Fetal MRI Characteristics of Exencephaly: A Case Report and Literature Review

Table 1

Comparison of the four cranial vault defect entities.

	Exencephaly	Anencephaly	Acalvaria	Acrania
Cerebrum	Enlarged, disorganized, and deformed mass of brain tissue	Flattened remnant of disorganized forebrain tissue admixed with ependymal, choroid plexus, and meningothelial cells	Present but deformed	Present but deformed
Cerebral hemispheres	Present but deformed	Absent	Present	Present
Cerebellum	Present but deformed	Absent	Present	Present
Covering of extracranial brain tissue	Vascular layer of epithelium	Angiomatous stroma (area cerebrovasculosa)	Dura and skin	Thick membrane
Calvarium	Absent above the orbits	Absent above the orbits	Absent above the orbits	Absent completely
Skull base	Normal	Normal	Normal	Absent
Facial structures	Normal	Deformed	Normal	Normal