Concussion can increase the risk of visually induced motion sickness.

Concussion can lead to various symptoms such as balance problems, memory impairments, dizziness, and/or headaches. It has been previously suggested that during self-motion relevant tasks, individuals with concussion may rely heavily on visual information to compensate for potentially less reliable vestibular inputs and/or problems with multisensory integration. As such, concussed individuals may also be more sensitive to other visually-driven sensations such as visually induced motion sickness (VIMS). To investigate whether concussed individuals are at elevated risk of experiencing VIMS, we exposed participants with concussion (n = 16) and healthy controls (n = 15) to a virtual scene depicting visual self-motion down a grocery store aisle at different speeds. Participants with concussion were further separated into symptomatic and asymptomatic groups. VIMS was measured with the SSQ before and after stimulus exposure, and visual dependence, self-reported dizziness, and somatization were recorded at baseline. Results showed that concussed participants who were symptomatic demonstrated significantly higher SSQ scores after stimulus presentation compared to healthy controls and those who were asymptomatic. Visual dependence was positively correlated with the level of VIMS in healthy controls and participants with concussion. Our results suggest that the presence of concussion symptoms at time of testing significantly increased the risk and severity of VIMS. This finding is of relevance with regards to the use of visual display devices such as Virtual Reality applications in the assessment and rehabilitation of individuals with concussion.

A computational model of motion sickness dynamics during passive self-motion in the dark.

Predicting the time course of motion sickness symptoms enables the evaluation of provocative stimuli and the development of countermeasures for reducing symptom severity. In pursuit of this goal, we present an Observer-driven model of motion sickness for passive motions in the dark. Constructed in two stages, this model predicts motion sickness symptoms by bridging sensory conflict (i.e., differences between actual and expected sensory signals) arising from the Observer model of spatial orientation perception (stage 1) to Oman's model of motion sickness symptom dynamics (stage 2; presented in 1982 and 1990) through a proposed "Normalized Innovation Squared" statistic. The model outputs the expected temporal development of human motion sickness symptom magnitudes (mapped to the Misery Scale) at a population level, due to arbitrary, 6-degree-of-freedom, self-motion stimuli. We trained model parameters using individual subject responses collected during fore-aft translations and off-vertical axis of rotation motions. Improving on prior efforts, we only used datasets with experimental conditions congruent with the perceptual stage (i.e., adequately provided passive motions without visual cues) to inform the model. We assessed model performance by predicting an unseen validation dataset, producing a Q2 value of 0.91. Demonstrating this model's broad applicability, we formulate predictions for a host of stimuli, including translations, earth-vertical rotations, and altered gravity, and we provide our implementation for other users. Finally, to guide future research efforts, we suggest how to rigorously advance this model (e.g., incorporating visual cues, active motion, responses to motion of different frequency, etc.).

Oxidative stress and motion sickness in one crew during competitive offshore sailing.

Competitive Offshore Ocean Sailing is a highly demanding activity in which subjects are exposed to psychophysical stressors for a long time. To better define the physiological adaptations, we investigated the stress response of subjects exposed to 3-days long ocean navigation with disruption of circadian rhythms. 6 male subjects were involved in the study and provided urine and saliva samples before setting sail, during a single day of inshore sailing, during 3-days long ocean navigation, and at the arrival, to measure oxidative stress, cortisol, nitric oxide metabolites (NOx) and metabolic response. Motion Sickness questionnaires were also administered during the navigation. The crew suffered a mean weight loss of 1.58 kg. After the long navigation, a significant increase in ROS production and decrease in total antioxidant capacity and uric acid levels were observed. Lipid peroxidation, NO metabolites, ketones, creatinine, and neopterin levels were also increased. Furthermore, a significant increase in cortisol levels was measured. Finally, we found a correlation between motion sickness questionnaires with the increase of NOx, and no correlation with cortisol levels. Physical and psychological stress response derived from offshore sailing resulted in increased oxidative stress, nitric oxide metabolites, and cortisol levels, unbalanced redox status, transient renal function impairment, and ketosis. A direct correlation between motion sickness symptoms evaluated through questionnaires and NOx levels was also found.

Left parietal involvement in motion sickness susceptibility revealed by multimodal magnetic resonance imaging.

