Electrographic Seizures after Convulsive Status Epilepticus in Children and Young Adults: A Retrospective Multicenter Study

Abstract

Objectives To describe the prevalence, characteristics and predictors of electrographic seizures following convulsive status epilepticus (CSE). Study design Multicenter retrospective study describing clinical and electroencephalographic (EEG) features of children (1 month-21 years) with CSE who underwent continuous EEG monitoring. Results Ninety-eight children (53 males) with a median age of 5 years with CSE underwent subsequent continuous EEG monitoring after CSE. Electrographic seizures (with or without clinical correlate) were identified in 32 subjects (33%). Eleven subjects (34.4%) had electrographic-only seizures, 17 subjects (53.1%) had electro-clinical seizures, and 4 subjects (12.5%) had an unknown clinical correlate. Of the 32 subjects with electrographic seizures, 15 subjects (46.9%) had electrographic status epilepticus. Factors associated with the occurrence of electrographic seizures after CSE were a prior diagnosis of epilepsy (p= 0.029) and the presence of interictal epileptiform discharges (p< 0.0005). The median (p25–p75) duration of stay in the pediatric intensive care unit was longer for children with electrographic seizures than for children without electrographic seizures [9.5 (3–22.5) versus 2 (2–5) days, Wilcoxon test, Z=3.916, p=0.0001]. Four children (4.1%) died before leaving the hospital and we could not identify a relationship between death and the presence or absence of electrographic seizures. Conclusions Following CSE, one-third of children who underwent EEG monitoring experienced electrographic seizures, and among these, one-third experienced entirely electrographic-only seizures. A prior diagnosis of epilepsy and the presence of interictal epileptiform discharges were risk factors for electrographic seizures.

Development and validation of a seizure prediction model in critically ill children

“…Consortia are already performing initial multi-center studies working toward these goals. 13, 24, 25 Our field will need to determine whether these multi-center data can be applied meaningfully at individual institutions despite inherent inter-institutional variability. These considerations guided our decision to develop the model using multi-center data and validate it using single center data, rather than vice versa.…”

“…13, 24, 25 The 11 sites were large academic medical centers with available pediatric neurology consultation and CEEG. Subjects had undergone clinically indicated CEEG as dictated by practice patterns at each institution and not any study protocol or national guideline.…”

“…First, the data are obtained from patients who have undergone CEEG at single or few institutions, 3, 7-9, 11, 12, 14, 17, 18 so the risk factors identified may not be useful if implemented at a different institution with different patient characteristics or CEEG practice. Although multi-center consortia are starting to study ES epidemiology, 13, 24, 25 multi-center data variability might preclude meaningful application at individual centers. Second, prior studies have not combined the identified risk factors to create clinically useful ES prediction models accounting for multiple risk factors.…”

Ictal propagation of high frequency activity is recapitulated in interictal recordings: Effective connectivity of epileptogenic networks recorded with intracranial EEG

“…Electrographic changes were correlated with clinical seizure semiology based on patient report and review of simultaneously recorded video. Electrographic seizures were defined as rhythmic evolving ictal patterns or low voltage fast activity lasting 10 or more seconds with no accompanying clinical changes (Sanchez Fernandez et al, 2014). Propagation of epileptiform activity was analyzed during ictal, preictal and interictal intervals;

ictal - 60–260 sec, depending on the seizure duration, recorded immediately after seizure onset,

preictal - 60–240 sec, depending on the availability of ECoG recordings, recorded immediately before seizure onset,

interictal (inter-1) - depending on the availability of ECoG recordings (not all interictal segments were saved for review in all patients), 300–500 sec, recorded at least 1 hour before a first seizure, or at least 24 hours before seizure onset and 24 hours after a seizure cessation (visual inspection of ECoG recordings did not revealed any evidence of sleep),

interictal (inter-2) - depending on the availability of ECoG recordings (not all interictal segments were saved for review in all patients), 300–500 sec, recorded at least 1 hour before seizure onset and 1 hour after seizure cessation (visual inspection of ECoG recordings did not revealed any evidence of postictal slowing or sleep).

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Status Epilepticus

“…If EEG is not available, additional empiric therapy may be required if there is a concern for NCSE. NCSE was documented in up to 1/3 of patients who were admitted to an ICU following treatment for an episode of convulsive SE (DeLorenzo et al 1998;Tay et al 2006;Sanchez Fernandez et al 2014b). Other indications for emergent EEG in patients prone to or being treated for SE includes the use of neuromuscular blockade and high-dose suppressive therapy for the treatment of refractory SE (see section on Treatment).…”