcranial magnetic stimulation (TMS) can modulate the motion perception of MdDS.

MATERIALS AND METHODS

Twenty-six TMS naive individuals received single administrations of continuous theta burst stimulation (cTBS) over the occipital cortex, cerebellar vermis, and lateral cerebellar hemisphere, in randomized order. A 0-100 point Visual Analogue Scale was used to assess acute changes in oscillating vertigo severity after each session. Repeated treatments were given over the target that led to the most acute reduction in symptoms. All treatments were performed with neuronavigation using the participant's own brain MRI. The Dizziness Handicap Inventory (DHI), MdDS Balance Rating Scale (MBRS), and Hospital Anxiety and Depression Scale (HADS) were assessed weekly at four pretreatment and six posttreatment time points.

RESULTS

Twenty participants chose either the occipital cortex (11) or cerebellar vermis (9) targets as most effective in reducing the oscillating vertigo; one chose lateral cerebellar hemisphere; five chose none. After 10 to 12 sessions of 1,200 pulses over the target of choice, 19 of 25 treatment completers noted ≥ 25% reduction, 12 of 25 ≥50% reduction, and 8 of 25 ≥75% reduction in oscillating vertigo intensity. A one-way repeated measures ANOVA of DHI, MBRS, and HADS scores before and after treatment showed significant reductions in DHI, MBRS, and the HADS Anxiety subscore immediately after treatment with most improvement lasting through posttreatment week 6. There were no significant Depression subscore changes. Participants who had chosen vermis stimulation had comparatively worse balance at baseline than those who had chosen occipital cortex stimulation.

CONCLUSION

cTBS over either the occipital cortex or cerebellar vermis is effective in reducing the oscillating vertigo of MdDS acutely and may confer long-term benefits. Sustained improvement requires more frequent treatments.

Transcranial Magnetic Stimulation as Treatment for Mal de Debarquement Syndrome: Case Report and Literature Review

This manuscript presents the case of an adult, male patient with mal de debarquement syndrome (MdDS); results from his experimental treatment with repetitive transcranial magnetic stimulation (rTMS) are also provided. Additionally, we included a review of literature related to the neurophysiology of MdDS and its treatment with rTMS. A 41-year-old man had been experiencing symptoms of MdDS, which initially emerged following a car ride, for 11 to 12 years. Pharmacologic approaches had failed to provide symptom relief; thus, we investigated an intervention using low-frequency (1 Hz) rTMS unilaterally for 2 consecutive weeks. The outcome measures included a standardized, computerized dynamic posturography test to quantify the patient's balance and identify abnormalities in his use of the sensory systems contributing to postural control, as well as the Hospital Anxiety and Depression Scale (HADS) to measure his anxiety and depression. An rTMS treatment log was created to document any adverse events. Following rTMS, the patient's balance scores improved significantly; these improvements were mostly related to the patient's increased reliance on the visual and vestibular systems. Our patient's HADS Anxiety and Depression subscores also showed improvement post-rTMS. The presented case study provides preliminary evidence that rTMS may be a noninvasive treatment option for improving balance, specifically in individuals with MdDS. This evidence can be used to further therapeutic research on, and provide strategies for treating, MdDS.

Pilot study on patients with Mal de Debarquement syndrome during pregnancy

Aim:

To evaluate if patients with Mal de Debarquement syndrome (MdDS) demonstrate different symptom levels or symptom type during pregnancy.

Materials & methods:

18 MdDS patients that were or had been pregnant during their condition were recruited to complete a retrospective online questionnaire. Respondents answered questions regarding their basic clinical data, diagnosis, triggers and differences in symptom level and symptom type during pregnancy and before pregnancy.

Results:

A total of 81.3% reported that their symptoms were reduced during pregnancy compared with before pregnancy. Respondents also reported a different perception of motion and experienced less dizziness while being pregnant.

Conclusion:

The physiological changes that occur during pregnancy improve the symptoms of patients with MdDS, and this is potentially attributable to the rise in estrogen and progesterone.

Mal de Debarquement syndrome (MdDS) is a rare neurological disorder characterized by a constant sensation of self-motion. More women are affected than men, and subsequently a hormonal implication has been theorized. This study aimed to evaluate if symptoms change in patients with MdDS during their pregnancy. A total of 18 MdDS patients were recruited to complete a retrospective online questionnaire. Among these, 81.3% of respondents reported that their symptoms were lower during pregnancy compared with before pregnancy. Respondents also reported a different perception of motion and experienced less dizziness while being pregnant. Our results support the hypothesis that pregnancy positively influences MdDS symptoms.

