Journal of Vestibular Research - Volume 5, issue 1

Authors: Chelette, Tamara L. | Martin, Eric J. | Albery, William B.

Article Type: Research Article

Abstract: The effect of head tilt on the perception of self-orientation while in a greater than one G environment was studied in nine subjects using the Armstrong Laboratory Dynamic Environment Simulator. After a 12-s stabilization period at a constant head tilt and G level, subjects reported their perception of the horizon by placing their right hand in a position they believed to be horizontal. Head tilt conditions ranged from -30° to +45° pitch over each of three head yaw positions. G levels ranged from one to four and were in the longitudinal axis of the body (Gz ). Hand position was recorded in …both the pitch and roll body axes. A function of head tilt did improve the fit of a multiple regression model to the collected data in both the pitch and roll axes (P < .05). The best fit was accomplished with a nonlinear function of G and head pitch. When the head remained level but the environment tilted with respect to the G vector (at angles similar to those perceived during head tilt), subjects accurately reported the environmental tilt. Head tilt under G can result in vestibular-based illusionary perception of environmental tilt. Actual environmental tilt is accurately perceived due to added channels of haptic information. Show more

Keywords: spatial orientation, tilt perception, G-excess illusion, regression model

DOI: 10.3233/VES-1995-5101

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 1-17, 1995

Authors: Kolev, Ognyan I.

Article Type: Research Article

Abstract: This study describes a hitherto unknown phenomenon in healthy humans: visual hallucinations evoked by caloric vestibular stimulation. The hallucinations are of elementary type. The following quantitative and qualitative characteristics of the hallucinatory images were measured: latency, duration, location in the visual field, relation to the provoked vertigo, colour of the hallucinatory image and the background, number, size, shape, distance from the eyes, and motion. Two mechanisms are proposed to explain the genesis of these hallucinations. One mechanism is direct: change in the spontaneous activity of the visual system in several levels; the other mechanism is indirect: transient haemodynamic disturbance in …the visual system. Show more

Keywords: visual hallucination, vestibular system, caloric stimulation

DOI: 10.3233/VES-1995-5102

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 19-23, 1995

Authors: Stout, Cynthia S. | Toscano, William B. | Cowings, Patricia S.

Article Type: Research Article

Abstract: Although there is general agreement that a high degree of variability exists between subjects in their autonomic nervous system responses to motion sickness stimulation, very little evidence exists that examines the reproducibility of autonomic responses within subjects during motion sickness stimulation. Our objectives were to examine the reliability of autonomic responses and symptom levels across five testing occasions using the (1) final minute of testing, (2) change in autonomic response and the change in symptom level, and (3) strength of the relationship between the change in symptom level and the change in autonomic responses across the entire motion sickness test. …The results indicate that, based on the final minute of testing, the autonomic responses of heart rate, blood volume pulse, and respiration rate are moderately stable across multiple tests. Changes in heart rate, blood volume pulse, respiration rate, and symptoms throughout the test duration are less stable across the tests. Finally, autonomic responses and symptom levels are significantly related across the entire motion sickness lest. Show more

Keywords: motion sickness symptoms, autonomic response stability, physiological responses, autonomic response stereotypy

DOI: 10.3233/VES-1995-5103

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 25-33, 1995

Authors: Böhmer, Andreas | Rickenmann, Jürg

Article Type: Research Article

Abstract: The subjective visual vertical, SV, was measured in the upright and side positions in 25 normal subjects and in 73 patients with various peripheral vestibular disorders. Significant deviations of SV (toward the affected ear) were found in 100% of the patients with vestibular nerve section and with Ramsay Hunt syndrome, in 89% of the patients with vestibular neuritis, and in 0% of the patients with benign paroxysmal positional vertigo. The deviation of SV gradually disappeared within a few weeks of the onset of the disease in all patients except in those with total VIIth nerve resection. SV is a parameter …of tonic afferent differences between the two labyrinths similar to vestibular spontaneous nystagmus but is mediated by other parts of the inner ear (probably the otolith organs) and thus provides additional information on the labyrinthine function. SV measured in 90° side positions, however, did not reveal asymmetric vestibular sensitivity, which is in contrast to SV tested during eccentric rotation in patients after vestibular neurectomy. Show more

Keywords: subjective visual vertical, side position, vestibular diseases, vestibular neurectomy

DOI: 10.3233/VES-1995-5104

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 35-45, 1995

Authors: Büttner, U. | Ott, M. | Helmchen, Ch. | Yousry, T.

