A Spectrum, Not a Dichotomy for Seizure Foretelling—Learning to Identify Ominous Patterns and Understand the Pediatric Ictal-Interictal Continuum

Excerpt

Among the tenets of neurocritical care, few are more commonly enforced than early identification and treatment of seizures. Rhythmic and periodic patterns (RPPs) are electroencephalographic patterns that disrupt the background of cerebral rhythms and are often associated with an increased risk of seizures (in most of these patterns, with the exception of generalized rhythmic delta activity). In fact, these patterns can meet criteria for electrographic seizures if they display evolution or reach the frequency threshold of discharges > 2.5 Hz [1]. However, certain RPPs that appear ictal yet fail to meet said criteria for unequivocal electrographic seizures could still reflect electroclinical seizures (or status epilepticus, depending on their burden); these are termed as patterns lying on the ictal-interictal continuum (IIC) in patients who have consciousness impairment [1]. Recognizing such patterns is crucial in clinical practice because clinicians should consider a therapeutic trial of antiseizure medication; electrographic response coupled with clinical improvement following such trials are diagnostic of electroclinical status epilepticus [2]. Admittedly, the set of criteria laid out by the American Clinical Neurophysiology Society (ACNS) [1] specifying which patterns lie on the IIC is arbitrary, but such designation has served to consolidate definitions for future research and for better understanding of their clinical impact. The majority of what is known about the IIC has been through adult prospective and retrospective cohort investigations, whereas a dearth of data guides the understanding of these RPPs in the pediatric population. …