Transcranial doppler ultrasound (TCD)

Transcranial doppler ultrasound (TCD) is a safe, non-invasive way of investigating the circulation in the head. It usually takes between 10-40 minutes and the patient needs to take no special precautions beforehand. TCD provides a way of measuring the speed and direction of blood flow around the base of the brain and is a useful diagnostic test in a number of patients with disorders of the circulation.

We carry out these measurements in three main groups of patients, they are:

Subarachnoid haemorrhage (SAH)

Where there is bleeding into the brain the arteries often narrow (spasm) because of the presence of blood in the space outside the arteries. Spasm resolves as the patient recovers, but TCD measurements help identify the extent to which it is present so that patients can have appropriate treatment.

Vascular disorders

TCD can help to identify abnormalities of the circulation in the head, whether caused by atherosclerosis or by congenital abnormalities of the circulation. Using the technique we can help to establish whether an artery is narrowed or blocked. We also use TCD in patients undergoing carotid endarterectomy (surgery to remove atherosclerosis in the neck arteries), enabling the surgeon to monitor the blood supply to the patient’s brain during the surgery.

Children with sickle cell disease

It has been shown that the presence of high blood velocities, measured by TCD, indicates an increased risk of stroke. We monitor velocities in these children on a regular basis to help ensure they are getting the treatment they need.