Transcranial Ultrasound to Detect Vertebral Artery Compression

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Swedish Vascular Ultrasound

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Patients who report symptoms of decreased blood flow with certain head positions (also known as vertebrobasilar ischemia) often describe dizziness, vertigo, fainting (syncope) and/or visual disturbances with head turning. These symptoms can be a result of an obstruction of blood flow due to compression of a vertebral artery.

Transcranial Doppler is used to detect changes in blood flow to the posterior circulation (back of the brain). During this test, the posterior cerebral arteries are monitored during different head positions. When blood flow velocity significantly drops with head turning, and there is a secondary response when the head is turned back to a neutral position, the exam indicates that there is a mechanical compression of the vertebral arteries. This result may lead to further evaluation, with potential surgery to relieve the compressing mechanism.

Because of the proximity of the cervical spine to the vertebral arteries, compression can also occur due to cervical bone spurs, bony malformations, lesions, disk rupture, abnormal muscle insertions, fractures, arthritis and dislocations.


Monitoring blood flow during provocative head positioning

Spectral Doppler waveform showing changes in flow with head turning

Test Indications

Patients with symptoms consistent with vertebrobasilar insufficiency, such as dizziness/vertigo, fainting (syncope) or near syncope, and/or visual disturbances associated with head movements

What to Expect

Prior to test

There is no preparation required

At the testing center

  • You will be asked about your medical and surgical history
  • You may have your blood pressure taken
  • You may be allowed to have a family member or friend with you in the exam room during the test

During the exam

  • There are two parts to the exam. Initially you will lie comfortably on a stretcher in the testing room; the lights will be dimmed
  • The technologist will apply water soluble gel and place the transducer at the temporal area in front of the ears and at the base of the skull
  • Doppler ultrasound amplifies the sound of the blood flow and you will hear a sound like a heartbeat
  • During the second part of the exam you will be sitting. The technologist will position a band like frame to your head to hold the ultrasound transducers in place during the testing
  • The technologist will assist you with performing various head turning maneuvers while your blood flow is monitored
  • The technologist will remove the fixation device and the ultrasound gel will be removed with a soft cloth

When the exam is done

You will be ready to leave depending on the results. If the technologist has critical findings you will be asked to wait at the facility for further instructions from your doctor after the results are conveyed. The technologist may need to take more images if requested by your physician.

How long will it take?

40 – 60 minutes

Will it hurt?

The ultrasound exam is non-invasive and painless


A specialized physician will analyze the images and send a report to your doctor. Your doctor will talk to you about the results and any further tests or treatments. After the test, call your doctor if you have worsening symptoms.