Ultrastructural study of enteric ganglia in three patients with Rett syndrome.

In order to verify whether a pseudo-obstruction syndrome was associated with morphological changes in enteric ganglia, we performed an ultrastructural study on rectal biopsy specimens in three patients with Rett syndrome. Features of enteric neurons, detected to a different extent in all three biopsy specimens, included an abnormal dilatation of endoplasmic reticulum with a disorganization of cisternae of the Golgi apparatus, and masses of unidentified electron-dense granulo-filamentous material, probably of lipidic origin, observed in the perikaryon. Large electron-lucent membrane-bound vacuoles were found mostly within satellite glial cells. Sometimes, the axon terminals were swollen and showed intraxonal vacuolization. We conclude that the reported findings do not represent a specific sign of degeneration and do not constitute a significant morphological marker of disease.

Brain perfusion abnormalities in Rett syndrome: a qualitative and quantitative SPET study with 99Tc(m)-ECD.

Rett syndrome is a progressive neurological paediatric disorder associated with severe mental deficiency, which affects only girls. The aim of this study was to determine if brain blood flow abnormalities detected with 99Tc(m)-ethyl-cysteinate-dimer (99Tc[m]-ECD) single photon emission tomography (SPET) can explain the clinical manifestation and progression of the disease. Qualitative and quantitative global and regional brain blood flow was evaluated in 12 girls with Rett syndrome and compared with an aged-matched reference group of children. In comparison with the reference group, SPET revealed a considerable global reduction in cerebral perfusion in the groups of girls with Rett syndrome. A large statistical difference was noted, which was more evident when comparing the control group with girls with stage IV Rett syndrome than girls with stage III Rett syndrome. The reduction in cerebral perfusion reflects functional disturbance in the brain of children with Rett syndrome. These data confirm that 99Tc(m)-ECD brain SPET is sensitive in detecting hypoperfused areas in girls with Rett syndrome that may be associated with brain atrophy, even when magnetic resonance imaging appears normal.