Progressive atrophy of the cerebrum in 2 Japanese sisters with microcephaly with simplified gyri and enlarged extraaxial space.

This is a case report that describes 2 sisters with microcephaly, simplified gyri, and enlarged extraaxial space. Clinical features of the cases include dysmorphic features, congenital microcephaly, failure of postnatal brain growth, neonatal onset of seizures, quadriplegia, and severe psychomotor delay. Neuroradiological imaging demonstrated hypoplasia of bilateral cerebral hemispheres with enlarged extraaxial spaces, simplified gyral patterns without a thickened cortex, hypoplastic corpus callosum, and enlarged lateral ventricles, with a reduction in gray and white matter volume during the prenatal and neonatal periods. Repeat MRI revealed progressive atrophy of the cerebral gray and white matter, with enlarged lateral ventricles, although the sizes of the bilateral basal ganglia, thalamus, and infratentorial structures were relatively preserved. These neuroradiological findings imply that this disease is caused by the gene involved in neuronal and glial proliferation in the ventricular zone and in tangential neuronal migration from the ganglionic eminence. The nature of the progressive degeneration of the hemispheric structures should be clarified.