Factors influencing clinical outcome in vestibular neuritis - A focussed review and reanalysis of prospective data.

Following vestibular neuritis (VN), long term prognosis is not dependent on the magnitude of the residual peripheral function as measured with either caloric or the video head-impulse test. Rather, recovery is determined by a combination of visuo-vestibular (visual dependence), psychological (anxiety) and vestibular perceptual factors. Our recent research in healthy individuals has also revealed a strong association between the degree of lateralisation of vestibulo-cortical processing and gating of vestibular signals, anxiety and visual dependence. In the context of several functional brain changes occurring in the interaction between visual, vestibular and emotional cortices, which underpin the aforementioned psycho-physiological features in patients with VN, we re-examined our previously published findings focusing on additional factors impacting long term clinical outcome and function. These included: (i) the role of concomitant neuro-otological dysfunction (i.e. migraine and benign paroxysmal positional vertigo (BPPV)) and (ii) the degree to which brain lateralisation of vestibulo-cortical processing influences gating of vestibular function in the acute stage. We found that migraine and BPPV interfere with symptomatic recovery following VN. That is, dizziness handicap at short-term recovery stage was significantly predicted by migraine (r = 0.523, n = 28, p = .002), BPPV (r = 0.658, n = 31, p < .001) and acute visual dependency (r = 0.504, n = 28, p = .003). Moreover, dizziness handicap in the long-term recovery stage continued to be predicted by migraine (r = 0.640, n = 22, p = .001), BPPV (r = 0.626, n = 24, p = .001) and acute visual dependency (r = 0.667, n = 22, p < .001). Furthermore, surrogate measures of vestibulo-cortical lateralisation were predictive of the amount of cortical suppression exerted over vestibular thresholds. That is, in right-sided VN patients, we observed a positive correlation between visual dependence and acute ipsilesional oculomotor thresholds (R2 0.497; p < .001), but not contralateral thresholds (R2 0.017: p > .05). In left-sided VN patients, we observed a negative correlation between visual dependence and ipsilesional oculomotor thresholds (R2 0.459; p < .001), but not for contralateral thresholds (R2 0.013; p > .05). To surmise, our findings illustrate that in VN, neuro-otological co-morbidities retard recovery, and that measures of the peripheral vestibular system are an aggregate of residual function and cortically mediated gating of vestibular input.

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.

Motion sickness.

Over 2000 years ago the Greek physician Hippocrates wrote, "sailing on the sea proves that motion disorders the body." Indeed, the word "nausea" derives from the Greek root word naus, hence "nautical," meaning a ship. The primary signs and symptoms of motion sickness are nausea and vomiting. Motion sickness can be provoked by a wide variety of transport environments, including land, sea, air, and space. The recent introduction of new visual technologies may expose more of the population to visually induced motion sickness. This chapter describes the signs and symptoms of motion sickness and different types of provocative stimuli. The "how" of motion sickness (i.e., the mechanism) is generally accepted to involve sensory conflict, for which the evidence is reviewed. New observations concern the identification of putative "sensory conflict" neurons and the underlying brain mechanisms. But what reason or purpose does motion sickness serve, if any? This is the "why" of motion sickness, which is analyzed from both evolutionary and nonfunctional maladaptive theoretic perspectives. Individual differences in susceptibility are great in the normal population and predictors are reviewed. Motion sickness susceptibility also varies dramatically between special groups of patients, including those with different types of vestibular disease and in migraineurs. Finally, the efficacy and relative advantages and disadvantages of various behavioral and pharmacologic countermeasures are evaluated.

Effects of prochlorperazine on normal vestibular ocular and perceptual responses: a randomised, double-blind, crossover, placebo-controlled study.

BACKGROUND: The present study investigated whether prochlorperazine affects vestibulo-ocular reflex (VOR) and vestibulo-perceptual function. METHODS: We studied 12 healthy naïve subjects 3 h after a single dose of oral prochlorperazine 5 mg in a randomised, placebo-controlled, double-blind, crossover study in healthy young subjects. Two rotational tests in yaw were used: (1) a threshold task investigating perceptual motion detection and nystagmic thresholds (acceleration steps of 0.5°/s(2)) and (2) suprathreshold responses to velocity steps of 90°/s in which vestibulo-ocular and vestibuloperceptual time constants of decay, as well as VOR gain, were measured. RESULTS: Prochlorperazine had no effect upon any measure of nystagmic or perceptual vestibular function compared to placebo. This lack of effects on vestibular-mediated motion perception suggests that the drug is likely to act more as an anti-emetic than as an antivertiginous agent.

