Abstract
Purpose: We report a case of febrile infection-related epilepsy syndrome (FIRES) with a lesion in the splenium of the corpus callosum, and explore the pathophysiology by conducting a literature review.
Case Report: A 10-year-old Japanese boy developed repetitive seizures after five days of febrile illness. MRI at admission revealed a splenial lesion with reduced diffusivity and low apparent diffusion coefficient. Apneic seizures with ocular gaze, facial twitching, with/without focal or bilateral tonic posturing necessitated high dose phenobarbital therapy under artificial ventilation for seven days. The splenial lesion disappeared on the follow-up MRI on day 3, but bilateral hippocampal lesions emerged on day 10. The seizures were mitigated by potassium bromide. At onset of encephalopathy, the platelet count and C-reactive protein (CRP) level were low.
Methods: Data from 21 individuals with FIRES and 32 individuals with mild encephalopathy/encephalitis with reversible splenial lesion (MERS) were collected from online bibliographic databases. Onset age, prodromal period, blood cell counts, CRP, electrolytes, and liver enzymes were compared between these two groups.
Results: Onset age, prodromal period, and liver enzymes were significantly higher and platelet count and CRP were lower in the FIRES group than in the MERS group.
Discussion: In our case, the initial MRI findings resembled those of MERS, but the subsequent clinical course and seizure semiology, as well as blood test results were consistent with a diagnosis of FIRES. A splenial lesion in FIRES may be associated with the relatively attenuated seizure activity during the acute phase in this and another reported case, which needs further corroborations.
