Rasmussen's Encephalitis MRI Findings

Rasmussen encephalitis is a chronic, progressive inflammation of the brain of un-known origin. The onset is in childhood and is characterized by an abrupt appearance of focal, persistent motor seizure activity (epilepsia partialis continua), followed by hemiplegia and progressive cognitive deterioration. Early diagnosis and treatment with immunoactive agents or hemispherectomy are sought to prevent the cognitive decline. A hypothesis of the pathogenesis is glutamate receptor autoimmunity associated with persistent viral infection. This receptor activation may trigger seizures in these patients.



CT and MRI Images of All patients display cortical atrophy associated with ipsilateral ventricular enlargement and caudate atrophy, more severe in those with hemiparesis. The most affected areas were insular, temporal and parietal regions. Gray and white matter focal signal intensity abnormalities (hyperintense signal in long TR-weighted images) were found in with hemiparesis.

Histopathologic examination of biopsy material reveals a characteristic triad of findings: perivascular lymphocytic cuffing of round cells, gliosis and microglial nodules. CT and MRI demonstrate progressive destruction of a single cerebral hemisphere. Decreased NAA and elevation of glutamate/glutamine levels on MRS are reported.



MRS performed showed increased lactate and choline and decreased NAA in atrophic regions in a patient with Rasmussen's Encephalitis.