Status epilepticus is a neurological emergency requiring immediate evaluation and management to prevent significant morbidity or mortality. Previously, status epilepticus was defined as a seizure with a duration equal to or greater than 30 minutes, or a series of seizures in which the patient does not regain normal mental status between seizures. The Neurocritical Care Society guidelines from 2012 revised the definition to a seizure with 5 minutes or more of continuous clinical and/or electrographic seizure activity, or recurrent seizure activity without recovery between seizures.
Status epilepticus may be convulsive, non-convulsive, or refractory. Convulsive status epilepticus consists of generalized tonic-clonic movements and mental status impairment. Non-convulsive status epilepticus is defined as seizure activity identified on an electroencephalogram (EEG), with no accompanying tonic-clonic movements. Refractory status epilepticus refers to continuing seizures (convulsive or non-convulsive) despite administration of appropriate anti-epileptic drugs.
Status epilepticus is the most common pediatric neurological emergency.
There are multiple etiologies for status epilepticus. Potential acute processes include:
Chronic processes that may result in status epilepticus include, pre-existing epilepsy with breakthrough seizures or non-use of anti-epileptic drugs, ethanol withdrawal, CNS tumors, and remote CNS pathology (e.g., traumatic brain injury, stroke).
Acute processes account for most cases of status epilepticus in adults. Febrile status epilepticus is the most common cause in pediatric patients. CNS infections and inborn errors of metabolism are also common etiologies in children. The majority of pediatric patients with the first presentation of status epilepticus have no previous history of seizures.
The incidence of status epilepticus has a bimodal age distribution with peaks during infancy and in the elderly. The incidence rate ranges between approximately 7 to 40 cases per 100,000 persons/year. Status epilepticus seems to be more common in males. A significant proportion of both children (16% to 38%) and adults (42% to 50%) with status epilepticus have a history of epilepsy. The short-term mortality (within 30 days) of status epilepticus ranges from 7.6% to 22% across all age groups and is highest amongst the elderly.
A seizure is a paroxysmal electrical discharge of the neurons in the brain resulting in a change of function or behavior. It is important to understand that a seizure is a CNS event and may present as convulsive or non-convulsive. There are both excitatory neurotransmitters (glutamate, aspartate, and acetylcholine) and inhibitory neurotransmitters (gamma-aminobutyric acid) and mechanisms (calcium ion-dependent potassium ion current, and magnesium blockade of N-methyl-d-aspartate (NMDA)) in the brain that play a role in the genesis and inhibition of isolated seizures. Excessive excitation and/or inadequate inhibition results in status epilepticus.
Status epilepticus is defined as a seizure with 5 minutes or more of continuous clinical and/or electrographic seizure activity, or recurrent seizure activity without recovery between seizures. The findings of convulsive status epilepticus include generalized tonic-clonic movements of the extremities and impaired mental status. Temporary focal neurological deficits (e.g., Todd’s paralysis) may be present in the post-ictal period. Non-convulsive status epilepticus presents with impaired mental status, and may or may not have subtle motor signs such as tonic eye deviation. In non-convulsive status epilepticus, seizure activity is seen on the EEG despite the absence or paucity of overt clinical signs.
The diagnosis of convulsive status epilepticus is made clinically but requires emergent neuroimaging and laboratory studies to identify a potential etiology. A head computed tomography (CT) scan is appropriate in most situations and most easily obtained. Magnetic resonance imaging (MRI) of the brain is more sensitive for identifying malformations in pediatric patients, but may be difficult to obtain and may require sedation. Laboratory studies should include bedside blood glucose level, serum electrolytes (sodium, potassium, calcium, and magnesium), BUN, creatinine, serum bicarbonate, a complete blood count, and a lumbar puncture with cerebrospinal fluid (CSF) evaluation. If the patient has a known seizure disorder, anti-epileptic drug levels should be obtained. Suspicion of toxic ingestion mandates toxicology studies (e.g., urine toxicology screen, serum levels of specific toxins such as theophylline or lithium). Other studies may be considered based on the presentation (liver function tests, inborn errors of metabolism, and coagulation studies). A pregnancy test should be obtained in all women of child-bearing years. An EEG should be obtained. Non-convulsive status epilepticus requires all of the previously mentioned imaging and laboratory studies for identification of an underlying etiology, but also requires EEG monitoring for diagnosis.
Status epilepticus must be addressed quickly and in an organized manner, with simultaneous assessment/management of the airway, breathing, and circulation, while also administering antiepileptic drug (AED) treatment. The primary goal of management is to definitively abort seizure activity as rapidly as possible while supporting the patient’s cardiovascular and respiratory status.
All patients with status epilepticus require hospital admission, preferably to the intensive care unit.
There are known risks of congenital disabilities due to exposure to some antiepileptic drugs (phenytoin, valproate sodium, and phenobarbital) during the first trimester of pregnancy. In the setting of status epilepticus, fetal well-being is dependent on immediate, successful management of seizure activity in the mother. Lorazepam is recommended for emergency control treatment if status epilepticus occurs during the first trimester. Levetiracetam should be considered for urgent control therapy in this setting as evidence suggests a lower risk of associated congenital disabilities in comparison to some other antiepileptic drugs (phenytoin, valproate sodium, and phenobarbital). If eclampsia is suspected, intravenous magnesium sulfate is the antiepileptic drug of choice. Delivery of the fetus is the definitive treatment of eclampsia.