Abstracts

Rationale:
To investigate the electroencephalogram (EEG) characteristics of febrile infection-related epilepsy syndrome (FIRES) in children at the acute phase, thus proposing an EEG based early initiation and rapidly escalation of immunotherapy.




Methods:
A retrospective study about 12 children with FIRES was conducted from May 2021 to March 2024.




Results:
All 12 patients (7 males and 5 females) presented with fever at first, with onset age of 3 years and 1 month to 13 years and 8 months (median age 8 years and 9 months), followed by frequent convulsions that rapidly progressed into convulsive status. During the acute phase, we identified the very rigid and unique ictal theta-alpha range regular rhythms repeatedly during the acute and/or subacute phase(Figure 1), which could be recorded from the 7th to the 89th day after the first seizure episode. The locations of the seizure origin showed a multi-focal feature, including the midline area(5 cases), the left frontal area(6 cases), the right frontal area (7 cases), the left central area (7 cases), the right central area (8 cases), the left parietal area(5 cases), the right parietal area(6 cases), the left temporal area(12 cases), the right temporal area(9 cases), the left occipital area(7 cases), the right occipital area(8 cases), The different original regions could be alternate, overlapping or independent with a wandering feature, and localized rarely spread to all leads. The ictal-EEG features above were found in all 12 patients. In addition, other EEG features included the disappearance of background activity and physiological sleep cycles in all children, and the appearance of posterior dominant rhythm（PDR）was clinically matched with a better mental status and fewer seizures. According to the existence of the above-mentioned characteristic ictal EEG, 12 patients were clinically treated with more active immunotherapy to achieve the purpose of clinical improvement. Among them, 2 patients were diagnosed with FIRES early according to the special ictal EEG manifestations at the acute stage, and tocilizumab immunotherapy was carried out on the 7th and 10th days of the course of the disease, respectively. The clinical symptoms of 2 patients including seizures and mental status were significantly improved, and the long-course EEG did not detect obvious seizures on the 21st and 28th days of the course of the disease, and the clinical prognosis was good.




Conclusions:
These findings suggested that ictal theta-alpha range regular rhythms with a multifocal, localized, wandering, alternative or overlapping origins might be a specific EEG biomarker during the acute/subacute stage in FIRES, providing a significant clue for early diagnosis and early intervention and rapidly escalation of immunotherapy in those patients, which could greatly shorten the course of the disease, reduce the duration of ICU and mechanical ventilation, lower the disability rate and mortality rate, and significantly improve the prognosis of FIRES patients.




Funding: The China Association Against Epilepsy Scientific Research Project（CU-2022-018）