Status epilepticus is a critical neurological emergency demanding immediate attention to mitigate the risk of significant complications or death. Traditionally, it was defined as a seizure lasting 30 minutes or more, or a series of seizures where the individual doesn’t regain their normal mental state between episodes. However, the Neurocritical Care Society updated this definition in 2012. Now, it’s defined as continuous seizure activity lasting 5 minutes or longer, identified clinically or through electrographic readings, or recurrent seizures without recovery in between.
This article delves into the evaluation and management of status epilepticus, emphasizing the importance of collaborative efforts from the healthcare team for optimal patient care.
Defining Status Epilepticus: A Neurological Emergency
Status epilepticus presents in various forms, including convulsive, non-convulsive, focal motor, and myoclonic, with the potential for any type to become refractory. Convulsive status epilepticus is characterized by generalized tonic-clonic movements coupled with impaired mental status. Non-convulsive status epilepticus involves seizure activity detected via electroencephalogram (EEG) without the prominent motor symptoms seen in convulsive seizures. Focal motor status epilepticus manifests as persistent motor activity in a limb or muscle group on one side of the body, potentially accompanied by a loss of consciousness. Myoclonic status epilepticus is another variant. Refractory status epilepticus describes persistent seizures, whether convulsive or non-convulsive, despite the administration of appropriate anti-epileptic drugs.
Alt text: Electroencephalogram (EEG) readout demonstrating characteristic seizure patterns indicative of non-convulsive status epilepticus.
Status epilepticus is a common pediatric neurological emergency.
What Causes Status Epilepticus? Exploring the Etiology
Status epilepticus arises from various causes. Acute triggers include:
- Central nervous system (CNS) infections like meningitis, encephalitis, and intracranial abscesses.
- Metabolic imbalances such as hypoglycemia, hyponatremia, hypocalcemia, hepatic encephalopathy, and inherited metabolic disorders in children.
- Cerebrovascular events (strokes).
- Head trauma, potentially with intracranial bleeding.
- Drug-related toxicity.
- Withdrawal syndromes from substances like alcohol, benzodiazepines, and barbiturates.
- Hypoxia.
- Hypertensive crises.
- Autoimmune conditions.
Chronic factors contributing to status epilepticus encompass pre-existing epilepsy with breakthrough seizures, non-adherence to anti-epileptic medications, alcohol withdrawal, CNS tumors, and prior CNS damage, such as traumatic brain injury or stroke.
In adults, acute causes are more common. Febrile seizures are the primary cause in children. CNS infections and inborn metabolic errors are also frequent etiologies in pediatric cases. Notably, many children experiencing status epilepticus have no prior history of seizures.
Understanding the Epidemiology of Status Epilepticus
Status epilepticus exhibits a bimodal age distribution, with peaks occurring in infancy and older adulthood. The incidence ranges from approximately 7 to 40 cases per 100,000 people annually. It appears to be more prevalent in males. A significant proportion of both children (16% to 38%) and adults (42% to 50%) with status epilepticus have a pre-existing history of epilepsy. The short-term mortality rate (within 30 days) ranges from 7.6% to 22% across all age groups, with the highest rates observed in the elderly.
Pathophysiology: The Mechanisms Behind Status Epilepticus
A seizure is defined as a sudden, uncontrolled electrical disturbance in the brain that can cause changes in your behavior, movements, feelings, and levels of consciousness. Seizures are CNS events that can be convulsive or non-convulsive. Neurotransmitters like glutamate, aspartate, and acetylcholine promote excitation, while gamma-aminobutyric acid (GABA) promotes inhibition. Mechanisms involving calcium and magnesium also play a role in regulating seizures. Status epilepticus results from excessive excitation and/or inadequate inhibition in the brain.
Alt text: Illustration depicting the disrupted balance between excitatory (e.g., glutamate) and inhibitory (e.g., GABA) neurotransmitters, contributing to the pathogenesis of epilepsy.
Status epilepticus can be classified based on several factors:
- Semiology (the clinical manifestations of the seizure)
- Etiology (the underlying cause)
- EEG correlates (the specific patterns observed on electroencephalography)
- Age of the patient
Recognizing Status Epilepticus: History and Physical Examination
Status epilepticus is defined as a seizure lasting five minutes or longer, or recurrent seizures without a return to baseline between seizures. Convulsive status epilepticus involves generalized tonic-clonic movements and impaired consciousness. Patients may experience temporary focal neurological deficits, such as Todd’s paralysis, after the seizure. Non-convulsive status epilepticus manifests as altered mental status, possibly with subtle motor signs like tonic eye deviation. EEG is essential for diagnosis, revealing seizure activity even without obvious clinical signs.
