Herniation to foramen magnum in the course of cerebellitis in a 4-year-old boy, as shown by CT and MRI : case report

Background: Acute cerebellitis is an uncommon but dangerous complication of infectious diseases. Besides neurological examination, neuroimaging (especially MR imaging) is very useful for diagnosing cerebellitis. Case Report: A 4-year-old boy was admitted to the hospital with a 1-week history of fever, vomiting and headache. His past medical history was unremarkable. The physical examination revealed disturbance of consciousness and truncal ataxia. He underwent urgent CT and MRI examinations which demonstrated isolated swelling of the cerebellar hemispheres and the vermis, with increased signal intensity in T2-weighted, FLAIR, and DWI sequence and a significant mass effect associated with tonsillar herniation. An emergent life-saving suboccipital craniectomy was performed with removal of the C1 vertebral arch. There was a gradual clinical improvement, and a follow-up brain MRI revealed disappearance of cerebellar swelling and of mass effect. Conclusions: Magnetic resonance (MR), including diffusion-weighted imaging (DWI) sequence, plays an important role in the diagnostic work-up of cerebellitis in children. This imaging method is very useful for detecting cerebellitis, evaluating its severity and monitoring the disease.