Cognitive Motor Dissociation in Disorders of Consciousness

This multinational cohort study investigated cognitive motor dissociation (CMD)—a condition in which patients with brain injury who appear unresponsive at the bedside demonstrate covert cognitive activity during task-based functional MRI (fMRI) or electroencephalography (EEG). Among 353 adults with disorders of consciousness, 241 had no observable response to verbal commands, yet 25% of them exhibited cognitive responses on imaging. CMD was more likely in younger patients, those with traumatic brain injury, and those assessed longer after injury. Even among patients who did respond behaviorally, 38% also showed task engagement on fMRI or EEG. The study underscores the limited concordance between clinical assessment and neuroimaging, and supports incorporating fMRI and EEG for detecting covert cognition, which may inform care decisions, prognosis, and ethical considerations around awareness in unresponsive patients

This multinational cohort study investigated cognitive motor dissociation (CMD)—a condition in which patients with brain injury who appear unresponsive at the bedside demonstrate covert cognitive activity during task-based functional MRI (fMRI) or electroencephalography (EEG). Among 353 adults with disorders of consciousness, 241 had no observable response to verbal commands, yet 25% of them exhibited cognitive responses on imaging. CMD was more likely in younger patients, those with traumatic brain injury, and those assessed longer after injury. Even among patients who did respond behaviorally, 38% also showed task engagement on fMRI or EEG. The study underscores the limited concordance between clinical assessment and neuroimaging, and supports incorporating fMRI and EEG for detecting covert cognition, which may inform care decisions, prognosis, and ethical considerations around awareness in unresponsive patients