Why Can EEG Bursts Stay Asymmetric During Propofol Anesthesia?

During burst suppression, an EEG alternates between bursts of electrical activity and intervals of marked suppression. When bursts differ across the two hemispheres, the recording before anesthesia can help explain the asymmetry.

What was visible before and during anesthesia

Mader and colleagues described a patient with a hemorrhagic right temporal cavernous malformation. Before propofol, the EEG showed right-sided lateralized periodic discharges and occasional focal electrographic seizures. Under propofol, burst suppression appeared on both sides, but the right-sided bursts were more complex. The authors identified remnants of the pre-existing periodic discharges within those bursts. After anesthetics were withdrawn, the original periodic pattern returned.

Separate seizure control from changes in the background

In this case, multiple medications suppressed the recorded seizures while periodic activity persisted. When reviewing an anesthesia timeline, compare the EEG segments before, during and after exposure. An asymmetric burst pattern alone cannot establish ongoing seizures or quantify the anesthetic dose. The report documents one patient with a focal brain lesion.

Source

Mader et al., case report of asymmetric drug-induced burst suppression