Status epilepticus (often simply called status) is a medical emergency where the brain will not stop having seizures.  In medicine, a person who is having status epilepticus is described as being "in status."

What is Status Epilepticus?
Definitions of status epilepticus have changed over time.  It used to be that a seizure had to last 20 or 30 minutes to be thought of as status epilepticus.  (Most normal seizures last only one to two minutes.)

Today, a person is usually described as being "in status" when:
 They have a seizure that lasts more than five minutes; OR
 They have more than one seizure without recovering in between.
 "Recovering" means that the person wakes up and knows who they are; where they are; and what day, month, or year it is.

Why is Status Epilepticus a Medical Emergency? 
Status epilepticus is very dangerous. About 10 - 20 % of the people who go into this status die from it.

Status Epilepticus is considered a medical emergency for many reasons:
 During a long seizure, it is very hard for the body to get oxygen to the brain and the heart.  
 Without enough oxygen, the brain cannot survive.  Not having enough oxygen can cause brain damage and death.
 When the heart does not get enough oxygen, it can start to beat in ways that are not normal.  If the heart goes without enough oxygen for long enough, it can stop beating.   
 Status can cause very high body temperatures (hyperthermia), which can damage the brain.
 Status can cause pulmonary edema - fluid in the lungs - which makes it hard or impossible to breathe.  This makes it even harder for oxygen to get to the brain, heart, and the rest of the body.
 The nerves in the brain can get damaged by the extra electricity in the brain that happens during long seizures.
 
If people in status get the right treatment quickly, they can survive with little or no brain damage.

Causes 
Only about one in four people who go into status epilepticus have epilepsy. The other three out of four people who go into status have never had a seizure before.  Status epilepticus can happen for many other reasons.

Illnesses
Many different illnesses can cause status epilepticus:
 In children, the most common cause of status is an infection with a fever
 Brain infection
 Brain tumor
 Stroke
 Hypoxia (not getting enough oxygen, especially to the brain)
 Gastroenteritis (a special form of diarrhea) while taking anticonvulsants
 Problems with metabolism (the way the body makes energy from food), like problems with the liver or kidneys

Injuries
Very bad injuries can also cause status:
 Injury to the head or brain
 Hemorrhage (very bad bleeding)

Drugs and medications
Illegal drugs, alcohol, and some medications can cause status:
 Illegal drugs
 When a person stops taking certain illegal drugs suddenly
 Bad reactions to some medicines, like some antidepressants
 When a patient does not take enough of certain medicines, or stops taking them suddenly
 Drinking too much alcohol
 When a person who drinks a lot of alcohol suddenly stops drinking (alcohol withdrawal), especially if the person gets delirium tremens from alcohol withdrawal

Other causes
 Exposure to nerve gas

Treatment
People in status epilepticus are unable to end their seizures on their own.  They are often unconscious and unable to react.

The most common way to end status is to inject special medicines that can stop seizures.  If these medicines do not help, the patient must be treated in the intensive care unit at a hospital.  Sometimes patients have to be put into a coma to stop very bad status epilepticus.

References

Medical emergencies