Levetiracetam, Lacosamide and Ketamine as Adjunctive Treatment of Refractory Status Epilepticus

40 18-70 year old men and women with refractory status epilepticus, defined as status epilepticus continuing for \>1 hour after completion of standard treatment with lorazepam (or midazolam) and i.v. phenytoin (or fos-phenytoin),will be enrolled. Participants will be randomized into four treatment arms, levetiracetam 4000 (Group A, n=10), lacosamide 600 mg (Group B, n=10), ketamine 2.5 mg/kg (group C,n=10),and phenobarbital 15 mg/kg (Group D, n=10) in a 1:1:1:1 ratio. Baseline evaluations will include continuous EEG, phenytoin levels prior to study intervention, CBC, CMP, serum Ca, Po4 and Mg. Treatment will consist of levetiracetam 4000 mg i.v. over 10 minutes, lacosamide 600 mg i.v. over 10 minutes, ketamine 2.5 mg/kg over 10 minutes, or phenobarbital 15 mg/kg mg i.v. at 100 mg/minute rate. Participants will be evaluated with ongoing physical examination and continuous EEG monitoring. Continuous EEG monitoring will be started before initiation of the study treatment, with documentation of electrographic status epilepticus. It will continue throughout the treatment period. Subjects will be observed for 1 hour clinically and with continuous EEG monitoring for cessation of SE. Participants in whom status epilepticus stops within 60 minutes of completion of study treatment will continue to receive phenytoin (150 mg i.v. q 12 hours, standard dose) and the study medication (levetiracetam 1500 mg i.v. q 12 hourly, lacosamide 300 mg q 12 hourly, ketamine 50 mg qid (vs. 40 mcg/kg/min i.v. infusion, as clinically applicable, or phenobarbital 90 mg i.v. q 12 hourly). Continuous EEG monitoring will continue for 72 hours to monitor for relapse of status epilepticus. Participants in whom status epilepticus fails to stop within 60 minutes after completion of study treatment ("non-responders") will undergo standard treatment with medically-induced coma, with intubation/ventilation and i.v. midazolam or propofol treatment at a dose to be titrated to EEG effect of "burst suppression" or suppression of all background activity. All patients, responders and non-responders alike, will continue treatment with phenytoin i.v., 150 mg q 12 hourly or, for conscious patients, 300 mg p.o. qhs for 72 hours after completion of study treatment. In patients requiring medical coma after study treatments (non-responders), medical coma will be discontinued after 48 hours. All participants will continue to be monitored with continuous EEG for 72 hours from completion of study treatment. If status epilepticus returns during this time, medical coma will be re-instituted and patients will be treated according to standard clinical care for prolonged SE