Dynamic tilt thresholds are reduced in vestibular migraine

Abstract

Vestibular symptoms caused by migraine, referred to as vestibular migraine, are a frequently diagnosed but poorly understood entity. Based on recent evidence that normal subjects generate vestibular-mediated percepts of head motion and reflexive eye movements using different mechanisms, we hypothesized that percepts of head motion may be abnormal in vestibular migraine. We therefore measured motion detection thresholds in patients with vestibular migraine, migraine patients with no history of vestibular symptoms, and normal subjects using the following paradigms: roll rotation while supine (dynamically activating the semicircular canals); quasi-static roll tilt (statically activating the otolith organs); and dynamic roll tilt (dynamically activating the canals and otoliths). Thresholds were determined while patients were asymptomatic using a staircase paradigm, whereby the peak acceleration of the motion was decreased or increased based on correct or incorrect reports of movement direction. We found a dramatic reduction in motion thresholds in vestibular migraine compared to normal and migraine subjects in the dynamic roll tilt paradigm, but normal thresholds in the roll rotation and quasi-static roll tilt paradigms. These results suggest that patients with vestibular migraine may have enhanced perceptual sensitivity (e.g. increased signal-to-noise ratio) for head motions that dynamically modulate canal and otolith inputs together.

Fig. 1

Motion profiles used for the dynamic (roll tilt, roll rotation) paradigms. The peak velocity and net displacement of the head are proportional to the peak acceleration (A).

Fig. 2

Examples of the staircase paradigm used to determine perceptual thresholds. Data are for 0.1 Hz roll tilts and peak acceleration of the sinusoid is plotted against trial number. After three correct responses the acceleration was reduced (3-down) and after each incorrect response it was increased (1-up) until 5 reversals had occurred.

Fig. 3

Thresholds (in deg) for each normal, migraine, and VM subject, 0.1 Hz dynamic roll tilt. VM patients are sub-divided into two groups, those with positional vertigo or positional exacerbation of vertigo (P) and those with vertigo that had no positional component (NP).