When the Ground Still Rocks: A Study of Disembarkment Syndrome in Maritime Workers

Mal de debarquement syndrome (MdDS) is a disorder of perceived motion most often occurring following a cruise. We report findings from a patient with MdDS who underwent a transcranial magnetic stimulation protocol to quantify cortical excitability. These data were compared to those from 40 controls. The patient with MdDS exhibited high levels of intracortical facilitation. These findings will provide insight on the pathophysiology of MdDS, and will help guide future work on this rare condition. Mal de debarquement syndrome (MdDS) occurs when habituation to passive background movement becomes resistant to readaptation to stable conditions and results in a phantom perception of self-motion. MdDS typically disappears quickly after return to stable ground; however, in rare instances the symptoms may persist for months to years (persistent MdDS). While the etiology of persistent MdDS is poorly understood, it does not appear to originate from vestibular dysfunction as vestibular tests are normal and the symptoms do not respond to vestibular therapy [2]. Rather, MdDS appears to be a disorder of neuroplasticity and sensory rearrangement [2]. To our knowledge, there have been no studies examining the neurophysiologic characteristics of the disorder. In this case study we report findings from a patient with persistent MdDS who underwent an extensive transcranial magnetic stimulation (TMS) protocol to quantify motor cortical excitability. Specifically, we quantified the duration of the corticospinal silent period using single-pulse TMS. The silent period is observed when a subject performs a slight contraction and a single TMS stimulus is applied to the motor cortex (Fig. 1a). Additionally, we quantified intracortical facilitation (ICF) and short-interval intracortical inhibition (SICI) using paired-pulse TMS. Paired-pulse TMS combines a conditioning stimulus (CP) with a test stimulus (TP) at different interstimulus intervals, and the relative change in motor evoked potential (MEP) size is expressed relative to an unconditioned test pulse. At a short interstimulus interval of 3 ms, the CP inhibits the MEP in comparison to the TP only (SICI), whereas at a longer interstimulus intervals of 15 ms it facilitates the MEP (ICF) (Fig. 1b). The patient was a 63-year-old female (160.2 cm, 77.3 kg) who complained of sensations of unsteadiness and a feeling of the floor moving under her feet after disembarking from a 7-day cruise *3.5 years ago (3/2007). She reported having to regularly reach out to steady herself against stationary objects, and that MdDS had greatly impacted her quality of life (subjective scoring of six out of ten on a visual analog scale for the impact of MdDS on her quality of life). Several other hallmark features of MdDS were present including mild cognitive slowing and transient improvement in symptoms with re-exposure to passive movement [2]. Physical examination was unremarkable. Diagnostic testing including sural sensory and peroneal motor conduction studies, needle EMG, and MRI of the brain were all normal. Additionally, the patient had unremarkable findings on Dix-Hallpike testing and the caloric reflex test. The patient did not have migraine or other primary headache as defined by the International B. C. Clark (&) Department of Biomedical Sciences, Ohio Musculoskeletal and Neurological Institute (OMNI), Ohio University, 211 Irvine Hall, Athens, OH 45701, USA e-mail: clarkb2@ohio.edu

Current consensus diagnostic criteria for vestibular migraine (VM) describes this as an episodic disorder. However, a minority of patients report prolonged (>72 h duration) or even persistent VM symptoms, prompting whether a chronic variant of vestibular migraine (CVM) should be introduced to the current classification and how best to define it. Here we summarize current evidence of such a potential chronic variant of VM and critically review proposed definitions for CVM. Potential approaches to establish a diagnostic framework for CVM include (a) following the distinction between episodic and chronic migraine headaches, namely, frequent and/or prolonged episodes of VM (but not persistent vertigo or dizziness) in the context of chronic migraine headaches or (b) daily dizzy spells over more than 6 months that responded well to prophylactic anti-migraine therapy. A key challenge when defining diagnostic criteria for CVM is how to distinguish it from other chronic vestibular syndromes such as motion sickness, persistent postural-perceptual dizziness (PPPD), and mal de débarquement syndrome. Indeed, more than 50% of patients with PPPD and up to 46% with mal de débarquement syndrome fulfil diagnostic criteria for episodic migraine headaches, suggesting these disorders may all lie along a spectrum. We propose that when VM becomes persistent, it is best classified as PPPD but that VM and PPPD are not mutually exclusive, such that patients with PPPD need not have features of VM, and the triggering event for persistent dizziness may be independent of migraine. However, further research is needed to better characterize the spectrum of clinical phenotypes in patients with chronic dizziness, migraine headaches and anxiety, to define whether a chronic variant of VM sufficiently differs from current persistent dizziness definitions.

