Clinical Correlates of Periodic Discharges and Nonconvulsive Seizures in Posterior Reversible Encephalopathy Syndrome (PRES)
The pathophysiological mechanisms of Posterior Reversible Encephalopathy Syndrome (PRES) and related seizures remain poorly understood. The prevalence and clinical significance of nonconvulsive seizures (NCSz) and related epileptiform patterns during continuous electroencephalography monitoring (CEEG) in PRES have not been well described.
To report the prevalence, characteristics and risk factors for NCSz and related highly epileptiform patterns in patients with PRES, and to determine their relation to imaging abnormalities and outcome.
Design, Setting and Participants
From a prospective CEEG database, we retrospectively identified patients with PRES and reviewed their medical charts. Based on CEEG findings, we designed a retrospective cohort study comparing two groups defined based on the presence or the absence of NCSz and/or periodic discharges (PDs).
Main outcomes and Measures
The prevalence and risk factors for PDs and NCSz, description of EEG and magnetic resonance imaging (MRI) abnormalities and functional outcome as measured by the Glasgow Outcome Scale (GOS) at hospital discharge.
Among 37 eligible patients, 23 (62%) had PDs or NCSz. The presence of NCSz was associated with the presence of PDs (15/22 vs. 1/15; p = 0.0002). NCSz and PDs were usually either lateralized or bilateral independent and predominated in the posterior regions. No clinical features were associated with the occurrence of PDs or NCSz. Cortical restricted diffusion on MRI was more frequent in the PDs/NCSz group (17/23 vs. 1/14; p < 0.001). PDs/NCSz were associated with worse outcome, with 3 deaths vs. 0 in the no PDs/NCSz group and fewer cases with low disability (4 vs. 9 cases with GOS = 5, p < 0.04).
Conclusions and Relevance
Our results reveal a high prevalence of NCSz and PDs in critically ill patients with PRES and an association with restricted diffusion and worse outcome, whether treating or preventing these EEG findings can improve outcome requires further research.
KeywordsPosterior reversible encephalopathy syndrome Nonconvulsive seizures Status epilepticus Periodic discharges Ictal-interictal continuum Continuous EEG monitoring Cytotoxic edema Magnetic resonance imaging
LB, BL, NR, EJG, LJH, NG: acquisition of data, analysis and interpretation of data; drafting the article or revising it critically for important intellectual content; and final approval of the version to be published.
Source of Support
Compliance with Ethical Standards
Conflict of interest
LB, BL, NR, and EJG have nothing to disclose. LJH has received research support from Yale University for investigator-initiated studies from Eisai and Upsher-Smith; consultation fees for advising from Ceribell, Eisai, Monteris, Neuropace, Sun Pharma, and Engage Therapeutics; royalties for authoring chapters for UpToDate-Neurology, chapters for Medlink—Neurology, and from Wiley for co-authoring the book “Atlas of EEG in Critical Care,” by Hirsch and Brenner; and honoraria for speaking from Neuropace. He spends about 25% of his clinical billable time implementing and interpreting critical care EEG studies. NG is a postdoctorate Clinical Master Specialist of the Fonds pour la Recherche Scientifique and has received research funding from le Fonds Erasme pour la Recherche Médical; royalties for authoring chapters for UpToDate-Neurology, and for authoring articles for Continuum (Neurology); and honoraria for speaking from UCB.
Ethical approval and informed consent
The study was approved by the institutional review boards of Hospital Erasme and of Yale University.
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