Rasmussen's encephalitis in a 6-year-old boy starting with a severe epileptic seizure, a prolonged postictal hemiparesis and an initially normal MRI of the brain

Introduction: Rasmussen's encephalitis (RE) is a rare disease of the brain characterized by (1) intractable focal seizures or epilepsia partialis continua, (2) progressive hemiparesis and (3) progressive atrophy of one cerebral hemisphere. The affected brain tissue shows a chronic inflammatory histopathology and an autoimmune reaction is suspected.

Therapeutic strategies include corticosteroids, IVIg, immunosuppressant drugs and plasmapheresis. Often a functional-hemispherectomy is required to stop the seizures and the neurological deterioration. In a recent study (Bien et al., Neurology, 2004) a therapy with Tacrolimus was successful in all cases.

Case report: A 6-vear-old boy had his first epileptic seizure with prolonged focal motor symptoms and loss of consciousness. It was followed by a flaccid paresis of the left side and complex neuropsychological symptoms with a hemi-neglect-syndrome and changes of consciousness. CT and MRI of the brain including MR angiography were normal 14 hours after onset of the disease. The CSF showed no signs of inflammation initially and after 3 days. The EEG was severely suppressed over the right hemisphere. On day 3 the hemiparesis remained unchanged, but severe focal myoclonic seizures occurred with increasing frequency. The MRI now showed an extended cortical inflammation and massive swelling of the right cortical hemisphere. These findings suggested an RE and therapy was started with high dose prednisolone and phenobarbitone. The seizures stopped after one day but the neurological function improved only incompletely, yet. A beginning atrophy of the right hemisphere was seen on MRI.

Conclusion: In patients with RE the MRI may be completely normal at the time of maximal symptoms and show extended pathological changes only after some days. Early therapy with high doses of steroids was effective in our case to stop the seizures and the progression of neurological symptoms. Early therapy with tacrolimus is another option.