Diagnosing Status Epilepticus: Evaluation and Testing
The diagnosis of convulsive status epilepticus relies on clinical observation, but it requires immediate neuroimaging and lab tests to identify the underlying cause. A head CT scan is commonly used and readily accessible. Brain MRI is more sensitive for detecting abnormalities in children but may require sedation and is more difficult to obtain.
Essential laboratory tests include bedside blood glucose, serum electrolytes (sodium, potassium, calcium, magnesium), BUN, creatinine, serum bicarbonate, complete blood count, and lumbar puncture with CSF analysis. In patients with known seizure disorders, anti-epileptic drug levels should be measured. Toxicology screenings are necessary if toxic ingestion is suspected. Additional tests may be considered based on the patient’s presentation (liver function tests, metabolic workup, coagulation studies). A pregnancy test is crucial for women of childbearing age. EEG monitoring is essential. Non-convulsive status epilepticus requires the same imaging and lab studies, along with EEG, for diagnosis.
Treatment Strategies for Status Epilepticus
Status epilepticus demands rapid and organized management, involving simultaneous assessment and support of airway, breathing, and circulation, along with the administration of antiepileptic medications. The primary goal is to stop seizure activity as quickly as possible while maintaining cardiovascular and respiratory function.
- Position the head to ensure an open airway, and prepare for rapid sequence intubation if needed.
- Administer supplemental oxygen.
- Monitor heart rate, respiratory rate, blood pressure, and oxygen saturation continuously.
- Establish vascular access.
- Check bedside blood glucose and treat hypoglycemia if present. Administer thiamine before dextrose if thiamine deficiency is suspected.
- Benzodiazepines are the first-line treatment for acute seizure control. Lorazepam is preferred due to its rapid onset, administered intravenously at 0.1 mg/kg. If lorazepam is unavailable, diazepam can be used. A repeat dose may be given if seizures persist. If intravenous access is not possible, benzodiazepines can be administered intramuscularly, rectally, nasally, or buccally.
- Antiepileptic drugs should be given concurrently with benzodiazepines, including fosphenytoin, phenytoin, levetiracetam, and valproic acid.
- If seizures continue after a second dose of benzodiazepines, the condition is classified as refractory status epilepticus.
- Refractory status epilepticus requires continuous infusion of an antiepileptic drug such as midazolam, pentobarbital, thiopental, or propofol.
- Magnesium sulfate is indicated for pregnant women with eclampsia.
- A neurologist should be consulted early in the management process.
All patients with status epilepticus require hospital admission, ideally to the intensive care unit.
Differential Diagnosis: Ruling Out Other Conditions
The differential diagnosis of status epilepticus includes:
- Acute intoxication
- Early catastrophic brain hypoxia
- Encephalopathy of toxic and metabolic origin
- Ischemic stroke
- Non-epileptic seizures
- Trauma
Prognosis: What to Expect After Status Epilepticus
The mortality rate for patients experiencing their first episode of generalized convulsive status epilepticus ranges from 16% to 20%. Mortality depends on the cause of status epilepticus, with anoxic status epilepticus carrying a mortality rate of up to 80%. Refractory status epilepticus has mortality rates between 35% and 60%. Some studies suggest that permanent neurological damage can occur after 30 minutes of status epilepticus. About 40% of patients with a first episode of status epilepticus develop subsequent epilepsy, and there is a 25% to 30% risk of recurrent status epilepticus.
Complications of Status Epilepticus
Complications can be categorized as medical or neurological, and as immediate or delayed.
Medical complications include cardiac arrhythmia, cardiac damage, respiratory failure, hypoventilation, hypoxia, aspiration pneumonia, pulmonary edema, fever, and leukocytosis.
Neurological complications include the development of chronic epilepsy and recurrent status epilepticus. Prolonged refractory status epilepticus can cause permanent neurological damage.
Consultations: Who to Involve
- Neurology
- Neurocritical care
Key Considerations and Additional Information
Certain antiepileptic drugs (phenytoin, valproate sodium, and phenobarbital) carry risks of congenital disabilities during the first trimester of pregnancy. In status epilepticus, the well-being of the fetus depends on the successful and timely management of seizures in the mother. Lorazepam is the recommended first-line treatment during the first trimester. Levetiracetam is an alternative option with a potentially lower risk of congenital disabilities. Intravenous magnesium sulfate is the preferred drug for eclampsia. Delivery of the fetus is the definitive treatment for eclampsia.
Enhancing Healthcare Team Outcomes
Effective management of status epilepticus requires a collaborative interprofessional team, including emergency and neurology nurses. Pharmacists ensure medication availability. Clinicians should avoid unnecessary imaging or lab work during active seizures. Rapid and organized assessment and management of airway, breathing, and circulation, along with prompt administration of antiepileptic drugs, are crucial. Once the patient is stable, further investigations can be initiated.
