Abstracts

Rationale: Subarachnoid hemorrhage (SAH) patients are at risk for early and late post-hemorrhage complications, including seizures, rebleeding, and delayed cerebral ischemia.

Delayed cerebral ischemia (DCI) is a common major contributor of major morbidity and mortality. About 30% of SAH patients develop DCI. Previous studies have revealed that factors such as: relative alpha variability, alpha-delta ratio, focal slowing, or late-appearing epileptiform abnormalities (5-8 days post bleed) portend development of DCI. Given this finding, prolonged continuous EEG (cEEG) monitoring is warranted in the SAH population, and particular attention should be made towards those patients with late onset rhythmic and periodic patterns (RPPs). The rationale of this study is to describe the clinical and electrographic characteristics of patients who meet clinical criteria of DCI who were admitted with SAH.

Methods: This was an observational case series with retrospective chart review of patients diagnosed with non-traumatic subarachnoid hemorrhage at Emory Healthcare hospitals from March 2015 to March of 2020. DCI criteria was as follows: a) new focal neurological impairment, or b) ≥2-point decrement of the Glasgow Coma Scale (GCS), persisting ≥1 hour, not attributable to other causes including re-rupture, hydrocephalus or elevated intracranial pressure, procedure-related complications, seizures, or systemic or metabolic abnormalities; or c) infarction on follow-up CT or MRI. The EEG data was obtained from the hospital’s Critical Care EEG database.

Results: Baseline characteristics and etiologies of SAH are outlined in table 1. The incidence of cerebral vasospasm on imaging (CTA/MRA) was 71/104 (68%). A total of 22 (21%) met clinical criteria for DCI. The average cEEG duration was 4.91 days. The average time from hospital admission to start of cEEG monitoring was 3.59 days. The predominating background frequencies were delta: 12 (54.5%), Theta: 7 (31.9%), alpha 3 (13.6%). The background was symmetric in 15/22 (68.18%) and asymmetric: 7/22 (31.81%). The backgrounds were continuous in 11 (50%), nearly continuous 3 (13.6%), discontinuous 5 (22.7%), burst suppressed 3 (13.6%). The presence of sporadic epileptiform discharges was 4/22 (18%). RPPs patterns were present in 17/22 (77.2%) of DCI patients. These were divided as follows: GRDA 5 (29.41%), GPDs 3 (17.6%), LRDA 4 (23.52%), LPDs 3 (17.6%), BIPDs 2 (11.76%). There were 2 patients (9.09%) who had seizures during monitoring.

Conclusions: The incidence of seizures and sporadic epileptiform discharges in our patient population were low, while RPPs were present in the majority of the patients. All of the patients who met criteria for DCI had radiographic evidence of vasospasm on CTA. Our findings show that identification of RPPs are highly associated with the development of DCI. This study adds to the literature on the role of EEG in SAH patients at risk for DCI.

Funding: Please list any funding that was received in support of this abstract.: None.