Status epilepticus is a term describing a state of continuous seizure activity. In the past, 30 minutes of continuing seizure or frequent attacks that prevent recovery was required for the definition of status to be met. However, since most seizures last less than four to five minutes, it is now understood that any seizure that continues five minutes or longer should be potentially considered as status epilepticus, and managed accordingly.
Nearly all types of seizures have the potential of occurring in a continuous or repeated fashion. There are two general categories: generalized status and focal status, depending on the clinical features of the situation. Generalized status can preferentially manifest with tonic, clonic, absence, and/or myoclonic seizures. Hence, status can be merely a prolongation of commonly observed individual seizure types. Non-convulsive status epilepticus can manifest with sustained or repeating complex partial seizures with a change in mental status, or simply as a focal seizure with limited physical signs but without alteration of consciousness. Status can occur in individuals who have epilepsy already. However, in some cases, the first seizure that a person experiences can be status epilepticus.
The epidemiology of status epilepticus varies depending on the study. However, in the United States the incidence is approximately up to 40 per 100,000 individuals. Therefore more than 100,000 cases of status occur annually. Up to 10% of all first-time seizures are situations of status epilepticus. The mortality of status epilepticus is roughly 20%. Those most at risk are the very young or the elderly. The causes of death vary depending on the age of the patient, presence of medical complications, duration of the uncontrollable seizures, and the underlying cause of the status epilepticus.
Causes and symptoms
The exact pathophysiology of why a seizure evolves into status is complex and not fully understood. However, status epilepticus has many causes, some of which are the same as causes of seizures in general. In infants, status can occur in the setting of perinatal hypoxia or anoxia (low oxygen or lack of oxygen) that injures the brain. Also, illness such as meningitis that can cause seizures can also be severe enough to cause status epilepticus. Metabolic disorders of infancy and childhood that can be causes of epilepsy can also produce status epilepticus. In adults, infections of the brain, strokes, brain tumors, and severe head trauma can cause seizures and hence status epilepticus.
Clinically, status epilepticus is basically a prolonged seizure situation. Individual seizures occurring frequently enough to impair full recovery to baseline function can be a manifestation of status epilepticus as well. A limited seizure such as an arm jerking without alteration of consciousness is called a simple or focal seizure. If it occurs continuously, the term epilepsy partialis continua is used. This is the least serious of the different types of status epilepticus. The more dangerous type is, of course, generalized tonic/clonic status. This is because cardiac arrhythmias or blood pressure changes can be life threatening. Also, breathing and oxygenation can be compromised, and patients may require ventilator assistance. Complex partial seizures and absence seizures are manifested with an alteration of consciousness. When these particular seizures become status, patients may simply appear confused or agitated. Since they are not having convulsions, they may be misdiagnosed as having a psychiatric symptom. Nevertheless, prompt and accurate diagnosis is important for proper management.
When convulsions are occurring, status is typically easily recognized. However, subtle status, as in complex partial or absence status, may necessitate an electroencephalogram (EEG) for diagnosis. The EEG is not only used for initial diagnosis, but is often left running for longer periods to monitor response to treatment. The recognition of seizure activity is only one of the urgent tasks in the care of the patient. The other major issue is to rapidly identify the cause of seizures and the status epilepticus. This involves testing blood for at least glucose, electrolytes, liver function, and illicit substances. Very low blood glucose or extreme changes in sodium, for example, can cause seizures. Infections such as meningitis can cause status. Rapidly assessed levels of older, commonly used seizure medications such as phenytoin, Phenobarbital , carbamazepine , and valproic acid are sometimes sought in cases where there is no available history from the patient. Indeed, one of the most frequent causes of status is low anticonvulsant levels in a patient with a history of epilepsy.
Patients in status epilepticus will often necessitate a neurologist to guide the management from the emergency department through the rest of the hospital stay. Social workers are important for discharge plans because many patients who survive status epilepticus may need skilled nursing or rehabilitation to fully recover prior to being discharged home.
