FIRES and IHHE: Delineation of the syndromes


  • Rima Nabbout

    Corresponding author
    1. Inserm, U663, Paris, France
    2. University Paris Descartes; CEA, Gif sur Y vete, France
    • Department of Pediatric Neurology, Referral Center for Rare Epilepsies, Necker Infants Maladies Hospital, APHP, Paris, France
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Address correspondence to Rima Nabbout, Department of Neuropediatrics, Centre de référence épilepsies rares, Hôpital Necker Enfants malades, 149 rue de Sèvres, 75015 Paris, France. E-mail:,


Idiopathic hemiconvulsion hemiplegia and epilepsy syndrome (IHHE) and febrile infection–related epilepsy syndrome (FIRES) are rare epileptic syndromes characterized by the occurrence of status epilepticus in a previously healthy child during or closely after a febrile episode. In both syndromes, there is no evidence of central nervous system infection (encephalitis) and the etiology remains unclear. Treatment is disappointing, particularly in FIRES, except for a response to ketogenic diet (KD) in half of patients. In IHHS, children develop hemispheric brain atrophy with contralateral hemiplegia, epilepsy, and a variable degree of cognitive deficit. Patients with FIRES develop refractory epilepsy with severe cognitive deficit affecting the temporal and frontal lobe functions. The role of inflammation is hypothesized with a vicious circle involving inflammation and seizure activity facilitated by brain maturation putting them under the concept of “acute encephalopathy with inflammation-mediated status epilepticus.”