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LEARNING OBJECTIVES
Upon completion of the chapter, the reader will be able to:
Describe the pathophysiology of status epilepticus.
Explain the urgency in diagnosis and treatment of status epilepticus.
Recognize the signs and symptoms of status epilepticus.
Identify the treatment goals for a patient with status epilepticus.
Formulate an initial treatment strategy for a patient in generalized convulsive status epilepticus.
Compare the pharmacotherapeutic options for refractory status epilepticus.
Describe adverse drug events associated with the pharmacotherapy of status epilepticus.
Recommend monitoring parameters for a patient in status epilepticus.
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Status epilepticus (SE) is a neurologic emergency that can lead to permanent brain damage or death. SE is defined as continuous seizure activity lasting more than 5 minutes or 2 or more seizures without a complete recovery of consciousness.1 Refractory status epilepticus (RSE) is unresponsive to emergent (first-line) and urgent (second-line) therapy.
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SE can present as nonconvulsive status epilepticus (NCSE) or generalized convulsive status epilepticus (GCSE). NCSE is characterized by persistent impaired consciousness without physical convulsions and is diagnosed with electroencephalography (EEG). GCSE is characterized by full-body motor seizures and involves the entire brain.
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EPIDEMIOLOGY AND ETIOLOGY
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The incidence of SE ranges from 9.9 to 41 per 100,000/year, with a mortality rate of 26%,2 and an estimated annual direct cost for inpatient admissions of $4 billion.3 It occurs most frequently in males, African Americans, children, and the elderly.
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It is important to evaluate etiologies of SE for timely and optimal seizure control. Causes of SE include metabolic disturbances (e.g., hyponatremia, hypernatremia, hyperkalemia, hypocalcemia, hypomagnesemia, hypoglycemia), central nervous system (CNS) disorders, infections, injuries, hypoxia, and drug toxicity (e.g., theophylline, isoniazid, cyclosporine, cocaine).4 Chronic causes of SE include preexisting epilepsy, chronic alcoholism (withdrawal seizures), CNS tumors, and strokes.4 In patients with epilepsy, common causes of SE are anticonvulsant withdrawal or subtherapeutic levels.
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Status epilepticus occurs when the brain fails to stop isolated seizures, due to a mismatch of neurotransmitters. Glutamate, the primary excitatory neurotransmitter, stimulates postsynaptic N-methyl-D-aspartate (NMDA) receptors, causing neuronal depolarization. Sustained depolarization causes neuronal injury and death.5 The primary inhibitory neurotransmitter, γ-aminobutyric acid (GABA), opposes excitation by stimulating GABAA receptors, producing hyperpolarization and inhibition of the postsynaptic cell membrane. GABA-mediated inhibition diminishes with continuous seizure activity, causing a decreased response to GABA-receptor agonists.6 Seizures lasting more than 30 minutes cause significant injury and neuronal loss because of excessive electrical activity and cerebral metabolic demand. Decreased GABAA-receptor response and increasing neuronal injury with prolongation of seizure activity necessitate rapid control of SE.
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Systemic changes appear in two phases during SE. Phase I occurs during the first 30 minutes, and phase II occurs after 30 to 60 minutes.7