Outcome Prediction of Consciousness Disorders in the Acute Stage Based on a Complementary Motor Behavioural Tool

Abstract

IntroductionAttaining an accurate diagnosis in the acute phase for severely brain-damaged patients presenting Disorders of Consciousness (DOC) is crucial for prognostic validity; such a diagnosis determines further medical management, in terms of therapeutic choices and end-of-life decisions. However, DOC evaluation based on validated scales, such as the Revised Coma Recovery Scale (CRS-R), can lead to an underestimation of consciousness and to frequent misdiagnoses particularly in cases of cognitive motor dissociation due to other aetiologies. The purpose of this study is to determine the clinical signs that lead to a more accurate consciousness assessment allowing more reliable outcome prediction.MethodsFrom the Unit of Acute Neurorehabilitation (University Hospital, Lausanne, Switzerland) between 2011 and 2014, we enrolled 33 DOC patients with a DOC diagnosis according to the CRS-R that had been established within 28 days of brain damage. The first CRS-R assessment established the initial diagnosis of Unresponsive Wakefulness Syndrome (UWS) in 20 patients and a Minimally Consciousness State (MCS) in the remaining13 patients. We clinically evaluated the patients over time using the CRS-R scale and concurrently from the beginning with complementary clinical items of a new observational Motor Behaviour Tool (MBT). Primary endpoint was outcome at unit discharge distinguishing two main classes of patients (DOC patients having emerged from DOC and those remaining in DOC) and 6 subclasses detailing the outcome of UWS and MCS patients, respectively. Based on CRS-R and MBT scores assessed separately and jointly, statistical testing was performed in the acute phase using a non-parametric Mann-Whitney U test; longitudinal CRS-R data were modelled with a Generalized Linear Model.ResultsFifty-five per cent of the UWS patients and 77% of the MCS patients had emerged from DOC. First, statistical prediction of the first CRS-R scores did not permit outcome differentiation between classes; longitudinal regression modelling of the CRS-R data identified distinct outcome evolution, but not earlier than 19 days. Second, the MBT yielded a significant outcome predictability in the acute phase (p<0.02, sensitivity>0.81). Third, a statistical comparison of the CRS-R subscales weighted by MBT became significantly predictive for DOC outcome (p<0.02).DiscussionThe association of MBT and CRS-R scoring improves significantly the evaluation of consciousness and the predictability of outcome in the acute phase. Subtle motor behaviour assessment provides accurate insight into the amount and the content of consciousness even in the case of cognitive motor dissociation.

Motor behavior unmasks residual cognition in disorders of consciousness

“…In addition, the MBT‐r identified signs of residual cognition in 75% of patients who were classified as unconscious (coma/UWS) by the CRS‐R. Moreover, presence of residual cognition at an early stage was related to subsequent consciousness recovery, in agreement with previous findings with the first version of the MBT . Our data, prospectively obtained in an ICU setting, support the notion that a wide range of cognitive capacities might be detected early after brain injury, and, more important, that their assessment is critical for determining an accurate prognosis .…”

“…In this respect, the validated scales used in the clinical evaluation of DOC are mainly based on residual motor output, therefore limiting their ability to unmask a patient's cognitive abilities to interact, in case of impaired motor efference/output. The Motor Behavior Tool (MBT) was developed as a complement to the Coma Recovery Scale‐Revised (CRS‐R), to identify subtle motor behavior not taken into account in the CRS‐R that could be useful to identify residual cognition in DOC patients. A previous preliminary study reported the usefulness of the MBT to predict outcome early after severe brain injury …”

“…The Motor Behavior Tool (MBT) was developed as a complement to the Coma Recovery Scale‐Revised (CRS‐R), to identify subtle motor behavior not taken into account in the CRS‐R that could be useful to identify residual cognition in DOC patients. A previous preliminary study reported the usefulness of the MBT to predict outcome early after severe brain injury …”

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

“…Observation of spontaneous motor behaviors (that may or may not be intentional) could help diagnose covert consciousness, e.g. using analytical approaches such as the revised Motor Behavior Tool or subjective approaches based on caregivers' collective intelligence such as the ‘DoC feeling’ . The examiner should be mindful of confounding factors such as cranial nerve palsies, central and peripheral causes of quadriplegia, severe spasticity, hypokinesia and bradykinesia, and hypertonus or hypotonus .…”

Assessment and Intervention with Patients with Severe Disorders of Consciousness

“…First, using supplements to (corrections of) the behavioral scales might be viewed as a practically relevant initiative to overcome the limitations of the scales and increase diagnostic accuracy. The aforementioned learning test strategies and the complementary motor behavior evaluation tool recently described by Pignat et al (2016) could be interpreted as examples of those supplements/corrections (Di Perri et al 2016;Lancioni et al 2014a;Monti 2012). Second, repeating the assessment over time and using combinations of behavioral and electrophysiological or neuroimaging procedures for such an assessment would constitute important cautionary conditions to curb the risks connected with individual fluctuations and reduce misdiagnosis Dolce et al 2015;Gilutz et al 2015).…”