Permanent loss of independence in adult febrile-infection-related epilepsy syndrome survivors: an underestimated and unsolved challenge

Long-term outcomes of adult cryptogenic febrile infection-related epilepsy syndrome (FIRES)

Background

Cryptogenic febrile infection-related epilepsy syndrome (FIRES) is a rare but catastrophic encephalopathic condition. We aimed to investigate the long-term outcome in adult cryptogenic FIRES.

Methods

This was a retrospective study based on the prospective database in the neuro-intensive care unit of a tertiary hospital in China. Consecutive adult patients with cryptogenic FIRES between July 2007 to December 2021 were included. Long-term outcomes included function independence, the development of drug-resistant epilepsy (DRE), remote recurrent status epilepticus (SE), anti-seizure medications (ASMs), and changes in the brain Magnetic Resonance Imaging (MRI).

Results

A total of 11 adult patients with cryptogenic FIRES were identified from 270 patients with SE. Four (36%) patients died in the hospital, with three of them withdrawing treatments, and one patient died 12 months after discharge. After the follow-up ranging from 12 to 112 months, 6 (55%) patients were still alive, and all of them achieved functional independence [modified Rankin Scale (mRS) 0-3]. 45% (5/11) patients developed DRE, 18% (2/11) had remote recurrent SE, and 55% (6/11) were on polytherapy with ASMs at the last follow-up. Most of the patients with initial normal or abnormal MRI had abnormalities in the hippocampus at follow-up, and most of the other MRI abnormalities found in the acute stage disappeared over time.

Conclusion

The outcome of adult cryptogenic FIRES is daunting. More than one-third of patients die in the hospital. Survivors of cryptogenic FIRES may regain functional independence, but they usually develop DRE and receive polytherapy of ASMs for a long time.

Functional outcomes of patients with NORSE and FIRES treated with immunotherapy: A systematic review

OBJECTIVE

To determine the frequency of good functional outcomes in patients with NORSE and FIRES treated with immunotherapy.

METHODS

We performed a systematic search of the MedLine and EMBASE databases to gather studies including at least 5 patients with NORSE or FIRES and at least one patient treated with immunotherapy, and reporting functional outcomes. Good functional outcome was defined as a modified Rankin Scale (mRS) score ≤ 2 (or an equivalent measure) at the last available follow-up assessment. Only patients with known functional outcomes were included in the analysis.

RESULTS

We analyzed 16 studies including a total of 161 patients with NORSE. Six studies were carried out only with FIRES patients (n = 64). Of the 161 patients with NORSE, 141 (87.5%) received immunotherapy. Outcome data were available for 135, 56 of whom (41.4%) achieved good functional outcomes. Twenty-four of the 58 patients with FIRES treated with immunotherapy and for whom outcome data were available achieved good functional outcomes (41.3%). Mortality rates in patients with NORSE and FIRES treated with immunotherapy were 20/121 (16.5%) and 6/58 (10.3%), respectively. By type of immunotherapy, good functional outcomes were achieved in 36/89 patients receiving glucocorticoids (40.4%), 27/71 patients receiving IV immunoglobulins (38%), 11/37 patients treated with plasma exchange (29.7%), 5/17 patients receiving rituximab (29.4%), and 2/13 patients receiving cyclophosphamide (15.3%).

CONCLUSION

Despite the lack of randomised clinical trials, immunotherapy is frequently prescribed to patients with NORSE and FIRES. However, rates of functional dependence and mortality remain high in these patients. Second-line therapies achieved lower rates of good outcomes, probably because they were administered to patients with more severe, refractory disease.