Repetitive transcranial magnetic stimulation (rTMS) as a treatment for chronic dizziness following mild traumatic brain injury

A 61-year-old man sustained a mild traumatic brain injury (mTBI) following a pedestrian versus vehicle traffic accident. Post injury, he began to experience symptoms including light-headedness, spatial disorientation, nausea, fatigue and prominent dizziness brought on by postural change, physical activity or eye movements. Symptoms of dizziness persisted for over 5 years, despite numerous extensive and rigorous vestibular and vision therapy regimens. All investigations suggested normal peripheral and central vestibular functioning. The patient underwent 10 sessions of repetitive transcranial magnetic stimulation (rTMS) treatment, with stimulation of the left dorsolateral prefrontal cortex at 70% of resting motor threshold and a frequency of 10 Hz. Dizziness symptom severity and frequency were reduced by greater than 50% at 3 months post treatment, with a clinically significant reduction of dizziness disability from 40 to 21 points on the Dizziness Handicap Inventory. We propose rTMS as a safe, effective and cost-effective treatment option for patients who experience persistent post-traumatic dizziness secondary to mTBI.

Treatment of Mal de Debarquement Syndrome in a Deployed Environment

We report the case of a 26-year-old Caucasian female with persistent sensations of forward and reverse movement with spontaneous onset. This worsened over 4 wk. The patient reported an episode of these symptoms 5 mo prior, which lasted for 3 mo before improving. Our case details the treatment of Mal de Debarquement syndrome, or Disembarkment Syndrome, in a deployed military environment. Mal de Debarquement was a term originally coined to describe the persistent sensation of rocking back and forth after disembarking a boat and returning to land. This is normal, and usually only lasts for minutes to hours. When it persists, it is called Mal de Debarquement Syndrome. The onset frequently coincides with travel and most commonly by boat, however it can also occur spontaneously as in this case. Currently, there are three different treatment options. The first involves medications that are often sedating. The second uses magnetic resonance imaging at high frequency to stimulate the areas of the brain thought to be involved. The third option is a form of physical therapy termed re-adaptation of the vestibular ocular reflex. As we were in a deployed military environment the first two options were unsafe and unavailable respectively. We employed an improvised version of re-adaptation of the vestibular ocular reflex. The patient demonstrated a 50% reduction in symptoms following 1 wk of treatment and as a result was safely able to complete her deployment.

Sham-Controlled Study of Optokinetic Stimuli as Treatment for Mal de Debarquement Syndrome

Introduction: Mal de Debarquement Syndrome (MdDS) is a condition characterized by a perception of self-motion in the absence of a stimulus, with two onset types: Motion-Triggered and Spontaneous. Currently, the pathophysiology is unknown and consequently, the therapeutic options are limited. One proposed treatment protocol, developed by Dai and colleagues is based on optokinetic stimulation, which aims to re-adapt the vestibular ocular reflex. This study aimed to reproduce the treatment protocol developed by Dai and colleagues and to assess if a placebo effect is present in the treatment protocol and lastly, aimed to further investigate the treatment on MdDS patient outcomes.

Method: Twenty-five MdDS patients (13 Motion-Triggered and 12 Spontaneous) were exposed to 5 consecutive days of optokinetic treatment (consisting of exposure to optokinetic stimuli with head movements). Eleven of these 25 patients were also exposed to 2 days of a sham treatment prior to the OKN treatment. Posturography measurements and reported symptoms [e.g., using the visual analog scale (VAS)] of patients were assessed throughout the treatment. Posturography data of the patients was compared with the data of 20 healthy controls.

Results: No placebo effect was recorded with any changes in postural data and VAS scale. After the optokinetic treatment, a significant improvement in postural control was observed in 48% of patients, of whom 70% were of the Motion-Triggered subtype (p-values: Area under the Curve—Anterior Posterior < 0.001; Area under the Curve—Medio Lateral p < 0.001, Confidence Ellipse Area (CEA) < 0.001, Velocity < 0.001).

Conclusion: The protocol was effective in approximately half of the MdDS patients that took part in the study, with no placebo effect recorded. The Motion-Triggered group responded better to treatment than the Spontaneous group. In addition to this, this study indicates that the greatest postural changes occur within the first 3 days of treatment, suggesting that a shorter protocol is possible. Overall, these findings support what was previously observed in Dai's studies, that optokinetic stimulation can reduce and ease self-motion perception in those with MdDS. Thus, validating the reproducibility of this protocol, suggesting that a consistent and uncomplicated implementation across treatment centers is possible.

