Abstract

Background
Though dizziness/vertigo and motion sickness commonly occur in migraine, the mechanisms of these associated symptoms remain unknown. Objective: The aim of this study was to determine interictal vestibular dysfunction in patients with migraine.
Methods
One hundred and thirty two patients with migraine (64 migrainous vertigo, 41 migrainous dizziness, and 25 migraine only) and 50 normal controls underwent evaluation of the vestibular function including spontaneous and induced nystagmus, bithermal caloric tests, and rotatory chair tests. Motion sickness was assessed using motion sickness susceptibility questionnaire (MSSQ).
Results
The per- and post-rotatory time constants (TC) of the vestibulo-ocular reflex (VOR) during step velocity rotation were increased in patients with migrainous vertigo/dizziness, compared with those in migraine only and normal controls. However, TCs did not differ between migraine only (13.8±2.8) and normal controls (14.3±3.3). The TCs were also prolonged in patients with severe motion sickness. Gain and phase of the VOR during sinusoidal harmonic acceleration, and tilt suppression of post-rotatory nystagmus were normal in migraine. The mean MSSQ score was highest in the migrainous vertigo group (101.4), followed by migrainous dizziness (77.5), migraine only (58.5) and control group (36.9) (p<0.05). Multiple regression analyses revealed an effect of motion sickness and age on the prolongation of TCs (p=0.034). The presence of associated dizziness/ vertigo or migraine itself did not affect the prolongation of TCs significantly.
Conclusion
Our results indicate that the increased TC in migrainous dizziness/vertigo is due to associated motion sickness. Dysfunction of nodulus and uvula may not account for increased TC in motion sickness. Innate hypersensitivity of the vestibular system may be an underlying mechanism of motion sickness in migraineurs.