Aneurysm & AVM Center
REVIEW OF SUBARACHNOID HEMORRHAGE (SAH)
| Aneurysm obliteration
| Post-obliteration care
Team approach | Key points
| Other sources of information
most common cause of nontraumatic subarachnoid hemorrhage (SAH) is hemorrhage
from an intracranial aneurysm. Other causes include vascular malformations, tumors,
and infection. The management of aneurysmal SAH has changed significantly over
the past few years. This change is mostly due to the demonstration of the superiority
of early surgery for clipping of ruptured aneurysms. This superiority derives
from the relative safety of early aneurysm surgery and the major threat of early
rebleeding (approximately 25% in three weeks after SAH).
To avoid rehemorrhage, rapid diagnosis of SAH is critical. In some cases when
a patient presents with "the worst headache of my life," the diagnosis
of SAH can be made by plain CT scan. If the CT scan does not show subarachnoid
blood or the clinical history is less specific (i.e. mild neck pain while lifting),
the clinician should pursue the diagnosis with a lumbar puncture. The fluid is
analyzed for cell counts to look for bloody CSF and xanthochromia. Once the diagnosis
of SAH is confirmed, then high resolution four- vessel cerebral angiography should
be done. Simply visualizing the presumed ruptured aneurysm is not sufficient given
the fact that 10-15% of patients will harbor more than one aneurysm.
We have adopted the above protocol for almost all patients with SAH. Occasionally
patients are in coma after SAH. Despite an initial poor neurologic condition,
up to 20% of these patients may make a reasonable recovery. This is especially
true for patients with acute hydrocephalus which can be easily treated with ventricular
The most effective
proven treatment for a patient with a ruptured cerebral aneurysm is to proceed
with microsurgical clipping of the lesion. This is currently indicated as soon
as possible after the initial hemorrhage. With the aneurysm adequately clipped,
the risk of rehemorrhage is avoided. In addition, if blood pressure elevation
is needed to treat cerebral vasospasm (see below), this can be done with greater
safety after aneurysm clipping.
unusual situations, forms of treatment other than surgery should be considered.
Current techniques for reaching the aneurysm endovascularly with a small catheter
make it possible to place small, soft, titanium coils in the aneurysm in order
to induce thrombosis; details regarding this form of treatment will be covered
in our next newsletter. Experience with coil obliteration of intracranial aneurysm
is just beginning. Longterm followup is needed to document efficacy of this form
of treatment. For patients facing high risk surgery due to medical or specific
neurologic problems, however, coils may be the answer.
Once the aneurysm is
treated, patients still face the threat of cerebral vasospasm. Ischemic symptoms
from vasospasm occur in about one-third of all patients with subarachnoid hemorrhage.
The risk of developing vasospasm can often be predicted by the amount of blood
present on a CT scan obtained one day after hemorrhage.
Today blood flow velocities of major intracranial vessels can be measured on a
daily basis using a transcranial doppler probe. This information is proving to
be extremely helpful in recognition of vasospasm before symptoms of cerebral ischemia
occur. Once recognized, treatment of vasospasm involves elevation of the blood
pressure (induced Hypertension), Hemodilution to improve cerebral
blood flow, and maintenance of high normal circulating blood volume (Hypervolemia).
This so-called "triple H" therapy, combined with monitoring with transcranial
Doppler (TCD), has proved effective in preventing stroke as a result of vasospasm.
In addition, a 21 day course of the calcium channel blocker nimodipine is given
at a dose of 60 mg by mouth every four hours.
If medical management with "triple H" therapy fails, endovascular techniques
can be used to dilate a cerebral artery in vasospasm. For endovascular angioplasty,
a small balloon is inflated in the brain artery to dilate the vessel and improve
cerebral blood flow.
Given the complexity
of evaluation, treatment and management of aneurysmal subarachnoid hemorrhage,
a team approach to the problem has proved useful. Neurosurgeons, interventional
neuroradiologists, and neurologists work together on specific management issues
to select and implement treatment to optimize outcome.
- Early diagnosis
of SAH is crucial to good results.
angiography identifies the cause of SAH.
obliteration of the aneurysm prevents rehemorrhage.
recognition and management of cerebral vasospasm minimizes stroke.
Ojemann RG, Ogilvy CS, Heros RC, Crowell RM, eds. Surgical Management of Cerebrovascular
Disease, Third edition. Williams & Wilkins, Baltimore, in press.