Content » Vol 44, Issue 6

Original report

Metabolic activity in external and internal awareness networks in severely brain-damaged patients

Aurore Thibaut, Marie-Aurélie Bruno, Camille Chatelle, Olivia Gosseries, Audrey Vanhaudenhuyse, Athena Demertzi, Caroline Schnakers, Marie Thonnard, Vanessa Charland-Verville, Claire Bernard, Mohammed Bahri, Christophe Phillips, Mélanie Boly, Roland Hustinx, Steven Laureys
DOI: 10.2340/16501977-0940


Objective: An extrinsic cerebral network (encompassing lateral frontoparietal cortices) related to external/sensory awareness and an intrinsic midline network related to internal/self-awareness have been identified recently. This study measured brain metabolism in both networks in patients with severe brain damage.
Design: Prospective [18F]-fluorodeoxyglucose-positron emission tomography and Coma Recovery Scale-Revised assessments in a university hospital setting.
Subjects: Healthy volunteers and patients in vegetative state/unresponsive wakefulness syndrome (VS/UWS), minimally conscious state (MCS), emergence from MCS (EMCS), and locked-in syndrome (LIS).
Results: A total of 70 patients were included in the study: 24 VS/UWS, 28 MCS, 10 EMCS, 8 LIS and 39 age-matched controls. VS/UWS showed metabolic dysfunction in extrinsic and intrinsic networks and thalami. MCS showed dysfunction mostly in intrinsic network and thalami. EMCS showed impairment in posterior cingulate/retrosplenial cortices. LIS showed dysfunction only in infratentorial regions. Coma Recovery Scale-Revised total scores correlated with metabolic activity in both extrinsic and part of the intrinsic network and thalami.
Conclusion: Progressive recovery of extrinsic and intrinsic awareness network activity was observed in severely brain-damaged patients, ranging from VS/UWS, MCS, EMCS to LIS. The predominance of intrinsic network impairment in MCS could reflect altered internal/self-awareness in these patients, which is difficult to quantify at the bedside.

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