Yamada K et al. (2006) Brain developmental abnormalities in Prader-Willi syndrome detected by diffusion tensor imaging. Pediatrics 118: e442–e448

Prader–Willi syndrome (PWS) is a complex neuroendocrine disorder, present from birth. Affected individuals are typically overweight, of short stature with low muscle tone, emotionally unstable, and have very mild to moderate learning disabilities. The demonstration in a quantitative analysis of brain development that patients with PWS have developmental abnormalities in specific areas of the brain provides a new insight into the pathophysiology of the syndrome.

The researchers use diffusion tensor imaging, based on high-field MRI, to examine the brains of eight patients with PWS and eight controls matched for age and gender. Higher trace value and reduced fractional anisotropy, both of which indicate deviation from regular development, were found in several specific brain regions in patients with PWS. Compared with controls, patients had a significantly higher trace value in the left frontal white matter and left dorsomedial thalamus (areas associated with psychiatric dysfunction; P <0.05). Additionally, patients had significantly reduced fractional anisotropy in the posterior limb of the internal capusle bilaterally (a region associated with motor dysfunction and perhaps connected to the 'central hypotonia' seen in Prader–Willi syndrome), and in the right frontal white matter and the splenium of the corpus callosum (areas relating to cognitive, visual, and spatial–perceptional function; P <0.05 for all). The affected regions identified in this study, therefore, correlate highly with the clinical features of PWS.