Destructive lesions of fetal brain (disruptions)
Introduction
Ischemia occuring as early as 26 weeks of gestation results in
necrosis which heals without obvious reactive astrocytosis.
A smooth-walled porencephallic cavity develops this way. An
insult timed in the second trimestr also disturbs the neuronal
migration resulting in polymicrogyria. Lesions arising later
in the third trimestr and perinatal period heal with gliosis
but without abnormal gyral pattern.
Etiology
- vascular occlusion
- diffuse hypoxic-ischemic brain necrosis
- pathology of twinning (intrauterine demise of the monochorionic
co-twin produces an episode of severe hypotension in the surviving twin)
- prenatal infections (toxoplasmosis, CMV, herpes simplex)
Classification
The lesions differ in the extent of cerebral destruction.
- Porencephaly
- Hydranancephaly
- “Basket brain” is a term used for extensive
bilateral porencephalic defects
- Multicystic encephalopathy