Autoimmune encephalitis is the most commonly identified cause of new-onset refractory status epilepticus, but half remain cryptogenic. Outcome at discharge is poor but improves during follow-up. Epilepsy develops in most cases. The role of anesthetics and immune therapies warrants further investigation.
Summary
Purpose
To examine patterns of use, efficacy and safety of intravenous ketamine for the treatment of refractory status epilepticus (RSE).
Methods
Multicenter retrospective review of medical records and EEG reports in ten academic medical centers in North America and Europe, including 58 subjects, representing 60 episodes of RSE were identified between 1999 and 2012. Seven episodes occurred after anoxic brain injury.
Key findings
Permanent control of RSE was achieved in 57% (34/60) of episodes. Ketamine was felt to have contributed to permanent control (“possible” or “likely” responses) in 32% (19/60) including seven (12%) in which ketamine was the last drug added (likely responses). Four of the seven likely responses, but none of the 12 possible ones, occurred in patients with post-anoxic brain injury. No likely responses were observed when infusion rates were lower than 0.9mg/kg/h; when ketamine was introduced at least eight days after SE onset; or after failure of seven or more drugs. Ketamine was discontinued due to possible adverse events in five patients. Complications were mostly attributed to concurrent drugs, especially other anesthetics. Mortality rate was 43% (26/60), but was lower when SE was controlled within 24h of ketamine initiation (16% vs. 56%, p=0.0047).
Significance
Ketamine appears to be a relatively effective and safe drug for the treatment of RSE. This retrospective series provides preliminary data on effective dose and appropriate time of intervention to aid in the design of a prospective trial to further define the role of ketamine in the treatment of RSE.
The investigated CBSDA has a high sensitivity and an acceptable specificity for triggering VNS. Despite the moderate effects on seizure frequency, combined open- and closed-loop VNS may provide valuable improvements in seizure severity and QOL in refractory epilepsy patients.
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