title: History of syncope predicts loss of consciousness after head trauma: Retrospective study.
abstract: BACKGROUND
  Head trauma may present as transient loss of consciousness (TLOC) currently classified as traumatic in origin, in contrast to non-traumatic forms, such as syncope. Whether past history of syncope predisposes to loss of consciousness after head injury has been poorly studied.
  
  
  METHODS
  A retrospective analysis of data obtained from 818 consecutive patients admitted to Emergency Departments was conducted. Face-to-face semi-structured interviews were performed, where patients' past history of syncope and head injury were explored. Head injury events were stratified as high- or low-energy trauma. Data regarding past syncopal events were explored in regard to number, age at the first occurrence, and syncope circumstances. Multivariate logistic regression model was applied to assess the relationship between loss of consciousness during head injury and past history of syncope.
  
  
  RESULTS
  Both past history of non-traumatic TLOC (odds ratio [OR] 3.78; 95% confidence interval [CI] 2.13-6.68, p < 0.001) and high-energy mechanism (OR 3.84; 95% CI 2.35-6.28, p < 0.001) predicted TLOC after head trauma. This relationship was even stronger when past episodes of TLOC were limited to those typical for reflex syncope (OR 4.34; 95% CI 2.34-7.89, p < 0.001). Further, the number of non-traumatic TLOC episodes in the patient's history was also predictive of TLOC after head injury (OR per 1 episode: 1.24; 95% CI 1.04-1.48, p = 0.015).
  
  
  CONCLUSIONS
  Syncope in a patient's history predicts loss of consciousness after head injury. The clinical importance of this finding merits further investigation.
authors.affiliation: Department of Medical Emer gency, Wroclaw Medical University, Wroclaw, Poland. dzysko@wp.pl.
authors.forename: Dorota
authors.initials: D
authors.lastname: Zyśko
authors.forename: Richard
authors.initials: R
authors.lastname: Sutton
authors.forename: Dariusz
authors.initials: D
authors.lastname: Timler
authors.forename: Stanisław
authors.initials: S
authors.lastname: Furtan
authors.forename: Olle
authors.initials: O
authors.lastname: Melander
authors.forename: Artur
authors.initials: A
authors.lastname: Fedorowski
mesh_terms: D000328:Adult; D006259:Craniocerebral Trauma / Q000150:complications* / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D011044:Poland / Q000453:epidemiology; D012189:Retrospective Studies; D013575:Syncope / Q000150:complications* / Q000175:diagnosis / Q000453:epidemiology; D015599:Trauma Severity Indices; D014474:Unconsciousness / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*