High Risk for Seizures Following Subarachnoid Hemorrhage Regardless of Referral Bias

Abstract

Background To investigate the frequency, predictors, and clinical impact of electrographic seizures in patients with high clinical or radiologic grade non-traumatic subarachnoid hemorrhage (SAH), independent of referral bias. Methods We compared rates of electrographic seizures and associated clinical variables and outcomes in patients with high clinical or radiologic grade non-traumatic SAH. Rates of electrographic seizure detection before and after institution of a guideline which made continuous EEG monitoring routine in this population were compared. Results Electrographic seizures occurred in 17.6 % of patients monitored expressly because of clinically suspected subclinical seizures. In unselected patients, seizures still occurred in 9.6 % of all cases, and in 8.6 % of cases in which there was no a priori suspicion of seizures. The first seizure detected occurred 5.4 (IQR 2.9–7.3) days after onset of subarachnoid hemorrhage with three of eight patients (37.5 %) having the first recorded seizure more than 48 h following EEG initiation, and 2/8 (25 %) at more than 72 h following EEG initiation. High clinical grade was associated with poor outcome at time of hospital discharge; electrographic seizures were not associated with poor outcome. Conclusions Electrographic seizures occur at a relatively high rate in patients with non-traumatic SAH even after accounting for referral bias. The prolonged time to the first detected seizure in this cohort may reflect dynamic clinical features unique to the SAH population.

Time to electroencephalography is independently associated with outcome in critically ill neonates and children

“…Due to logistical and ethical issues, few data are available regarding the yield of cEEG on patients in the ICU with no clinical suspicion of seizures. In a series of 69 adults with nontraumatic subarachnoid hemorrhage, the first 17 patients underwent cEEG for clinical suspicion of electrographic seizures, but the following 52 patients underwent cEEG as part of a protocol regardless of clinical suspicion . In patients with clinical suspicion, electrographic seizures occurred in 17.7%, whereas in the patients on cEEG per protocol, electrographic seizures occurred in 9.6%; furthermore, among the 35 patients monitored per protocol and without a clinical suspicion for seizures, electrographic seizures occurred in only 8.6% .…”

“…24 In patients with clinical suspicion, electrographic seizures occurred in 17.7%, whereas in the patients on cEEG per protocol, electrographic seizures occurred in 9.6%; furthermore, among the 35 patients monitored per protocol and without a clinical suspicion for seizures, electrographic seizures occurred in only 8.6%. 24 These results suggest that the incidence of seizures is higher in patients in whom cEEG is placed for a clinical suspicion of electrographic seizures. Our sample is not representative of all patients in the ICU, and our results are generalizable to patients who have a clinically indicated cEEG in the ICU.…”

Epileptiform abnormalities predict delayed cerebral ischemia in subarachnoid hemorrhage

“…There is a broad range of seizure rates reported in SAH populations, from 7–19% (Claassen et al 2005; O’Connor et al 2014; Kondziella et al 2015; De Marchis et al 2016). Our rate of 5.6% is slightly lower than previous reports, though in concordance with previously recorded seizure rates using subdural electrodes (Dreier et al 2012).…”

Prophylactic Antiepileptics and Seizure Incidence Following Subarachnoid Hemorrhage

“…Despite this increased seizure incidence, AEDs were not associated with lower risk in this patient subset, a finding corroborated by other reports. 21,22 Sensitivity analyses were also performed to evaluate and control for characteristics that may have increased the likelihood of having EEG monitoring (i.e. interaction effects).…”