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Neurol Neuroimmunol Neuroinflamm. 2017 Sep 25;4(6):e396. doi: 10.1212/NXI.0000000000000396. eCollection 2017 Nov.

Cryptogenic NORSE: Its distinctive clinical features and response to immunotherapy.

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Department of Neurology (T.I., N.K., J.K., N.T., A.Kaneko, D.I., E.K., K.N.), Department of Pediatrics (Y.N.), and Department of Pathology (A.H.), Kitasato University School of Medicine; Department of Clinical Laboratory (Y.O.), Kitasato University Hospital, Sagamihara, Japan; Department of Neurology (H.A., T.H.), Shizuoka City Shimizu Hospital, Shizuoka, Japan; Department of Emergency and Critical Care Medicine (J.K.), Nippon Medical School Tama Nagayama Hospital, Tama, Japan; Department of Neurology (K.Y., Y.S., Y.U.), School of Medicine, Fukushima Medical Hospital and Fukushima Global Medical Science Center (Y.U.), Advanced Clinical Research Center, Fukushima Medical University, Fukushima, Japan; Department of Neurology (M.W., H.T.), Ehime Prefectural Central Hospital, Matsuyama, Japan; and Department of Neurology (A.Kosakai), Keiyu Hospital, Yokohama, Japan.



To report the distinctive clinical features of cryptogenic new-onset refractory status epilepticus (C-NORSE) and the C-NORSE score based on initial clinical assessments.


A retrospective study was conducted for 136 patients with clinically suspected autoimmune encephalitis who underwent testing for autoantibodies to neuronal surface antigens between January 1, 2007, and August 31, 2016. Eleven patients with C-NORSE were identified. Their clinical features were compared with those of 32 patients with anti-NMDA receptor encephalitis (NMDARE).


The clinical outcome of 11 patients (median age, 27 years; 7 [64%] women) with C-NORSE was evaluated after a median follow-up of 11 months (range, 6-111 months). Status epilepticus was frequently preceded by fever (10/11 [91%]). Brain MRIs showed symmetric T2/fluid-attenuated inversion recovery hyperintensities (8/11 [73%]) and brain atrophy (9/11 [82%]). Only 2 of the 10 treated patients responded to the first-line immunotherapy, and 4 of the 5 patients treated with IV cyclophosphamide responded to the therapy. The long-term outcome was poor in 8 patients (73%). Compared with 32 patients with NMDARE (median age, 27 years; 24 [75%] women), those with C-NORSE had more frequent prodromal fever, status epilepticus, ventilatory support, and symmetric brain MRI abnormalities, had less frequent involuntary movements, absent psychobehavioral symptoms, CSF oligoclonal bands, or tumor association, and had a worse outcome. The C-NORSE score was higher in patients with C-NORSE than those with NMDARE.


Patients with C-NORSE have a spectrum of clinical-immunological features different from those with NMDARE. The C-NORSE score may be useful for discrimination between them. Some patients could respond to immunotherapy.

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