Cranial Anatomy
Hemorrhage is the medical term for bleeding.
The rupture of one of the brain's blood vessels can cause bleeding
into the subarachnoid space - beneath the arachnoid membrane, on
top of the pia mater - and into brain tissue. The bleeding usually
stops, at least temporarily, when a clot forms over the ruptured
area.
The most frequent cause of spontaneous subarachnoid hemorrhage (not
due to injury) is the rupture of a small aneurysm, or bulging sac,
on one of the blood vessels that supplies the brain. It is usually
impossible to determine why the aneurysm forms and bursts, but the
condition is common in adults and may be associated with aging,
diabetes, pregnancy, hypertension (high blood pressure), heredity,
or trauma.
Cerebral aneurysms are usually of three types: saccular
with a narrow "neck" (called "berry" aneurysms because of their
shape and their tendency to occur in clusters); saccular with a
broad base; and fusiform, in which a short section of the artery
bulges all the way around. Each shape determines the degree of difficulty
a surgeon faces in attempting to treat the problem.
An aneurysm ruptures spontaneously - even during sleep - and therefore
is not related to the strain of hard work, sexual intercourse, or
other physical activity.
Although it is not always possible to discover the exact source
of bleeding, other causes of spontaneous subarachnoid hemorrhage
include: arteriovenous malformations, small angiomas, certain types
of infections, and bleeding disorders.
A ruptured cerebral aneurysm at first causes severe headache, which
can be followed by nausea, vomiting, double vision or sensitivity
to light, neck pain or stiffness, weakness, memory loss, paralysis,
coma, or death.
How severe the symptoms are and how long they last will depend on
the amount and location of the bleeding. Blood in and around the
brain can cause pressure, swelling, and brain irritation, which
can lead to drowsiness, confusion, weakness or paralysis, memory
loss, speech problems, behavior changes, or coma (complete loss
of consciousness).
The blood vessels around the aneurysm are irritated by the blood
from the hemorrhage and will at times go into a state of spasm,
tightening and narrowing. This vasospasm ("vaso" meaning vessel)
can occur any time after the rupture until the hemorrhaged blood
has been absorbed by the body, and it can increase any or all symptoms.
It is the body's own attempt to prevent a second hemorrhage by restricting
the flow of blood through the vessels around the aneurysm. Vasospasm
thus reduces pressure on the delicate aneurysm but unfortunately
also reduces the normal blood supply to parts of the brain.
Ongoing research is being done to discover a medicine that will
control vasospasm; as yet, none has proven effective.
Other complications from subarachnoid hemorrhage, such as hydrocephalus,
hematoma (blood clot), and brain swelling, involve the brain; but
other body systems can also be affected because of the severe nature
of the illness. Pulmonary embolus, heart abnormalities, and bleeding
from an ulcer may cause further complications.
Several tests are used to confirm the diagnosis of ruptured cerebral
aneurysm. Some are explained in the latter portion of this section.
Because cerebrospinal fluid flows within the subarachnoid space,
a sample of CSF taken during a spinal tap at the base of the spine
will show blood from the hemorrhage. A CT scan will show blood inside
the skull and indicate how much bleeding has occurred.
To find the source of the hemorrhage, an angiogram is performed,
which may have to be repeated to try to pinpoint the aneurysm's
exact location.
Because the aneurysm can rupture again, a quiet, restful atmosphere
is important. The patient usually is placed in the Intensive Care
Unit (ICU), a highly specialized area providing close observation
with specialized nursing care. Complete bedrest without physical
strain is essential while the patient's condition stabilizes - usually
in preparation for surgery.
Medications will be given when necessary to reduce pain, control
blood pressure, relieve stress, and maintain fluid balance.
If necessary, a respirator may be used to help the patient breathe
and to control intracranial pressure. Most often, however, oxygen
is merely administered to the patient through nasal prongs or a
mask.
Various monitoring devices may be used to assess the patient's condition
during recuperation. Among the most common are: an EKG (heart) monitor,
an ICP monitoring device, a Swan-Ganz catheter to assess the patient's
fluid balance, and an arterial line to continuously measure blood
pressure and aid in drawing frequent blood samples for laboratory
study.
Intravenous (I.V.) fluids may be given until liquids and food can be taken
adequately by mouth. The amount of fluid given will be closely monitored
until the dangers of brain swelling (edema) and vasospasm lessen.
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