Brain function in the vegetative state.
Positron emission tomography (PET) techniques represent a useful tool to better understand the residual brain function in vegetative state patients. It has been shown that overall cerebral metabolic rates for glucose are massively reduced in this condition. However, the recovery of consciousness from vegetative state is not always associated with substantial changes in global metabolism. This finding led us to hypothesize that some vegetative patients are unconscious not just because of a global loss of neuronal function, but rather due to an altered activity in some critical brain regions and to the abolished functional connections between them. We used voxel-based Statistical Parametric Mapping (SPM) approaches to characterize the functional neuroanatomy of the vegetative state. The most dysfunctional brain regions were bilateral frontal and parieto-temporal associative cortices. Despite the metabolic impairment, external stimulation still induced a significant neuronal activation (i.e., change in blood flow) in vegetative patients as shown by both auditory click stimuli and noxious somatosensory stimuli. However, this activation was limited to primary cortices and dissociated from higher-order associative cortices, thought to be necessary for conscious perception. Finally, we demonstrated that vegetative patients have impaired functional connections between distant cortical areas and between the thalami and the cortex and, more importantly, that recovery of consciousness is paralleled by a restoration of this cortico-thalamo-cortical interaction.
Laureys
Steven
S
Cyclotron Research Center, Department of Neurology, CHU Sart Tilman, University of Liège, Liège, Belgium. steven.laureys@ulg.ac.be
Antoine
Sylvie
S
Boly
Melanie
M
Elincx
Sandra
S
Faymonville
Marie-Elisabeth
ME
Berré
Jacques
J
Sadzot
Bernard
B
Ferring
Martine
M
De Tiège
Xavier
X
van Bogaert
Patrick
P
Hansen
Isabelle
I
Damas
Pierre
P
Mavroudakis
Nicolas
N
Lambermont
Bernard
B
Del Fiore
Guy
G
Aerts
Joël
J
Degueldre
Christian
C
Phillips
Christophe
C
Franck
George
G
Vincent
Jean-Louis
JL
Lamy
Maurice
M
Luxen
André
A
Moonen
Gustave
G
Goldman
Serge
S
Maquet
Pierre
P
D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D003243:Consciousness / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D006801:Humans; D009434:Neural Pathways / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D018458:Persistent Vegetative State / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D020127:Recovery of Function / Q000502:physiology; D013788:Thalamus / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D014055:Tomography, Emission-Computed