Rett syndrome: H-1 spectroscopic imaging at 4.1 Tesla

Rett syndrome, a neurodevelopmental disorder predominantly affecting girls, is characterized by regression of psychomotor development, communication d ysfunction, and hand stereotypies. Brain morphologic studies demonstrate in creased neuronal packing density and reduced dendritic arborizations, sugge sting an arrest or interruption of normal maturation. Numerous neurotransmi tter systems have been implicated. Among these, cerebrospinal fluid glutama te levels are elevated and glutamate receptors, particularly in putamen, ar e reduced. Therefore, H-1 spectroscopy at 4.1 Tesla was used to evaluate gl utamate, creatine, and N-acetylaspartate in six girls with Rett syndrome an d four normal sibling controls. The ratio of creatine to N-acetylaspartate was significantly elevated in white matter, primarily reflecting reduced N- acetylaspartate levels, and normal in gray matter. The glutamate to N-acety laspartate ratio was elevated in gray matter and normal in white matter. Th ese findings are consistent with previous neuropathologic and neurochemical findings and indicate the feasibility of imaging these metabolites in vivo .