Abstracts

Rationale: Up to 40% of patients with ischemic stroke may present neurological degradation (ND). ND worsens prognosis and can be due to several causes linked to stroke or its systemic complications. However, the underlying reason is identified in only half of the cases. We postulated that unrecognized nonconvulsive seizures (NCSz) and status epilepticus (NCSE) might explain ND in a substantial proportion of patients with ischemic stroke and aimed to determine their prevalence as well as risk factors.  Methods: We retrospectively identified all continuous EEG (CEEG) performed in patients with ischemic stroke at Hôpital-Erasme, ULB, Brussels between January 2014 and December 2016. We included patients with ND, defined as worsening neurological deficit or worsening alteration of consciousness, as judged by the clinical team. We analysed CEEG for the presence of NCSE, NCSz, periodic discharges (PDs), defined and categorized according to recent definitions and terminology. The acute or chronic use of antibiotics, psychotropic and antiepileptic drugs were recorded. EEG improvement upon treatment was defined as cessation of ictal activity. Biological abnormalities were sought at CEEG onset. Good outcome was assessed at discharge as a modified Rankin Scale (mRS) score inferior to 2 at three months.  Results: Of 1355 CEEG performed during the study period, we identified 81 (6%) in patients with ischemic stroke and ND, which represented 7% (81/1247) of all patients with ischemic stroke admitted to our institution during the study period. Demographic and clinical characteristics are presented in Table 1. Nonconvulsive seizures occurred in 10/81 (12%) patients, of which 4 (5%) fulfilled the criteria for NCSE. Anti-epileptic treatment was given in 8/10 cases and resulted in clinical and EEG improvement in 7/8. Seventeen of 81 (21%) patients had PDs (10 lateralized, 6 generalized and 1 multifocal). Of those, 5 also had NCSz. The use of recanalization therapy was associated with a lower rate of NCSz or PDs (5/22 [23%] vs. 46/59 [73%]; p Conclusions: Nonconvulsive seizures and PDs are frequent (27%) and may contribute to the clinical worsening of patients with ND after ischemic stroke. Lack of reperfusion therapy was associated with a higher rate of seizures and PDs. Our findings suggest that patients with unexplained ND after ischemic stroke should undergo CEEG. Further prospective studies are needed to confirm these findings and assess the potential protective role of antiepileptic drugs in that context.  Funding: No funding.