Multimodal assessment of minimally conscious state and cognitive motor dissociation in neurocritical care: A critical review.
Authors
Affiliations (1)
Affiliations (1)
- Department of Neurology, University of Milan, Milan, Italy. Electronic address: [email protected].
Abstract
Minimally conscious state (MCS) is characterized by inconsistent but clearly discernible clinical and behavioral evidence of consciousness. Cognitive motor dissociation (CMD) or covert consciousness refers to a condition characterized by a marked dissociation in which a preserved but unacknowledged (covert) cognitive capacity exists in some patients with severe brain injury who show absent or non-purposeful behavioral responses. Traditionally underrecognized by standard neurological examination, this condition may carry significant implications for prognostication and critical care decision-making. Early identification of preserved cognitive processing challenges reductionist views of coma and may help prevent premature withdrawal of life-sustaining therapies. This review synthesizes the principal clinical, electrophysiological, and neuroimaging tools capable of detecting CMD, including advanced bedside examination strategies, behavioral rating scales, structural and functional MRI, EEG reactivity and complexity metrics, machine-learning-based analyses, and multimodal approaches. Although novel technologies - such as task-based fMRI, TMS-EEG, and FDG-PET - offer promising means to infer preserved network connectivity, expert clinical examination and validated scales such as the Coma Recovery Scale-Revised (CRS-R) remain critically important and continue to be among the most widely supported diagnostic methods. Integrating repeated behavioral assessments with quantitative neurophysiological data yields a more comprehensive understanding of residual cognitive function, yet challenges persist, including high false-negative rates, susceptibility to sedation and arousal fluctuations, and limited standardization across modalities. Ethical considerations surrounding the diagnosis of CMD are equally significant, especially in relation to goals-of-care decisions, neuro-palliative strategies, and family communication. Ultimately, while the detection of CMD is essential to contemporary neurocritical practice, its practical implications for therapeutic decision-making remain incompletely defined, mandating individualized, cautious interpretation within a patient-centered clinical framework.