One of us systematically examined 78 anencephalics (in the broad sense of the term) in the Central Pathological Laboratory in Rotterdam. On the basis of differences with respect to the closure of the neural tube, the material could be divided into three groups:
(1) In 18 cases there was faulty closure in the rostral portion of the brain;
(2) In 15 cases there was a defect in the caudal portion of the brain and the rostral portion of the spinal cord;
(3) In 45 .cases there was a defect both in the entire brain and in the spinal cord.
In all these cases, the skull and vertebral column participated in the closure-defect.
|Localization of Brain Defect||Female||Male|| Sex Dominance |
|Rostral brain||6||12||Male +|
|Caudal brain and rostral spinal cord||14||1||Female +|
|Total brain and spinal cord||36||9||Female +|
This Table shows that anencephaly clearly preferentially affects the female sex. This was already known, and is confirmed by the Rotterdam material (56 females v. 22 males) but, if we consider the groups of anencephalics separately, then those with a closure defect in the rostral portion of the brain (the so-called hemicephalics or merencephalics) occupy a unique position: here the male sex predominates, in contrast to the other groups, where the caudal part of the CNS is much more extensively involved. This supports the opinion that “hemicephaly" should be considered a special type of anencephaly.
V.W.D. Schenk et al. Two Rhombencephalic Anencephalics, BRAIN—VOL. XCI, 497-506