Radiological Findings in Congenital and Acquired Occlusions of the Foramina of Magendie and Luschka

Abstract

Hydrocephalus secondary to occlusion of the outlets of the fourth ventricle was initially described by Dandy and Blackfan in 1914 (15). In 1921 Dandy (16) described the surgical and pathological findings in the two major types of occlusion of these foramina; congenital and acquired (post-traumatic or postinfectious) and set forth the roentgenographic findings in the latter (basilar adhesive arachnoiditis). Taggart and Walker (45) have done the most extensive work on the congenital variety to date. Because of the distinctive radiographic, clinical, and pathological findings, Benda (3) in 1954 referred to the congenital type as the Dandy-Walker syndrome. Since several cases of basilar arachnoiditis and postsurgical cyst formation have been reported as examples of the Dandy-Walker syndrome (12, 19, 20, 42, 46), it is the purpose of this paper to attempt to clarify the differentiation of congenital occlusion of the foramina of the fourth ventricle (Dandy-Walker syndrome) from acquired occlusion (basilar adhesive arachnoiditis). The Congenital Type; Dandy-Walker Sundrome The Dandy-Walker syndrome may be defined as a developmental anomaly of the fourth ventricle and cerebellum in which the foramen of Magendie is atretic. The incidence of the Dandy-Walker syndrome in hydrocephalic patients is difficult to assess, but it is quite rare (4, 14); we have found 85 cases in the world literature. There is no sex predilection. Approximately 60 per cent of the patients were under the age of two years at the time they presented with symptoms. The age range at the time of diagnosis was from newborn to fifty-nine years. A relatively high incidence and a wide variety of congenital anomalies are associated with the Dandy-Walker syndrome. These include agenesis of the corpus callosum (9, 14, 22, 34, 36, 43, 48, 52), encephaloceles (36), porencephaly (9, our Case I) , cavum septi pellucidi and hypospadias (our Case I), tracheoesophageal fistula (our Case II) , polycystic kidneys (14, 26), gliosis and forking of the cerebral aqueduct (14), herniation of accessory lobe of liver through the foramen of Morgagni (23), Meckel's diverticulum (45), macroglossia, prognathism, double vagina, bicornuate uterus, and fetal ovaries (44). The etiology of the Dandy-Walker syndrome is unknown. There is nothing to suggest a genetic origin. The pathologic findings are quite distinctive (3, 6, 14, 25, 45). Dilatation of the fourth ventricle is gross and cyst-like, occupying most of the greatly expanded posterior fossa (Fig. 1). There is also dilatation of the aqueduct of Sylvius, third and lateral ventricles. The ependyma of the posterior wall of the fourth ventricle and the arachnoid is compressed into one adherent membrane (7) arising from the brain stem in the same manner as a normal roof.