Motion sickness susceptibility in healthy subjects and vestibular patients: effects of gender, age and trait-anxiety.

Several studies have suggested that anxiety may play a role in motion sickness susceptibility (MSS) variability. This study aimed to assess motion sickness susceptibility in healthy subjects and chronic vestibular patients and to investigate its relationship to gender, age and trait-anxiety. Healthy subjects (n=167) and chronic dizzy patients with various vestibulopathies (n=94), aged from 20 to 92 years old, were asked to complete Motion Sickness Susceptibility questionnaire (MSSQ) and trait-anxiety questionnaire (STAI-B). When patients were divided into those who had vestibular loss (n=51) vs. patients without vestibular loss (n=43), the MSSQ scores (mean ± SD) for patients with vestibular loss (18.8 ± 30.9) were lower than healthy subjects (36.4 ± 34.8), who were lower than vestibular patients without vestibular loss (59.0 ± 39.7). These significant differences could not be explained by gender, age, trait-anxiety, or interaction. Women had higher MSS than men, and MSS declined with age for healthy subjects and vestibular patients. The overall relationship between anxiety and MSS scores was weak and only reached significance in healthy subjects. These results support the conclusion that the vestibular system is heavily involved in MSS and that trait-anxiety may play a role in MSS but only in healthy subjects.

Effect of temporal relationship between respiration and body motion on motion sickness.

BACKGROUND: This study investigated the effect controlling the phase of respiration on the development of nausea provoked by periodic motion at 0.2 Hz which is maximal for provocation of motion sickness. METHODS: Subjects were exposed to 60 degrees peak-peak, pitch backwards from upright motion while viewing a video of the environment with 180 degrees phase delay. Motion duration was a maximum of 30 min and frequency was set to match individuals' spontaneous respiration. Conditions were: A, spontaneous breathing; B, inspiration cued to begin when head-down; C, inspiration cued to begin when upright; D, inspiration cued with a +/-18 degrees desynchronizing phase drift with respect to the tilt cycle. Nausea was rated and ventilation was recorded. RESULTS: Magnitudes of nausea ratings were ordered D

[18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) as a diagnostic tool for neurofibromatosis 1 (NF1) associated malignant peripheral nerve sheath tumours (MPNSTs): a long-term clinical study.

BACKGROUND: Malignant peripheral nerve sheath tumours (MPNSTs) are difficult to detect in neurofibromatosis 1 (NF1) individuals. The purpose was to evaluate [(18)F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) and PET computed tomography (CT) as a diagnostic tool for MPNST in NF1 patients with symptomatic plexiform neurofibromas and to verify the diagnosis by pathology and clinical follow-up. PATIENTS AND METHODS: NF1 individuals with symptomatic plexiform neurofibromas underwent clinical evaluation and magnetic resonance imaging. Qualitative FDG PET and PET CT associated with semi-quantitative maximum standard uptake value (SUVmax) assessed possible malignant change. Excision/biopsy verified the diagnosis when possible and clinical follow-up was undertaken in all patients. RESULTS: In all, 116 lesions were detected in 105 patients aged 5-71 years, including 80 plexiform neurofibromas, five atypical neurofibromas, 29 MPNST and two other cancers. Biopsy confirmed the findings in 59 tumours and no MPNST was diagnosed on clinical follow-up of 23 lesions diagnosed as benign on FDG PET and PET CT. FDG PET and PET CT diagnosed NF1-associated tumours with a sensitivity of 0.89 [95% confidence interval (CI) 0.76-0.96] and a specificity of 0.95 (CI 0.88-0.98), but the SUVmax level did not predict tumour grade. CONCLUSION: FDG PET and PET CT is a sensitive and specific diagnostic tool for NF1-associated MPNST. Other PET tracers will be required to solve the problem of predicting tumour grade.

Cognitive performance in light current users and ex-users of ecstasy (MDMA) and controls.

