Intracranial arterial aneurysms / by Walter E. Dandy.

  • Walter Dandy
Date:
1944
Catalogue details

Licence: In copyright

Credit: Intracranial arterial aneurysms / by Walter E. Dandy. Source: Wellcome Collection.

    18/178 page 8
    It seems to me that there can be but one explanation of aneurysms of the congenital type. It is known that the arterial trunks are de¬ rived from a capillary network which is gradually reduced, and that little “nubbins” remain on the arterial trunks where the smaller ves¬ sels are absorbed. It is probable that from these “nubbins” the little miliary (berry) aneurysms develop: and defective walls are to be expected in vestigial structures. The studies by Miss Hager also lead to the belief that aneurysms are a part in the congenital maldevelop- ment of the vascular system of the brain, especially involving the circle of Willis. The explanation of aneurysms on the intracranial division of the internal carotid artery—which in the adult is without branches between the ophthalmic and posterior communicating ar¬ teries—is probably that they are early embryologic branches that subsequently atrophy and are normally lost. The development of an aneurysmal sac with a narrow neck would appear to be the result of an incomplete disappearance of one of these vessels. At times the continuity of even the normal trunks is broken by this changing and absorbing process in the capillary bed. An excellent example is seen in two aneurysms of the internal carotid artery (Jacques, 1926; Slany, 1938) and two near the termination of the basilar artery (Slany, 1938; McDonald and Korb, 1939) all occurring where the posterior communicating artery should have been present but was absent. Certainly all aneurysms now recognized as congenital have their origin in defects incident to the resolution of the early vascu¬ lar bed. Ruptured and Unruptured Aneurysms Ruptured aneurysms were present in 64, and unruptured in 44 cases. If the number of aneurysms instead of cases is considered, the ruptured number 64 and the unruptured 69—relative percentages of 48 and 52. Over half of the patients with ruptured aneurysms died within 48 hours, and half of these within 24 hours. The immediate re¬ sult of each rupture depends largely, of course, upon the size of the arterial perforation and, to a considerable extent, upon whether or not tissues are in apposition with the artery at the point of rupture. If the hemorrhage passes directly into the subarachnoid space, the rupture will usually cause death. If the hemorrhage passes into the cerebral substance, the adjacent tissues may stop the hemorrhage and
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