•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 40-60 yrs.
•May also rupture intracerebrally.
•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
•Ruptures when an area becomes thinned and there is a
period of hypertension or straining.
aneurysms are found incidentally at autopsy 1-2%
of the time. Vascular malformations are much less common.
•Aneurysms occur on the anterior Circle of Willis 80%
of the time. Anterior communicating artery and middle
cerebral artery at the trifurcation are the most
comman places for one to arise.
•Subarachnoid hemorrhage due to a
aneurysm or vascular malformation usually produces
the sudden onset of a severe headache (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
|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, vascular malformation,
|General Micro Description|
•Microscopically in subarachnoid hemorrhage there are
red and white blood cells in the leptomeninges.
•After three days macrophages can be seen phagocytosing degenerating blood cells.
• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp. 1311-1313.