title: Effects of transcutaneous electrical nerve stimulation on motion sickness induced by rotary chair: a crossover study.
abstract: OBJECTIVE
  Motion sickness (MS) is evoked by the conflict among somatosensory, visual, and vestibular input. Some of the MS symptoms and signs are mediated by activation of the autonomic nervous system (ANS). Transcutaneous electrical nerve stimulation (TENS), a maneuver used for pain control, was found to influence cardiovascular responses through ANS reflex, and to enhance motor function, visuospatial abilities, postural control, and cognitive function. The purpose of the present study is to investigate the effects of TENS on MS.
  
  
  METHODS
  Fifteen (15) healthy young men participated in a within-subjects crossover study. Each completed four test sessions (control, rotation, TENS, TENS+rotation) in randomized order. Rotary chair (120°/s) combined with pitch movement of the subject's head was used as a model to provoke MS. Whole rotation protocol consisted of 5 1-minute rotations, each separated by a 1-minute rest period. TENS protocol involved simultaneous electrical stimulation of posterior neck and Zusanli acupoint.
  
  
  METHODS
  Motion sickness susceptibility was rated on a standardized questionnaire (Motion Sickness Susceptibility Questionnaire). Motion sickness symptoms, blood pressure (BP), skin temperature, heart rate (HR), and heart rate variability (HRV) were measured. Saliva samples were collected to analyze the level of stress markers. Cognitive function was evaluated with d2 test prior to and after MS provocation.
  
  
  RESULTS
  Spinning by itself significantly decreased task response speed and contraction. MS symptom scores, BP, as well as the sympathetic parameter of HRV increased progressively with MS provocation (p<0.05), but skin temperature decreased (p=0.023). Severity of MS symptoms significantly decreased with TENS intervention (p<0.05). After TENS treatment, subjects were able to concentrate better and showed fewer errors in a cognitive test. Salivary cortisol concentration significant decreased after TENS treatment.
  
  
  CONCLUSIONS
  Sympathetic activity increased but parasympathetic activity decreased during MS. TENS was effective in reducing MS symptoms as well as alleviating cognitive impairment.
authors.affiliation: Institute of Aerospace and Undersea Medicine, School of Medicine, National Defense Medical Center, Taipei, Taiwan, ROC. hrchu@ndmctsgh.edu.tw
authors.forename: Hsin
authors.initials: H
authors.lastname: Chu
authors.forename: Min-Hui
authors.initials: MH
authors.lastname: Li
authors.forename: Szu-Hsuan
authors.initials: SH
authors.lastname: Juan
authors.forename: Wen-Yao
authors.initials: WY
authors.lastname: Chiou
mesh_terms: D015669:Acupuncture Points; D000328:Adult; D001288:Attention; D001794:Blood Pressure; D003071:Cognition; D003072:Cognition Disorders / Q000209:etiology / Q000517:prevention & control*; D018592:Cross-Over Studies; D004558:Electric Stimulation; D006257:Head; D006304:Health Status; D006339:Heart Rate; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008297:Male; D009041:Motion Sickness / Q000503:physiopathology / Q000523:psychology / Q000628:therapy*; D009333:Neck; D009483:Neuropsychological Tests; D011187:Posture; D012146:Rest; D012399:Rotation; D012463:Saliva / Q000378:metabolism; D012720:Severity of Illness Index; D012881:Skin Temperature; D011795:Surveys and Questionnaires; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D055815:Young Adult
chemical_list: D006854:Hydrocortisone