Long-Term Follow-Up of Intratympanic Methylprednisolone Versus Gentamicin in Patients With Unilateral Menière's Disease.

OBJECTIVES: To determine whether long term (>48 months) symptomatic vertigo control is sustained in patients with Menière's disease from a previous comparative trial of intratympanic methylprednisolone versus gentamicin, and if the two treatments remain nonsignificantly different at long-term follow-up. STUDY DESIGN: Mail survey recording vertigo frequency in the previous one and six months, further intratympanic treatment received, and validated symptom questionnaires. SETTING: Outpatient hospital clinic setting. PATIENTS: Adult patients with definite unilateral refractory Menière's disease, who previously received intratympanic treatment in a comparative trial. INTERVENTION: A survey of trial participants who received intratympanic gentamicin (40 mg/mL) or methylprednisolone (62.5 mg/mL). OUTCOME MEASURES: Primary: number of vertigo attacks in the 6 months prior to receiving this survey compared with the 6 months before the first trial injection. Secondary number of vertigo attacks over the previous 1 month; validated symptom questionnaire scores of tinnitus, dizziness, vertigo, aural fullness, and functional disability. RESULTS: Forty six of the 60 original trial patients (77%) completed the survey, 24 from the gentamicin and 22 from the methylprednisolone group. Average follow-up was 70.8 months (standard deviation 17.0) from the first treatment injection. Vertigo attacks in the 6 months prior to receiving the current survey reduced by 95% compared to baseline in both drug groups (intention-to-treat analysis, both p < 0.001). No significant difference between drugs was found for the primary and secondary outcomes. Eight participants (methylprednisolone = 5 and gentamicin = 3) required further injections for relapse after completing the original trial. CONCLUSION: Intratympanic methylprednisolone treatment provides effective long-lasting relief of vertigo, without the known inner-ear toxicity associated with gentamicin. There are no significant differences between the two treatments at long term follow-up.

Impact of vertigo and spatial disorientation on concurrent cognitive tasks.

Disorientation may draw attention from other activities and its impact on cognition may cause pilot error and problems of concentration in dizzy patients. Tasks used to study the impact of disorientation include number processing, intelligence scales and Brookes matrices (reproduction of 2xD patterns of numbers vs. nonsensical sentences), and Stroop tasks to probe selective effects on spatial versus verbally-loaded tasks. This variety of tasks has been used to evaluate cognitive performance in numerous scenarios, including visual-vestibular mismatch, vection, spinning, coriolis, balancing, and flight maneuvers. A meta-analysis provides an overview of how spatial disorientation may affect cognition: Substantial individual differences in managing disorientation are to be expected; errors on cognitive tasks occur during the first few experiences of a disorienting situation and subjects rapidly learn to "quarantine" this "novelty effect"; familiarity with and practice on a test gives protection against disorientation; task performance continues to suffer if the protagonist is unaware of disorientation; with disorientation that demands external resolution (e.g., interpretation of instruments) the subject must learn to switch priority to the cognitive task; there is a moderate preferential impact of disorientation on spatial tasks; anxiety of real situations probably exacerbates the impact of disorientation.

Adaptation of ventilation to 'buffeting' in vehicles.

OBJECTIVES: Short exposures to buffeting in a vehicle driving over rough terrain induce an increase in the frequency of respiration resulting in hyperpnoea and hypocapnia. The present study investigates the adaptation to buffeting-induced hyperpnoea. METHODS: We monitored ventilation and cardiovascular function in nine healthy young adults prior to, throughout and post a 30 minute simulation of buffeting. RESULTS: All subjects had a consistent elevation of respiratory frequency throughout motion. End-tidal CO(2) decreased during the first 5 minutes of buffeting due to a transient increase in minute ventilation. Elevation of respiratory frequency was facilitated by shortening of inspiration without change in expiratory time. Tidal volume was maintained which resulted in an increase in mean inspiratory flow during buffeting. At later stages of motion there was a partial return to normal for mean inspiratory flow, minute ventilation and end-tidal CO(2)because of a slight reduction in tidal volume whilst inspiratory time remained shortened. Salivary cortisol levels were unaffected by motion, suggesting that the hyperpnoea was not secondary to non-specific stress. INTERPRETATION: The cause of elevated respiratory frequency during buffeting could be due to mechanical action on the torso, vestibular-respiratory drive or a protective reinforcement of the torso.

Cognitive impairment by spatial disorientation.

INTRODUCTION: Maintaining spatial orientation is a biological imperative. When orientation is threatened, attention resources are diverted to regaining orientation, possibly to the detriment of attention required by concurrent tasks. Hence, a factor in aviation mishaps may be the negative impact of disorientation on concurrent performance, such as interpreting instruments. We examined how subjects learn to manage the impact of acute disorienting stimuli on concurrent spatial cognitive tasks. METHODS: Subjects performed the Manikin (MAN) and Choice Reaction Time (CRT) tests under three disorienting experiments: i) after self-controlled head rolls, N = 16; ii) during rotation of the background field of view, N = 12; and iii) after head movements provoking Coriolis during body rotation in yaw, N = 6. RESULTS: Number correct and reaction times on the MAN task were negatively affected by each type of disorientation only when the task was performed in the presence of disorienting motion presented early in the experimental session. Later in the session, subjects learned to attain best performance levels irrespective of disorientation. Performance on the CRT task, which has good stimulus response compatibility with little high order processing, was unaffected. The slight symptoms of malaise provoked by disorientation did not interfere with performance in experiments (i) and (ii) but more severe symptoms in (iii) correlated with loss of performance. CONCLUSION: Our studies suggest that the ability to maintain a high level of cognitive performance is susceptible to impairment when novel circumstances of disorientation are encountered. Extensive practice on particular tasks protects against encounters with novel disorientation. Once disorientation is identified, its potential impact on multitasking may be quarantined despite disorientation symptoms. The results indicate the need for over-training on tasks and experience with a wide variety of disorientation scenarios.

Tachypnea and hypocapnia are induced by 'buffeting' in vehicles.

Normal physiological responses to vehicular buffeting were studied during a 5 minute mild 'off road' exposure in a motion simulator. The ride provoked an initial increase in heart rate and blood pressure and a significant hypocapnia of P(ET) CO(2) 34 mm Hg caused by tachypnea, which took 5 minutes to recover. Motion induced hypocapnia could be a source of distress for vulnerable subjects and patients when travelling.