The Neurophysiology and Treatment of Motion Sickness

BACKGROUND

Seasickness and travel sickness are classic types of motion illness. Modern simulation systems and virtual reality representations can also induce comparable symptoms. Such manifestations can be alleviated or prevented by various measures.

METHODS

This review is based on pertinent publications retrieved by a PubMed search, with special attention to clinical trials and review articles.

RESULTS

Individuals vary in their susceptibility to autonomic symptoms, ranging from fatigue to massive vomiting, induced by passive movement at relatively low frequencies (0.2 to 0.4 Hz) in situations without any visual reference to the horizontal plane. Younger persons and women are considered more susceptible, and twin studies have revealed a genetic component as well. The various types of motion sickness are adequately explained by the intersensory conflict model, incorporating the vestibular, visual, and proprioceptive systems and extended to include consideration of postural instability and asymmetry of the otolith organs. Scopolamine and H1-antihistamines, such as dimenhydrinate and cinnarizine, can be used as pharmacotherapy. The symptoms can also be alleviated by habituation through long exposure or by the diminution of vestibular stimuli.

CONCLUSION

The various types of motion sickness can be treated with general measures to lessen the intersensory conflict, behavioral changes, and drugs.

A new theory on GABA and Calcitonin Gene-Related Peptide involvement in Mal de Debarquement Syndrome predisposition factors and pathophysiology

INTRODUCTION

Mal de Debarquement Syndrome (MdDS) is a condition characterized by a sensation of motion in the absence of a stimulus, which presents with two subtypes depending on the onset: Motion-Triggered, and Spontaneous or Non-Motion Triggered. MdDS predominantly affects women around 40-50 years of age and a high number of patients report associated disorders, such as migraine and depression. The pathophysiology of MdDS is unclear, as is whether there are predisposing factors that make individuals more vulnerable to developing the condition. Hormonal changes in women similarly to what observed in migraineous patients, as well as depression disorder, have been examined as potential key factors for developing MdDS. Studies on migraine and depression have revealed correlations with hormonal fluctuations in females as well as aberrant levels of some key neurotransmitters such as Gamma-Aminobutyric Acid (GABA) and inflammatory neuropeptides like Calcitonin Gene-Related Peptide (CGRP). Consequently, this manuscript aims to propose a new hypothesis on the predisposing factors for MdDS and a new concept that could contribute to the understanding of its pathophysiology.

NEW HYPOTHESIS

Recent findings have demonstrated a role for hormonal influences in MdDS patients, similar to previous observations in patients with depression and migraine. We hypothesize the involvement of gonadal hormones and aberrant neurotransmitter levels, including the GABAergic and serotonergic systems, in MdDS pathophysiology. Our theory is that certain individuals are more vulnerable to develop MdDS during specific gonadal hormonal phases. Furthermore, we hypothesize that it may be possible to identify these individuals by measurement of an existing imbalance of these neurotransmitters or inflammatory neuropeptides like CGRP.

FURTHER EVALUATION OF THE HYPOTHESIS

According to one theory, MdDS is considered as a maladaptation of the Vestibular Ocular Reflex (VOR) and velocity storage. When considering this theory, it is essential to highlight that the brainstem nuclei involved in the VOR and the velocity storage include GABA_b sensitive neurons, which appear to produce inhibitory control of velocity storage. Responses of these GABA_b sensitive neurons are also modulated by CGRP. Thus an alteration of the GABAergic network by imbalances of inhibitory neurotransmitters or CGRP could influence signal integration in the velocity storage system and therefore be directly involved in MdDS pathophysiology.

CONSEQUENCE OF THE HYPOTHESIS AND FUTURE STUDIES

A hormonal and neurotransmitter imbalance may act to predispose individuals in developing MdDS. Future studies should focus on the hormonal influences on neurotransmitters (e.g. GABA) and on the trial of CGRP antagonist drugs for the treatment of MdDS patients.

