Exploring impaired consciousness: the MRI approach.
OBJECTIVE
To summarize the application of advanced MRI sequences such as magnetic resonance spectroscopy, diffusion tensor imaging and functional MRI for the evaluation of patients with altered consciousness.


RESULTS
Magnetic resonance spectroscopy, volumetry and diffusion tensor imaging have shown promising results in the evaluation of traumatic or anoxo-ischaemic brain lesions and can detect damage of the brainstem, basal ganglia and white matter tracts not visible on conventional sequences. A diffusion tensor imaging study has raised the possibility of detecting ongoing axonal regrowth many years after the initial injury in minimally conscious patients. Functional MRI studies have shown that a high level of brain activities, such as recognizing one's own name or imagining playing tennis, can be preserved in vegetative patients.


CONCLUSIONS
The development of quantitative imaging could lead to a more objective evaluation of the extent of destruction or preservation of critical brain areas at the acute phase of brain injury, which could be integrated in multi-parametric decisional strategies for these patients. Functional imaging could help define borders between the various levels of altered consciousness and detect the presence of cryptic residual functions in vegetative or minimally conscious patients. This approach could eventually help determine the neurological outcome and make individual blueprints of the preserved brain activities in severely brain injured patients.
Galanaud
Damien
D
Department of Neuroradiology, University of Paris VI, Pierre et Marie Curie, Pitié-Salpêtrière Hospital, Paris, France. galanaud@dat.org
Naccache
Lionel
L
Puybasset
Louis
L
D001921:Brain / Q000473:pathology* / Q000503:physiopathology*; D003243:Consciousness / Q000502:physiology; D003244:Consciousness Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000592:standards / Q000639:trends; D004185:Disability Evaluation; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000592:standards / Q000639:trends*; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology; D011237:Predictive Value of Tests