The vestibulocochlear bases for wartime posttraumatic stress disorder manifestations
Section snippets
Introduction/Background
The story of WWI trench warfare as the historic cauldron for what we now know as Posttraumatic Stress Disorder (PTSD), is also the untold story of the vestibular system. In the first published study on “shell shock”, author Charles Myers, an English psychologist and Army volunteer, reported 3 cases with transient amblyopia (contracted vision), anosmia and amnesia whose presentation then eluded explanation for a unified pathophysiology [1]. In the light of the current knowledge establishing a
The hypothesis/theory
Vestibular innervations of the semicircular canal, extend to the hippocampal “Place cells” [2], [3], the parahippocampal “Grid cells” [4], [5], [6] and the limbic “Head Direction” cells [36], [37], [38], [39]. This links the superficial interoceptive vestibular organelle and the deeper exteroceptive hippocampus in a common functional tract within the vestibulo-auditory pathway [40], [41], [42], [43]. Blast wave exposure compounds its destructive effect in fluid-filled structures such as the
Evaluation of the hypothesis/idea
The pairing of the auditory (cochlear) with the vestibular nerve in humans has been established embryologically and persists functionally in adult life [77]. The cochlear component organizes sounds that filters through the ears as consonance versus dissonance using the tonotopic cochlear-auditory cortex association to create a coherent registry to the brain [78], [79], while the vestibular part gives the body a sense of position relative to the inner and outer environment. The vestibular nerve
Empirical data
The vulnerable population affected in combat-related PTSD can be viewed in parallel with the progressive rise of Blast injury in major wartime conflicts [116], [117], [118], [119], [120], [121], [122], [123]. A temporal comparison of the prevailing mechanisms of injury for wartime head injuries (1861–2009) is depicted in Fig. 2 showing the start and steady rise of blast injuries since WWI when PTSD symptoms attributable to the vestibulo-cochlear pathway (“Shell- Shock”) were first described.
The vestibulocochlear working theory for the development of PTSD manifestations complement the existing theories behind PTSD.
The current and past DSM classification systems attempting to define the limits of PTSD as a theoretical framework through historical criteria were structured to better evaluate previous and ongoing psychotherapies or combined pharmaco-psychotherapies as they are used for full-blown (complete criteria) PTSD [132]. There is no evidence to support the conclusion that a sufferer with incomplete PTSD criteria is not afflicted with an early form of the same disorder evolving as part of a spectrum
Disclaimer
The opinions or assertions contained herein are the private ones of the author/s and are not to be construed as official or reflecting the views of the Department of Defense, the Uniformed Services University of the Health Sciences or any other agency of the U.S. Government.
Acknowledgements
Sources of support in the form of Grants: Army Research Organization Proposal Number ARO #60697-LS, Award No. W91NF-11-1-0374.
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2019, Journal of the American Academy of Audiology