Congenital Brain Malformations

Dorsal induction, primary neurulation / neural tube defects (3-4wk)

  • Craniorachischisis total       3wk
  • Anencephaly 4wk
  • Myeloschisis 4wk
  • Encephalocele 4wk
  • Myeloencephalocele 4wk
  • Chiari malformation 4wk
  • Hydromyelia 4wk

Ventral induction (5-10 wk)

  • Atelencephaly 5wk
  • Holoprosencephaly 5-6wk
  • Septo-optic dysplasia 6-7wk
  • Agenesis og the septum pellucidum 6wk
  • Diencephalic cyst 6wk
  • Cerebral hemihypoplasia or aplasia 6wk
  • Lobar hypoplasia or aplasia 6wk
  • Hypoplasia or aplasia of the cerebellar hemispheres 6-8wk
  • Hypoplasia or aplasia of the vermis 6-10wk
  • Dandy-Walker syndrom or variant 7-10wk
  • Craniosinostosis 6-8wk

Neuronal proliferation, differentiation and hystogenesis (2-5mo)

  • Micrencephaly 2-4mo
  • Megalencephaly 2-4mo or later
  • Unilateral megalencephaly 2-4mo or later
  • Neurofibromatosis 5wl-6mo
  • Tuberous sclerosis 5wl-6mo
  • Sturge-Weber syndrome 5wl-6mo
  • von Hippel-Lindau disease 5wl-6mo
  • Ataxia-teleangiectasia 5wl-6mo
  • Other neurocutaneus syndromes 5wl-6mo
  • Congenital vascular malformations 2-3mo
  • Congenital tumors of the nervous system 2-5mo
  • Aqueduct stenosis 4mo
  • Colpocephaly 2-6mo
  • Porencephaly 3-4mo
  • Multicystic encephalopathy 3-4mo
  • Hydranencephaly 3-4mo or later

Migration (2-5mo)

  • Shizencephaly 2mo
  • Lissencephaly 3mo
  • Pachygyria 3-4mo
  • Polymicrogyria 5mo
  • Neuronal heterotopias 5mo
  • Anomalies of the corpus callosum 3-5mo

Myelination (7mo gestation - 18mo of age)

  • Hypomyelination Variable
  • Retarded myelination Variable
  • Accelerated myelination Variable

*Numbers in parentheses indicate an inclusive time period. Numbers without parentheses are more focal time points. Modifed from van der Knapp MS, Valk J: Classification of congenital abnormaities of the CNS. AJNR 9:315-326, 1988