Susceptibility to motion sickness varies greatly across individuals. However, the neural mechanisms underlying this susceptibility remain largely unclear. To address this gap, the current study aimed to identify the neural correlates of motion sickness susceptibility using multimodal MRI. First, we compared resting-state functional connectivity between healthy individuals who were highly susceptible to motion sickness (N = 36) and age/sex-matched controls who showed low susceptibility (N = 36). Seed-based analysis revealed between-group differences in functional connectivity of core vestibular regions in the left posterior Sylvian fissure. A data-driven approach using intrinsic connectivity contrast found greater network centrality of the left intraparietal sulcus in high- rather than in low-susceptible individuals. Moreover, exploratory structural connectivity analysis uncovered an association between motion sickness susceptibility and white matter integrity in the left inferior fronto-occipital fasciculus. Taken together, our data indicate left parietal involvement in motion sickness susceptibility.

Idiosyncratic multisensory reweighting as the common cause for motion sickness susceptibility and adaptation to postural perturbation.

Numerous empirical and modeling studies have been done to find a relationship between postural stability and the susceptibility to motion sickness (MS). However, while the demonstration of a causal relationship between postural stability and the susceptibility to MS is still lacking, recent studies suggest that motion sick individuals have genuine deficits in selecting and reweighting multimodal sensory information. Here we investigate how the adaptation to changing postural situations develops and how the dynamics in multisensory integration is modulated on an individual basis along with MS susceptibility. We used a postural task in which participants stood on a posturographic platform with either eyes open (EO) or eyes closed (EC) during three minutes. The platform was static during the first minute (baseline phase), oscillated harmonically during the second minute (perturbation phase) and returned to its steady state for the third minute (return phase). Principal component (PC) analysis was applied to the sequence of short-term power density spectra of the antero-posterior position of the center of pressure. Results showed that the less motion-sick a participant is, the more similar is his balance between high and low frequencies for EO and EC conditions (as calculated from the eigenvector of the first PC). By fitting exponential decay models to the first PC score in the return phase, we estimated, for each participant in each condition, the sluggishness to return to the baseline spectrum. We showed that the de-adaptation following platform oscillation depends on the susceptibility to MS. These results suggest that non motion-sick participants finely adjust their spectrum in the perturbation phase (i.e. reweighting) and therefore take longer to return to their initial postural control particularly with eyes closed. Thus, people have idiosyncratic ways of doing sensory reweighting for postural control, these processes being tied to MS susceptibility.

Pyruvate accumulation may contribute to acceleration-induced impairment of physical and cognitive abilities: an experimental study.

BACKGROUND: Fatigue can be induced after acceleration exposure, however its mechanism is still unclear. The aim of the present study was to examine whether metabolites' changes can decrease cognitive and physical function after acceleration. METHODS: Graybiel scale and Fatigue Self-rating scale were used to assess the seasickness and fatigue degrees of 87 male seafarers respectively after sailing. To test the effect of pyruvate on cognitive and physical functions, five different doses of pyruvate were administrated into rats. Insulin can reduce the accumulation of pyruvate. To observe the insulin effect on pyruvate, cognitive and physical functions after acceleration, insulin administration or treatment of promoting insulin secretion was used. Physical and cognitive functions were assessed using open field test (OFT), morris water maze (MWM) and loaded swimming test (LST) in animals. RESULTS: Physical and cognitive abilities were decreased obviously, and serum pyruvate increased mostly in human and rats after acceleration. Compared with vehicle group, physical and cognitive abilities were significantly decreased after pyruvate administration. Besides, we found a significant decline in adenosine triphosphate (ATP) concentration and pyruvate dehydrogenase (PDH) activity in the hippocampus, prefrontal cortex, liver, and muscle of rats treated with acceleration or pyruvate injection, while insulin administration or treatment of promoting insulin secretion markedly alleviated this decline and the impairment of physical and cognitive abilities, compared with the control group. CONCLUSION: Our results indicate that pyruvate has a negative effect on physical and cognitive abilities after acceleration. Insulin can inhibit pyruvate accumulation and cognitive and physical function after acceleration exposure.

Thermal infrared imaging based facial temperature in comparison to ear temperature during a real-driving scenario.

