Abstract
Objective: Following severe brain injury, up to 16% of adults showing no clinical signs of cognitive function nonetheless have preserved cognitive capacities detectable via neuroimaging and neurophysiology; this has been designated cognitive-motor dissociation (CMD). Pediatric medicine lacks both practice guidelines for identifying covert cognition, and epidemiologic data regarding CMD prevalence.
Methods: We applied a diverse battery of neuroimaging and neurophysiological tests to evaluate two adolescents (aged 15 and 18) who had shown no clinical evidence of preserved cognitive function following brain injury at age 9 and 13 respectively. Clinical evaluations were consistent with minimally conscious state (minus) and vegetative state, respectively.
Results: Both subjects’ EEG, and one subject’s fMRI, provided evidence that they could understand commands and make consistent voluntary decisions to follow them. Both subjects’ EEG demonstrated larger-than-expected responses to auditory stimuli, and intact semantic processing of words in context.
Interpretation: These converging lines of evidence lead us to conclude that both subjects had preserved cognitive function dissociated from their motor output. Throughout the 5+ years since injury, communication attempts and therapy had remained uninformed by such objective evidence of their cognitive abilities. Proper diagnosis of CMD is an ethical imperative. Children with covert cognition reflect a vulnerable and isolated population; the methods outlined here provide a first step in identifying such persons to advance efforts to alleviate their condition.
- Received October 27, 2021.
- Accepted March 7, 2022.
- Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.
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