Previous research has shown that heavy users of ecstasy (MDMA) may suffer impaired cognitive functioning, and the present study set out to investigate whether such impairment might also be found in light users or ex-users of MDMA. Sixty subjects, comprising 20 current light users, 20 ex-users, and 20 non-users of ecstasy, were tested on an extensive battery of cognitive tests. Current light users of ecstasy achieved significantly lower scores on the overall cognitive test battery than did the non-users (p = .011), though there were no significant differences on any individual subtests. However, the scores obtained by the ex-users of ecstasy did not differ significantly from those of the non-users. It was concluded that current light users of ecstasy show a small but significant cognitive impairment, but that no such impairment is detectable in ex-users who had abstained from the drug for at least 6 months.

Motion sickness and tilts of the inertial force environment: active suspension systems vs. active passengers.

BACKGROUND: Maneuvering in vehicles exposes occupants to low frequency forces (< 1 Hz) which can provoke motion sickness. HYPOTHESIS: Aligning with the tilting inertial resultant (gravity + imposed horizontal acceleration: gravito-inertial force (GIF)) may reduce motion sickness when tilting is either 'active' (self-initiated; Experiment 1) or 'passive' (suspension machinery; Experiment 2). METHODS: Exp 1: Twelve seated subjects were exposed to continuous horizontal translational oscillation through the body x-axis (3.1 m x S(-2) peak acceleration, 0.20 Hz) while making head tilts which were either aligned or misaligned (180 degrees out of phase) with respect to GIF. The two sessions were one week apart at the same time of day, counterbalanced for order. Head tilts were controlled by tracking a moving LED display and head trajectory was verified by accelerometry. Motion continued until moderate nausea was achieved (motion endpoint) or until a 30 min cut-off. Exp 2: A different group of 12 subjects were exposed to continuous horizontal translational sinusoidal oscillation through the body x-axis (2.0 m x S(-2) peak acceleration, 0.176 Hz) while seated in a cab which was tilted by suspension machinery around the y-axis of the ears so that GIF was aligned or misaligned (180 degrees out of phase) with the body z-axis. RESULTS: Exp 1: Mean +/- SD time to motion endpoint was significantly longer for aligned (19.2 +/- 12.0 min) than for misaligned (17.8 +/- 13.0 min; p < 0.05, two-tail). Exp 2: Mean +/- SD time to motion endpoint was significantly shorter for aligned (21.8 +/- 10.9 min) than for misaligned (28.3 +/- 5.8 min; p < 0.01, two-tail). CONCLUSIONS: Whether or not compensatory tilting protects against (Exp 1) or contributes to (Exp 2) motion sickness may be influenced by whether the tilting is under the active control of the person (e.g., car driver) or under external control (e.g., passenger in a high-speed tilting train).

A motion sickness maximum around the 0.2 Hz frequency range of horizontal translational oscillation.

BACKGROUND: Low frequency translational oscillation can provoke motion sickness in land vehicles, ships and aircraft. Although controlled motion experiments indicate a progressive increase in nauseogenicity as frequency decreases toward 0.2 Hz, few data are available on the existence of a definite maximum nauseogenic potential of motion around 0.2 Hz, or decreased nauseogenicity below this frequency. HYPOTHESIS: Nauseogenicity should be maximal around 0.2 Hz. METHODS: We selected 12 subjects for high motion sickness susceptibility, and they were exposed to horizontal sinusoidal motion (1.0 m.s(-2) peak acceleration) at 3 different frequencies (0.1, 0.2 and 0.4 Hz), at 1-wk intervals at the same time of day, according to a factorial design. Subjects were seated comfortably in the upright position with head erect. Fore-aft motion was through the body and head X-axis. Motion was stopped (motion endpoint) at moderate nausea or after 30 min. RESULTS: The proportion of subjects experiencing moderate nausea was maximal at the intermediate frequency: 8/12 at 0.1 Hz, 12/12 at 0.2 Hz, 7/12 at 0.4 Hz. The mean time to motion endpoint was significantly (p < 0.01) shorter at the intermediate frequency: 18.0 min at 0.1 Hz; 11.2 min at 0.2 Hz; 20.2 min at 0.4 Hz. Similar frequency patterns emerged for other sickness ratings. The equivalent times to achieve moderate nausea using estimated values to correct for subjects who reached the 30 min time cut-off were: 22.7 min at 0.1 Hz; 11.2 min at 0.2 Hz; 28.1 min at 0.4 Hz. CONCLUSIONS: A maximum nauseogenic potential around 0.2 Hz was substantiated.

Seasonality, social zeitgebers and mood variability in entrainment of mood. Implications for seasonal affective disorder.