Motion Sickness is associated with a variety of symptoms, which differ in occurrence rate and intensity between individuals. In order to research the cause of car sickness and develop countermeasures, it is important to determine symptoms and their severity objectively. A tool for this purpose could be the assessment of physiological reactions due to motion sickness. This paper describes and discusses a methodology to identify changes in facial skin temperatures in a real-driving study. Common techniques had to be adjusted in order to meet the requirements given by the challenges of in-car-recording. The examined data was generated in a previous study, which was designed to research motion sickness in a driving environment. A pre-processing technique had to be developed to magnify features on the face and subsequently improve the tracking in thermal imagery. After the pre-processing, regions of interest (ROI) were manually marked and tracked in thermal images. The thereby assessed facial skin temperatures were compared to tympanic temperatures. Derived temperatures from the forehead as well as from the 20 hottest pixels within the face indicated a better tracking, while the nose tip was more affected by detection errors. The correlation of the three features with the tympanic temperature showed remarkable differences between a baseline measurement and the actual driving. Less than 10% of the data derived during the driving and up to 30% of the data during the baseline measurement correlated highly. It is concluded that detecting changes in facial skin temperature using thermal infrared imaging in a moving car is challenging and results are hardly comparable to tympanic temperatures. Future research should aim at the different influencing factors of skin and tympanic temperature, while enhancing tracking or detection of ROI could be achieved by reducing the passengers' movements or choosing the target area more carefully.

Sea Voyage Training and Motion Sickness Effects on Working Ability and Life Quality After Landing.

BACKGROUND: The effects of seasickness on working performance during motion exposure have been reported, while the aftereffects on working ability and life quality decline (WLD) still remain unclarified.METHODS: Two cohorts of healthy male Chinese subjects received either a single (SSV) or repeated (RSV) sea voyage training program on different vessels. A seasickness incidence (SSI) questionnaire was administered to assess the prevalence of seasickness symptoms (vomiting, nausea, other, or no symptoms). A WLD questionnaire was used to survey the general feeling of WLD (severe, moderate, slight, and none) by a 4-point score as well as the incidence rate (IR) of specific WLD items within 24 h after landing.RESULTS: The RSV cohort had lower overall IR of WLD than the SSV cohort (54.64% vs. 63.78%, N 657 for both cohorts). The landing ship trainees in both cohorts showed higher general WLD score and higher IRs of physical fatigue, sleep disorder, and spontaneous locomotion decrement than those trained on the small vessels. Subjects with vomiting or nausea had higher general WLD score and higher IRs of concentration distraction, physical fatigue, anorexia, and spontaneous locomotion decrement than those with no symptoms. Higher IRs of firing accuracy decline (SSV: 21.35% vs. 7.13%, 9.14%; RSV: 22.11% vs. 9.28%, 5.27%), equipment operation disturbance (SSV: 16.85% vs. 3.57%, 6.85%; RSV: 20.47% vs. 7.85%, 7.03%) were also observed in the vomiting subjects than those with other symptoms and no symptoms.DISCUSSION: Significant WLD after landing was associated with transportation types, seasickness severity, and habituation during sea voyage training.Qi R-R, Xiao S-F, Su Y, Mao Y-Q, Pan L-L, Li C-H, Lu Y-L, Wang J-Q, Cai Y-L. Sea voyage training and motion sickness effects on working ability and life quality after landing. Aerosp Med Hum Perform. 2021; 92(2):9298.

Beyond sensory conflict: The role of beliefs and perception in motion sickness.

Illusory self-motion often provokes motion sickness, which is commonly explained in terms of an inter-sensory conflict that is not in accordance with previous experience. Here we address the influence of cognition in motion sickness and show that such a conflict is not provocative when the observer believes that the motion illusion is indeed actually occurring. Illusory self-motion and motion sickness were elicited in healthy human participants who were seated on a stationary rotary chair inside a rotating optokinetic drum. Participants knew that both chair and drum could rotate but were unaware of the actual motion stimulus. Results showed that motion sickness was correlated with the discrepancy between participants' perceived self-motion and participants' beliefs about the actual motion. Together with the general motion sickness susceptibility, this discrepancy accounted for 51% of the variance in motion sickness intensity. This finding sheds a new light on the causes of visually induced motion sickness and suggests that it is not governed by an inter-sensory conflict per se, but by beliefs concerning the actual self-motion. This cognitive influence provides a promising tool for the development of new countermeasures.

