Clinical signs of visual-vestibular interaction.

Halmagyi, G. Michael; Gresty, Michael A.

doi:10.1136/jnnp.42.10.934

Cited by 77 publications

(22 citation statements)

References 16 publications

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“…Impairment of visual suppres sion of vestibular nystagmus as generated in a rotatory test is mostly known in cases with brainstem/cerebellum pathology [15,16], These structures are also found to be involved when the interaction of visual and vestibular signals have been investigated in neurophysiological studies [17], Therefore it is reasonable to assume that the impaired visual suppression during toluene exposure depends upon the influence of this solvent on this region of the brain. Differences in distribution of solvents may be caused by a different content of lipid-rich structures within the brain.…”

Section: Discussionmentioning

confidence: 99%

Impairment of Visuo-Vestibular Interaction in Humans Exposed to Toluene

Hydén¹,

Larsby²,

Andersson³

et al. 1983

ORL

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15 healthy volunteers were investigated in a vestibulo-oculomotor test battery during toluene exposure. The concentration was comparable to the threshold limit value. The results were compared to an identical air experiment. The intoxication caused an impaired visual suppression during a pseudo-random oscillatory swing test and also an increased saccade speed. Other vestibular-oculomotor parameters were normal. The findings are in accordance with our earlier study on styrene in humans, showing that the visual suppression test and the saccade test are sensitive parameters assessing neurotoxic influences by organic solvents.

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Section: Discussionmentioning

confidence: 99%

Impairment of Visuo-Vestibular Interaction in Humans Exposed to Toluene

Hydén¹,

Larsby²,

Andersson³

et al. 1983

ORL

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“…This capacity to suppress the vestibular ocular reflex is called VOR Suppression.VOR Suppression is initiated by vision and its mechanisms and pathways are similar,if not identical, to those of the smooth pursuit system. Clinically, a patient with broken pursuit, as a result, say, of a cerebellar or brainstem lesion, will almost always show an inability to suppress his vestibular nystagmus [2,25].VOR suppression can be easily investigated by oscillating the patient on a swivel chair whilst attempting to fixate on his thumbs placed right in front of him (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Vision and vertigo

Bronstein

2004

Journal of Neurology

148

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This review deals with two syndromes, oscillopsia and visual vertigo. Oscillopsia is the illusion of oscillation of the visual surroundings. For diagnosis purposes one should ask, when does the oscillopsia occur? If oscillopsia is only present during head (or whole body) movements, the likely underlying cause is a bilateral defect in the vestibulo-ocular reflex (VOR). The more common causes are post meningitic vestibular damage, gentamicin ototoxicity or bilateral idiopathic vestibular failure. When oscillopsia develops after specific head positions, it is usually due to a positional nystagmus, usually the result of brainstem-cerebellar disease. When the oscillopsia is largely unrelated to head movements, one should ask, is it fairly constant or is it in attacks (paroxysmal)? If the oscillopsia is constant it is usually due to the presence of a clinically observable nystagmus; the most common is downbeat nystagmus but the most visually disabling is pendular nystagmus. If the oscillopsia comes in brief attacks it is usually due to a paroxysmal nystagmus as observed in irritative VIII nerve and brainstem lesions. However, the most common cause of paroxysmal oscillopsia is a non organic condition called voluntary nystagmus. Treatment of oscillopsia is often pharmacological but disappointing; the best chance of success is carbamazepine for paroxysmal disorders secondary to structural vestibular nerve/nuclear lesions.Visual vertigo should not be confused with oscillopsia. It can be defined as dizziness provoked by visual environments with large size (full field) repetitive or moving visual patterns. Patients with visual vertigo report discomfort in supermarkets and when viewing movement of large visual objects, eg crowds, traffic, clouds or foliage. Visual vertigo is present in many patients with a history of a peripheral vestibular disorder, particularly those who are visually dependent (ie subjects who use vision preferentially for postural and space orientation control). Patients with visual vertigo benefit from the addition to their standard vestibular rehabilitation of optic flow (optokinetic) stimuli and exercises involving visuo-vestibular conflict.

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“…The proposed mechanism holds that when VOR generates eye movements off target, slip of the target image on the retina stimulates a cancelling pursuit movement. The hypothesis has gained support from clinical studies which have shown that patients with neurological disorders in whom pursuit is defective seem to have roughly corresponding disorders of VORS.2 3 Nevertheless, these studies lacked any kind of systematic investigation of the dynamic range of frequency response and velocity limits of the relevant oculomotor functions in the patients studied.…”

mentioning

confidence: 96%

The relationship between disordered pursuit and vestibulo-ocular reflex suppression

1983

Journal of Neurology, Neurosurgery & Psychiatry

171

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SUMMARY The performance of the smooth pursuit reflex and the ability to suppress the vestibuloocular reflex were assessed in 10 normal subjects and in patients with a variety of diseases of the central nervous system. Pursuit was measured as the maximum velocity of slow phase eye movement in response to a laser target moving sinusoidally at various frequencies up to 1 Hz and with amplitudes stepped up to 350 peak. Suppression of the vestibulo-ocular reflex was assessed with subjects seated in a Barany chair rotating sinusoidally in yaw at matching frequencies. The breakpoint of vestibulo-ocular reflex suppression was defined as the peak velocity of oscillation at which nystagmus appeared on electro-oculographic recording as determined by the method of ascending and descending thresholds. For normal subjects, at all frequencies, the breakpoint of suppression corresponded closely with the peak velocity of pursuit at the corresponding frequency of target oscillation. In some patients pursuit and suppression were comparably impaired. In others either pursuit or suppression could be selectively impaired with the other function left intact. The results demonstrate that the mechanisms of pursuit and visual suppression of the vestibulo-ocular reflex have similar dynamics and share a common pathway at least to the level of the cerebellum. Thereafter, there is presumably an anatomical and functional dissociation of the signals mediating the two functions. The key area involved appears to be the flocculus for lesions of this structure alone cause impairment of both functions. The findings also indicate that the appropriate way to test smooth pursuit in relationship to suppression is to increase the amplitude of target oscillation until the peak slow eye movement velocity is determined for each frequency. The finding that increasing excursion increases maximum pursuit velocity supports the view that pursuit has an acceleration limit which is more critical in determining performance than velocity limitations. The results establish the assessment of vestibulo-ocular reflex suppression as a powerful test of the integrity of CNS function independent of its previous association with disordered pursuit.The function of the vestibulo-ocular reflex (VOR) is to generate compensatory eye movements which stabilise fixation on stationary targets during active and passive head movements. During pursuit of moving targets by active head turning, the VOR must be over-ridden, otherwise it would tend to drive the eyes in the inappropriate direction. This process is termed vestibulo-ocular reflex suppression (VORS). Experiments on normal subjects have demonstrated that there is a strong similarity between the frequency

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Clinical signs of visual-vestibular interaction.

Cited by 77 publications

References 16 publications

Impairment of Visuo-Vestibular Interaction in Humans Exposed to Toluene

Impairment of Visuo-Vestibular Interaction in Humans Exposed to Toluene

Vision and vertigo

The relationship between disordered pursuit and vestibulo-ocular reflex suppression

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