BACKGROUND: Seasonal variations in mood (seasonality) appear to be entrained to light, a physical zeitgeber. We hypothesised that people high in seasonality may be responsive to a range of zeitgebers, because of greater mood variability. We investigated whether the moods of people high in seasonality were more strongly entrained to the calendar week, a social zeitgeber, and whether any such effect was dependent on variability of mood. METHODS: 53 participants (14 male, 39 female; overall mean age=30) completed a daily mood report, over 56 consecutive days. Participants also completed the Seasonality Score Index (SSI) of the Seasonal Pattern Assessment Questionnaire. Each participant's time series of daily mood was analysed by spectral analysis to quantify the strength of their weekly mood cycle. RESULTS: Participants with high SSI scores (> or =11) had significantly stronger weekly mood cycles than those with low SSI scores (<11), and significantly greater variability in mood. Covarying for mood variability reduced the difference between high and low SSI groups in mean strength of weekly mood cycle to non-significance. LIMITATIONS: The time series of moods obtained was relatively short, and moods among high seasonal participants may have been affected by seasonal weather variability. CONCLUSIONS: People high in seasonality appear to be more responsive to external zeitgebers, and this could be linked to their greater variability in mood. The integration of research on mood variability with research on SAD appears to be warranted.

Autonomic response to real versus illusory motion (vection).

This study explored the cardiovascular responses to illusions of self-motion (vection) induced in normal subjects according to the hypothesis that vection may be a model for vertigo in vestibular disease. Responses were obtained from 10 men who were exposed to rapid tilts of 20 degrees and 30 degrees rolling from the upright position down to the right or left shoulder. These responses were compared with those evoked during the illusion of roll-tilt vection provoked by a torsionally rotating visual field. Comparisons were made between 10-second data epochs before and after stimulus onset. In response to vection, blood pressure (BP) in the radial artery rose consistently in six subjects, and in all of these, a pressor response to real tilt was also observed. The remaining four subjects consistently had decreased BP in response to vection, and their BPs were affected little by tilt. Subjects whose BP increased with vection and tilt may have been dominated by tendency to arousal, whereas those whose BP decreased may reveal the more appropriate response to tilt from the upright position, which is a decrease in BP. This may reflect individual stereotypes and differences in the relative contributions of somatosensory and vestibular control of autonomic regulation.

Graviceptive control of blood pressure in man.

The purpose of the study was to demonstrate a rapid 'graviceptive' influence on blood pressure in man. Subjects, sitting in an electrically powered car, made discrete head tilts, some of which were unpredictably accompanied by transient linear accelerations of the car i) with head tilting to align with the direction of the resulting inertial force vector (gravity + car acceleration) so that the graviceptors were not stimulated; ii) with head tilting in the opposite direction 'misaligning' which stimulated the graviceptors but otherwise maintained similarity of other sensory inputs. Stimuli were dispensed in a balanced, cross over, repeated measures design on 8 normal males. Recordings were made of arterial blood pressure in the left radial artery, the electrocardiogram and plethysmographic responses in the right hand first digit. Comparisons of 10s pre-stimulus baseline with 10s post stimulus responses. Misaligned head tilts provoked highly significant peak increases in systolic (7.6-9.4 mm Hg) and diastolic (5-6 mm Hg) BP and average BP over 10s was significantly raised. Head tilts maintaining alignment with the inertial force vector provoked raised systolic BP by 4-6 mm Hg for only one or two heartbeats. Head movements alone caused a slight lowering of BP. Effects were evident within 1-2 heartbeats of the acceleration onset. The results demonstrate that the graviceptors have a direct influence on BP in normal man. They also help to explain the profound vaso-vagal symptoms of patients with vertigo and why patients with autoregulatory impairment may be further compromised by uncontrolled accelerating and braking when they are transported in an ambulance.

Health-related correlates of gambling on the British National Lottery.

The National Lottery has been estimated as being played by 65% of the adult British population. This study investigated whether higher average weekly spending on the Lottery is associated with various health-related variables. Results from a survey of 482 British adults (mean age = 33.3 yr.), consisting of 107 students and 375 people in employment, indicated that those who spent more on the Lottery had significantly poorer social functioning (Social Functioning scale of the SF-36 Health Survey), higher weekly alcohol and cigarette consumption, and lower frequency of social support (Emotional and Social Interaction scales of the Medical Outcomes Study Social Support Survey). By contrast, higher lottery spending was not associated with poorer general mental health (General Health Questionnaire). Manual workers spent over twice the weekly amount on the Lottery compared to nonmanual workers. Consumption of alcohol and cigarettes was lower than recently published UK norms. Results suggest that higher Lottery spending among the general adult population possibly may be linked specifically to restrictions in social activity. The association of Lottery spending with alcohol and cigarette use among a sample whose consumption was relatively low appears to require explanation within psychological theories of addiction. The over-all pattern of results is discussed in relation both to addiction theory and to the Lottery's widespread appeal and availability.

