Diffuse but Non-homogeneous Brain Atrophy: Identification of Specific Brain Regions and Their Correlation with Clinical Severity in Rett Syndrome

Abstract

Background

Rett syndrome is a genetic neurodevelopmental disorder that predominantly affects girls. While microcephaly is a common feature, there is limited information on the detailed structural changes in the brain. This study aimed to identify regional brain volume abnormalities and explore the correlation between brain volume and clinical characteristics.

Methods

We compared the regional brain volumes of 20 female children with Rett syndrome to those of 25 healthy female children. Additionally, we assessed the correlation between regional brain volume, Clinical Severity Scores, and epilepsy status.

Results

Significantly smaller volumes were observed in all brain regions, including the cerebral cortex, cerebral white matter, subcortical gray matter, cerebellum, and brainstem. Within the cortical regions, volume reduction was prominent in the left precentral, right lateral occipital, left precuneus, left inferior parietal, and right medial orbitofrontal cortices. After correcting for intracranial volumes, volume reduction was more prominent in the cerebral cortices than in the cerebral white matter. Small volumes were consistently observed, regardless of age. Negative correlations were observed between the volumes of multiple regions and the Clinical Severity Scores. There were no correlations among regional brain volume, seizure control, or duration of epilepsy.

Conclusion

The mechanism underlying the cortical-dominant volume reduction remains unclear; however, it may be caused by altered synapse development associated with methyl-CpG-binding protein 2 gene abnormalities. Characteristic impairments in visual recognition and deterioration of motor function in Rett syndrome may be associated with significant volume reduction in specific cortical regions, such as the lateral occipital cortex, precuneus, and precentral gyrus.