and associates (1954) this was also true of all vein of Galen malformations described in the literature. The arteries in this direct anastomosis may divide and recombine with themselves or other arteries to form a lace-like network prior to its communication with the vein of Galen. This network is most frequently observed in the symptomatic newborn.

Incidence of cerebral arteriovenous malformations The true incidence of cerebral arteriovenous malformations is unknown and is probably much greater than is stated in the literature. With improved diagnostic techniques, especially the cerebral angiogram, an increased in- cidence should become apparent. Dandy (1928), found a 1.4 per cent in- cidence in relation to all verified brain tumors, while Mackensie (1953) estimated their occurrence as 1 per cent of all neurological admissions. Neither the reviews of Dandy ( 1 928), Olivecrona and Riives (1948), Mac- kensie (1 953), Potter (1 9 5 3 , or Paterson and McKissock (1956) described examples of involvement of the vein of Galen.

During the past three years, ten children with verified cerebral vascular malformations were seen by us. This represents approximately I per cent of all pediatric neurology admissions. Five or 50 per cent of the children had involvement of the vein of Galen. In the five previous years, there were an additional three children with vein of Galen malformations. Of these eight children, five were girls and three were boys. There are 35 patients reported in the literature with this condition. Of these, 25 were boys and 10 were2 girls. The discrepancy between the two groups probably is of little signifi- cance because of the small size of the sample.

Case reports Patient 1

W.V.W., an 1 1 month old white male, was admitted to the Child Neurology Service on October 20, 1960 because of an enlarging head which first became apparent at three months of age. At eight months the head circumference was 55 an. (S.D.” + 1’0). The anterior fontanelle was not bulging and measured 7 x 5 cm. A diagnosis of arrested hydrocephalus was made, since both by history and observation there was no recent increase in head size.

At 11 months the head size increased to 58.8 cm. with a tense 7 x 6 cm. anterior fontanelle. Neurological examination demonstrated increased muscle tone most marked

S. D. Standard Deviation.

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