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Cerebral aneurysms can be caused by brain trauma,
infection, hardening of the arteries (atherosclerosis), or abnormal
rapid cell growth (neoplastic disease), but most seem to arise from
a congenital, or developmental, defect. These congenital aneurysms
occur more frequently in women. Whatever the cause may be, the inner
wall of the blood vessel is abnormally thin and the pressure of the
blood flow causes an aneurysm to form.
Most aneurysms go unnoticed until they rupture.
However, 10-15% of unruptured cerebral aneurysms are found because
of their size or their location. Common warning signs include
symptoms that affect only one eye, such as an enlarged pupil, a
drooping eyelid, or pain above or behind the eye. Other symptoms are
a localized headache, unsteady gait, a temporary problem with sight,
double vision, or numbness in the face.
Some aneurysms bleed occasionally without
rupturing. Symptoms of such an aneurysm develop gradually. The
symptoms include headache, nausea, vomiting, neck pain, black-outs,
ringing in the ears, dizziness, or seeing spots.
Eighty to ninety percent of aneurysms are not
diagnosed until after they have ruptured. Rupture is not always a
sudden event. Nearly 50% of patients who have aneurysmal SAHs also
experience "the warning leak phenomenon." Persons with warning leak
symptoms have sudden, atypical headaches that occur days or weeks
before the actual rupture. These headaches are referred to as
sentinel headaches. Nausea, vomiting, and dizziness may accompany
sentinel headaches. Unfortunately, these symptoms can be confused
with tension headaches or migraines, and treatment can be delayed
until rupture occurs.
When an aneurysm ruptures, most victims
experience a sudden, extremely severe headache. This headache is
typically described as the worst headache of the victim's life.
Nausea and vomiting commonly accompany the headache. The person may
experience a short loss of consciousness or prolonged coma. Other
common signs of a SAH include a stiff neck, fever, and a sensitivity
to light. About 25% of victims experience neurological problems
linked to specific areas of the brain, swelling of the brain due to
fluid accumulation (hydrocephalus), or seizure. |