Overview of congenital neurologic anomalies

[Michiko]

Congenital brain anomalies usually cause severe neurologic deficits; some may be fatal.
Some of the most serious neurologic anomalies (eg, anencephaly, encephalocele, spina bifida) develop in the first 2 mo of gestation and represent defects in neural tube formation (dysraphism). Others, such as lissencephaly, result from problems with neuronal migration (see Malformed Cerebral Hemispheres), which occurs between 9 wk and 24 wk of gestation. Hydranencephaly and porencephaly are secondary to destructive processes that occur after the basic architecture of the brain has formed. Some anomalies (eg, meningocele) may be relatively benign.
There are many causes of congenital brain anomalies, including many previously unknown genetic factors.
Amniocentesis and ultrasonography permit accurate in utero detection of many malformations, and newer fetal MRI techniques are increasingly useful. Parents need psychologic support when a malformation is detected and also genetic counseling, because the risk of having a subsequent child with such a malformation is high.