title: A comparison of head dynamic response and brain tissue stress and strain using accident reconstructions for concussion, concussion with persistent postconcussive symptoms, and subdural hematoma.
abstract: OBJECTIVE
  Concussions typically resolve within several days, but in a few cases the symptoms last for a month or longer and are termed persistent postconcussive symptoms (PPCS). These persisting symptoms may also be associated with more serious brain trauma similar to subdural hematoma (SDH). The objective of this study was to investigate the head dynamic and brain tissue responses of injury reconstructions resulting in concussion, PPCS, and SDH.
  
  
  METHODS
  Reconstruction cases were obtained from sports medicine clinics and hospitals. All subjects received a direct blow to the head resulting in symptoms. Those symptoms that resolved in 9 days or fewer were defined as concussions (n = 3). Those with symptoms lasting longer than 18 months were defined as PPCS (n = 3), and 3 patients presented with SDHs (n = 3). A Hybrid III headform was used in reconstruction to obtain linear and rotational accelerations of the head. These dynamic response data were then input into the University College Dublin Brain Trauma Model to calculate maximum principal strain and von Mises stress. A Kruskal-Wallis test followed by Tukey post hoc tests were used to compare head dynamic and brain tissue responses between injury groups. Statistical significance was set at p < 0.05.
  
  
  RESULTS
  A significant difference was identified for peak resultant linear and rotational acceleration between injury groups. Post hoc analyses revealed the SDH group had higher linear and rotational acceleration responses (316 g and 23,181 rad/sec(2), respectively) than the concussion group (149 g and 8111 rad/sec(2), respectively; p < 0.05). No significant differences were found between groups for either brain tissue measures of maximum principal strain or von Mises stress.
  
  
  CONCLUSIONS
  The reconstruction of accidents resulting in a concussion with transient symptoms (low severity) and SDHs revealed a positive relationship between an increase in head dynamic response and the risk for more serious brain injury. This type of relationship was not found for brain tissue stress and strain results derived by finite element analysis. Future research should be undertaken using a larger sample size to confirm these initial findings. Understanding the relationship between the head dynamic and brain tissue response and the nature of the injury provides important information for developing strategies for injury prevention.
authors.affiliation: School of Human Kinetics, University of Ottawa;
authors.forename: R Anna
authors.initials: RA
authors.lastname: Oeur
authors.affiliation: School of Human Kinetics, University of Ottawa;
authors.forename: Clara
authors.initials: C
authors.lastname: Karton
authors.affiliation: School of Human Kinetics, University of Ottawa;
authors.forename: Andrew
authors.initials: A
authors.lastname: Post
authors.affiliation: School of Human Kinetics, University of Ottawa;
authors.forename: Philippe
authors.initials: P
authors.lastname: Rousseau
authors.affiliation: School of Human Kinetics, University of Ottawa;
authors.forename: T Blaine
authors.initials: TB
authors.lastname: Hoshizaki
authors.affiliation: Clinical Epidemiology, Ottawa Hospital Research Institute, Ottawa, Ontario;
authors.forename: Shawn
authors.initials: S
authors.lastname: Marshall
authors.affiliation: Department of Neurosurgery, Centre de Santé et de Services Sociaux (CSSS) Gatineau (Hull site), Quebec, Canada;
authors.forename: Susan E
authors.initials: SE
authors.lastname: Brien
authors.affiliation: Department of Orthopedics and Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, Minnesota;
authors.forename: Aynsley
authors.initials: A
authors.lastname: Smith
authors.affiliation: Injury Prevention Research Office and Division of Neurosurgery, St. Michael's Hospital, and University of Toronto, Ontario, Canada; and.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Cusimano
authors.affiliation: School of Mechanical and Materials Engineering, University College Dublin, Ireland.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Gilchrist
mesh_terms: D000059:Accidents; D000293:Adolescent; D001696:Biomechanical Phenomena / Q000502:physiology; D001921:Brain / Q000473:pathology / Q000503:physiopathology*; D001924:Brain Concussion / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006408:Hematoma, Subdural / Q000473:pathology / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D038223:Post-Concussion Syndrome / Q000473:pathology / Q000503:physiopathology*; D013314:Stress, Mechanical
keywords: Hybrid III headform; MADYMO = Mathematical Dynamic Models; PPCS = persistent postconcussive symptoms; SDH = subdural hematoma; TBI = traumatic brain injury; UCDBTM = University College Dublin Brain Trauma Model; accident reconstruction; concussion; finite element modeling; persistent postconcussive symptoms; subdural hematoma; traumatic brain injury