Sign Up for a Free Account
  • Updated 09.23.2023
  • Released 04.01.2010
  • Expires For CME 09.23.2026

Malformations of the brain



Neuroembryology is the basis for understanding both normal and abnormal development of the nervous system. Developmental malformations mainly result from an alteration, suppression, or interruption in one or more of the several developmental processes that occur more simultaneously than sequentially. Such an alteration is often due to a mutation or deletion of one or more genes that program neural development in a precise temporal and spatial sequence. Such genes are often expressed as gradients along one or more of the three axes of the neural tube. Acquired lesions of the fetal brain also can produce malformations. Induction is the influence of one embryonic tissue on another, and the nervous system is intimately related to surrounding tissues to be both induced by them and also influence their development. Correlations must always be considered between morphogenesis and genetic programming. The nervous system also must be seen as a whole, not narrowly focused on one part, such as the cerebral cortex or cerebellum, because genetic mutations often affect multiple systemic structures even if the clinical manifestations are predominantly referable to one part of the brain. In addition, various structures of the brain are interconnected by synaptic networks and axonal projections as well as functionally.

Key points

• Maturation of developmental process within the nervous system, including differentiation and maturation of individual cells, normally occurs in a genetically programmed synchronous and predictable temporal pattern.

• Developmental processes in the nervous system are mostly simultaneous and overlapping rather than sequential in a series.

• Development and maturational timing are altered not only in genetic disorders, but also by acquired epigenetic disorders affecting the fetus, such as exposure to teratogenic toxins including alcohol, fetal cerebral infarcts, and congenital infections.

• Function does not necessarily require complete neuroanatomical maturation.

• CNS malformations may exhibit altered timing of developmental processes with maturational delay, arrest, or even precociousness.

• In laminated cortices, such as the cerebral and cerebellar, dysmorphic alteration may be focal, as in focal cortical dysplasias, or generalized as in congenital metabolic encephalopathies.

• The persistence of transitory and vestigial structures of the fetal brain may cause neurologic disease.

This is an article preview.
Start a Free Account
to access the full version.

  • Nearly 3,000 illustrations, including video clips of neurologic disorders.

  • Every article is reviewed by our esteemed Editorial Board for accuracy and currency.

  • Full spectrum of neurology in 1,200 comprehensive articles.

  • Listen to MedLink on the go with Audio versions of each article.

Questions or Comment?

MedLink®, LLC

3525 Del Mar Heights Rd, Ste 304
San Diego, CA 92130-2122

Toll Free (U.S. + Canada): 800-452-2400

US Number: +1-619-640-4660



ISSN: 2831-9125