Ocular counter-rolling in scuba divers with motion sickness.

OBJECTIVE: Motion sickness (MS) is a familiar condition to scuba divers. The purpose of this study was to compare otolith organ function of scuba divers who have MS to those without MS. METHOD: Video-oculography (VOG) goggles were used to measure video ocular counter-roll (vOCR) in 50 healthy scuba divers with no vestibular pathology. Divers with MS (n = 30) had Graybiel motion sickness (GMS) scores of ≥1 point, and divers without MS (n = 20) had GMS scores of 0. Divers with MS also completed the Motion Sickness Susceptibility Questionnaire short form (MSSQs). For all divers, otolith-ocular function of both ears was tested separately via vOCR testing, which was performed during 30° head tilt. An R-L side asymmetry ratio for vOCR values (%OCRA) was compared to divers' static OCR. RESULTS: MSSQs and %OCRA scores differed significantly (p<0.01and p<0.001, respectively) between divers with MS and divers without MS. Their %OCRA scores and severity of MS were significantly correlated. Female divers were more susceptible to MS. ROC analysis for %OCRA revealed that the AUC for divers with MS and divers without MS was 0.8967 (95% CI, 0.8114 to 0.9819), the specificity was 1.000, and the sensitivity was 0.700, with a cutoff value of 45.946. CONCLUSION: Physiological differences between R-L otolith organ function could affect the severity and susceptibility to MS. Female hormones may also increase susceptibility to MS. Thus, MS may be a physiological phenomenon induced by functional ear differences in the absence of pathology. As MS is caused by multiple factors, otolaryngologists need to consider various causative factors beyond those related to otolith organ function in scuba divers with MS.

Test-retest reliability of the virtual reality sickness evaluation using electroencephalography (EEG).

No reliable quantitative and objective measurement method for virtual reality (VR) sickness has been firmly established to date. Electroencephalography (EEG) may be a strong candidate to evaluate VR sickness objectively. However, no test-retest evaluation has been made for VR sickness using EEG. To recruit VR sickness-sensitive participants, we tested 858 participants (age = 20's-50's) using the Motion Sickness Susceptibility Questionnaire (MSSQ). Among them, we recruited 21 males (average age = 25.0) who obtained the 75th percentile of scores on the MSSQ (32.9 ± 5.7). VR sickness was evaluated twice (one week apart) using EEG with VR video content designed to cause VR sickness. A Simulation Sickness Questionnaire (SSQ) was also used to evaluate VR sickness. In terms of the reliability of EEG, ICC and Cronbach's alpha analyses showed that three waves (delta, theta, and alpha) were consistent in two areas (frontal and central). A significant difference in EEG was also found repeatedly between the baseline and VR sickness (delta, theta, and alpha) in two areas (frontal and central). We evaluated EEG for its reliability and found specific waves and areas that showed good consistency and significant changes associated with VR sickness. These findings may support further research of VR sickness evaluation.

Joint and individual effectiveness of galvanic cutaneous stimulation and tactile stimulation at decreasing Simulator Adaptation Syndrome.

This research was focused on investigating the effectiveness of galvanic cutaneous stimulation and tactile stimulation jointly and individually at mitigating Simulator Adaptation Syndrome. Forty drivers (mean age = 23.1 ± 3.4 years old, twenty women) participated in a driving simulation experiment. Total scores of the Simulator Sickness Questionnaire, head movements (an index of body balance), and driving performance variables were compared across four different stimulation conditions: i) baseline (where no stimulation was presented), ii) galvanic cutaneous stimulation and iii) tactile stimulation deployed individually, and iv) both techniques deployed jointly. The results showed that both techniques presented in conjunction alleviate Simulator Adaptation Syndrome and improve driving performance more effectively than when they are presented in isolation. Importantly, reduced head movements were only revealed when galvanic cutaneous stimulation was applied. We concluded that the reduction of this syndrome is due to an improvement of body balance (elicited by galvanic cutaneous stimulation), and a distraction from the symptoms (elicited by tactile stimulation). We encourage the use of both techniques simultaneously to decrease Simulator Adaptation Syndrome.

Vestibular modulation of skin sympathetic nerve activity in sopite syndrome induced by low-frequency sinusoidal motion.

