Serial MRI and MRS studies with unusual findings in Rasmussen's encephalitis

Rasmussen's syndrome is characterized by intractable seizures and progressi ve neuropsychiatric deterioration secondary to unilateral cortical inflamma tion and tissue destruction. Diagnosis of Rasmussen's syndrome in the early phase depends mainly on the clinical features. Neuroimaging and histopatho logic examinations may not be specific during this period. We report a case of Rasmussen's syndrome followed by serial MRI and magnetic resonance spec troscopy (MRS) studies over a 3- to 16-month period. A healthy 6-year-old b oy presented with focal motor seizures. An MRI study demonstrated prominent enlargement and T2 hyperintensity of the left mesial temporal lobe and per isylvian region. This early finding evolved to volume loss and later progre ssive atrophy of the ipsilateral hemisphere when epilepsia partialis contin ua occurred. Being aware of those early MRI features in a patient with incr easing frequency of focal motor seizures should suggest Rasmussen's syndrom e. In addition, we found prominently increased myoinositol concentration in atrophic cortex which might reflect increased gliosis in the late period o f the disease.