Outcome prediction of consciousness disorders and awareness detection in the acute stage based on behavioural responses of existing coma scales

In patients with disorder of consciousness (DOC), awareness preservation is related to a better outcome prognosis (34). The dissociation of identified signs of awareness by laboratory assessment while undetected by bedside behavioural examination, is defined as cognitive motor dissociation (CMD) (1, 22-27). The rate of misdiagnosis is about 30% (18-21). Current researches emphasize enlarged bedside evaluation as it is easily administered and more economical (26). The Motor Behavioural Tool (MBT) had provided accurate insight into the content of consciousness, and had improved significantly the correlation with the outcome prediction during the acute stage, while the CRS-R sub-scores per se did not (1). We propose to further the exploration of supplementary motor behavioural signs by studying the predictability of the emergence defined by the CRS-R as well as the ability to detect CMD of the clinical items of three existing scales: The FOUR, the GCS and the NCS. We enrolled 35 patients with first CRS-R, MBT and the 3 aforementioned scales evaluation performed within 28 days post-injury. One evaluation of each scale was selected for every patient. The FOUR has 4 items, the GCS 3, and the NCS 4, that means 11 items, all rated with a sub-score which were the analysed variables. A first class of 8 group and 4 comparisons were made depending on the first and last CRS-R assessment, the latter defining the emergence: DOC patient emerging (1a) vs not emerged (1b), UWS (1c) and MCS (1e) emerging vs not emerged (1d) and (1f), and patients showing no CRS-R change (1g) vs those showing upper class of CRS-R (1h). A second class of 5 groups with 3 comparisons were made according to the MBT assessment at the admission and the last CRS-R evaluation : CMD patients (2a) vs true DOC (2b) at the entry in the unit, true DOC with DOC at last CRS-R (2c) vs CMD with emergence at last CRS-R (2e), and CMD with DOC at last CRS-R (2d) vs CMD with emergence at last CRS-R (2e). The statistical testing was based on a non-parametric Mann-Whitney U test to see whether there is a difference of sub-scores when comparing two groups for the same item. The p-value was > 0.05 for all comparisons; in other word, none item enables to predict the outcome defined by the last CRS-S classification or to make the CMD diagnosis according to the MBT. Moreover, 26% of CMD patients were classified as DOC on the last CRS-R which can be related to the rate of misdiagnosis found in the literature. Those findings address explicitly the issue of how performing the clinical evaluation to overcome this underestimation of the degree and level of consciousness, and how essential it is to develop and render more accurate the bedside evaluation of awareness.