NORSE: 5 Important Facts


Although rare, new onset refractory status epilepticus can be life threatening if not identified quickly.



I’m Dr. Andrew Wilner, and welcome to Neurology Times update. Today I’ll review a recent article in the journal Neurology, Neuroimmunology, and Neuroinflammation, which discussed the etiologies and treatment of NORSE-New Onset Refractory Status Epilepticus.


NORSE is defined as new onset refractory status epilepticus in a previously healthy patient without an obvious cause. NORSE is rare, but life-threatening. Other names for this syndrome include “devastating epileptic encephalopathy in school-age children” (DESC), “febrile infection-related epilepsy syndrome” (FIRES), and acute encephalitis with refractory repetitive partial seizures” (AERRPS).


I still remember the case of an 11-year-old previously healthy girl that I treated in the ICU for new onset status epilepticus. This was decades ago, and NORSE had yet to be named. It was incredibly frustrating as the standard treatments for status epilepticus failed, and we had no clue why.


Etiologies of NORSE include autoantibody, paraneoplastic, and viral, while some remain cryptogenic. Cryptogenic cases tend to have a worse outcome. Investigation of a patient with NORSE should include autoantibody testing, CSF examination, and a malignancy survey. In one study, the most common etiology of immune-mediated NORSE was anti-NMDA receptor encephalitis (NMDARE).

Neuroimaging Abnormalities

Persistent status epilepticus may result in MRI abnormalities including symmetric increased diffusion weighted images (DWI) or T2/fluid attenuated inversion recovery (FLAIR) signals in the amygdala, basal ganglia, claustrum, hippocampus, insula, perisylvian operculum and thalamus. These abnormalities may resolve over time, but brain atrophy may also occur.


Treatment for patients with NORSE includes traditional anticonvulsant therapy for status epilepticus. In addition, many patients receive immunotherapy, such as IV methylprednisolone, IV immunoglobulin, plasma exchange or cyclophosphamide.

Cases related to autoantibodies should generally receive immunogenic therapy. Some patients with cryptogenic NORSE may also respond, possibly because of undetectable autoantibodies. Because the results of autoantibody testing may take weeks, it is often unclear which patients should be immediately treated with immune modulators.

Summary: NORSE: 5 Important Facts

1. NORSE is a syndrome of new onset refractory status epilepticus in a previously healthy person.

2. Etiologies of NORSE include autoantibody, paraneoplastic, viral, and cryptogenic causes.

3. Anti-NMDA receptor encephalitis is a common autoimmune cause of NORSE.

4. Transient bilateral symmetric MRI abnormalities may occur that are likely related to prolonged seizure activity. Brain atrophy may result.

5. Immune therapy may be appropriate, and even some patients with cryptogenic NORSE may respond.


Although rare, it is important to rapidly identify cases of NORSE as they are life-threatening and may respond to traditional antiepileptic and immunogenic therapy.

Thank you for watching today’s Neurology Times update. I’m Dr. Andrew Wilner, reporting for Neurology Times.


Dr Wilner is Associate Professor of Neurology at the University of Tennessee Health Science Center and a staff physician at Regional One Health in Memphis, TN. Dr. Wilner's latest book, Bullets and Brains, is a collection of over 100 essays that focus on the intersection of neurology and society. Twitter: @drwilner.


1. Iizuka T, Kanazawa N, Kaneko J et al. Cryptogenic NORSE. Its distinctive clinical features and response to immunotherapy. Neurol Neuroimmunol Neuroinflamm. 2017;4:e396;doi:10.1212/NXI.0000000000000396.

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