Abstracts

Rationale:
Acute brain injury (ABI) is an important cause of acquired epilepsy, but specific clinical and electroencephalographic characteristics predicting increased risk of epilepsy in this population remain unclear. With the increasing use of continuous electroencephalography (cEEG) monitoring in ABI patients, the utility of EEG in predicting later development of epilepsy has become an area of interest. Therefore, we aimed to explore the association between acute cEEG findings and subsequent development of epilepsy in patients with ABI.
Method:
This was a retrospective study of patients admitted to a tertiary care center from January 1, 2017 to December 31, 2018. We included patients who had 1) ABI on presentation defined as ischemic or hemorrhagic stroke, traumatic brain injury (TBI), posterior reversible encephalopathy syndrome (PRES), or encephalitis, 2) cEEG ≥ 6 hours during the index admission, and 3) ≥ 12 months of follow-up. Exclusion criteria were 1) history of epilepsy, 2) prior remote brain injury or other brain lesion, with new-onset clinical or electrographic seizures at the time of presentation meeting criteria for epilepsy, and 3) anoxic brain injury during index admission. EEG variables included the presence of electrographic or electroclinical seizures and the presence of interictal epileptiform activity (EA), which included lateralized periodic discharges (LPDs), lateralized rhythmic delta activity (LRDA), generalized periodic discharges (GPDs), and sporadic interictal epileptiform discharges (sIEDs). We compared patients with and without EA on cEEG and the primary outcome was development of epilepsy, defined as the occurrence of spontaneous clinical seizures following hospital discharge.
Results:
The study included 101 ABI patients (37.6% women) with a median (IQR) age of 56 (46-65). Median (IQR) time to cEEG was 2 (1-5) days. Thirty-one (30.7%) patients had EA on cEEG. There was no statistically significant difference in age, sex, etiology of ABI, mental status, and time to cEEG between patients with EA and those without EA. Patients with EA were more likely to develop acute seizures (19.4% vs. 4.3%, p=0.023), and were more likely to be discharged on anti-seizure drugs (74.2% vs. 32.9%, p=0.001). During a median (IQR) follow-up of 19.1 (16.2-24.3) months, 25.7% of patients developed epilepsy. The proportion of patients who developed epilepsy was significantly higher in patients with EA compared to patients without EA (41.9% vs. 18.6%, p=0.025). On multivariable Cox regression analysis, after adjusting for baseline variables, the risk of new-onset epilepsy following ABI was significantly higher in patients with EA compared to those without EA (hazard ratio [HR] 3.4; 95% CI 1.4-8.3; p=0.007).
Conclusion:
In patients with ABI, EA on cEEG is associated with >3-fold increased risk of developing new-onset epilepsy during follow-up. EEG performed early during the course of ABI may be a useful prognostic tool for assessing the risk of development of epilepsy.
Funding:
:None