title: Aetiological differences in neuroanatomy of the vegetative state: insights from diffusion tensor imaging and functional implications.
abstract: BACKGROUND
  An improved in vivo understanding of variations in neuropathology in the vegetative state (VS) may aid diagnosis, improve prognostication and help refine the selection of patients for particular treatment regimes. The authors have used diffusion tensor imaging (DTI) to characterise the extent and location of white matter loss in VS secondary to traumatic brain injury (TBI) and ischaemic-hypoxic injury.
  
  
  METHODS
  Twelve patients with VS (seven TBI, five ischaemic/hypoxic injuries) underwent MRI including DTI at a minimum of 3 months postinjury. Mean apparent diffusion coefficient, fractional anisotropy and eigenvalues were obtained for whole-brain grey and white matter, the pons, thalamus, ventral midbrain, dorsal midbrain and the corpus callosum. DTI measures of supratentorial damage were compared with a summed measure from the JFK modified Coma Recovery Scale (CRS-R) and with a three-point scale of functional magnetic resonance imaging (fMRI) response to an auditory paradigm to assess whether residual integrity of supratentorial white matter connectivity correlated with cortical processing.
  
  
  RESULTS
  Conventional radiological approaches did not detect lesions in regions where quantitative DTI demonstrated abnormalities. There was evidence of marked, broadly similar, abnormalities in the supratentorial grey- and white-matter compartments from both aetiologies. In contrast, discordant findings were found in the infratentorial compartment, with DTI abnormalities in the brainstem confined to the TBI group. Supratentorial DTI abnormalities correlated with the CRS-R as well as responses to an fMRI paradigm that detected convert cognitive processing.
  
  
  CONCLUSIONS
  DTI may help to characterise differences in patients in VS. These findings may have implications for response to therapies, and should be taken into account in trials of interventions aimed at arousal in VS.
authors.affiliation: University Division of Anaesthesia, University of Cambridge, Box 93, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK. vfjn2@wbic.cam.ac.uk
authors.forename: Virginia F J
authors.initials: VF
authors.lastname: Newcombe
authors.forename: Guy B
authors.initials: GB
authors.lastname: Williams
authors.forename: Daniel
authors.initials: D
authors.lastname: Scoffings
authors.forename: Justin
authors.initials: J
authors.lastname: Cross
authors.forename: T Adrian
authors.initials: TA
authors.lastname: Carpenter
authors.forename: John D
authors.initials: JD
authors.lastname: Pickard
authors.forename: David K
authors.initials: DK
authors.lastname: Menon
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D001930:Brain Injuries / Q000150:complications / Q000473:pathology; D003128:Coma / Q000473:pathology; D003244:Consciousness Disorders / Q000209:etiology / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000473:pathology; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D018458:Persistent Vegetative State / Q000209:etiology* / Q000473:pathology*; D020127:Recovery of Function; D055815:Young Adult