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Abstract of the Week

September Topic of the month: Back to Basics

No 486: September 6, 2019

Verdecchia DH, Monzón AM, Urbina Jaimes V, Oliveira FR, Paiva L da S, Carvalho TD de. Patient-Reported and Performance Outcomes Significantly Improved in Elderly Patients with Vestibular Impairment following Rehabilitation: A Retrospective Study. Journal of Aging Research. August 2018:1-8. doi:10.1155/2018/5093501.
OBJECTIVE: To describe the results of a vestibular rehabilitation (VR) program in the timed up and go (TUG), gait speed (GS), and dizziness handicap inventory (DHI) scores for elderly vestibular patients in a developing country.

METHODS: Descriptive study with retrospective data collected from the clinical records of vestibular patients. The following information was recorded: sex, age, type of vestibular disorder, DHI score, and performance in TUG and GS, before and after participation in a VR program taking place from January 1 to August 30, 2017. The VR program consisted of 10 twice weekly sessions in the clinic and daily exercises at the patient's home. We used Student's t-test for paired and Wilcoxon's test according to the data distribution. The level of significance was 5%.

RESULTS: Data from 57 patients(49 females; 78 ± 5.8 years old) were used. There were statistically significant differences in TUG (12.52 versus 11.56), GS (0.81 versus 0.90 m/s), DHI total handicap (46 versus 24), physical (14 versus 8), emotional (14 versus 6), and functional (18 versus 12) domains.

CONCLUSION: The functional outcome measures reported, including TUG, gait speed, and DHI, reflect statistically significant improvements in elderly patients after vestibular rehabilitation; the DHI improvements are clinically relevant.
PMID: 30225142


August Topic of the month: Motion Sensitivity

No 485: August 2, 2019

Clément G, Deguine O, Bourg M, Pavy-LeTraon A. Effects of vestibular training on motion sickness, nystagmus, and subjective vertical. J Vestib Res. 2007.
Pitch head-and-trunk movements during constant velocity rotation are a provocative vestibular stimulus that produces vertigo and nausea. When exposed to this stimulus repeatedly, motion sickness symptoms diminish as the subjects habituate. Acetylleucine is a drug that is used to treat acute vestibular vertigo. In this study, we wanted to ascertain whether this drug (a) lessened motion sickness or delayed habituation; (b) accelerated the recovery following habituation; and (c) whether changes in the subjective vertical accompanied habituation. Twenty subjects were administered acetylleucine or placebo in a double-blind study during a five-day vestibular training. Horizontal vestibulo-ocular reflex, optokinetic nystagmus, smooth pursuit, and subjective visual vertical were evaluated before, during, and up to two months after the vestibular training. Based on Graybiel's diagnostic criteria, motion sickness decreased steadily in each vestibular training session, and there was no difference between the scores in the acetylleucine and placebo groups. Post-rotatory nystagmus peak velocity and time constant also declined in both groups at the same rate. Thus, acetylleucine neither reduced the nausea associated with this provocative stimulus, nor hastened the acquisition or retention of vestibular habituation of motion sickness and nystagmus. There was no difference in optokinetic nystagmus and smooth pursuit between the acetylleucine and placebo groups. However, subjects showed larger error in the subjective visual vertical after habituation, which indicates that spatial orientation is also affected by vestibular training.
PMID: 18626134

No 484: August 24, 2019

Chu H1, Li MH, Juan SH, Chiou WY. Effects of transcutaneous electrical nerve stimulation on motion sickness induced by rotary chair: a crossover study. J Altern Complement Med. 2012 May;18(5):494-500. doi: 10.1089/acm.2011.0366. Epub 2012 Apr 26.
OBJECTIVES: 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.

SUBJECTS AND DESIGN: 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.

OUTCOME MEASURES: 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.

PMID: 22537562


No 483: August 16, 2019 

Takeuchi N, Mori T, Suzukamo Y, Izumi SI. Modulation of Excitability in the Temporoparietal Junction Relieves Virtual Reality Sickness. Cyberpsychol Behav Soc Netw. 2018.
Virtual reality (VR) immersion often provokes subjective discomfort and postural instability, so called VR sickness. The neural mechanism of VR sickness is speculated to be related to visual-vestibular information mismatch and/or postural instability. However, the approaches proposed to relieve VR sickness through modulation of brain activity are poorly understood. Using transcranial direct current stimulation (tDCS), we aimed to investigate whether VR sickness could be relieved by the modulation of cortical excitability in the temporoparietal junction (TPJ), which is known to be involved in processing of both vestibular and visual information. Twenty healthy subjects received tDCS over right TPJ before VR immersion. The order of the three types of tDCS (anodal, cathodal, and sham) was counterbalanced across subjects. We evaluated the subjective symptoms, heart rate, and center of pressure at baseline, after tDCS, and after VR immersion. VR immersion using head-mounted displays provoked subjective discomfort and postural instability. However, anodal tDCS over right TPJ ameliorated subjective disorientation symptoms and postural instability induced by VR immersion compared with sham condition. The amelioration of VR sickness by anodal tDCS over the right TPJ might result from relief of the sensory conflict and/or facilitation of vestibular function. Our result not only has potential clinical implications for the neuromodulation approach of VR sickness but also implies a causal role of the TPJ in VR sickness.

PMID: 29792509 


No 482: August 8, 2019

Wang L, Cao Y, Tan C, Zhao Q, He S, Niu D, Tang G, Zou P, Xing L. Uncoupling VOR and vestibuloautonomic retention to Coriolis acceleration training in student pilots and control subjects. J Vestib Res. 2017.
PURPOSE: Explore the different vestibular physiologic response retention patterns after Coriolis acceleration training in student pilots and extend the results for use with Chinese astronauts in the future.

METHODS: Twelve healthy control male subjects were screened from males familiar with vestibular training and who physically resembled the astronauts. Fourteen student pilots were selected from 23 participants by rotational vestibular function tests. All subjects were exposed to five-day continuous or intermittent Coriolis acceleration training. Subjective motion sickness (MS) symptom scores, electrocardiography, electrogastrography (EGG), post-rotatory nystagmus and renin-angiotensin system responses were measured before, during and after rotational vestibular function tests at different times after vestibular training.
RESULTS: Subjects could tolerate 10 min or 15 min of vestibular with mild MS symptoms. Retention of vestibular autonomic responses (retention of MS symptom scores, heart rate variability, power density of EGG, variations in levels of arginine vasopressin) were approximately 1 week for control subjects and approximately 5 weeks for student pilots. Decreases in slow-phase velocity of post-rotatory nystagmus were maintained for 14 weeks for control subjects and 9 weeks for student pilots.

CONCLUSIONS: Retention of the vestibulo-autonomic reaction after vestibular training was different for control subjects and student pilots. All parameters related to autonomic responses could be maintained at low levels after vestibular training for approximately 1 week for control subjects and approximately 5 weeks for student pilots. Uncoupling patterns between post-rotatory nystagmus and the vestibulo-autonomic reaction may be helpful in the design of clinical rehabilitation plans for balance-disorder patients and for exploration of artificial gravity in future space missions.

PMID: 29064824

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