Cerebral vasospasm is a narrowing of portions or segments of one or more brain arteries. It is identified on special imaging and ultrasound studies. Vasospasm is usually discussed in relation to aneurysmal subarachnoid hemorrhage (aSAH). It may also be seen with other causes of brain hemorrhage, trauma or surgery, but it is generally less severe in these circumstances.
When cerebral vasospasm is seen on imaging studies, it is referred to as radiographic vasospasm. This may develop in up to 70% of patients with aSAH. It will typically occur 4–14 days after hemorrhage, with a peak at 7–10 days. Vasospasm is not a rapid narrowing and opening of the arteries, but rather a steadily progressive narrowing of portions of arteries which then slowly resolve.
About 30% of patients with radiographic vasospasm will develop symptoms that require treatment. This is referred to as clinical or symptomatic vasospasm. Patients with symptomatic vasospasm may have new neurological deficits that can result in a permanent stroke if treatment is not successful.
Because of the potential risks associated with cerebral vasospasm, patients are closely monitored for 7–14 days following aSAH, even if they have done well with treatment of the ruptured aneurysm.
Signs and Symptoms
Symptoms of clinical or symptomatic vasospasm may include:
- Increased headache
- Confusion or sleepiness
- Trouble speaking
- Difficulty with vision
- Numbness or weakness of the face, arms or legs, typically on one side of the body
Beyond its relationship to aSAH, the underlying cause of vasospasm is not fully known.
Radiographic vasospasm may be detected on special imaging or ultrasound studies which are checked routinely following aSAH. The development of symptoms typically seen with clinical vasospasm will quickly trigger investigation. Often, this will begin with blood tests and a CT scan to exclude other causes for these symptoms. If another cause is not identified, specific testing for vasospasm is done. These tests include: computed tomography ( CT ) scans, transcranial doppler (TCD) ultrasound, CT angiogram ( CTA ), cerebral angiography , magnetic resonance angiography ( MRA ), magnetic resonance imaging ( MRI ) or CT perfusion .
During the period of risk for vasospasm, efforts are made to maintain both blood pressure and intra-vascular volume (the volume of blood and fluid in the circulatory system). Although some treatment may be started when severe radiographic vasospasm is identified, it usually is reserved for patients who are symptomatic with clinical vasospasm.
- Nimodipine This medication is usually started within the first 96 hours following aSAH. It has been shown to reduce the risk for new neurological deficits from vasospasm. Nimodipine can lower blood pressure. Occasionally, the drug may need to be stopped due to this side effect.
- “Triple-H” therapy This refers to treatment with hypertension/hypervolemia/hemodilution. Sometimes, one or more of these measures are employed intentionally to treat symptomatic vasospasm. Often, they are used passively during the period of vasospasm. For instance, the blood pressure may be allowed to reach a higher level without being treated. The exact recommendations for triple-H therapy are often re-assessed.
- Hypertension Mild to moderate increases in blood pressure are generally allowed after the aneurysm is treated. In patients with symptomatic vasospasm, medicines may be used to increase the systolic blood pressure until symptoms resolve, or up to a ceiling of 220 mmHg.
- Hypervolemia For symptomatic vasospasm, increased intra-vascular volume may be used in an effort to improve the flow of blood to the brain. This usually requires placement of a central venous pressure (CVP) line to monitor the amount of extra IV fluids being administered.
- Hemodilution This is a decrease in the concentration of blood cells. It generally is allowed to happen passively rather than by active treatment.
- Cerebral angioplasty This is a neuro-interventional procedure. A catheter (small tube) is placed in an artery and guided up to the brain. A small balloon may be inflated in the narrowed brain artery to open it up to normal size (balloon angioplasty). This is usually done for severe vasospasm in the larger arteries of the brain. Medications may also be injected through the catheter to relax the arteries. This is usually done for smaller arteries and may need to be repeated over several days.