Abstracts

Rationale: Status epilepticus (SE) is associated with chronic neurological dysfunction and high mortality rate. Refractory SE (RSE) is defined as SE that does not respond to first- and second-line antiepileptic drugs. Super-refractory (SRSE) is defined as SE that persists for >= 24 hours after administration of anesthesia or recurs after its withdrawal. In cases of SE treated with intravenous (IV) ketamine IV, long-term EEG recording reveals changes in background activity as well as epileptiform activity and anesthetic patterns. We aimed to determine the ketamine effect on EEG background and epileptiform abnormalities and their association with outcome in patients affected by SE. Methods: We reviewed 20 critical-care EEG (cEEG) performed on patients with RSE or SRSE who received ketamine infusion as part of treatment from 2014 to 2019. We collected patient demographic information as well as etiology, EEG patterns before and after ketamine infusion, and patient outcomes.  Results: Twenty patients with SE had an average age of 49.5 years (range 31-72) and five were women. Ten patients had focal SE, six had myoclonic SE after cardiac arrest, and four patients had non-convulsive status epilepticus (NCSE). All patients were refractory to standard treatment and anesthetic medications. Twelve patients (60%) showed improvement in the background with the appearance of theta/non-dominant alpha frequencies in the first 30 minutes to 3 hours after starting IV Ketamine therapy. These waveforms progressed with the appearance of low-voltage beta frequencies that persisted in the first 24 hours. There was a gradual reduction in seizure frequency in those with focal SE or NCSE or reduction in the amount, duration, and amplitudes of generalized epileptiform discharges in those with myoclonic SE.  Ketamine infusion lasted 2-3 days. Recurrence of SE occurred in 2 of 12 patients within 2-3 days after stopping the ketamine therapy. Eight patients who did not show changes in background activity also did not show any reduction in seizure activity or generalized epileptiform discharges after ketamine infusion. These patients also had no response to any other subsequent treatments after ketamine infusion and had poor clinical outcome. Conclusions: Ketamine infusions in SE yields characteristic background activity. These changes seen within the first 24 hours after infusion were associated with significantly higher chance of aborting SE with IV ketamine, even in RSE or SRSE. These EEG changes can serve as a possible marker for predicting successful treatment outcome in refractory and super-refractory SE as well as guiding treatment strategies. Further, multi-center clinical trials may be warranted to determine ketamine's role in the treatment of SE. Funding: No funding