2.  Blood to the brain is supplied by four major blood vessels
that join together at the Circle of Willis at the base of the
brain. Smaller branch arteries leave the circle to supply
brain cells with oxygen and nutrients.
 Artery junction points may become weak, causing
ballooning of the blood vessel wall that can form a small
sac or aneurysm.
 Cerebral aneurysms are common, but most are
asymptomatic and are found incidentally at autopsy.
 Aneurysms can leak or rupture causing symptoms from
severe headache to stroke-like symptoms, or death.
 The health care practitioner needs to maintain a high
incidence of suspicion to make the diagnosis, since many
patients may have an initial small leak of blood causing
symptoms before a catastrophic bleed occurs.
 Diagnosis of a brain aneurysm may require CT scans,
lumbar puncture, or angiography.
 Treatment to repair the aneurysm may involve
neurosurgery to put a clip across the weak blood vessel
wall or clipping by interventional radiology.

4.  The Circle of Willis is the junction of the four
many arteries that supply the brain with nutrition
(oxygen and glucose) two carotid arteries and two
vertebral arteries.
 This loop of arteries is located at the base of the
brain and sends out smaller branch arteries to all
parts of the brain.
 The junctions where these arteries come together
may develop weak spots.
 These weak spots can balloon out and fill
with blood, creating the outpouchings of
blood vessels known as aneurysms. These sac-
like areas may leak or rupture, spilling blood into
surrounding tissues.

5.  The most common types of aneurysms involve the aorta, the
large vessel that carries oxygen-containing blood away from the
heart. In particular, aneurysms most commonly develop in the
abdominal portion of the aorta and are designated abdominal aortic
aneurysms. Abdominal aortic aneurysms are most common in men
over the age of 60. Most aortic aneurysms are caused by
atherosclerosis ("hardening of the arteries") since this condition
can weaken the walls of the aorta and lead to thinning and
widening of the affected areas.
 Another type of aneurysm is a brain aneurysm. Brain
aneurysms are widened areas of arteries or veins within the brain
itself. A special type of brain aneurysm is known as a berry
aneurysm. Berry aneurysms are small, berry-shaped outpouchings
of the main arteries that supply the brain and are particularly
dangerous since they are susceptible to rupture, leading to often
fatal bleeding within the brain. Brain aneurysms can occur at any
age but are more common in adults.

6.  high blood pressure
 atherosclerosis
 trauma heredity
 abnormal blood flow at the junction
where arteries come together.
 smoking
There are other rare causes of aneurysms.
 Mycotic aneurysms are caused by
infections of the artery wall
 Tumors and trauma can also cause
aneurysms to form
 Drug abuse, especially cocaine, can cause
the artery walls to inflame and weaken.

7. Brain aneurysms (aneurysms within arteries in the brain)
are a common occurrence. At autopsy, incidental
asymptomatic aneurysms are found in more than 1% of
people. Most aneurysms remain small and never become an
issue or are diagnosed. Some, however, may gradually
become larger and exert pressure on surrounding brain
tissue and nerves and may be diagnosed because of
symptoms such as:
 headache
 numbness
 weakness of one side of the face
 a dilated pupil or change in vision.
The greater concern is a brain aneurysm that leaks or
ruptures, and potentially causes stroke or death.
 Bleeding leaks into one of the membranes that covers the
brain and spinal canal and is known as a subarachnoid
hemorrhage (sub= beneath + arachnoid=one of the brain
coverings + hemorrhage=bleeding).

8.  The headache associated with a
leaking aneurysm is severe. Blood is
very irritating to the brain and causes
significant pain. Patients may
describe the "worst headache of
their life," The headache may be
associated with
 nausea,
 vomiting, and
 change in vision.
 a subarachnoid hemorrhage also causes
pain and stiffness of the neck
 seizures.

9. The diagnosis of brain aneurysm begins with a high
index of suspicion by the health care
practitioner. The history of the headache, an acute
onset of the worst headache of the patient's life,
associated with a stiff neck and an ill-appearing
patient on physical examination, typically lead the
health care practitioner to order a
 CT (computerized tomography) scan of the
head. This will show a subarachnoid hemorrhage in
more than 90% of cases of ruptured aneurysm. In
the few cases that are not recognized by CT, the
health care practitioner may consider performing a
 lumbar puncture (LP, or spinal tap) to identify
blood in the cerebrospinal fluid that runs in the
subarachnoid space.

10. If the CT or the LP reveals the presence of blood,
angiography is performed to identify where the
aneurysm is located and to plan treatment.
 Angiography (angio=artery +graphy= picture) is
a procedure in which a small flexible tube is threaded
into one of the brain's arteries, and dye is injected
while pictures are taken. Newer technology allows
angiography to be done in association with CT or
magnetic resonance imaging (MRI).
 Magnetic resonance angiography (MRA).
Similar to a CTA, MRA uses a magnetic field and
pulses of radio wave energy to provide pictures of
blood vessels inside the body. As with CTA and
cerebral angiography, a dye is often used during
MRA to make blood vessels show up more clearly.

11. Migraine headache,
meningitis, tumor, and
stroke all may cause
neurologic symptoms.
Based on the patient's
presentation, the health
care practitioner will need
to decide which tests and
studies to use to establish
the correct diagnosis.

12.  Surgical Clipping: A neurosurgeon can operate
on the brain by cutting open the skull,
identifying the damaged blood vessel and putting
a clip across the aneurysm. This prevents blood
from entering the aneurysm and causing further
growth or blood leakage.
 Coil Embolization: A neurosurgeon or
interventional radiologist can thread a tube
through the arteries, as with an angiogram,
identify the aneurysm, and fill it with coils of
platinum wire or with latex. This prevents further
blood from entering the aneurysm and resolves
the problem. This procedure is less invasive and
is believed to be safer than surgical clipping,
although it may not be as effective at reducing
the risk of a later rupture. It should be done in a
large hospital where many such procedures are
done.

13.  Prior, during, and after surgery,
attention is paid to protect the
brain and its blood vessels from
potential further damage.
 vitals signs are monitored
frequently
 heart monitors are used to watch
for abnormal heart rhythms.
 medications may be used to
prevent blood vessel spasm,
seizure, agitation, and pain.

14. Brain aneurysms are deadly. About 10% of patients
with a ruptured aneurysm die
 before receiving medical care.
 If untreated, another 50% will die within a
month,
 with 25% of patients sustaining another bleeding
episode within a week. Aside from the bleeding
issues, there is significant risk of artery spasm
leading to stroke.
Survival rates are increased
 by early presentation to the hospital,
 early aneurysm repair, and
 control of potential blood vessel spasm with
medications.