Journal of Vestibular Research - Volume 23, issue 2

Authors: Clarke, Andrew H. | Just, K. | Krzok, W. | Schönfeld, U.

Article Type: Research Article

Abstract: The study addresses the question as to what extent the otolith-mediated gravity vector maintains the stability of the coordinate frames of the vestibulo-ocular reflex and the oculomotor system, described by Listing's Plane. Under normal 1 G conditions it has been demonstrated in the monkey that Listing's Plane (LP) and the 3D vestibulo-ocular response (3D-VOR) are close to collinear [10]. In the present study the coordinate frames of the oculomotor system and the three-dimensional vestibulo-ocular reflex (3D-VOR) system were measured under one-g gravity conditions and during a period of prolonged microgravity, on-board the International Space Station (ISS). To this …end, the coordinate frame of the oculomotor system is described in Listing's coordinates and that of the 3D-VOR system by the minimal gain vector. The findings demonstrate that under Earthbound, one-g conditions the two coordinate frames diverge by approximately 20° in the human. In the absence of the gravity vector the radical loss in the otolith-mediated contribution to the dynamic VOR leads to a reduction of the torsional VOR component and in turn to a forward tilt of the oculomotor coordinate frame, described by the minimal gain vector. In contrast, the torsional component of LP during horizontal and vertical saccades was found to increase, resulting in a backward tilt of LP. Together with the backward tilt of LP a small but consistent change in LP vergence was observed. The thickness of LP did not appear to change in the absence of gravity. The changes in coordinate frame orientation persisted over the six-month periods spent in zero gravity. The postflight measurements demonstrate that re-adaptation to preflight values proceeds over several days to weeks. The findings demonstrate that the gravity vector represents a common reference for vestibular and oculomotor responses. They also support the idea that the gravity vector provides a central reference for the entire sensorimotor complex. Show more

Keywords: Listing's plane, vestibulo-ocular reflex, microgravity, three-dimensional eye tracking, gravity vector

DOI: 10.3233/VES-130476

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 61-70, 2013

Authors: Aasen, T. | Goplen, F. | Nordahl, S.H.G.

Article Type: Research Article

Abstract: In this paper we analyzed optokinetic nystagmus (OKN) signals for underlying information patterns. Fourteen OKN signals were recorded in five healthy subjects. First, we tested the correlation between nystagmus slow and fast phases. Previously, it has been suggested that the correlation is higher between the amplitude of the slow phase and the following fast phase, compared to the correlation between the fast phase and the following slow phase. However, we found no such difference. This is in agreement with the view that the saccade performed by the eye is not determined by the previous slow phase, but is free to …move voluntarily in order to focus on an object of interest. Second, we analyzed the information entropy contained in the sequence of optokinetic nystagmus amplitudes, and found a short-term information pattern. Further analysis of these patterns could eventually lead to more knowledge about the vestibular and oculomotor systems. Show more

Keywords: Optokinetic nystagmus, vertigo, symbolic dynamics, information pattern

DOI: 10.3233/VES-130481

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 71-75, 2013

Authors: Lee, Choongheon | Honaker, Julie A.

Article Type: Research Article

Abstract: The gaze stabilization test (GST) is used not only in examining gaze stability required by daily life activities, but also in identifying unilateral or bilateral vestibular deficits. However, a computerized GST (CGST) is an expensive assessment, which cannot be commonly used in most clinics. Validation of low-cost and low-technical clinical tests is required to decrease health care costs. The purpose of this study was to measure the accuracy of a new GST (NGST) in a cohort of healthy young adults with no history of vestibular or balance disorders, as well as the test-retest reliability when re-assessed 5–7 days. Subjects identified …a visual target while actively and passively performing head movements in the yaw plane at an initial screening velocity of 130 degs/sec. The main outcome was a strong positive correlation in both active and passive NGST head movement amplitude degree and head movement velocity. Passive head movements had good accuracy (85%) to identify healthy individuals with no history of vestibular or balance disorders. In addition, the NGST has good test-retest reliability in head movement amplitude degree (r=0.795) and head movement velocity (r=0.797) of passive NGST within two testing sessions. Show more

Keywords: Gaze stabilization test, vestibular-ocular reflex, visual acuity, vestibular screening test

DOI: 10.3233/VES-130482

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 77-84, 2013

Authors: Aoki, Mitsuhiro | Tanaka, Kunihiko | Wakaoka, Takanori | Kuze, Bunya | Hayashi, Hisamitsu | Mizuta, Keisuke | Ito, Yatsuji