Article Type: Research Article

Abstract: The case of a 55-year-old female is presented, in whom first a loss of the vestibular and hearing function on the left side occurred with sudden onset, and 3 days later an additional loss of functions on the right side occurred. No other neurological symptoms were present. Angiography and MRI scan revealed vertebrobasilar dolichoectasia with a thrombus attached to the wall of the basilar artery. Anticoagulative therapy improved hearing function on the right side sufficiently to allow conversation. Vestibular organs remained unresponsive to caloric irrigation. This bilateral loss of eighth nerve function is discussed as a rare case of bilateral …ischemia of the labyrinthine artery due to basilar dolichoectasia. Show more

Keywords: vertebrobasilar dolichoectasia, labyrinthine artery, loss of vestibular function

DOI: 10.3233/VES-1995-5105

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 47-51, 1995

Authors: Tighilet, Brahim | Leonard, Jacques | Lacour, Michel

Article Type: Research Article

Abstract: Unilateral lesion of the vestibular system induces posturo-locomotor deficits that are compensated for with time. Drug therapy is currently used to improve the recovery process and to facilitate vestibular compensation. Betahistine dihydrochloride is an histamine-like substance that has been employed in vestibular pathology; it was found effective in many forms of vertigo and in vestibular-related syndromes. Investigations performed in animal models have shown betahistine-induced neuronal modulations in the vestibular nuclei complex and interactions with the H1 and H3 histamine receptors. Potentially, this substance is therefore capable to interfere with some recovery mechanisms and to improve the behavioral adaptations. …But there is at present a total lack of data concerning the influence of betahistine treatment on vestibular compensation in animal models. The aim of this study was to understand the pharmacological activity of betahistine in the restoration of posture and locomotor balance functions in unilateral vestibular neurectomized cats. Posture recovery was assessed by quantifying the surface reaction of the cat’s support as measured while standing erect on its four legs, at rest. Locomotor balance recovery was determined using the rotating beam test, by measuring the maximal performance (max. P.) of the cat and its locomotion speed regulation during the postoperative time period. We have compared the recovery profile and time course of these static (posture) and dynamic (equilibrium) functions in three groups of cats. Two experimental groups were treated at daily doses of 50 mg/kg and 100 mg/kg, respectively. Betahistine dihydrochloride was given orally until complete recovery of posturo-locomotor functions. One untreated control group served as the reference. Results showed that postoperative treatment strongly accelerated the recovery process in both treated groups, inducing a time benefit of around 2 weeks as compared to the controls. Maximum performance of the cats on the rotating beam as well as locomotion speed regulation were highly correlated to the postoperative development of the cat’s support surface, indicating that compensation of the static vestibulospinal deficits conditioned the subsequent locomotor balance recovery. These behavioral data showed that betahistine dihydrochloride constitutes a useful drug therapy for the symptomatic treatment of central vestibular disorders in our animal model of unilateral vestibular lesion. Improvement of vestibular compensation under betahistine postoperative treatment, as evidenced here for the posture and locomotor balance functions, is discussed both in terms of aspecific effect (histamine-induced increase of the level of vigilance) or more direct action in the vestibular nuclei (histamine-induced rebalance of neuronal activity on both sides). Show more

Keywords: vestibular compensation, posture, locomotor balance, betahistine, cat

DOI: 10.3233/VES-1995-5106

Citation: Journal of Vestibular Research, vol. 5, no. 1, pp. 53-66, 1995