Longitudinal study of MRS metabolites in

This study analyses the evolution of metabolite changes in an 8-year-old boy with focal Rasmussen encephalitis. Five MRI examinations, including magnetic resonance spectroscopy (MRS) were performed over 9 months. Following complex partial status, T2-weighted imaging showed transient dramatic signal increase in the left superior temporal gyrus and mesial temporal struc-tures. Subsequent scans showed resolution of the swell-ing and signal normalization, with development of slight focal atrophy. MRS after status showed a reduction in N-acetylaspartate, total creatine and trimethylamines. Subsequent scans showed complete resolution of these metabolite abnormalities, followed later by development of further abnormal metabolite values. Lactate and glutamine/glutamate were elevated after status. After surgery, ex vivo high-®eld 1H and 31P MRS con®rmed metabolite abnormalities (elevated choline and decreased aspartate, N-acetylaspartate, [1H]glutamate together with altered [31P]phospholipid ratios. These ®ndings suggested active disease process in the anterior region of the excised superior temporal gyrus. We conclude that Rasmussen encephalitis is a combination of progressive encephalitic damage and ¯uctuating seizure effects, in which neuronal injury and recovery can occur. MRS measurements at a single time point should consider the ¯uctuating metabolite pro®le related to seizure activity