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| Subarachnoid Hemorrhage |
| Etiology •Most common cause of subarachnoid hemorrhage outside of trauma is a ruptured berry aneurysm. •The berry aneurysm is a small, saclike structure at the branchpoints of arteries with a wall which does not contain a media or internal elastic lamina and therefore can easily rupture during periods of hypertension or stress. •Most commonly ruptures when the patient is in his 40's or 50's. •May also rupture intracerebrally. |
| Pathogenesis •Aneurysms are thought to be due to congenital absence of the media and internal elastic lamina with ballooning as the blood pulsates through the vessels over the years. •Ruptures occur when an area becomes thinned and there is a period of hypertension or straining., |
| Epidemiology •Berry aneurysms are found incidentally at autopsy 1-2% of the time. Vascular malformations are much less common. •Aneurysms occur in the anterior Circle of Willis 80% of the time. The Anterior communicating artery and middle cerebral artery at the trifurcation are the most common sites of origin. |
| General Gross Description •Subarachnoid hemorrhage is blood in the leptomeninges, usually at the base of the brain, and most often due to rupture of a berry aneurysm or vascular malformation, or trauma. |
| General Microscopic Description •Red and white blood cells in the leptomeninges. •After three days, macrophages clean up degenerating blood cells. |
| Clinical Correlation •Subarachnoid hemorrhage due to a ruptured berry aneurysm or vascular malformation usually produces the sudden onset of a severe headach (the worst headache of the patient's life) followed by progressive depression of consciousness to the point of coma if the hemorrhage is large enough. •If the patient is in good enough condition an aneurysm may be clipped with a metal clip at its neck or a vascular malformation may be occluded by intrarterial plastic material. |
| References • Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1307-8, 1311-13. |
| Subarachnoid Hemorrhage |
| Synopsis by: M.L. Grunnet M.D. (TX1500M37000)[26] |
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