What are vestibular ocular reflex abnormalities in multiple sclerosis (MS)?

Updated: Feb 21, 2019
  • Author: Fiona Costello, MD, FRCP; Chief Editor: Hampton Roy, Sr, MD  more...
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Answer

Answer

Some patients with MS report difficulties tracking objects while they are in motion or when they are observing a moving target. Normally, during visual tracking, head movements accompany eye movements, with smooth pursuit allowing suppression of the normal vestibular ocular reflex. With MS lesions of the cerebellar floccus, vestibular ocular reflex cancellation is ineffective, which causes loss of fixation during head and eye movements. [40] Consequently, affected individuals experience retinal slippage [40] off the target of interest, and compensatory catch-up saccades are produced.

The integrity of the vestibular ocular reflex can be tested by asking the patient to perform rapid head thrusts while attempting to fixate on a stationary target. [49] If vestibular ocular reflex function is impaired, fixation will not be maintained and a compensatory saccadic eye movement opposite the direction of the head movement will be detectable. [49] In this context, patients may describe oscillopsia but lack clinically apparent nystagmus. [49]

Patients with multiple sclerosis are also predisposed to impaired suppression of the normal vestibular ocular reflex. [49] Normal suppression of the vestibular ocular reflex is needed to combine smooth head and eye movements during visual tracking. [49] To determine whether this problem exists clinically, a patient can be asked to focus on the thumb of his or her outstretched hand while rotating in a swivelling chair. If vestibular ocular reflex cancellation is impaired, a series of catch–up saccades is observed while the head is in motion. [49] The eyes will be observed to drift off the target (thumb) opposite the direction of the patient’s head movement. [40] Abnormal suppression of the vestibular ocular reflex often indicates cerebellar dysfunction and occurs in concert with smooth pursuit abnormalities. [49] Vestibular rehabilitation therapy may prove beneficial for some patients with MS. [50]


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