Abstracts

Rationale: Nonconvulsive seizures (NCS) are common in critically ill adult patients with acute neurologic conditions. However, the effect of NCS on patient outcomes remains unclear. In this study, we aimed to determine the effect of NCS on patients' short-term outcome, and to assess the clinical and EEG characteristics associated with NCS.  Methods: We retrospectively identified 219 adult patients from the EEG reporting system who underwent continuous EEG monitoring (cEEG) between January and June 2018. Patients with anoxic brain injury were excluded from the study. The effects of NCS on in-hospital mortality, length of hospital stay and disability on discharge (defined as a modified Rankin scale of 4 or more) were studied. Results: Of the 219 patients included in our study, a total of 14% (n=31) had NCS on cEEG, of which 42% had their first NCS recorded during the first hour of cEEG monitoring. The presence of clinical seizures prior to cEEG (OR=1.787; 95% CI=1.197-2.667), history of epilepsy (OR=1.508; 95% CI=1.027-2.215) and comatose state (29% vs. 16%; p=0.0006) were associated with NCS. Among EEG characteristics, the presence of interictal epileptiform discharges (p<0.0001), lateralized periodic discharges (p<0.0001) and lateralized rhythmic delta activity (p=0.02) were associated with NCS. NCS was significantly associated with longer in-hospital stay (23.68 +- 24.84 vs.17.14 +- 20.52; p=0.036) . However, there was no significant association between NCS and in-hospital mortality (9.6% [n=3] vs. 10.6% [n=20]; p=0.1) or worse disability on discharge (63% [n=19] vs. 47% [n=90]; p=0.29).  Conclusions: NCS is associated with the longer in-hospital stay but not with in-hospital mortality or worse disability on discharge in adult patients. Funding: No funding