Malformations of cortical development: 2005

Malformations of cortical development are an interesting group of congenital malformations that result from abnormal proliferation of stem cells, abnormal migration of neurons to the cerebral cortex, abnormal organization of neurons within the cortex, or a combination of these factors (1). Our knowledge of malformations of cortical development has dramatically increased over the past 15 years as a result of the tremendous advances that have been made in molecular biology (2–4) and neuroimaging (5).

Once considered to be rare disorders that were seen only in institutionalized patients with severe mental retardation and epilepsy, malformations of cortical development are now know to be common causes of epilepsy and cerebral palsy. Indeed, many patients with malformations of cortical development are asymptomatic, the disorder being found by routine imaging for other causes or when a relative with epilepsy or developmental delay is found to have a malformation (6). In this lecture, the current classification of malformations of cortical development will be discussed, along with insights into how current neuroimaging can best be used to identify and provide insight into both the malformations and into brain development (7–13).

References: 1. Barkovich AJ, Kuzniecky RI, Jackson GD, Guerrini R, Dobyns WB. Classification system for malformations of cortical development: Update 2001. Neurology 2001;57:2168–2178.

2. Walsh CA. Genetics of neuronal migration in the cerebral cortex. MRDD Res Rev 2000;6:34–40.

3. Marin O, Rubenstein JLR. A long remarkable journey: tangential migration in the telencephalon. Nature Rev 2001;2:780–790.

4. Xu Q, Cobos I, De La Cruz E, Rubenstein JLR, Anderson SA. Origins of cortical interneuron subtypes. J Neurosci 2004;24:2612–2622.

5. Barkovich AJ, Raybaud CA. Neuroimaging in disorders of cortical development. Neuroimaging Clin N Am 2004;14(2):231–254.

6. Cho W, Seidenwurm D, Barkovich. AJ. Adult onset of neurologic dysfunction associated with cortical malformations. AJNR Am J Neuroradiol 1999;20:1037–1043