Sopite syndrome, centered around the drowsiness, lethargy, and irritability associated with motion sickness, can be induced by exposure to low-frequency motion. It is known that the vestibular apparatus plays an important role in the pathogenesis of motion sickness, which features several autonomic responses, and we have previously documented increased vestibular modulation of skin sympathetic nerve activity (SSNA) and an increase in skin blood flow associated with nausea. Here, we assessed whether imperceptibly slow sinusoidal motion, sufficient to induce sopite syndrome but not nausea, also modulates SSNA and skin blood flow. Participants were seated upright and exposed to a randomized set of sinusoidal linear accelerations, ranging from 0.03 Hz at 0.5 mG to 0.2 Hz at 5 mG, via a motorized platform. At all frequencies vestibular modulation was greater than the cardiac modulation of SSNA, but cardiac modulation and skin blood flow were both significantly lower during the motion than at baseline. We conclude that sopite syndrome is associated with a marked modulation of sympathetic outflow to the skin and cutaneous vasoconstriction.NEW & NOTEWORTHY Little is known about the autonomic consequences of sopite syndrome-the drowsiness that can be induced by low-amplitude cyclic motion. We recorded skin sympathetic nerve activity (SSNA) in seated participants exposed to slow sinusoidal linear acceleration (0.03-0.2 Hz), which preferentially activates hair cells in the utricular part of the otolithic organs, at amplitudes that generated no sensations of motion. At all frequencies, there was a clear vestibular modulation of SSNA and cutaneous vasoconstriction.

Patients With Vestibular Migraine are More Likely to Have Occipital Headaches than those With Migraine Without Vestibular Symptoms.

OBJECTIVE: To determine whether patients with vestibular migraine are more likely to suffer from an occipital headache than patients with migraine without vestibular symptoms. BACKGROUND: Vestibular migraine is an underdiagnosed disorder in which migraine is associated with vestibular symptoms. Anatomical evidence and symptomatology hint at the involvement of brain structures in the posterior fossa (back of the head location). We hypothesized that vestibular migraine patients are more likely than migraineurs without vestibular symptoms to experience headaches located in the back of the head, that is, occipital headaches. METHODS: A retrospective cross-sectional study was conducted at the University of Iowa Hospital and Clinics. Chart analysis of 169 patients was performed. The primary outcome was the location of the headache in vestibular migraine patients and migraineurs without vestibular symptoms. The secondary outcomes included the association of vestibular migraine with gender, age at onset of headache, age at onset of vestibular symptoms (such as vertigo, head motion-induced dizziness), aura, motion sickness, other associated symptoms, family history of headaches, and family history of motion sickness. RESULTS: In vestibular migraine group, 45/103 (44%) had occipital location for their headaches vs 12/66 (18%) in migraine patients without vestibular symptoms, for an odd's ratio of 3.5 (95% CI = 1.7-7.2, P < .001). Additionally, the age at onset of headache was greater in the vestibular migraine group (28 ± 12 vs 18 ± 9 years, P < .001) and motion sickness was more common (41/98 (42%) in the vestibular migraine group, 1/64 (2%) in the migraine without vestibular symptoms group, P < .001). CONCLUSIONS: This study suggests that patients with vestibular migraine are more likely to have occipital headaches than patients with migraine without vestibular symptoms. Our data support the initiation of a prospective study to determine whether a patient presenting with occipital headaches, with late onset of age of headache, and with a history of motion sickness is at an increased risk for the possible development of vestibular migraine.

Individual predictors of the susceptibility for motion-related sickness: A systematic review.

BACKGROUND: Individuals seem to be differently susceptible to motion-related sickness (motion sickness, visually induced sickness etc.). Investigations of the reasons for these different susceptibilities have revealed many potential factors that could predict individual susceptibility to motion-related sickness. OBJECTIVE: This paper attempts to conduct a comprehensive literature review on inter-individual predictors of susceptibility to motion-related sickness using systematic approaches. METHODS: After a systematic literature research, titles and abstracts of 1778 publications were screened for relevance. Reference lists of selected publications were searched for additional studies. This procedure yielded 184 relevant publications. RESULTS: The identified predictors were clustered into demographic, physiological and psychological aspects. Among these predictors, the factors gender, length of velocity storage and anxiety showed the greatest predictive power. In addition, individual susceptibility to motion-related sickness is also to a large extent dependent on the degree of habituation to the aversive stimulus. CONCLUSIONS: Some of the identified influencing factors seem to have different effects on physically and visually induced motion sickness. More research is needed to close gaps, especially on predictive factors of visually induced motion sickness.