Article Type: Research Article

Abstract: Background: The morbidity of orthostatic hypotension (OH) increases with aging and the elderly often complain of dizziness associated with OH, which is implicated in white matter lesions (WMLs) on MRI. However little is known how WMLs are contributed to the development of dizziness in elderly patients. Objective: We evaluated the involvement of cerebral WMLs in the vertical perception in the elderly with OH. Methods: This study consisted of 71 dizzy patients who underwent the examinations including the Schellong orthostatic test and subjective visual vertical (SVV) test. Results: The male patients aged ⩾ …65 years with OH (1.9 ± 0.9°) showed a significantly higher magnitude of variance of SVV, which reflects an impaired vertical perception, in comparison with the male patients aged ⩾ 65 years without OH and the male patients aged < 65 years with OH (1.0 ± 0.4°, 0.9 ± 0.4°, p < 0.05). The variance of SVV significantly correlated with the volume of WMLs in both sides on MRI in the male, but not female patients (p < 0.01). Conclusions: Our results suggest that severe WMLs in the elderly with OH are involved in impaired perception of verticality, resulting in inducing subjective dizziness. Show more

Keywords: Vertical perception, cerebral white matter lesions, elderly, orthostatic hypotension

DOI: 10.3233/VES-130479

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 85-93, 2013

Authors: Kim, C.-H. | Shin, J.E. | Kim, T.S. | Shim, B.S. | Park, H.J.

Article Type: Research Article

Abstract: The HSN test is a simple examination that can be easily performed by clinicians, however only a few studies have analyzed the 2-dimensional characteristics of HSN in patients with MD. The objective of the study was to characterize different types of 2-dimensional head-shaking nystagmus (HSN) in patients with Meniere's disease (MD). Sixty-five patients with definite MD were enrolled. HSN was considered pathologic, if slow-phase velocity (SPV) was ⩾ 4°/s and was classified as paretic or recovery according to the direction, and as monophasic or biphasic according to the presence of direction change. HSN was categorized as pure horizontal, mixed or …pure vertical. When vertical SPV was larger than horizontal SPV, HSN was categorized as perverted. Forty-four patients (68%) had pathologic HSN and 28 patients (43%) had pathologic canal paresis. Monophasic-paretic HSN was the most common and followed by biphasic-paretic HSN, monophasic-recovery HSN and biphasic-recovery HSN. Delayed-peak monophasic-paretic HSN, which was not observed in vestibular neuritis, was found in 6 patients with MD. Thirty-three patients (51%) had a vertical component, which was monophasic and downbeat in 32 (97%). Every pathologic HSN in horizontal plane had higher SPV in horizontal plane than that of vertical plane. Perverted HSN was found in 4 patients, of whom 3 had pure vertical and one had mixed type HSN. Our data showed that HSN is a sensitive detector of vestibular dysfunction. HSN showed diverse types with a new type of delayed-peak HSN. Vertical components of HSN were observed in about half, but they were negligible compared to horizontal components. Weak perverted HSN (vertical SPV ⩽ 4°/s) could be found in patients with MD. Show more

Keywords: Vertigo, vestibular function tests, nystagmus, caloric test, head shaking, Meniere's disease

DOI: 10.3233/VES-130478

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 95-100, 2013

Authors: Akdal, Gülden | Özge, Aynur | Ergör, Gül

Article Type: Research Article

Abstract: Background: We assessed frequency of vestibular symptoms in Headache Clinic patients over 10 years. Methods: A descriptive study of 5111 consecutive patients with tension-type headache or migraine, analyzed for dizziness/ vertigo accompanying headache and for a lifetime history of motion-sickness, cyclic vomiting, recurrent abdominal pain or atopy. Migraine patients were re-grouped as those with vestibular symptoms (dizziness/vertigo or motion sickness) and those without and their data then re-analyzed. Results: There were 1880 migraine patients and 3231 tension-type headache patients. Significantly more migraine patients than tension-type headache patients experienced vestibular symptoms (p< 0.0001). The migraine …with vestibular symptoms group was significantly younger (p< 0.05) had more aura, more phonophobia with migraine attacks (p< 0.0001). Menstruation and reported sleep problems impacted on headaches. While past history of cyclical vomiting, recurrent abdominal pain or atopy was about twice as common in migraine with aura and it was also more common in migraine with vestibular symptoms than migraine without vestibular symptoms. Conclusions: Vestibular symptoms are common in migraine patients. Migraine with vestibular symptoms might constitute a special group, one more likely to have had cyclic vomiting, recurrent abdominal pain or atopy. Show more

Keywords: Headache, migraine, vertigo, dizziness, motion sickness

DOI: 10.3233/VES-130477

Citation: Journal of Vestibular Research, vol. 23, no. 2, pp. 101-106, 2013