Early brain MRIs in a patient with presumed juvenile Alexander disease, obtained at the age of four years

Extensive cerebral white matter abnormalities are seen on these T2-weighted images (B), with sparing of the occipital U fibers (arrows, B). The signal abnormality is more pronounced in the frontal than in the occipital white matter. There is an irregular periventricular rim of low signal intensity (arrowheads, B). The basal ganglia and thalamus have a mildly increased signal intensity. Within the posterior fossa, signal abnormalities are seen in the central part of the medulla, the hilus of the dentate nucleus, and the cerebellar hemispheric white matter, characteristically with the normal dentate nucleus prominently visible in between (A).