Disorders of Consciousness (DoC): different DoC categories or a continuum of responsiveness recovery?
Behavioural lscales, such as the Coma Recovery Scale-Revised (CRS-R), are universally considered the gold standard for responsiveness assessment, although overt command-following as well as functional communication may vary over time, especially in relation to the presence of caregivers, the comorbidities, language disorders and iatrogenic side effects. The current taxonomy and the labelling in the different DoC categories may be arbitrary, since the consensus on how often the CRS-R should be repeated in order to be considered diagnostic might be questionable (Wannez et al., 2017).
Several authors have suggested that covertly conscious non responsive patients should be assigned to a new category labelled either Non-behavioural Minimally Conscious State, Functional Locked-in Syndrome (Formisano et al., 2013) and finally Cognitive-Motor Dissociation (Schiff, 2015). Several authors suggested mental imagery fMRI or EEG paradigms to reduce the high misdiagnosis rate in DoC patients, reported as up to 40%.
EAN Guideline on the Classification of Coma and Chronic DoC: Protocol (follows the practical recommendations for the process of proposing, planning and writing a neurological management guideline by EAN task forces).
The primary aim of the EAN Scientific Panel Coma & Chronic DoC is to provide the European neurological community with the state-of-the-art evidence regarding diagnosis and classification of coma and DoC, including: clinical bedside examination techniques; laboratory investigations based on functional neuroimaging (fMRI, PET) and EEG (including transcranial magnetic stimulation) and produce an EAN guideline on the classification of coma and chronic DoC.
key points
- Disorders of Consiousness
- Unresponsive Wakefulness Syndrome
- Minimally Conscious State
- Covert Cognition
- Coma Recovery Scale Revised
1. Formisano, R., D’Ippolito, M., & Catani, S. (2013). Functional locked-in syndrome as recovery phase of vegetative state. Brain injury, 27(11), 1332-1332.
2. Pignat, J. M., Mauron, E., Jöhr, J., de Keranflec'h, C. G., Van De Ville, D., Preti, M. G., ... & Frackowiak, R. (2016). Outcome Prediction of Consciousness Disorders in the Acute Stage Based on a Complementary Motor Behavioural Tool. PloS one, 11(6),
3. Wannez, S., Heine, L., Thonnard, M., Gosseries, O., & Laureys, S. (2017). The repetition of behavioural assessments in diagnosis of disorders of consciousness. Annals of neurology.