Longitudinal study of MRS metabolites in Rasmussen's encephalitis

Abstract

This study analyses the evolution of metabolite changes in an eight-year-old boy with focal Rasmussen’s encephalitis. Five MR-imaging examinations, including MR 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 structures. Subsequent scans showed resolution of the swelling and signal normalization, with development of slight focal atrophy. MRS showed transient reduction in N-acetylaspartate, total creatine and trimethylamines. Later scans showed complete resolution of these metabolite abnormalities, followed by development of abnormal metabolite values. Lactate and glutamine/glutamate (Glx) were elevated after status. After surgery, ex-vivo high-field 1H and 31P MRS confirmed metabolite abnormalities (elevated choline and decreased aspartate, N-acetylaspartate, glutamate (1H) together with altered phospholipid ratios (31P). This suggested a more active disease process in the anterior region of the excised superior temporal gyrus. We conclude that even Rasmussen's encephalitis is a dynamic and active process of disease progression and seizure effects where neuronal injury and recovery of neuronal impairment can occur.