The Significance of Emerging Electroencephalographic Patterns in Critically Ill Patients

Abstract

A large proportion of critically ill patients have altered mental state or coma, and the electroencephalogram (EEG) is the only way of adequate monitoring for seizures and status epilepticus (SE). As continuous EEG monitoring (cEEG) expanded there were many EEG patterns where the clinical relevance remained uncertain.

The thesis utilized the Critical Care EEG Monitoring Research Consortium (CCEMRC) publicly available database to study the associations of Rhythmic and Periodic Patterns with seizures and SE. Bilateral asymmetric lateralized rhythmic delta activity (LRDA-ba), burst suppression with highly epileptiform bursts (HEBs), and burst suppression with identical bursts (IBs) were identified as specific cohorts to describe or confirm the clinical significance.

The cEEG from 12,450 adult patients showed the overall rate of seizures was 9.8% with 3.5% qualifying as SE. Clinical etiologies and EEG patterns with the greatest associations were described. The cohort with LRDA-ba was statistically distinct from Generalized Rhythmic Delta Activity (GRDA), with greater acute focal structural brain injuries and focal EEG features of cortical excitability.

For BS patterns, the presence of HEBs was a major determinant of seizure recurrence in patients with refractory status epilepticus (RSE). This could not determined by conventional measures of BS, such as duration or amplitude of bursts or interburst intervals. For adult survivors of cardiac arrest, identical bursts (IBs) were validated as a very poor prognostic indicator, also demonstrating that how “identical” bursts were strengthened these associations.

The thesis overall makes significant headway in our understanding of cEEG and it provides clinicians with robust data to be able to make decisions at the patient level. This sets the stage for future work using well-designed prospective trials to determine reversible factors that improve patient outcomes.