New-Onset Refractory Status Epilepticus (NORSE)

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It is possible that the main title of the report New-Onset Refractory Status Epilepticus (NORSE) is not the name you expected.

Disorder Subdivisions

  • None

General Discussion

New-onset refractory status epilepticus (NORSE) is defined as refractory status epilepticus without an obvious cause after initial investigations; "initial" typically refers to 1-2 days, which is adequate time to rule out strokes, brain masses, drug overdoses, and herpes encephalitis. Refractory status epilepticus (SE) is a condition in which patients suddenly experience continuous seizures or a flurry of very frequent seizures (the definition of "SE") that do not respond to standard anticonvulsant medications (the definition of "refractory"). Seizures are thought to be due to an excess of pro-inflammatory molecules in the brain, perhaps triggered by a simple viral infection, although no clear cause has ever been demonstrated. Affected individuals are most often treated for weeks in an intensive care unit because they require prolonged anesthesia with coma-inducing drugs to control their seizures. NORSE carries a high rate of complications and mortality, but a significant proportion of patients do eventually recover. Epilepsy (a life-long predisposition to unprovoked seizures) and cognitive issues are common among survivors although a small minority of them eventually return to a normal lifestyle.

Refractory status epilepticus most commonly complicates an acute brain injury (stroke, trauma, infection, etc.) or a serious medical illness. It may also occur in people with a chronic seizure disorder. In a significant minority of cases, however, refractory SE strikes out of the blue and no cause can be identified. These cases are known as cryptogenic new-onset refractory SE, or NORSE.

NORSE has been reported under different names, including:
•cryptogenic new-onset refractory status epilepticus (cryptogenic NORSE)
•presumed encephalitis with refractory status epilepticus

In addition, several epilepsy syndromes in infants and children share many similarities with NORSE. It is not clear whether they are different age-related manifestations of the same disease or separate entities, but all these syndromes have in common an acute onset, a prolonged course of refractory SE, and inflammatory features in the CSF. These related disorders include:

•febrile illness-related epilepsy syndrome (FIRES; see separate NORD report)
•idiopathic hemiconvulsion-hemiplegia and epilepsy syndrome (IHHES)
•devastating epilepsy in school-aged children (DESC)
•acute encephalitis with refractory, repetitive partial seizures (AERRPS).

Supporting Organizations

American Epilepsy Society

135 South LaSalle Street
Suite 2850
Chicago, IL 60603
Tel: 312-883-3800

CURE: Citizens United for Research in Epilepsy

430 W. Erie
Suite Suite 210
Chicago, IL 60654
Tel: (312)765-7118
Fax: (312)255-1801
Tel: (800)765-7118

Child Neurology Foundation

201 Chicago Ave, #200
Minneapolis, MN 55415
Tel: (952)641-6100
Fax: (952)881-6276
Tel: (877)263-5430

Epilepsy Foundation

8301 Professional Place
Landover, MD 20785-7223
Tel: (866)330-2718
Fax: (877)687-4878
Tel: (800)332-1000

Genetic and Rare Diseases (GARD) Information Center

PO Box 8126
Gaithersburg, MD 20898-8126
Tel: (301)251-4925
Fax: (301)251-4911
Tel: (888)205-2311

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). For a full-text version of this report, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only.

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Last Updated:  4/11/2016
Copyright  2016 National Organization for Rare Disorders, Inc.