Vestibulo-Ocular Responses, Visual Field Dependence, and Motion Sickness in Aerobatic Pilots.

BACKGROUND: Aerobatic flight is a challenge for the vestibular system, which is likely to lead to adaptive changes in the vestibular responses of pilots. We investigated whether aerobatic pilots, as individuals who experience intense vestibular stimulation, present modifications of the vestibular-ocular reflex, motion sickness susceptibility and intensity, visual vertical estimation, and visual dependence as compared to normal volunteers.METHODS: To evaluate vestibulo-ocular reflexes, eye movements were recorded with videonystagmography while subjects were rotated on a rotatory chair with the axis of rotation being vertical (canal-ocular reflex) or inclined to 17° (otolith-ocular reflex). Motion sickness was evaluated after the rotatory test using the Graybiel diagnostic criteria. General motion sickness susceptibility and visual field dependence were also evaluated.RESULTS: Averaged data did not show significant difference in canal-ocular reflex and otolith ocular-reflex between groups. However, a significant asymmetry in otolith-driven ocular responses was found in pilots (CW 0.50 ± 1.21° · s-1 vs. CCW 1.59 ± 1.12° · s-1), though visual vertical estimation was not altered in pilots and both groups were found field independent. Pilots were generally less susceptible to motion sickness (MSSQ scores: 2.52 ± 5.59 vs. 13.5 ± 11.36) and less affected by the nauseogenic stimulation (Graybiel diagnostic criteria 3.36 ± 3.81 vs. 8.39 ± 7.01).DISCUSSION: We did not observe the expected habituation in the group of aerobatic pilots. However, there was a significant asymmetry in the otolith-driven ocular responses in pilots, but not in the controls, which may result from the asymmetry in piloting protocols.Kuldavletova O, Tanguy S, Denise P, Quarck G. Vestibulo-ocular responses, visual field dependence, and motion sickness in aerobatic pilots. Aerosp Med Hum Perform. 2020; 91(4):326-331.

Motion sickness symptoms during jumping exercise on a short-arm centrifuge.

Artificial gravity elicited through short-arm human centrifugation combined with physical exercise, such as jumping, is promising in maintaining health and performance during space travel. However, motion sickness symptoms could limit the tolerability of the approach. Therefore, we determined the feasibility and tolerability, particularly occurrence of motion sickness symptoms, during reactive jumping exercises on a short-arm centrifuge. In 15 healthy men, we assessed motion sickness induced by jumping exercises during short-arm centrifugation at constant +1Gz or randomized variable +0.5, +0.75, +1, +1.25 and +1.5 Gz along the body axis referenced to center of mass. Jumping in the upright position served as control intervention. Test sessions were conducted on separate days in a randomized and cross-over fashion. All participants tolerated jumping exercises against terrestrial gravity and on the short-arm centrifuge during 1 Gz or variable Gz at the center of mass without disabling motion sickness symptoms. While head movements markedly differed, motion sickness scores were only modestly increased with jumping on the short-arm centrifuge compared with vertical jumps. Our study demonstrates that repetitive jumping exercises are feasible and tolerable during short-arm centrifugation. Since jumping exercises maintain muscle and bone mass, our study enables further development of exercise countermeasures in artificial gravity.

Cardiovascular testing of seasickness in healthy volunteers on life rafts.