The treatment of status depends on identifying quickly the underlying cause, if any. In cases of hypoglycemia, thiamine must be administered just prior to glucose supplementation. This is because some individuals, alcoholics for example, may be deficient in thiamine and a correction of glucose levels without thiamine supplementation can cause a condition known as Wernicke's encephalopathy . Sodium must be corrected slowly or a condition called central pontine myelinolysis can occur. A computed tomography (CT ) scan of the brain is often ordered to evaluate for any brain trauma. A lumbar puncture may be performed to determine if there is meningitis so appropriate antibiotics can be used. Overall, in cases that an identifiable cause of status can be found, the key to successful treatment is the management of the underlying cause itself. There are published guidelines for the treatment of seizures themselves. Initially, a sedative such as lorazepam or diazepam is given, which can stop many seizures at least temporarily while a longer-acting anticonvulsant such as phenytoin takes effect. If seizures persist, then the addition of Phenobarbital is typically added. Since this particular medication, when fully loaded, causes respiratory depression , an anesthesiologist is consulted to manage ventilator assistance. Status epilepticus is managed and treated in an intensive care unit with EEG monitoring to continually assess the response to seizure medications. When Phenobarbital fails to stop the ongoing seizures, a number of other medications are considered, such as a midazolam drip or propofol. Anesthetic dosages of these particular medications are usually effective in suppressing seizure activity. Approximately every 24 hours, the dosage is reduced to determine if seizures recur or not. The severity of status can vary widely. Sometimes, it is effectively treated within one to two hours and other times the status is severe and extremely resistant to treatment and lasts for weeks. In such cases, the mortality rate is significant because of risk of medical complications such as pneumonia and blood clots.
Recovery and rehabilitation
The recovery from status epilepticus will depend on its duration. If status can be effectively stopped in a relatively short period of time, complete neurological recovery is possible. The longer the seizures persist, the greater the chance of cerebral injury. Also, the longer the status epilepticus, the more difficult it is to stop. A complication of status epilepticus can actually be the development of epilepsy in a percentage of cases.
The prognosis with status epilepticus will depend on the duration of status and co-existing medical problems. The prognosis is good for recovery if status can be stopped in a relatively short period of time (hours) and there are no complications such as infection, active cardiac problems, or other active medical issues. However, prognosis for complete recovery is less favorable as status persists for long periods of time. Co-existing medical problems will complicate management and chance for a negative outcome.
It is important to be on the lookout for subtle status situations that may go unrecognized. An EEG is a relatively easy way to rule in or rule out presence of active seizures. It is crucial to respond urgently to status epilepticus because the longer the seizures continue the more difficult they are to stop.
Browne, T. R., and G. L. Holmes. Handbook of Epilepsy, 2nd edition. Philadelphia: Lippinocott Williams & Wilkins, 2000.
Engel, Jr., J., and T. A. Pedley. Epilepsy: A Comprehensive Textbook. Philadelphia: Lippincott-Raven, 1998.
Hauser, W. A., and D. Hesdorffer. Epilepsy: Frequency, Causes, and Consequences. New York: Demos Publications, 1990.
Wyllie, E. The Treatment of Epilepsy: Principles and Practice, 3rd edition. Philadelphia: Lippincott Williams & Wilkins. 2001.
Epilepsy Foundation of America's Working Group on Status Epilepticus. "Treatment of Convulsive Status Epilepticus: Recommendations of the JAMA." Journal of the American Medical Association 270 (1993): 854–859.
Hesdorffer, D. C., G. Logroscino, G. Cascino, J. F. Annegers, and W. A. Hauser. "Risk of Unprovoked Seizure after Acute Symptomatic Seizure: Effect of Status Epilepticus." Annals of Neurology 44 (1998): 908–912.
American Epilepsy Society. 342 North Main Street, West Hartford, CT 06117-2507. (860) 586-7505. <http://www.aesnet.org>.
Epilepsy Foundation of America. 4351 Garden City Drive, Landover, MD 20785-7223. (800) 332-1000. <http://www.epilepsyfoundation.org>.
Roy Sucholeiki, MD