Cortical Statistical Correlation Tomography of EEG Resting State Networks

Resting state networks (RSNs) have been found in human brains during awake resting states. RSNs are composed of spatially distributed regions in which spontaneous activity fluctuations are temporally and dynamically correlated. A new computational framework for reconstructing RSNs with human EEG data has been developed in the present study. The proposed framework utilizes independent component analysis (ICA) on short-time Fourier transformed inverse source maps imaged from EEG data and statistical correlation analysis to generate cortical tomography of electrophysiological RSNs. The proposed framework was evaluated on three sets of resting-state EEG data obtained in the comparison of two conditions: (1) healthy controls with eyes closed and eyes open; (2) healthy controls and individuals with a balance disorder; (3) individuals with a balance disorder before and after receiving repetitive transcranial magnetic stimulation (rTMS) treatment. In these analyses, the same group of five RSNs with similar spatial and spectral patterns were successfully reconstructed by the proposed framework from each individual EEG dataset. These EEG RSN tomographic maps showed significant similarity with RSN templates derived from functional magnetic resonance imaging (fMRI). Furthermore, significant spatial and spectral differences of RSNs among compared conditions were observed in tomographic maps as well as their spectra, which were consistent with findings reported in the literature. Beyond the success of reconstructing EEG RSNs spatially on the cortical surface as in fMRI studies, this novel approach defines RSNs further with spectra, providing a new dimension in understanding and probing basic neural mechanisms of RSNs. The findings in patients' data further demonstrate its potential in identifying biomarkers for the diagnosis and treatment evaluation of neuropsychiatric disorders.

Perspective: Stepping Stones to Unraveling the Pathophysiology of Mal de Debarquement Syndrome with Neuroimaging

Mal de debarquement syndrome (MdDS) is a neurological condition typically characterized by a sensation of motion, which in most cases manifests after disembarking from a vehicle (e.g., boat, plane, and car). However, the same symptoms can also occur spontaneously. Two main theories of the pathophysiology of MdDS are briefly summarized here. In this perspective, we aimed to report the most recent findings on neuroimaging studies related to MdDS, as well as to suggest further potential research questions that could be addressed with the use of neuroimaging techniques. A detailed analysis of previous work on MdDS has led to five main research questions that could be addressed in new neuroimaging studies. Furthermore, in this perspective, we propose new stepping-stones to addressing critical research questions related to MdDS and its pathophysiology. We propose considerations for new studies, as well as a detailed analysis of the current limitations and challenges present when studying MdDS patients. We hope that our examination of the nuances of MdDS as a neurological disorder will contribute to more directed research on this topic.

Assessing rTMS effects in MdDS: Cross-modal comparison between resting state EEG and fMRI connectivity

Repetitive transcranial magnetic stimulation (rTMS) has been increasingly explored for many neurological and neuropsychiatric conditions. However, the response rate is variable depending on baseline conditions. Optimizing rTMS protocols to improve treatment effects and response rates will depend on reliably assessing brain state conditions. In this regard, neural activity guided optimization has shown potential in several neuroimaging studies. In this paper, we present our ongoing work on optimizing rTMS treatment of a balance disorder called Mal de Debarquement Syndrome (MdDS), a motion perception disorder caused by entrainment to background motion. Our previous work has revealed that a neuroimaging marker of resting state functional connectivity may help predict therapeutic effect. Motivated by our previous pilot study with fMRI, the present study aims to extend the investigation to EEG data that were simultaneously acquired with fMRI, with the aim of transferring the fMRI imaging marker to a more accessible neural recording technology. Our current findings demonstrate that integrating EEG with fMRI measures of neural synchrony and functional connectivity may hold promise in optimizing rTMS protocols.

Treatment of the Mal de Debarquement Syndrome: A 1-Year Follow-up

The mal de debarquement syndrome (MdDS) is a movement disorder, occurring predominantly in women, is most often induced by passive transport on water or in the air (classic MdDS), or can occur spontaneously. MdDS likely originates in the vestibular system and is unfamiliar to many physicians. The first successful treatment was devised by Dai et al. (1), and over 330 MdDS patients have now been treated. Here, we report the outcomes of 141 patients (122 females and 19 males) treated 1 year or more ago. We examine the patient’s rocking frequency, body drifting, and nystagmus. The patients are then treated according to these findings for 4–5 days. During treatment, patients’ heads were rolled while watching a rotating full-field visual surround (1). Their symptom severity after the initial treatment and at the follow-up was assessed using a subjective 10-point scale. Objective measures, taken before and at the end of the week of treatment, included static posturography. Significant improvement was a reduction in symptom severity by more than 50%. Objective measures were not possible during the follow-up because of the wide geographic distribution of the patients. The treatment group consisted of 120 classic and 21 spontaneous MdDS patients. The initial rate of significant improvement after a week of treatment was 78% in classic and 48% in spontaneous patients. One year later, significant improvement was maintained in 52% of classic and 48% of spontaneous subjects. There was complete remission of symptoms in 27% (32) of classic and 19% (4) of spontaneous patients. Although about half of them did not achieve a 50% improvement, most reported fewer and milder symptoms than before. The success of the treatment was generally inversely correlated with the duration of the MdDS symptoms and with the patients’ ages. Prolonged travel by air or car on the way home most likely contributed to the symptomatic reversion from the initial successful treatment. Our results indicate that early diagnosis and treatment can significantly improve results, and the prevention of symptomatic reversion will increase the long-term benefit in this disabling disorder.

