A group of international experts in the fields of electroencephalography, adult and pediatric epilepsy, and neurocritical care convened to provide a proposed consensus statement on the definitions of new-onset refractory status epilepticus (NORSE), febrile infection-related epilepsy syndrome (FIRES), and infantile hemiconvulsion-hemiplegia and epilepsy (IHHE) syndrome, as reported in Epilepsia.
The primary consensus statement involved standardizing the definition of NORSE. In patients without epilepsy or other preexisting relevant neurologic disorder with NORSE without a clear acute or active toxic, metabolic, or structural cause, NORSE is designated as a clinical presentation rather than a specific diagnosis. Many patients with NORSE have viral infections and autoimmune syndromes, and these diagnoses can often present as NORSE.
Additionally, FIRES is defined as a subcategory of NORSE in the updated consensus. This NORSE subcategory can be applied to patients of any age and excludes the majority of pediatric febrile status epilepticus cases. In the consensus, FIRES requires prior febrile infection that started between 2 weeks and 24 hours before the onset of refractory status epilepticus. Additionally, FIRES can be present with or without fever at onset of status epilepticus.
The newly proposed consensus statement also defines IHHE syndrome, stating this syndrome is specifically demonstrated in patients <2 years old. In addition, IHHE typically presents as NORSE with accompanying high-grade fever, unilateral motor seizures, and unilaterally abnormal acute imaging at refractory status epilepticus onset. Following this, hemiparesis lasting at least 24 hours is a requirement for IHHE diagnosis.
Using these definitions, the investigators hope that clinicians will be able to “answer questions such as why some patients become super-refractory; whether NORSE preceded by a febrile infection (ie, FIRES) is different than other cases of NORSE; whether etiologies and responses to treatments differ by age; if and when early immune treatment is beneficial; and many other questions.”
Hirsch LJ, Gaspard N, van Baalen A, et al. Proposed consensus definitions for new-onset refractory status epilepticus (NORSE), febrile infection-related epilepsy syndrome (FIRES), and related conditions [published online February 5, 2018]. Epilepsia. doi:10.1111/epi.14016