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Background: Acute encephalopathy during childhood represents a highly heterogeneous group of infectious and non-infectious pathologies. According to a recent nationwide survey on acute childhood encephalopathy in Japan, the combination of clinical and radiographic features left approximately half of the affected children unclassified, mainly because of the lack of disease-specific biomarkers.

Case: Herein, we document a school-aged boy who manifested with acute encephalopathy that was characterized by a prolonged fever, altered mental status, urinary retention, and intention tremor lasting for more than a month. Accompanying features included syndrome of inappropriate secretion of antidiuretic hormone, pleocytosis with elevated interleukin-6 and interferon-gamma levels in the cerebrospinal fluid, and a transient splenial lesion on neuroimaging. No pathogens were identified, and C-reactive protein was negative throughout his clinical course. This constellation of clinical features was not compatible with any of the existing entities of acute pediatric encephalopathy.

Discussion: Our retrospective literature review identified two additional school-aged male patients who exhibited highly similar clinical courses. The prolonged altered mental status with pleocytosis in the cerebrospinal fluid and a transient splenial lesion in the absence of serum inflammatory markers suggest a primary central nervous system pathology.

Conclusion: This combination of features defines this presumably new group of acute childhood febrile encephalopathy with prolonged fever and ataxia in school-aged boys.


ataxia cytokine splenium of the corpus callosum febrile encephalopathy urinary retention hyponatremia pleocytosis

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Okada, R., Sakaguchi, Y., Matsushige, T., Kamimaki, I., Takenouchi, T., & Takahashi, T. (2019). Acute childhood encephalopathy with prolonged fever, pleocytosis and elevated inflammatory cytokines in the cerebrospinal fluid and transient splenial lesion. Journal of the International Child Neurology Association, 1(1).


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