New ventriculographic aspects of the Arnold-Chiari malformation.

The Neuroanatomical complex which is known as the Arnold-Chiari malformation was initially described in 1891 by Chiari (6, 7) and was next cited by Arnold in 1894 (1, 16). Russell and Donald (15) are credited with introducing the Arnold-Chiari deformity into the English literature, but morphologically little was added to the original description until Cameron (4), citing a triad of previously unrecorded intracranial abnormalities which he found in Arnold-Chiari specimens, mentioned thickening of the interthalamic ramus (massa intermedia), hypoplasia of the falx cerebri, and partial obliteration of the great cerebral fissure. This data never received attention in the subsequent radiological literature, and, indeed, although numerous reports of the Arnold-Chiari malformation have appeared in the world's literature since the initial description (2, 11, 13, 17, 18), interest has been centered on the hind-brain abnormality with speculation as to its etiology (3, 9, 12). Through a ventriculographic assessment o...