Susceptibility to motion sickness is not increased following spinal cord injury

BACKGROUND: There are two leading theories on the origin of motion sickness. One, the sensory conflict theory, states that sensory information provided by one sensory channel does not match the expected input from another channel; commonly, these two inputs originate in the vestibular system and the eyes. The second theory - the postural instability theory - states that motion sickness comes about not through sensory conflict, but through an inability to control one's posture. OBJECTIVE: Given that people with a motor-complete spinal cord injury cannot control their muscles below the level of the spinal lesion, we predicted that susceptibility to motion sickness would be higher in individuals who have suffered a spinal cord injury. METHODS: Twenty-one people living with chronic spinal cord injury (9 quadriplegics, 12 paraplegics) completed the Motion Sickness Susceptibility Questionnaire (MSSQ), via an online survey, to compare susceptibility to motion sickness before and after injury. RESULTS: Spinal cord injury, regardless of level, did not produce an increase in susceptibility to motion sickness. CONCLUSION: We have tested the general validity of the postural-instability theory by assessing susceptibility to motion sickness in individuals with spinal cord injury. Despite the loss of postural control, there was no increase in motion sickness susceptibility.