Discordant Observation of Brain Injury by MRI and Malignant Electroencephalography Patterns in Comatose Survivors of Cardiac Arrest following Therapeutic Hypothermia

Abstract

Background and Purpose Malignant EEG patterns are considered predictive of poor outcome in comatose survivors of cardiac arrest. We hypothesize that malignant patterns by EEG are associated with evidence of more severe brain injury on MRI. Materials and Methods Retrospective review of clinical, imaging and EEG data of 33 adult comatose survivors of cardiac arrest following therapeutic hypothermia was performed. Outcomes measured included discharge destination and survival. Imaging studies were visually scored for severity of brain injury. Mean whole brain apparent diffusion coefficient (wbADC) and percentage of severely injured brain (ADC < 700 ×10−6mm2/sec) were calculated. Continuous EEG interpretation was characterized as malignant or non-malignant. Nonparametric tests were performed to assess the relationship of patient outcome, MRI and EEG patterns. Results Subjects with anatomic evidence of diffuse brain injury were less likely to have malignant EEG patterns. Subjects with malignant EEG patterns, invariably associated with bad outcomes, were observed to have wbADC measures similar to subjects with non-malignant EEG patterns and good outcome and different than subjects with non-malignant EEG patterns and bad outcomes. Regional hippocampal or basal ganglia injury was associated with bad outcome regardless of EEG findings. Conclusions We found discordant evidence of brain injury by MRI and EEG, refuting our initial hypothesis. Malignant EEG patterns were generally more frequent in subjects with less severe brain injury by MRI. These findings suggest a complementary role of MRI and EEG and support the aggressive treatment of malignant EEG patterns in this population.

Topography of MR lesions correlates with standardized EEG pattern in early comatose survivors after cardiac arrest

“…As already mentioned by the authors of this study, one can postulate that this finding is explained by the extensive structural brain damages impeding the generation of detectable epileptiform activity. This also corroborates the conclusions of the study from Mettenburg et al, 15 who reported that EEG patterns defined by the presence of epileptiform activity were associated with less severe brain injury in the MRI.…”

“…Currently, there is no consensus about the way to characterize patterns in diffusion restriction for outcome prognostication after CA. Among different approaches, the whole-brain averaged ADC value, 15,27 the percentage of brain volume below a certain threshold, 10 or the topography of regions with reduced ADC 30 have been used. Since automated methods with voxel-wise ADC measurements are not yet widely available for clinical use, 30 we decided to use an anatomical based classification.…”

“…14 One previous study was explicitly designed to compare MR and EEG findings in comatose patients after CA. 15 Surprisingly, the authors reported that "malignant" EEG patterns were more frequent in patients with less severe MR findings. However, the definition of malignant EEG pattern used for this study was primarily based on the presence of epileptiform activity.…”

Efficacy and safety of perampanel oral loading in postanoxic super‐refractory status epilepticus: A pilot study

“…Notably, a recent study showed that epileptiform EEG patterns do not consistently reflect diffuse cortical injury assessed by cerebral MRI. 23 In the present series, we observed a remarkable efficacy of perampanel oral loading (6-12 mg) in terminating superrefractory NCSE in postanoxic patients within 72 hours of administration. In all cases, perampanel was added to the antiepileptic and anesthetic drug regimen already in use.…”

Combination of Initial Neurologic Examination, Quantitative Brain Imaging and Electroencephalography to Predict Outcome After Cardiac Arrest

“…We have recently demonstrated heterogeneity in MRI findings between those with malignant and non-malignant cEEG patterns. 34 These data suggest that patients with diffuse cerebral edema may lack the neuronal substrate necessary to generate malignant EEG patterns. Severe edema is more likely to result in profound suppression of EEG.…”