New-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES): State of the art and perspectives

Febrile infection-related epilepsy syndrome (FIRES) is a devastating epilepsy affecting normal children after a febrile illness. FIRES presents with an acute phase with super-refractory status epilepticus and all patients progress to a chronic phase with persistent refractory epilepsy. The typical outcome is severe encephalopathy or death. The authors present 7 children from 5 centers with FIRES who had not responded to antiepileptic drugs or other therapies who were given cannabadiol (Epidiolex, GW Pharma) on emergency or expanded investigational protocols in either the acute or chronic phase of illness. After starting cannabidiol, 6 of 7 patients' seizures improved in frequency and duration. One patient died due to multiorgan failure secondary to isoflourane. An average of 4 antiepileptic drugs were weaned. Currently 5 subjects are ambulatory, 1 walks with assistance, and 4 are verbal. While this is an open-label case series, the authors add cannabidiol as a possible treatment for FIRES.

Fever-induced refractory epileptic encephalopathy in school-aged children (FIRES), and idiopathic hemiconvulsion-hemiplegia syndrome (IHHS) are both triggered by fever, although evidence for a causal microorganism or an autoimmune phenomenon is lacking. FIRES begins in school age with status epilepticus lasting several weeks, involves perisylvian areas including mesial temporal structures, and is followed by pharmacoresistant epilepsy with major cognitive deterioration. IHHS begins in infancy with unilateral clonic status epilepticus and is followed by hemiplegia with pharmacoresistant epilepsy. The aetiology of FIRES and IHHS remains unknown, although clinical features and experimental models point to a likely vicious cycle involving inflammation and seizure activity that depends on the stage of brain maturation. We therefore propose to group these conditions under the concept of acute encephalopathy with inflammation-mediated status epilepticus. In addition to preliminary but encouraging clinical observations, there are theoretical reasons to consider the ketogenic diet as an early means to control both seizures and inflammation.

New-onset refractory status epilepticus (NORSE) is defined as a state of persistent seizures with no identifiable etiology in patients without preexisting epilepsy that lasts longer than 24h despite optimal therapy. Management of NORSE is challenging, and the role of immunotherapy (IT) is unclear. We identified patients fulfilling the criteria for NORSE at a single institution. These patients were described, analyzed, and compared with NORSE cases available from the literature. Finally, a pooled analysis of available case series was conducted to compare the outcomes in patients who received IT with those not treated with IT during the course of NORSE in order to generate hypotheses for further research. In our case series, NORSE was diagnosed in 11 patients (9 females) with a mean age of 48 years and a mean duration of 54.4 days. Autoantibodies were identified in 7 patients, of which anti-GAD (glutamic acid decarboxylase) and anti-NMDAR (N-methyl-D-aspartate receptor) were most frequent. Of the 11 patients, 8 were treated with IT (intravenous steroids, immunoglobulins, plasmapheresis, or a combination), and 4 received chemotherapy. Of the 8 patients treated with IT, 6 had favorable outcomes (defined as any outcome other than death, vegetative state, or inability to take care of oneself) compared with 0 out of 3 patients who did not receive IT. Difference in outcomes was significant (p=0.026). Pooled analysis of all identified case series, including ours, showed a statistically significant effect (p=0.022), with favorable outcomes in 42% of the patients who received any IT compared with 20% in those who did not. In all patients with refractory SE and negative comprehensive investigations, a diagnosis of NORSE should be considered. This would aid planning for early immunotherapy. Currently, only Class IV evidence for the use of immunotherapy in NORSE is available. Prospective multicenter studies are necessary to assess the true efficacy of IT in NORSE.