The evolution of metabolite changes in an 8-year-old boy with focal Rasmussen encephalitis was studied by MRI and MRS at the Brain Research Institute, University of Melbourne, Australia. Serial structural and metabolite changes during a 9-month period which included an episode of complex partial status epilepticus showed focal swelling and a marked increase in T2-weighted signal intensity in the superior temporal gyrus following status. Follow-up scans showed resolution of the swelling and the development of slight focal atrophy. MRS showed a reduction in N-acetylaspartate, total creatine and trimethylamines after status. These metabolite changes had resolved in subsequent MRS scans. After surgery, metabolite abnormalities confirmed by MRS suggested active disease in the anterior region of the excised superior temporal gyrus. Rasmussen encephalitis is characterized by a progressive encephalitic process that shows fluctuating evidence of neuronal damage and recovery related to seizures. 
COMMENT. Longitudinal studies of MRS metabolites in Rasmussen encephalitis reveal a fluctuating metabolite profile related to seizure activity, indicating the limitations of MRS at a single point in the course of the disease.