Neuro-anatomical localization of EEG identical bursts in patients with and without post-anoxic myoclonus

Background: The electroencephalograph (EEG) pattern of burst suppression with identical bursts (BSIB), with or without myoclonus, occurs often after resuscitation from cardiac arrest. These patterns are associated with severe brain injury but their neuropathological basis is unknown. Using EEG source localization, we tested whether post-cardiac arrest myoclonus was associated with specific anatomical distribution of BSIB.

Methods: We performed a single center, case-control study of EEG-monitored post-cardiac arrest patients with BSIB. We determined the presence of myoclonus from clinical notes and video recordings. We generated normalized source density maps (sLORETA) for the first 0.5 s of each burst projected onto a standard anatomic model, and compared proportion of EEG power in the precentral gyrus (motor cortex) to the rest of the brain.

Results: We included 20 patients, 10 with and 10 without myoclonus. Patients with myoclonus had greater electrical activation localized to the precentral gyrus compared to those without (median 3.25 [IQR 2.74-3.59] vs 2.68 [IQR 2.66-2.71], P = 0.04). There was no difference between groups in region of burst origin.

Conclusion: Among patients with BSIB after cardiac arrest, those with clinical myoclonus have more electrocortical activation in the precentral gyrus.