Altered functional brain connectivity in patients with visually induced dizziness

Background

Vestibular patients occasionally report aggravation or triggering of their symptoms by visual stimuli, which is called visually induced dizziness (VID). These patients therefore experience dizziness, discomfort, disorientation and postural unsteadiness. The underlying pathophysiology of VID is still poorly understood.

Objective

The aim of the current explorative study was to gain a first insight in the underlying neural aspects of VID.

Methods

We included 10 VID patients and 10 healthy matched controls, all of which underwent a resting state fMRI scan session. Changes in functional connectivity were explored by means of the intrinsic connectivity contrast (ICC). Seed-based analysis was subsequently performed in visual and vestibular seeds.

Results

We found a decreased functional connectivity in the right central operculum (superior temporal gyrus), as well as increased functional connectivity in the occipital pole in VID patients as compared to controls in a hypothesis-free analysis. A weaker functional connectivity between the thalamus and most of the right putamen was measured in VID patients in comparison to controls in a seed-based analysis. Furthermore, also by means of a seed-based analysis, a decreased functional connectivity between the visual associative area and the left parahippocampal gyrus was found in VID patients. Additionally, we found increased functional connectivity between thalamus and occipital and cerebellar areas in the VID patients, as well as between the associative visual cortex and both middle frontal gyrus and precuneus.

Conclusions

We found alterations in the visual and vestibular cortical network in VID patients that could underlie the typical VID symptoms such as a worsening of their vestibular symptoms when being exposed to challenging visual stimuli. These preliminary findings provide the first insights into the underlying functional brain connectivity in VID patients. Future studies should extend these findings by employing larger sample sizes, by investigating specific task-based paradigms in these patients and by exploring the implications for treatment.

•

Visually-induced patients present decreased functional connectivity of vestibular-related brain regions.

•

Visually-induced dizziness patients present increased functional connectivity of visual and cerebellar brain regions.

•

These findings might underlie typically seen symptoms in visually-induced dizziness, i.e. an overreliance on visual cues.

•

This is the first exploratory study investigating the underlying neural aspects of visually-induced dizziness.

•

These preliminary findings should be extended by larger sample sizes and by supplementing rsfMRI with task-based paradigms.

Randomized Single Blind Sham Controlled Trial of Adjunctive Home-Based tDCS after rTMS for Mal De Debarquement Syndrome: Safety, Efficacy, and Participant Satisfaction Assessment

BACKGROUND

Mal de debarquement syndrome is a medically refractory disorder characterized by chronic rocking dizziness that occurs after exposure to passive motion. Repetitive transcranial magnetic stimulation (rTMS) can acutely suppress the rocking dizziness but treatment options that extend the benefit of rTMS are needed.

OBJECTIVES

1) To determine whether transcranial direct current stimulation (tDCS) added after rTMS can extend the benefit of rTMS; 2) to determine whether participants can safely perform tDCS at home.

METHODS

Participants were given five days of rTMS (1 Hz right DLPFC/10 Hz left DLPFC in right-handers, vice versa in left-handers), according to a previously piloted protocol. They received three days of training on tDCS self-administration and were then randomized to either real or sham tDCS for four-weeks (anode left DLPFC/cathode right DLPFC for right-handers, vice versa for left-handers).

RESULTS

Twenty-three participants completed the study. Those who received real tDCS after rTMS showed significant improvements in the degree of rocking perception as measured by the MdDS Balance Rating Scale and anxiety ratings by Week 4 of tDCS and a trend for improvement on the Dizziness Handicap Inventory. Two rTMS non-responders responded well to subsequent open-label tDCS. Side effects were mild and not different between real and sham tDCS. There were no episodes of skin burns in a group total of 556 sessions of tDCS. Satisfaction was rated high.

CONCLUSIONS

Home-based tDCS can be performed safely and may be beneficial in selected individuals. Adequate teaching, automatic device safety features, and a good communications infrastructure are components of successful home therapy.