Febrile Infection-Related Epilepsy Syndrome

Febrile infection-related epilepsy syndrome (FIRES) is an epilepsy syndrome in which new-onset refractory status epilepticus (NORSE) is preceded by febrile illness 24 hours to 2 weeks prior to the onset of seizures. The term was previously used for a paediatric syndrome but was redefined to include all ages.

FIRES was previously to refer to this syndrome in children aged three to fifteen years old. A healthy child that may have been ill in the last few days or with a lingering fever goes into a state of continuous seizures. The seizures are resistant to seizure medications and treatments, though barbiturates may be administered. Medical diagnostic tests may initially return no clear diagnosis and may not detect any obvious swelling on the brain. The syndrome is very rare: it may only affect 1 in 1,000,000 children.

Signs and symptoms

FIRES starts with a febrile illness up to two weeks before seizure onset. These seizures damage the frontal lobe's cognitive brain function such as memory and sensory abilities. This can result in learning disabilities, behavioral disorders, memory issues, sensory changes, and possibly death. Children continue to have seizures throughout their lives.

EEG Findings

EEG findings suggest FIRES is a focal process with focal onset seizures. In a 2011 study of 77 FIRES patients, 58 had focal seizures. Of the 58, 50 had secondarily generalizing seizures (seizures that evolve from focal to generalized). On a 10-20 scalp electrode EEG, the ictal activity commonly begins temporally and spreads hemispherically and/or bilaterally. Interictally, patients may have slowing that may be considered an encephalopathic pattern. A recent study of 12 FIRES patients demonstrated diffuse delta-theta background slowing interictally in all 12 cases.

Cause

The cause of FIRES is not known. There are some common clinical symptoms, such as onset after a nonspecific febrile illness, gastrointestinal illness, or upper respiratory infection. This prior illness is often cleared 1–14 days prior to the patient's first seizures. There are theories of an immunological source, a genetic predisposition, and an inflammation-mediated process, but the definite cause is unknown. It is more common in boys more than girls.

Diagnosis

FIRES is difficult to diagnose due to its rarity and lack of definitive biomarker. It is often diagnosed by ruling out other options such as infectious, toxic, metabolic, and genetic causes. FIRES will consist of two phases - acute and chronic. The acute phase consists of highly recurrent focal seizures, rapidly evolving into refractory status epilepticus. The chronic phase consists of drug-resistant epilepsy with cognitive impairment.

Treatment

• Ketogenic diet is effective in some cases, with efficacy ranging from 16% to over 85%
• Vagus nerve stimulation helps control seizure activity after recovery from status.
• Intravenous immunoglobulin treatment is being explored as an option to treat this form of epilepsy.
• Barbiturates have been shown to be effective in treating status epilepsy.

History

FIRES was named in 2008 by Dr. Andreas van Baalen and colleagues. Previous names include AERRPS (acute encephalitis with refractory, repetitive partial seizures), DESC (Devastating Epilepsy in School-aged Children), and NORSE (New-Onset Refractory Status Epilepticus).