Veterans without mTBI are more likely to benefit from bilateral electrical vestibular stimulation

Abstract

Damage to the vestibular system is often an unrecognized outcomeof mild Traumatic Brain Injury (mTBI). Ocular torsion can be used as a methodfor determining proper vestibular function of the otoliths with the applicationof imperceptible stochastic noise (SN) used to enhance the otolith‐ocular reflex. The goal of this work was to determine if Veterans with vestibular dysfunction withand without a history of mTBI would show a benefit from imperceptible SN.History of TBI was collected in 122 Veterans (86% male, age 53.7 ± 9.9 years). Thirty‐nine Veteransreported history of mTBI and 76 reported no history. Seven Veterans reported moderateTBI and were excluded from study analysis. History of mTBI was classified as areport of head injury immediately followed by loss of consciousness (less than 30 minutes) or any period of confusion or disorientation. Otolith dysfunctionscreening was performed on 102 Veterans and 41 Veterans returned to participatein repeated testing with and without SN. To assess otolith function andimprovement using imperceptible SN, ocular torsion was collected in response tosinusoidal tilt in the roll plane ± 20 degrees at a frequency of 0.03125 Hz (32sec/cycle). Ocular torsion (OT) gain was used to compare otolith function andimprovement over sham trials using SN.Veterans screened for otolith dysfunction showed similarrates between groups (58% Ctrl vs 57% mTBI). Veterans with no history of mTBIshowed a significant improvement in OCR with SN over those who reported historyof mTBI (mean improvement 21.3±21% Ctrl vs 1.8±19% mTBI, p=0.008). Statistical significance in OCR improvement remainedwhen adjusted for age (p=0.011). While no difference in mean age was observedbetween groups, Veterans with a history of mTBI showed a higher OCR gain withoutSN (0.09 ± 0.04 Ctrl vs 0.12 ± 0.05 mTBI, result not significant).These data show that while Veterans with a history ofmTBI demonstrate similar rates of vestibular impairment in otolith‐ocularreflexes, they may be less likely to benefit as a group from bilateralimperceptible electrical stimulation. Further investigation to clarify vestibular‐mediatedpathways of improvements using imperceptible SN are needed and evaluation of unilateraland canal deficits in adjusting for the use of SN may be a beneficialmodification for those that report a history of mTBI.Support or Funding InformationSupportedby DoD grant W81XWH‐14‐2‐0012This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.