. The diseases of infancy and childhood. the cerebrospinal fluidis formed by the choroid plexus in the lateral, third and fourth ventricles—but that it is not absorbed there. It passes out of the brain throughthe aqueduct of Sylvius into the fourth ventricle and from there to thesubarachnoid space by means of the foramina of Magendie and ofLuschka. There is an automatic regulation of production and absorp- 772 DISEASES OF THE NERVOUS SYSTEM tion by means of which the amount of fluid is maintained at theproper level. Hydrocephalus results when the aqueduct or the foraminaare obstructed; or when
. The diseases of infancy and childhood. the cerebrospinal fluidis formed by the choroid plexus in the lateral, third and fourth ventricles—but that it is not absorbed there. It passes out of the brain throughthe aqueduct of Sylvius into the fourth ventricle and from there to thesubarachnoid space by means of the foramina of Magendie and ofLuschka. There is an automatic regulation of production and absorp- 772 DISEASES OF THE NERVOUS SYSTEM tion by means of which the amount of fluid is maintained at theproper level. Hydrocephalus results when the aqueduct or the foraminaare obstructed; or when in consequence of injury to the meninges as aresult of inflammation, the cerebrospinal fluid can not be absorbed withsufficient rapidity from the subarachnoid space. In the latter instancethe fluid is dammed back toward its source and the greatest pressure isthus exerted on the interior of the ventricles. Obstruction to the flow from the ventricles is frequently broughtabout by a narrowing or complete absence of the aqueduct. ( Fig. 105.—Sagittal Section of Normal Brain op an 8 Months Old Child, showingPatent Aqueduct of Sylvius. (From Dandy and Blackfan.) 104, 105.) This condition must be considered a congenital of the foramina, however, is almost always the result ofinflammation. This may occur in intra-uterine life or at any time afterbirth. Except for those cases plainly following upon meningococcusmeningitis, the organism causing the inflammation is unknown. Inter-ference with the absorption of cerebrospinal fluid is dependent upon someprevious meningeal inflammation. It is probable that this in turn maybe of intra-uterine or extra-uterine origin. No sufficient pathologicalexamination of cases due to this cause has been made. It is the opinionof Dandy and Blackfan that the diminished absorption is due to adhe-sions limiting the size of the subarachnoid space. CHRONIC INTERNAL HYDROCEPHALUS 773 In a large proportion of cases the disease i
Size: 1522px × 1641px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1920
