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Preservation of Brain Activity in Unresponsive Patients Identifies MCS Star.

Authors :: Thibaut A
Panda R
Annen J
Sanz LRD
Naccache L
Martial C
Chatelle C
Aubinet C
Bonin EAC
Barra A
Briand MM
Cecconi B
Wannez S
Stender J
Laureys S
Gosseries O
Source :: Annals of neurology [Ann Neurol] 2021 Jul; Vol. 90 (1), pp. 89-100. Date of Electronic Publication: 2021 Jun 01.
Publication Year :: 2021
Abstract: Objective: Brain-injured patients who are unresponsive at the bedside (ie, vegetative state/unresponsive wakefulness syndrome - VS/UWS) may present brain activity similar to patients in minimally conscious state (MCS). This peculiar condition has been termed "non-behavioural MCS" or "MCS*". In the present study we aimed to investigate the proportion and underlying brain characteristics of patients in MCS*.<br />Methods: Brain <superscript>18</superscript> F-fluorodeoxyglucose Positron Emission Tomography (FDG-PET) was acquired on 135 brain-injured patients diagnosed in prolonged VS/UWS (n = 48) or MCS (n = 87). From an existing database, relative metabolic preservation in the fronto-parietal network (measured with standardized uptake value) was visually inspected by three experts. Patients with hypometabolism of the fronto-parietal network were labelled "VS/UWS", while its (partial) preservation either confirmed the behavioural diagnosis of "MCS" or, in absence of behavioural signs of consciousness, suggested a diagnosis of "MCS*". Clinical outcome at 1-year follow-up, functional connectivity, grey matter atrophy, and regional brain metabolic patterns were investigated in the three groups (VS/UWS, MCS* and MCS).<br />Results: 67% of behavioural VS/UWS presented a partial preservation of brain metabolism (ie, MCS*). Compared to VS/UWS patients, MCS* patients demonstrated a better outcome, global functional connectivity and grey matter preservation more compatible with the diagnosis of MCS. MCS* patients presented lower brain metabolism mostly in the posterior brain regions compared to MCS patients.<br />Interpretation: MCS* is a frequent phenomenon that is associated with better outcome and better brain preservation than the diagnosis of VS/UWS. Complementary exams should be provided to all unresponsive patients before taking medical decisions. ANN NEUROL 2021;90:89-100.<br /> (© 2021 The Authors. Annals of Neurology published by Wiley Periodicals LLC on behalf of American Neurological Association.)