Detecting cognitive motor dissociation in unresponsive brain-injured patients: a prospective cohort study using active task-based EEG

This study aimed to assess the prevalence and prognostic value of cognitive motor dissociation (CMD) detected by active task-based electroencephalography (EEG) in a cohort of patients with disorders of consciousness (DoC). In a prospective cohort study, we enrolled 56 consecutive clinically unresponsive patients with acute or chronic brain injury. Patients underwent EEG recording during an active motor imagery task following spoken commands. Functional outcomes were assessed using the Glasgow Outcome Scale-Extended (GOS-E) at 6 months. Ten healthy volunteers served as a control group. Among the 56 unresponsive patients, 6 (10.7%) were identified as CMD-positive. The favorable-outcome rate (GOS‑E ≥ 4) was higher in the CMD-positive group (2/6, 33.3%) than in the CMD-negative group (4/50, 8.0%), although the difference did not reach statistical significance (Fisher’s exact p = 0.12). At 6‑month follow‑up, no deaths occurred in the CMD‑positive group ( n = 6), compared with a mortality rate of 16% (8/50) in the CMD‑negative group. Given the limited sample size, these descriptive results are hypothesis-generating and require confirmation in larger prospective cohorts. In the healthy control group, 9 of 10 participants (90%) were task‑positive; the only task‑negative participant reported having fallen asleep during the experiment. Most healthy volunteers reported feeling drowsy and easily distracted while performing the task. Active task‑based EEG can detect CMD in a subset of behaviorally unresponsive patients, and its presence was descriptively associated with more favorable outcomes. However, the detection rate in our cohort was lower than previously reported, and healthy controls frequently experienced sleepiness during the task. These findings support the prognostic value of EEG‑detected CMD while highlighting the need for more sensitive, patient‑adapted paradigms. The flowchart illustrates the sequential process of patient behavioral scale assessment, data processing, and follow-up. CRS-R, Coma Recovery Scale–Revised; PSD, power spectral density; SVM, support vector machine