Persistent postural perceptual dizziness (PPPD) is a common functional vestibular disorder that is triggered and sustained by a complex interaction between physiological and psychological factors affecting spatial orientation and postural control. Past functional neuroimaging research and one recent structural (i.e., voxel-based morphometry-VBM) study have identified alterations in vestibular, visuo-spatial, and limbic brain regions in patients with PPPD and anxiety-prone normal individuals. However, no-one thus far has employed surface based morphometry (SBM) to explore whether cortical morphology in patients with PPPD differs from that of healthy people. We calculated SBM measures from structural MR images in 15 patients with PPPD and compared them to those from 15 healthy controls matched for demographics, personality traits known to confer risk for PPPD as well as anxiety and depressive symptoms that are commonly comorbid with PPPD. We tested for associations between SBM measures and dizziness severity in patients with PPPD. Relative to controls, PPPD patients showed significantly decreased local gyrification index (LGI) in multi-modal vestibular regions bilaterally, specifically the posterior insular cortices, supra-marginal gyri, and posterior superior temporal gyri (p < 0.001). Within the PPPD group, dizziness severity positively correlated with LGI in visual areas and negatively with LGI in the right superior parietal cortex. These findings demonstrate abnormal cortical folding in vestibular cortices and correlations between dizziness severity and cortical folding in visual and somatosensory spatial association areas in PPPD patients, which provides new insights into the pathophysiological mechanisms underlying this disorder.

Vestibular migraine and persistent postural perceptual dizziness: Handicap, emotional comorbidities, quality of life and personality traits

Scuba diving is a popular recreational and professional activity with inherent risks. Complications related to barotrauma and decompression illness can pose significant morbidity to a diver's hearing and balance systems. The majority of dive-related injuries affect the head and neck, particularly the outer, middle and inner ear. Given the high incidence of otologic complications from diving, an evidence-based approach to the diagnosis and treatment of otic pathology is a necessity. We performed a systematic and comprehensive literature review including the pathophysiology, diagnosis, and treatment of otologic pathology related to diving. This included inner, middle, and outer ear anatomic subsites, as well as facial nerve complications, mal de debarquement syndrome, sea sickness and fitness to dive recommendations following otologic surgery. Sixty-two papers on diving and otologic pathology were included in the final analysis. We created a set of succinct evidence-based recommendations on each topic that should inform clinical decisions by otolaryngologists, dive medicine specialists and primary care providers when faced with diving-related patient pathology.

The problem of chronic functional dizziness is highly relevant nowadays. In case of a great number of patients suffering from persistent postural-perceptual dizziness, lack of a unified understanding of the pathogenesis, diagnostic mistakes, and, as a result, improper treatment lead to a deterioration in the quality of life and disability.&#x0D; The purpose of the review is to analyse and highlight the persistent postural-perceptual dizziness problem, to explore the currently existing pathogenetic concepts, methods of diagnosis and treatment of this group of patients.&#x0D; Domestic and foreign scientific papers have been analysed using the largest world citation databases according to the following keywords: psychogenic dizziness, chronic subjective dizziness, vestibular rehabilitation, stabilometry, persistent postural-perceptual dizziness, postural phobic instability, selective serotonin reuptake inhibitors, cognitive behavioral therapy.&#x0D; The data of 78 scientific works of the research subject are the basis of the review. The article presents a brief historical background, contemporary conceptions of pathogenesis, symptoms and clinical manifestations of persistent postural-perceptual dizziness. The particular attention is given to the diagnostic methods and treatment principles. Relevant questionnaires and diagnostic scales as well as the Barany Society criteria are also considered. A multidisciplinary approach to treatment which allows to achieve a lasting positive effect is described.&#x0D; Segregation of persistent postural-perceptual dizziness into a separate nosological item, understanding of its pathogenesis, an integrated approach to diagnosis with assessment of structural, functional and mental disturbances, just like complex therapeutic strategies make а fully recovery possible.

