Perceived Head Orientation and Eye Movements Are Abnormal in Vestibular Migraine during Combined Canal-Otolith Stimulation (P02.254)

Abstract

Objective: We tested the hypothesis that the rotational information provided by the semicircular canals and the gravito-inertial information provided by the otolith organs are synthesized abnormally by the brain in patients with vestibular migraine. Background Vestibular migraine (VM), defined as vestibular symptoms such as vertigo generated by migraine mechanisms rather than other inner ear or brain abnormalities, is a common and disabling problem. Despite its frequency, the pathophysiology of VM remains uncertain and no specific defect has been described. Given the high frequency of positional dizziness and nystagmus in VM and reduced perceptual thresholds during roll tilt which we previously documented, we examined percepts of head tilt and eye movements during combined canal-otolith stimulation in VM to determine if canal-otolith integration is abnormal. Design/Methods: We studied 8 patients with VM, 8 migraine patients without dizziness, and 8 normal controls. Percepts of head orientation were measured with a somatosensory bar during fixed-radius centrifugation with the centrifugal force aligned with the inter-aural axis, and eye movements were measured after post-rotational tilts of the head in the roll plane. Results: Percepts of roll tilt during centrifugation developed more slowly in VM subjects compared to the control groups. The shift of the eye9s rotational axis was larger after post-rotational tilts in VM and these subjects did not show the negative correlation between the size of the axis shift and the extent of VOR tilt-suppression that was evident in the control groups. Conclusions: Percepts of head orientation during centrifugation and eye movements produced by post-rotational tilt were different in VM compared to normal and migraine control groups. The results are consistent with an enhanced interaction between canal and otolith cues in VM and suggest that this mechanism may contribute to the vestibular symptoms and motion intolerance that are associated with migraine. Disclosure: Dr. Lewis has nothing to disclose. Dr. Wang has nothing to disclose. Dr. Balkwill has nothing to disclose.