Neurovascular Surgery Brain Aneurysm & AVM Center
CLINICAL REVIEW OF SUBARACHNOID HEMORRHAGE (SAH)

Evaluation | Aneurysm obliteration | Post-obliteration care
Team approach | Key points | Other sources of information

The 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).

Evaluation

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 drainage.

Aneurysm obliteration

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.

In certain 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.

Post-obliteration care

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.

Team approach

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.

Key points

• Early diagnosis of SAH is crucial to good results.
• Prompt angiography identifies the cause of SAH.
• Early obliteration of the aneurysm prevents rehemorrhage.
• Early recognition and management of cerebral vasospasm minimizes stroke.

Other information sources on subarachnoid hemorrhage

Ojemann RG, Ogilvy CS, Heros RC, Crowell RM, eds. Surgical Management of Cerebrovascular Disease, Third edition. Williams & Wilkins, Baltimore, in press.