This study used resting state functional magnetic resonance imaging (rsfMRI) to investigate whole brain networks in patients with persistent postural perceptual dizziness (PPPD). We compared rsfMRI data from 38 patients with PPPD and 38 healthy controls using whole brain and region of interest analyses. We examined correlations among connectivity and clinical variables and tested the ability of a machine learning algorithm to classify subjects using rsfMRI results. Patients with PPPD showed: (a) increased connectivity of subcallosal cortex with left superior lateral occipital cortex and left middle frontal gyrus, (b) decreased connectivity of left hippocampus with bilateral central opercular cortices, left posterior opercular cortex, right insular cortex and cerebellum, and (c) decreased connectivity between right nucleus accumbens and anterior left temporal fusiform cortex. After controlling for anxiety and depression as covariates, patients with PPPD still showed decreased connectivity between left hippocampus and right inferior frontal gyrus, bilateral temporal lobes, bilateral insular cortices, bilateral central opercular cortex, left parietal opercular cortex, bilateral occipital lobes and cerebellum (bilateral lobules VI and V, and left I-IV). Dizziness handicap, anxiety, and depression correlated with connectivity in clinically meaningful brain regions. The machine learning algorithm correctly classified patients and controls with a sensitivity of 78.4%, specificity of 76.9%, and area under the curve=0.88 using 11 connectivity parameters. Patients with PPPD showed reduced connectivity among the areas involved in multisensory vestibular processing and spatial cognition, but increased connectivity in networks linking visual and emotional processing. Connectivity patterns may become an imaging biomarker of PPPD.

ObjectiveTo explore the incidence, risk factors, and comorbidities of persistent postural-perceptual dizziness (PPPD) after stroke.MethodsPatients with acute stroke and vestibular symptoms were enrolled prospectively and continuously. Baseline information, risk factors, imaging materials, and diagnosis were collected. PPPD, anxiety, depression, and quality of life were followed up in 6months after stroke. Binary logistic regression was used to identify the risk factors of PPPD.ResultsIn this study, 284 patients (82.0% of males) were enrolled, with a mean age of 56.33 ± 11.87years. Thirty-five patients (12.3%) had PPPD in 6-month follow-up. Patients with PPPD had a higher proportion of clinically significant anxiety and clinically significant depression and a lower three-level five-dimension EuroQol (EQ-5D-3L) index. Binary logistic regression analysis identified medulla oblongata stroke (OR, 5.549; p < .001), cerebellar stroke in posterior inferior cerebellar artery (PICA) territory (OR, 2.449; p = .026), and clinically significant anxiety at discharge (OR, 5.030; p < .001) were significant predictors for PPPD.ConclusionsAbout 12.3% of stroke patients with vestibular symptoms developed PPPD at 6months after stroke, with a higher prevalence of psychological comorbidities and decreased quality of life. Medulla oblongata lesion, cerebellar (PICA territory) lesion, and clinically significant anxiety at discharge were independent risk factors for PPPD.

