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KEY CONCEPTS
Status epilepticus (SE) is a neurologic emergency that may be associated with significant morbidity and mortality.
Generalized convulsive status epilepticus (GCSE) is defined as any recurrent or continuous seizure activity lasting longer than 30 minutes in which the patient does not regain baseline mental status. Any seizure that does not stop within 5 minutes should be aggressively treated as impending SE.
There are two types of SE, GCSE and nonconvulsive status epilepticus (NCSE). GCSE is the most common type and can be divided into four stages: (1) impending, (2) established, (3) refractory, and (4) super-refractory.
Although the pathophysiology of GCSE is unknown, experimental models have shown that there is a dramatic decrease in γ-aminobutyric acid (GABA)–mediated inhibitory synaptic transmission and that glutamatergic excitatory synaptic transmission sustains the seizures.
During prolonged GCSE, GABAA receptors move from the synaptic membrane into the cytoplasm where they become functionally inactive. A loss of these receptors on the synaptic surface may result in time-dependent pharmacoresistance to benzodiazepines. The number and activities of glutamatergic N-methyl-D-aspartate (NMDA) receptors also increase, suggesting a role for ketamine.
The main purpose of treatment is to prevent or decrease morbidity and mortality of prolonged seizures. Pharmacologic treatment needs to be rapid and aimed at terminating both electrical and clinical seizures. The probability of poorer outcomes increases with an increased length of electroclinical seizure activity.
Although IM midazolam, IV lorazepam, IV diazepam, and phenobarbital effectively terminate seizures lasting at least 5 minutes, IV lorazepam is the preferred benzodiazepine for initial treatment of GCSE because of its efficacy and long duration of action in the central nervous system (CNS). In patients without an established IV site, midazolam is the preferred benzodiazepine for intramuscular and intranasal administration.
Although practice is slowly moving to other anticonvulsants, the hydantoins (ie, phenytoin, fosphenytoin) continue to be the long-acting anticonvulsants used most frequently. Insufficient data exist regarding the comparative efficacy of these two anticonvulsants; however, fosphenytoin is better tolerated and hence preferred. Either should be given concurrently with benzodiazepines.
The second anticonvulsant administered is less effective than the first “standard” anticonvulsant in both adults and pediatric patients. The third anticonvulsant may be significantly less effective.
If GCSE is not controlled by two anticonvulsants (a benzodiazepine and a standard antiepileptic drug), it is considered to be refractory. In these cases, anesthetic doses of midazolam, pentobarbital, or propofol may be used and assessed with continuous EEG monitoring.
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Patient Care Process for Status Epilepticus
Collect (some items may be deferred to a later time due to time constraints associated with a medical emergency)
Patient characteristics (eg, age, weight)
Time of seizure onset and duration of seizure activity (see Table 74-2)
Past medical history (eg, known epilepsy and type or prior seizure, drug-allergies) (see Table 74-1)
Social history (eg, ethanol use, illicit drug use, ketogenic diet)
Complete a medication history of current prescription, over-the-counter (OTC) medications, herbals ...