OBJECTIVES: The role of the cardiovascular system in the development of seasickness remains uncertain. MATERIAL AND METHODS: Overall, 18 healthy students (10 males and 8 females) aged 18-24 years volunteered in the project, spending 2-7 h on life rafts. The cardiovascular system was examined with impedance cardiography. Susceptibility and symptoms of seasickness were evaluated by the Motion Sickness Susceptibility Questionnaire Shortform (MSSQ-Short) and the Motion Sickness Assessment Questionnaire (MSAQ). The Visual Analogue Scale (VAS), ranging 0-10, was used to assess nausea, dizziness and mood. The parameters were assessed at 2 time points. RESULTS: Differences in the heart rate (HR), the thoracic fluid content index (TFCI), the stroke index (SI) and the Heather index (HI) before launching the life rafts and after leaving them were observed (78.6, 20.8, 55.6 and 15.9 vs. 70.1, 19.7, 60.5 and 17.9, with p-values of 0.002, <0.001, 0.003 and 0.004, respectively). Females reacted with changes in SI and HR more vividly, whereas males regulated more HI and TFCI. In addition, HR correlated significantly with the central and peripheral symptoms in MSAQ, stroke volume (SV) with peripheral and sopite-related ones, SI with overall ones, and pulse pressure with overall, gastrointestinal and central ones (Spearman's rank correlation coefficient [ρ] was -0.478, -0.711, 0.476, 0.472, 0.525, -0.476, -0.579 and -0.584, respectively). As regards MSSQ-Short, it correlated negatively with sopite-related symptoms in MSAQ (ρ= -0.486). Mood in VAS correlated significantly with gastrointestinal symptoms, SI and the cardiac index (CI) (ρ = -0.752, -0.492 and -0.489, respectively). CONCLUSIONS: It was found that HR correlated negatively, and SV/SI correlated positively, with the severity of seasickness symptoms measured with MSAQ. Gender is probably an independent factor influencing reactions to motion. Women react with SI increase whereas men react with increased heart contractility (HI rise). Negative mood in seasickness evaluated with VAS seems to be mostly determined by gastrointestinal symptoms assessed with MSAQ and diminished cardiovascular indices (both CI and SI). Int J Occup Med Environ Health. 2020;33(4):467-77.

Vestibular Function and Motion Sickness Susceptibility: Videonystagmographic Evidence From Oculomotor and Caloric Tests.

Purpose Motion sickness (MS) is a common condition that affects millions of individuals. Although the condition is common and can be debilitating, little research has focused on the vestibular function associated with susceptibility to MS. One causal theory of MS is an asymmetry of vestibular function within or between ears. The purposes of this study, therefore, were (a) to determine if the vestibular system (oculomotor and caloric tests) in videonystagmography (VNG) is associated with susceptibility to MS and (b) to determine if these tests support the theory of an asymmetry between ears associated with MS susceptibility. Method VNG was used to measure oculomotor and caloric responses. Fifty young adults were recruited; 50 completed the oculomotor tests, and 31 completed the four caloric irrigations. MS susceptibility was evaluated with the Motion Sickness Susceptibility Questionnaire-Short Form; in this study, percent susceptibility ranged from 0% to 100% in the participants. Participants were divided into three susceptibility groups (Low, Mid, and High). Repeated-measures analyses of variance and pairwise comparisons determined significance among the groups on the VNG test results. Results Oculomotor test results revealed no significant differences among the MS susceptibility groups. Caloric stimuli elicited responses that were correlated positively with susceptibility to MS. Slow-phase velocity was slowest in the Low MS group compared to the Mid and High groups. There was no significant asymmetry between ears in any of the groups. Conclusions MS susceptibility was significantly and positively correlated with caloric slow-phase velocity. Although asymmetries between ears are purported to be associated with MS, asymmetries were not evident. Susceptibility to MS may contribute to interindividual variability of caloric responses within the normal range.

Visual Vertigo, Motion Sickness, and Disorientation in Vehicles.

Environmental circumstances that result in ambiguity or conflict with the patterns of sensory stimulation may adversely affect the vestibular system. The effect of this conflict in sensory information may be dizziness, a sense of imbalance, nausea, and motion sickness sometimes even to seemingly minor daily head movement activities. In some, it is not only exposure to motion but also the observation of objects in motion around them such as in supermarket aisles or other places with visual commotion; this can lead to dizziness, nausea, or a feeling of motion sickness that is referred to as visual vertigo. All people with normal vestibular function can be made to experience motion sickness, although individual susceptibility varies widely and is at least partially heritable. Motorists learn to interpret sensory stimuli in the context of the car stabilized by its suspension and guided by steering. A type of motorist's disorientation occurs in some individuals who develop a heightened awareness of perceptions of motion in the automobile that makes them feel as though they may be rolling over on corners and as though they are veering on open highways or in streaming traffic. This article discusses the putative mechanisms, consequences and approach to managing patients with visual vertigo, motion sickness, and motorist's disorientation syndrome in the context of chronic dizziness and motion sensitivity.