This study aimed to compare postural sway characteristics and evaluate postural sway as a potential biomarker for persistent postural-perceptual dizziness (PPPD) to clarify diagnostic boundaries. A total of 36 participants were enrolled, including 26 (72.2%) with PPPD, five (13.9%) with psychogenic vertigo, and five (13.9%) healthy controls. Postural sway tests were conducted on all participants, measuring the center of pressure (CoP) area, CoP length, and Romberg ratio. A subgroup analysis was also performed based on the presence of preceding organic diseases. The postural sway tests were conducted using a force platform under standardized conditions. Each participant stood barefoot on a stable surface for 60 seconds with eyes open and then with eyes closed, while data were sampled at 100 Hz. The results showed that both the PPPD and psychogenic vertigo groups exhibited significantly larger CoP areas compared to healthy controls, indicating increased postural instability. However, no significant difference was found between the PPPD and psychogenic vertigo groups. While CoP length in the PPPD group was similar to that of healthy controls, the psychogenic vertigo group showed a significantly greater CoP length with eyes closed. These findings suggest that patients with PPPD maintain fine postural control despite increased sway, indicating preserved central nervous system adaptation. No differences were observed between primary and secondary PPPD (s-PPPD). Overall, the postural sway characteristics of PPPD closely resembled those of psychogenic vertigo, supporting the notion that both conditions share features of functional dizziness disorders. Future research should include larger, age- and sex-matched cohorts, along with advanced posturography methods and detailed symptom assessments, to refine diagnostic criteria.

Objective: Persistent postural-perceptual dizziness (PPPD) is a common cause of chronic dizziness, but only a few studies have reported its clinical characteristics, and no related research has been performed in China. Therefore, the purpose of this study was to analyze the characteristics of PPPD for the first time in China. Design: Data was collected from all patients during standard clinical practice, and further to evaluate the characteristics of PPPD comparing with the control group. Study sample: A total of 43 patients diagnosed with PPPD were selected as the study group for analysis. Results: Women were significantly more represented in the study group than men, and in the majority of cases the age of onset was in middle-age, and sleep quality was clearly decreased compared with controls, with more statistically significantly higher levels of anxiety. Personality analysis identified that neuroticism was significantly higher than in controls. Conclusions: In this sample we showed that PPPD was more represented in female patients, the age of onset was 40–60 years old, the majority of patients had sleep disorders, anxiety was the main mood disorder to be identified, and personality analysis found that neurotic personality may be the risk factor for developing PPPD. Further large scale studies are suggested in China.

Persistent postural-perceptual dizziness (PPPD) is a recently defined diagnostic syndrome characterized by chronic symptoms of dizziness, unsteadiness, and/or non-spinning vertigo. Although PPPD has been studied in adults, reports in the pediatric population are few. The goal of this study was to describe the presentation and treatment of PPPD in a group of pediatric patients. Retrospective chart review. Tertiary referral center. ≤21 years old, who met Bárány Society consensus criteria for a diagnosis of PPPD and were followed for ≥6 months or until symptom resolution. Patient demographics, comorbidities, symptom chronicity, and response to treatment(s). Of the 53 patients identified, 44 (83.0%) were women. Mean age at the time of initial evaluation was 14.6 years old. Common diagnoses in addition to PPPD included benign paroxysmal positional vertigo (64.2%), vestibular migraine (56.6%), and anxiety (28.3%). A high proportion of patients (43.4%) reported initially missing school or work due to their symptoms. Eighteen patients (34.0%) reported symptom resolution ranging from 2 to 48 months after diagnosis (median 9 mo). Of these patients, 15 of 18 attended physical therapy (PT), 11 of 18 attended cognitive behavioral therapy (CBT) and/or biofeedback therapy, and 10 of 18 took selective serotonin reuptake inhibitor (SSRI) medications, and 7 of 18 (40%) did a combination of all three therapies. PPPD can impact patients at a young age, and prolonged symptoms present a significant burden to children and adolescents, many of whom are unable to attend school. Treatments such as PT, CBT, and SSRI medication may be effective.