Variations in self-reported health by occupational grade in the British Post Office: the Q-health project.

Between 1995 and 1998 a national sample of 58,501 (42,885 males, 15,616 females) Post Office employees (29%) completed and returned a postal questionnaire survey providing information on demographic characteristics, physical and psychological health, health and lifestyles and health screening behaviour. Response rates by occupational grade were as follows: manual (male 69.3%, females 43.6%); clerical (male = 11.8%, female, 42.3%); middle management (males 15.5%, females 10.7%) and senior management (males 3.4%, females 3.3%). A number of differences in health status occurred with occupational grade. Angina, high blood pressure, obesity, smoking, arthritis, disability, GP consultations and abnormal smears were all more prevalent in lower occupational grades. Height, job satisfaction, seat belt use and breast self-examination were also lower in lower status jobs. Some findings were unexpected: GHQ scores indicated better mental health in lower grades, whilst knowledge and frequency of testicular self-examination and attendance for mammograms were higher in lower grades. Self-reports for asthma, diabetes and family history of bowel cancer were also greater in higher grades. These findings are considered in terms of response bias, health selection, the psychosocial work environment, occupational health interventions and the nature, meaning and organization of social position within the Post Office.

Motion sickness susceptibility questionnaire revised and its relationship to other forms of sickness.

The Reason and Brand Motion Sickness Susceptibility Questionnaire (MSSQ) has remained unchanged for a quarter of a century. The primary aims of this investigation were to improve the design of the MSSQ, simplify scoring, produce new adult reference norms, and analyse motion validity data. We also considered the relationship of sickness from other nonmotion causes to the MSSQ. Norms and percentiles for a sample of 148 subjects were almost identical to the original version of this instrument. Reliability of the whole scale gave a Cronbach's standardised item alpha of 0.86, the correlation between Part A (child) and Part B (adult) was r = 0.65 (p < 0.001), and test-retest reliability may be assumed to be better than 0.8. Predictive validity of the MSSQ for motion sickness tolerance using laboratory motion devices averaged r = 0.45. Correlation between MSSQ and other sources of nausea and vomiting in the last 12 months, excluding motion sickness itself, was r = 0.3 (p < 0.001), migraine was the most important contributor to this relationship. In patients (n = 101) undergoing chemotherapy, there were significant correlations between MSSQ and chemotherapy-induced nausea and vomiting. Migraine also appeared as a predictor of chemotherapy-induced sickness. It was concluded that the revised MSSQ can be used as a direct replacement of the original version. The relationship between motion sickness susceptibility and other causes of sickness, including migraine and chemotherapy, points to the involvement of the vestibular system in the response to nonmotion emetogenic stimuli. Alternatively, this relationship may reflect individual differences in excitability of the postulated final common emetic pathway.

Objective and subjective time courses of recovery from motion sickness assessed by repeated motion challenges.

The aim of this study was to determine whether the time course of recovery of tolerance, as assessed objectively by rechallenge with motion, paralleled the subjective recovery from motion sickness. Subjects (n = 20) were exposed to 5 pairs of nauseogenic motion challenges in which the time interval between the end of the first and the start of the second of each pair ranged from 15 min to 2 h. The cross-coupled motion challenge had an incrementing profile of rotational velocity from 4 degrees to 92 degrees.s-1 in steps of 4 degrees.s-1 every 30 s, with 8 head movements per 30 s, of approximately 45 degrees, and was continued to the point of moderate nausea. Objective loss of tolerance decreased from 15 min to 60 min after the first challenge, but increased again at 2 h. By contrast, most individuals reported subjective recovery by 15 min to 30 min. It was concluded that there is an underlying effect of motion sickness that sensitizes the response to subsequent motion for a period of at least 2 h. This underlying objective effect can occur in the absence of subjective symptoms, has a slower time course than the subjective recovery from symptoms, and appears to be non-monotonic.