title: Persistent vegetative state and minimally conscious state: a systematic review and meta-analysis of diagnostic procedures.
abstract: BACKGROUND
  Acute brain damage can cause major disturbances of consciousness, ranging all the way to the persistent vegetative state (PVS), which is also known as "unresponsive wakefulness syndrome". PVS can be hard to distinguish from a state of minimal preserved consciousness ("minimally conscious state," MCS); the rate of misdiagnosis is high and has been estimated at 37-43%. In contrast, PVS is easily distinguished from brain death. We discuss the various diagnostic techniques that can be used to determine whether a patient is minimally conscious or in a persistent vegetative state.
  
  
  METHODS
  This article is based on a systematic review of pertinent literature and on a quantitative meta-analysis of the sensitivity and specificity of new diagnostic methods for the minimally conscious state.
  
  
  RESULTS
  We identified and evaluated 20 clinical studies involving a total of 906 patients with either PVS or MCS. The reported sensitivities and specificities of the various techniques used to diagnose MCS vary widely. The sensitivity and specificity of functional MRI-based techniques are 44% and 67%, respectively (with corresponding 95% confidence intervals of 19%-72% and 55%-77%); those of quantitative EEG are 90% and 80%, respectively (95% CI, 69%-97% and 66%-90%). EEG, event-related potentials, and imaging studies can also aid in prognostication. Contrary to prior assumptions, 10% to 24% of patients in PVS can regain consciousness, sometimes years after the event, but only with marked functional impairment.
  
  
  CONCLUSIONS
  The basic diagnostic evaluation for differentiating PVS from MCS consists of a standardized clinical examination. In the future, modern diagnostic techniques may help identify patients who are in a subclinical minimally conscious state.
authors.affiliation: Department of Neurology, Therapiezentrum Burgau, Neurological Clinic and Policlinic, Großhadern Hospital, Ludwig-Maximilian-Universität, Institute of Ethics, History and Theory of Medicine, Ludwig-Maximilians-Universität München, Institute for Medical Data Processing, Biometrics and Epidemiology, Ludwig-Maximilian-Universität München, Department of Neurology, University of Ulm.
authors.forename: Andreas
authors.initials: A
authors.lastname: Bender
authors.forename: Ralf J
authors.initials: RJ
authors.lastname: Jox
authors.forename: Eva
authors.initials: E
authors.lastname: Grill
authors.forename: Andreas
authors.initials: A
authors.lastname: Straube
authors.forename: Dorothée
authors.initials: D
authors.lastname: Lulé
mesh_terms: D001931:Brain Mapping / Q000706:statistics & numerical data*; D003128:Coma / Q000175:diagnosis* / Q000453:epidemiology; D003937:Diagnosis, Differential; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D003943:Diagnostic Techniques, Neurological / Q000706:statistics & numerical data*; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D018458:Persistent Vegetative State / Q000175:diagnosis* / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity