Status Epilepticus and the Use of Continuous EEG Monitoring in the Intensive Care Unit

Abstract

Status epilepticus (SE) is one of the major neurologic emergencies. Newer data about the genesis and treatment of this condition are available to help improve our understanding and management. Approximately 150,000 cases of generalized convulsive SE occur in the United States each year. Clinically apparent seizures complicate about 8% of intensive care unit admissions, and another 10% of ICU patients suffer electrographic seizures in the course of another critical illness. Some of these cases result from previously under-recognized epileptogenic effects of commonly used drugs, such as cefepime. Continuous EEG (cEEG) recording is necessary for both diagnosis and management in these patients, especially since anticonvulsant drugs may abolish motor activity without stopping seizures. Recent studies have underscored the utility of benzodiazepines as the first-line agents for SE termination. The recently published Rapid Anticonvulsant Medication Prior to Arrival Trial (RAMPART) demonstrates that the more rapidly treatment is administered, the more effective it will be. When SE fails to respond to usual doses of benzodiazepines, it should be considered refractory to conventional anticonvulsants, and a general anesthetic approach is likely to be necessary. While definitions have varied, patients should be managed for SE after 5 minutes of seizure activity. Management of a patient with SE involves three phases: termination of SE, prevention of recurrence, and treatment of complications. The typical anticonvulsants have limited ability to terminate SE; lorazepam is the most useful, controlling SE in 65% of patients experiencing generalized convulsive SE. If the first conventional anticonvulsant fails, others are unlikely to be useful, and one of the newer anticonvulsants or a general anesthetic agent should be considered. EEG is crucial in the diagnosis and classification of potential seizures. cEEG monitoring helps to guide anticonvulsant therapy in patients with SE and those with frequent seizures. In addition, cEEG has the potential for presymptomatic diagnosis of delayed neurologic deterioration in patients with subarachnoid hemorrhage and for the differential diagnosis of stroke subtypes, especially when cEEG is subjected to signal processing.