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The various forms of status epilepticus (SE) represent critical neurologic conditions associated with significant morbidity and mortality rates, requiring prompt diagnosis and rapid seizure control to minimize permanent neuronal injury.
- Recently revised definition of SE asserts that SE is a result of failure of the processes responsible for seizure cessation or from the initiation of mechanisms which lead to abnormally prolonged seizures (T1).
- T1 defines the time point that is considered “prolonged” and is different depending on the type of SE that is present.
- T1 determines the earliest time when treatment should be started.
- For convulsive SE, it is set at 5 minutes; for nonconvulsive SE, it is set at 10 minutes; and for absence SE, it is set at 2 minutes.
- Furthermore, SE is defined as a condition that can have long-term consequences, if not terminated within a set time period (T2), leading to neuronal death, neuronal injury, and/or alteration of neuronal networks.
- T2 defines the time point at which SE should be controlled to prevent long-term consequences.
- For convulsive SE, it is set at 30 minutes; for nonconvulsive SE, it is set at 30 to 60 minutes; and for absence SE, it is unknown.
- SE presents in various forms and revised classification has divided it into the following:
- SE with prominent motor symptoms: encompassing convulsive SE, characterized by excessive abnormal muscle contractions, which may be sustained, or interrupted; generally tonic-clonic in nature
- SE without prominent motor symptoms: encompassing nonconvulsive SE, characterized without prominent motor symptoms, comprising continuous or fluctuating states of mentation without tonic–clonic activity
- Refractory SE: seizure activity persisting despite adequate treatment with initial and secondary pharmacologic treatment
- Overall incidence is 9.9 to 41 cases per 100,000 per year.
- A recent meta-analysis found the pooled incidence rate to be 12.6/100,000 per year.
- Results of trend studies show an increase in incidence of SE in the past few decades in the United States.
- 760,117 hospital discharges with a diagnosis of SE from 1979 to 2010, with SE accounting for 0.07% of all hospital admissions in the United States over this period
- Predominant sex: male > female (annual relative risk 1.1 in males, p < 0.0001)
- Racial differences: blacks (13.7/100,000) > other races (7.4/100,000) > whites (6.9/100,000)
- Bimodal age distribution: greatest number in those <1st decade of life (14.3/100,000) and >60 years (28.4/100,000)
- Other prospective population studies show similar bimodal distribution of SE.
- 125,000 to 195,000 patients per year present with generalized convulsive SE.
- Mortality rates in the United States range from 19% to 22% based on two large prospective population-based studies.
- The overall mortality rates do not show a change in trend over the last few decades.
- Elderly patients experience the highest case fatality rate.
- Cost: Mean hospital cost $18,834 in United States and annual direct costs are projected at $4 billion.
Etiology and Pathophysiology
- Acute symptomatic etiology is the leading etiology-specific cause of SE, with epilepsy history, CNS infection, and CVA being the most common overall.
- Pediatric consideration:
- Infection with fever not involving CNS (52% of cases) was the major etiology of SE and then remote CNS insult (39%) and low anticonvulsant levels (21%).
- Adults consideration:
- Three major etiologies include low anticonvulsant levels (34%), remote symptomatic epilepsy (24%), and CVA (22%).
- Geriatric consideration:
- The most important cause of SE is CVA, followed by acute cardiac, respiratory, or hepatic decompensation, trauma, epilepsy, and dysnatremia.
- Cerebrovascular diseases:
- Ischemic stroke, bleeding (intracerebral, subarachnoid), hematoma (subdural, epidural), sinus venous thrombosis, vascular dementia, tumors
- CNS infections:
- Meningitis, encephalitis, PML, toxoplasmosis, TB, prion disease, fungal disease, HIV-related disease
- Neurodegenerative diseases:
- Alzheimer disease, frontotemporal dementia, etc.
- Head trauma:
- Closed, open, penetrating head injury
- Alcohol (intoxication, withdrawal, Wernicke), drugs, neurotoxins, heavy metals
- Withdrawal or low antiepileptic drugs levels
- Cerebral hypoxia or anoxia
- Metabolic disturbances:
- Electrolyte imbalance, glucose imbalance, organ failure, acidosis, renal failure, hepatic encephalopathy
- Autoimmune disorders:
- Multiple sclerosis (MS), Hashimoto encephalopathy, anti-NMDA encephalopathy, Rasmussen encephalitis, etc.
- Idiopathic, cryptogenic
Risk factors of SE linked to its etiology above; other factor, a previous history of SE (recurrence rate in children, 17%; in those with neurologic abnormality, 50%)
Commonly Associated Conditions
Movement disorders, psychogenic; transient ischemic attack (TIA), CVA, migraines, somatoform disorders, Todd paralysis