Vestibular migraine (VM) is a usual trigger of episodic vertigo. Patients with VM often experience spinning, shaking, or unsteady sensations, which are usually also accompanied by photophobia, phonophobia, motor intolerance, and more. VM is often associated with a number of comorbidities. Recurrent episodes of VM can affect the patient's emotions, sleep, and cognitive functioning to varying degrees. Patients with VM may be accompanied by adverse moods such as anxiety, fear, and depression, which can gradually develop into anxiety disorders or depressive disorders. Sleep disorders are also a common concomitant symptom of VM, which significantly lower patients' quality of life. The influence of anxiety disorders and sleep disorders may reduce cognitive functions of VM, such as visuospatial ability, attention, and memory decline. Clinically, it is also common to see VM comorbid with other vestibular disorders, making the diagnosis more difficult. VM episodes are relieved but lingering, in which case VM may coexist with persistent postural-perceptual dizziness (PPPD). Anxiety may be an important bridge between recurrent VM and PPPD. The clinical manifestations of VM and Meniere's disease (MD) overlap considerably, and those who meet the diagnostic criteria for both can be said to have VM/MD comorbidity. VM can also present with positional vertigo, and some patients with VM present with typical benign paroxysmal positional vertigo (BPPV) nystagmus on positional testing. In this paper, we synthesize and analyze the pathomechanisms of VM comorbidity by reviewing the literature. The results show that it may be related to the extensive connectivity of the vestibular system with different brain regions and the close connection of the trigeminovascular system with the periphery of the vestibule. Therefore, it is necessary to pay attention to the diagnosis of comorbidities in VM, synthesize its pathogenesis, and give comprehensive treatment to patients.

The cause of persistent postural-perceptual dizziness (PPPD) is considered to be chronic dysfunction of the regulatory system for maintaining equilibrium in general and that of the vestibular system in particular, which causes a persistent sensation of dizziness and/or unsteadiness. The pathogenetic mechanisms of PPPD are associated with impaired adaptation to an acute vertigo or unsteadiness episode due to various causes (vestibular, lipothymic, or emotional). Patients severely experience PPPD, which often leads to avoidant behavior and even disability. The timely diagnosis of this disorder and the use of right treatment, including vestibular rehabilitation, antidepressants, and cognitive behavioral therapy, are of great importance. Currently developed new treatments for PPPD are highly therapeutically effective. Among the medicines, Ginkgo biloba extract has been shown to be effective in improving vestibular compensation.

Persistent Postural-Perceptual Dizziness (PPPD) is a chronic functional vestibular disorder characterized by exacerbation of symptoms by standing, movements, and/or visual stimulation. The Niigata PPPD Questionnaire (NPQ) is an effective screening tool for identifying PPPD, typically with a score of 27 or higher. However, NPQ scores of 27 or more can also occur in diseases other than PPPD.

This study proposes a "modular management" approach for vestibular neuritis (VN) to reduce chronicization and improve patient prognosis. The approach involves multi-factor grading and hierarchical intervention and was found to be more effective than traditional treatment strategies. This retrospective analysis compared two groups of VN patients from two medical institutions. The intervention group of 52 patients received "modular management," while the control group of 51 patients did not receive this kind of management. Analyzed the early treatment strategies, 6-month prognosis, and other indicators of the two groups of patients, compared and analyzed their overall prognosis, and identified the risk factors affecting the chronicization. The modular management group had lower dizziness severity, better balance, lower anxiety, and higher video head impulse testing (v-HIT) gain after 6 months of onset. Analysis of factors related to persistent postural-perceptual dizziness (PPPD) in patients with VN showed positive correlations between the time from onset to diagnosis and PPPD, and Vertigo Symptom Scale (VSS), Dizziness Handicap Inventory (DHI), anxiety, and depression. Normalized vestibular rehabilitation was negatively correlated with PPPD, while gender, age, and early steroid use had no significant correlation. The multi-factor logistic regression model correctly classified 93.20% of the study subjects with a sensitivity of 87.50% and specificity of 94.90%. The proposed "modular management" scheme for VN is a comprehensive and dynamic approach that includes health education, assessment, rehabilitation, therapy, evaluation, and prevention. It can significantly improve patient prognosis and reduce chronicization by shifting from simple acute treatment to continuous management.