Efficacy and Safety of Ketamine in Refractory/Super-refractory Nonconvulsive Status Epilepticus: Single-Center Experience

Refractory/super-refractory nonconvulsive status epilepticus (r/srNCSE) is an acute life-threatening neurocritical entity with significant morbidity. Failure to control SE in its earlier stages leads to multiple molecular alterations in the brain such as downregulation of GABA-A and upregulation of NMDA receptors. Recently ketamine, an NMDA receptor antagonist, has gained increased attention as a therapeutic choice in controlling refractory/super-refractory SE. We aimed to analyze the efficacy and safety profile of ketamine in our center. We retrospectively identified all the patients with nonconvulsive SE who received ketamine during their follow-up in our neurological intensive care unit between 2009 and 2019. Information about demographic, clinical, and laboratory findings; concurrent antiseizure and anesthetic medications; time of initiation, dose and duration of ketamine infusion; any adverse effects and finally prognosis were collected. The effect of day of ketamine initiation and duration of infusion on ketamine efficacy were analyzed statistically. Seven patients (4 males, 3 females; age: 44-86 years) were included in the study. Encephalitis was the most common etiology. Concurrent antiseizure medications varied between 2 and 5. Six patients received midazolam before/during ketamine infusion. Ketamine was initiated 2 to 7 days after the onset of EEG monitoring and lasted 3 to 24 days with a maximum infusion dose ranging between 1 to 5 mg/kg/h. It was definitely effective in 4 patients, and possibly effective in an additional patient. Earlier initiation was correlated with higher efficacy (P = .047). There was a trend toward higher efficacy with longer duration of infusion (P = .285). Overall prognosis was poor with 29% mortality rate. Temporary hepatic failure occurred in 1 patient. Ketamine appears to be a promising drug in r/srNCSE. Earlier and prolonged infusion, as well as combination with benzodiazepines may increase its efficacy. Adverse events are rarely observed.