Fig 8.

MR images show severe HPE, classified as alobar, with sylvian angle of 135°. First impression of the cerebral cortex is one of pachygyria, but the cortical thickness measures only 3 mm. The cortex appears thick because of the profound microcephaly. This case illustrates some of the difficulties of the DeMyer classification, as the interhemispheric fissure and ventricular systems are much better developed than the basal ganglia and white matter. The basal ganglia, might be considered alobar HPE, but the interhemispheric development suggests mild semilobar HPE.

A, Axial fast spin-echo (4000/90) MR image shows apparently thickened cortex with few gyri and shallow sulci. Thalami are incompletely separated, and no basal ganglia are seen, nor were they seen at other levels.

B, Axial fast spin-echo (4000/90) MR image obtained at a higher level shows an interhemispheric fissure spanning the posterior two-thirds of the cerebrum; the falx cerebri (arrows) is present posteriorly.