Primary central white matter hypoplasia of the neocortex.

Leukodystrophies, or diseases of the white matter, represent acute or ongoing damage to the oligodendrocytes of the central nervous system. Early childhood white matter disease is most commonly observed after hypoxic ischemic insults, with acute magnetic resonance imaging changes followed by atrophy or periventricular leukomalacia. Dysmyelination occurring in the setting of inborn errors of metabolism is characterized by progressive changes with high signal intensity in white matter on magnetic resonance imaging. This report presents a patient whose magnetic resonance imaging scans demonstrated hypoplasia of myelin in the telencephalon, without clinical or magnetic resonance imaging evidence of inflammatory dysmyelination. Clinical features included intractable seizures, severe hypotonia, and dysmorphic facial features coupled with a static failure to gain developmental milestones. Together, the clinical and magnetic resonance imaging findings are evidence of a primary failure of myelination in the neocortex.