Abstract

Hydranencephaly is characterized by absence of cerebral hemisphere forming unilocular sac, intact meninges and a rather normal skull vault. The wall of the sac is coposed of meninges and some of dense glial tissue and the sac is filled with cerebrospinal fluid. This anomaly is considered to be the result of secondary destruction of a brain after having developed to a certain degree of maturation, and accordingly should be distinguished from anencephaly that is always associated with acrania. We report a case of hydranencephaly in a still-born female delivered after 38 weeks gestation from a 33 year-old multipara woman who was uneventful during this preganancy. She measured 4.1㎏ in weight and 54.0㎝ in height. There was no anomalies on external examination except for an enlarged head, 40㎝ in occipito-frontal circumference. The brain was changed to unilocular sac showing remnants of cerebrum, midbrain, and cerebellum on the floor of the cranium. The sac was filled with xanthochromic cerebrospinal fluid, about 600㏄ in toto, and was walled off by intact meninges and skull bone. Microscopically, the thin membranous wall of the sac consisted of leptomeningeal layers closely connected with inner glial tissue. The cerebellum and remaining brainstem as well as spinal cord were preserved. No other internal anomalies were found.