Cognitive Motor Dissociation Found in 1 in 4 Unresponsive Patients, New Study Reports

A new study published in The New England Journal of Medicine suggests that cognitive motor dissociation (CMD), a condition where unresponsive patients show brain activity, may be more prevalent than previously estimated. CMD occurs when patients who appear unresponsive due to severe brain injury exhibit brain activity detectable via functional MRI (fMRI) or EEG during cognitive tasks. The study found that 25% of patients with disorders of consciousness displayed CMD, compared to earlier estimates of 10% to 20%.

This prospective cohort study included 353 adults with impaired consciousness resulting from traumatic brain injury (TBI), cardiac arrest, stroke, or hypoxia. Participants were assessed using the Coma Recovery Scale–Revised (CRS-R) and divided into two groups: those who responded to verbal commands and those who did not. Among the 241 participants who did not respond to commands, 60 were found to have CMD when assessed by either fMRI or EEG. The likelihood of detecting CMD was higher in patients with brain trauma, younger individuals, and those with a longer duration since the injury. The study also showed that participants assessed using both fMRI and EEG were more likely to be diagnosed with CMD.

These findings highlight the possibility that more patients with severe brain injuries may retain some level of cognitive function than what current behavioral assessments reveal. The study's detection rates for CMD were 5% to 10% higher than previously reported, emphasizing the need to improve fMRI and EEG methods to enhance diagnostic accuracy.

The detection of CMD has important clinical implications, as it may refine the way healthcare professionals assess cognitive activity in patients with disorders of consciousness. Standardizing and simplifying fMRI and EEG protocols for CMD detection could help identify more patients who may benefit from targeted treatment strategies. Further research is needed to explore whether recognizing CMD can lead to improved outcomes for these patients.