Increased vestibular contribution to posture control in individuals with chronic headache

Abstract

Numerous studies have identified an association between headache disorders and vestibular symptoms, such as dizziness, vertigo, and motion sensitivity. Using bipolar, binaural galvanic vestibular stimulation (GVS), our objectives were to (1) determine the degree of vestibular sensitivity in borderline headache sufferers, and (2) characterize the postural response to vestibular perturbation in these individuals. Fourteen volunteers participated in this study: 8 individuals with chronic headache (6 with migraine and 2 with tension type headache (TTH)), and 6 healthy control subjects. Thirty trials of 15-second duration were conducted across 6 conditions (GVS left (L) or right (R), or no stimulation (No GVS) with either eyes open (EO) or eyes closed (EC)). Peak medial-lateral (M-L) centre of pressure (CoP) was calculated during quiet stance. Headache subjects demonstrated significantly higher peak displacement of the M-L CoP than control subjects (p=0.0461). Although peak M-L CoP in both the EO (p = 0.0753) and EC (p=0.09623) visual conditions were not significantly different between headache sufferers compared to healthy controls, there is some suggestion that people with chronic headache may use vestibular information to a greater extent and that the presence of vision may not sufficiently compensate for vestibular induced instability. The initial push M-L CoP was not significantly different between groups, suggesting different sensory contributions for the initial and latter response to GVS. People with chronic headache exhibit increased postural sway, which may reflect the re-weighting of sensory information with an increased vestibular and a reduced visual contribution to postural control. These results support existing research on vestibular abnormalities in chronic headache sufferers that may provide a basis for future treatment therapies.