Cognitive Motor Dissociation in Disorders of Consciousness: An Individual Participant Data Meta-Analysis
Poul P Laigaard1, Fawzi W Abla1, Melika Hassani1
1Department of Neurology, Copenhagen University Hospital-Rigshospitalet, Copenhagen, Denmark.
Introduction:
In patients with disorders of consciousness (DoC), behavioral assessment often underestimates awareness when motor output is absent or unreliable. Cognitive motor dissociation (CMD) refers to patients who appear unresponsive but demonstrate volitional brain responses during neurodiagnostic tests. We characterized clinical and methodological factors associated with CMD detection.
Methods:
Studies published between January 2000 and May 2026 were identified through MEDLINE, Embase, and Scopus. Individual participant data were analyzed using mixed-effects logistic regression. Study quality was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2.
Results:
Fifty-six studies with 1248 patients (mean age 45.5 years; 66.1% male; 44.5% unresponsive wakefulness syndrome [UWS]) were included. In unadjusted analyses, CMD detection was lower in anoxic (OR 0.43, 95% CI 0.29-0.66) and cerebrovascular (OR 0.59, 95% CI 0.37-0.98) compared to traumatic brain injury, and higher in minimally conscious state minus (MCS-) compared to UWS (OR 1.64, 95% CI 1.14-2.35). In multivariable models, anoxic (OR 0.35, 95% CI 0.23-0.55) and cerebrovascular (OR 0.51, 95% CI 0.32-0.84) etiologies remained independently associated with lower CMD detection, while MCS- remained associated with higher detection (OR 1.50, 95% CI 1.02-2.23). Time since injury, diagnostic modality and task paradigms were not independently associated with CMD detection. Overall, the studies showed a relatively low risk of bias.
Conclusions:
CMD is common but varies by etiology and clinical state. Its detection appears to be independent of the time of injury, the task paradigm, and the diagnostic modality, highlighting the importance of standardized protocols and longitudinal studies.
