Transcranial Doppler (TCD) versus Computed Tomography Angiography (CTA) for the detection of cerebral vasospasm after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage is caused by the rupture of an intracranial
arterial aneurysm. It is a serious medical and life-threathening condition:
one-third of the patients dies before reaching the hospital, one-third dies
within the hospital of is severely disabled after discharge and one-third has
no or minimal neurological deficits. Closure of the aneurysm is the treatment
in the acute phase, to prevent rebleeding. The aneurysm can be closed by
surgery (clipping of the aneurysm) or by endovascular coiling. During the first
3 weeks of an subarachnoid hemorrhage, several complications can occur, such as
cerebral vasospasm. Vasospasm develop due to the blood in the subarachnoid
spacce, and can lead to ischemic strokes due to insufficient cerebral blood
flow. It is of importance to detect cerebral vasospasm in an early phase to
prevent secondary ischemia.
The detection method of clinically relevant cerebral vasospasm is a matter of
debate. A gold standard is a conventional angiography (DSA), however, the DSA
is an invasive procedure and carries a 1-2% of complication risk. Currently,
transcranial doppler (TCD) is often used to detect vasospasm. TCD is a
non-invasive way to detect vasospasm and can be performed at patient bedside.
The major disadvantages of TCD are that only a small part of the intracranial
vasculature can be measured and that vasospasm found on TCD were often not
clinically symptomatic. Moreover TCD is a time-consuming technique and the
quality of the results is dependent of the experience of the investigator.
There are studies that demonstrate that CT-angiography (CT-A) reliably detect
vasospasm compared to DSA. The advantage of CT-A is that during the same CT
scan the brain parenchyma can also be visualised and cerebral ischemia can be
detected. The disadvantage of this technique is is use of intravenous iodine
contrast and the radiation exposure of the CT scan. A recent national guideline
in the Netherlands does not state which technique should be used to detect
vasospasm. A comparison of CT-A and TCD is therefore needed to reveal which
diagnostic method is the best way to detect vasopasm

Assessment of the diagnostic accuracy of CTA for the detection of vasospasm
after SAH in comparison to TCD.

This study is an observation pilot study in which prospectively consecutive
patients with a subarachnoid hemorrhage are included. All patients are screened
with TCD 2-3 times a week for vasospasm, according to the local management
guidelines. Besides TCD, a CT-A scans are made for each patient on day 5 and 10
and in case of clinical deterioration. The results of TCD and CTA are compared
and linked to clinical symptoms. In case of clinically symptomatic vasospasm,
patients are treated according to a pre-defined protocol which is documenten in
the local management guidelines. After finishing the pilot studies, we are
planning to set-up a large scale cost-effectiveness study in order to
investigate which method is most efficient.

By participation, the patients receive two additional CT-A scans to detect
vasospasm. This means that patients have to be transported from the ward or
intensive care unit (ICU) to the radiology department and have to be
transferred from bed to the CT scan and vice-versa. As headache is a frequent
complaint of patients with subarachnoid hemorrhage, this additional scan can be
an extra burden for the patient, although all patients receive adequate
painmedication. The same accounts also for transportation to the
neurophysiology department, but sometimes TCD is done at the bedside of the
patient on the ICU.
The CT-A scan carries a risk of contrast nephropathy due to the iodine
containing contrast. However, the renal function is carefully monitored during
the hospitalization.
The CT-A scans give also an extra radiation exposure to the patients, the
cumulative dose is, however, low. The possible advantage of a better vasospasm
detection outweigh the very small risks of these extra radioation exposure.