Cross-coupling vestibular stimulation: motion sickness and the vestibulo-sympathetic reflex

• Published in: Journal of neurology Vol. 264; no. Suppl 1; pp. 96 - 103
• Main Authors: Romano, Fausto, Caramia, Nicoletta, Straumann, Dominik, Nalivaiko, Eugene, Bertolini, Giovanni
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.10.2017; Springer Nature B.V
• Subjects: Adaptation, Physiological; Adult; Analysis of Variance; Brain stem; Conductance; Eye Movements - physiology; Female; Galvanic Skin Response - physiology; Healthy Volunteers; Humans; Male; Medicine; Medicine & Public Health; Middle Aged; Motion detection; Motion sickness; Motion Sickness - physiopathology; Nausea; Neurology; Neuroradiology; Neurosciences; Original Communication; Oscillations; Reflex, Vestibulo-Ocular - physiology; Rhythms; Rotation; Spectrum Analysis; Sweating; Vestibular system; Yawning - physiology; Motion sickness; Cross-coupling; Skin conductance level; Vestibulo-sympathetic reflex; Sweating response
• DOI: 10.1007/s00415-017-8496-x
• ISSN: 0340-5354; 1432-1459

Motion sickness is associated with a variety of autonomic symptoms, presumably due to proximity or functional interconnectivity between the autonomic centers in the brainstem and the vestibular system. A direct influence of the vestibular system on cardiovascular variables, defined as the vestibulo-sympathetic reflex, has been reported previously. Our aim was to investigate the sudomotor components of the autonomic responses associated with motion sickness during passive cross-coupling stimulation (“roll while rotating”). Healthy subjects ( n  = 17) were rotated at 40°/s around an earth-vertical yaw axis alone and in combination with sinusoidal roll oscillations (0.2 Hz). Motion sickness was assessed verbally every minute using a 1–10 scale, while recording DC and AC skin conductance levels (SCL) from the forehead. Yaw rotation alone provoked neither motion sickness nor variations of forehead sweating. Yet during cross-coupling stimulation all subjects reported motion sickness. Higher motion sickness scores (>5) were associated with significantly higher amplitudes of AC-SCL events compared to the lower scores (0.22 ± 0.01 vs. 0.11 ± 0.01 µS, respectively). Frequency domain analysis of the AC-SCL events revealed a peak at 0.2 Hz, coinciding with the frequency of the chair rolls. The total power of AC-SCL signals did not match the trend of motion sickness scores across conditions. We conclude that: (1) although SCL is related to motion sickness, it does not follow the perceived sickness closely; (2) the discrepancy between SCL and motion sickness and the rhythmic AC-SCL events could reflect a sudomotor component of the vestibulo-sympathetic reflex.