Continuous EEG monitoring and midazolam infusion for refractory nonconvulsive status epilepticus.

BACKGROUND

Although cIV-MDZ has emerged as a popular alternative to barbiturate therapy for refractory status epilepticus (RSE), experience with its use for this indication is limited.

OBJECTIVE

- To evaluate the efficacy of continuous intravenous midazolam (cIV-MDZ) for attaining sustained seizure control in patients with RSE.

METHODS

The authors reviewed 33 episodes of RSE treated with cIV-MDZ in their neurologic intensive care unit over 6 years. All patients were monitored with continuous EEG (cEEG). MDZ infusion rates were titrated to eliminate clinical and EEG seizure activity; cIV-MDZ was discontinued once patients were seizure-free for 24 hours. Acute treatment failures (seizures 1 to 6 hours after starting cIV-MDZ), breakthrough seizures (after 6 hours of therapy), post-treatment seizures (within 48 hours of discontinuing therapy), and ultimate treatment failure (frequent seizures that led to treatment with pentobarbital or propofol) were identified.

RESULTS

All patients were in nonconvulsive SE at the time cIV-MDZ was started; the mean duration of SE before treatment was 3.9 days (range 0 to 17 days). In addition to benzodiazepines, 94% of patients had received at least two antiepileptic drugs (AED) before starting cIV-MDZ. The mean loading dose was 0.19 mg/kg, the mean maximal infusion rate was 0.22 mg/kg/h, and the mean duration of cIV-MDZ therapy was 4.2 days (range 1 to 14 days). Acute treatment failure occurred in 18% (6/33) of episodes, breakthrough seizures in 56% (18/32), post-treatment seizures in 68% (19/28), and ultimate treatment failure in 18% (6/33). Breakthrough seizures were clinically subtle or purely electrographic in 89% (16/18) of cases and were associated with an increased risk of developing post-treatment seizures (p = 0.01).

CONCLUSIONS

Although most patients with RSE initially responded to cIV-MDZ, over half developed subsequent breakthrough seizures, which were predictive of post-treatment seizures and were often detectable only with cEEG. Titrating cIV-MDZ to burst suppression, more aggressive treatment with concurrent AED, or a longer period of initial treatment may reduce the high proportion of patients with RSE who relapse after cIV-MDZ is discontinued.