THIS paper is an analysis of the anatomical features of the Arnold-Chiari malformation in an attempt to elucidate the morphogenesis of the anomaly. In the first part of the paper, the various theories which have been advanced are criticized from the accumulated data of my own and other workers' findings. In the second part of the paper a new theory is advanced, which, it is claimed, satisfactorily explains the anatomical features.
The Arnold-Chiari malformation is an anomaly of the hindbrain consisting of two components: (a) a variable displacement of a tongue of tissue derived from the inferior cerebellar vermis into the upper cervical canal and (b) a similar caudal dislocation of the medulla and fourth ventricle. The descriptive literature regarding this malformation has been fully summarized in a previous paper.1 Despite the abundance of this descriptive literature, there appears to be no unanimity of opinion regarding the morphogenesis of
BRIAN PEACH. The Arnold-Chiari MalformationMorphogenesis. Arch Neurol. 1965;12(5):527–535. doi:10.1001/archneur.1965.00460290083009