New ventriculographic aspects of the Arnold-Chiari malformation.

Abstract

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 of the pathological aspects previously elucidated by Cameron, and other aspects not hitherto commented upon, we have come to recognize a unique appearance of the Arnold-Chiari cases in addition to the well known caudal herniation of cerebellum, brain stem, and fourth ventricle. The present investigation represents a documentation and an evaluation of the specificity of these abnormal findings. Materials and Methods All proved cases of Arnold-Chiari malformation, seen at the Hospital for Sick Children, in which pneumography had been performed were considered suitable for analysis. In all, the same parameters were evaluated for their presence and graded as to their extent. A similar evaluation was undertaken of a large series of normal pneu-moencephalograms and a series of cases of aqueduct stenosis. The latter group was chosen because it represents another entity often present from birth and associated with obstructive hydrocephalus. The anatomical features elucidated in this report were examined in mounted sagittally sectioned specimens and in fresh previously undis-sected specimens. Results A. Results of Ventriculography: Ventriculograms of 62 patients diagnosed as having the Arnold-Chiari malformation were analyzed. This group was comprised of 21 boys and 41 girls with an age range of newborn to five years. The mean age was six and two-tenths months, but the median age and mode were only three months. (a) Anterior deformity: Of the 62 cases of Arnold-Chiari malformation, an abnormal anterior wall of the third ventricle was identified in 40 (64 per cent).