Transcranial Doppler

"Stethoscope to the  brain"

TCD is a non-invasive ultrasound method used to examine the blood circulation within the brain. This is similair to the well-known carotid ultrasound study that is used to exam the arteries in the neck.

 

 

Case courtesy of Dr Sachintha Hapugoda, https://radiopaedia.org  From the case https://radiopaedia.org/cases/51777

F A C T  S H E E T  F O R  P A T I E N T S  A N D  F A M I L I E S


Transcranial Doppler (TCD) and Bubble Studies - TCD and bubble studies
evaluate the blood flow to and in your brain.                   


This fact sheet explains two tests that can help your
doctor assess the blood flow to and in your brain.
These tests may also help identify a heart problem
that can affect the blood in your brain.


What is a transcranial Doppler study (TCD)?
A transcranial Doppler study (TCD) is a safe, painless
test that evaluates the blood flow to and in your brain.
This test uses high-frequency sound waves that you can’t
hear or feel. As the sound waves bounce off blood vessels,
information is sent to a computer screen. Analyzing the
information helps your doctor look for problems that
might keep your brain from getting enough oxygen.
Your doctor might use a TCD study to assess:
•Whether arteries are narrowed by plaque (fatty buildup)
or by one or more tiny blood clots.
•Whether anticoagulation medication is working to
dissolve blood clots in the arteries
•Whether arteries have gone into spasm (tightened up).
This can happen after an aneurysm (weakened part)
of a blood vessel bursts.


The TCD test is also used to monitor blood flow in
the brain during surgery or after a head injury.


What is a bubble study?
A bubble study is a TCD that includes injecting tiny
bubbles into a blood vessel. The sound waves show
whether the bubbles reach your brain.


This test is most often used to find out if you have an
abnormal opening between the chambers of your heart.
Normally, oxygen-poor blood comes to the right side of
your heart, which sends it to the lungs to get oxygen. The
oxygen-rich blood returns to the left side of your heart,
which pumps it to your body. An abnormal opening can
allow oxygen-poor blood to leak over to the left side. This
leaked blood misses the trip to the lungs, so it’s pumped to
your body without picking up the oxygen your body needs.
Because the lungs dissolve bubbles in the blood, we can
use injected bubbles to see if any blood is skipping its
trip to the lungs. If this happens, it means your brain is
getting oxygen-poor blood.


Why might I need a TCD or bubble study?
Your doctor might recommend this test if:
• You have had a stroke or a TIA (mini-stroke), with
symptoms such as numbness or weakness, confusion,
trouble seeing, headache, or loss of coordination
• You have had a brain aneurysm
• You have frequent migraines (very bad headaches)
• You have unexplained blood clots in your system
• You have unexplained low blood oxygen levels
• You have had a head trauma
• You are having surgery that can affect blood flow
to the brain

What happens during a TCD study?
A TCD study takes about an hour. Here’s what happens:
• Getting ready: You’ll either lie down on a padded
exam table or sit in a chair. The technician will prepare
the area to be tested by putting a small amount of gel
on the skin.
• During a TCD study that looks for blood vessel
narrowing or spasms, the technician will move a
hand-held device called a transducer on your skin.
Depending on what the doctor is looking for, the
test will include one or more of the areas below.
––The sides of your head above your ears
–– Under your chin
––The hollows in the back of your neck (you’ll sit or
lie on your side and hold your head down)
–– On your closed eyelids (don’t worry — the gel
won’t hurt your eyes, and the transducer is moved
very lightly over the skin)
• During a TCD study that looks for tiny blood clots,
the technician will hold a transducer against your head
(or you will wear a headset) and the technician will
listen to the arteries inside your brain for up to an hour.


What happens during a bubble study?
A bubble study takes about 20 to 30 minutes. Here’s what
happens during the test:
• Getting ready: You’ll lie down on a padded exam table
or sit in a chair. An IV (intravenous line) will be placed
in your wrist or arm. The technician will prepare the
area to be tested by putting a small amount of gel
on the skin.
• Headset: The technician
will fit you with a
transducer headset.
• Injection: As you sit or lie
still, the technician will
inject into your IV a saline
(saltwater) solution that
contains tiny bubbles. The
transducers in the headset
will send out sound waves
to detect any bubbles that
reach your brain.


What happens after the test?
After either type of test, here’s what happens:
• Preparing to leave. The gel will be wiped off. If you
had an IV, it will be removed.
• Getting the results. Your doctor will analyze the test.
You’ll get the results in a later appointment.
Potential benefits Risks and potential complications Alternatives
A TCD or bubble study can:
• Identify whether spasms, clots, or plaque
are blocking blood flow to the brain
• Identify whether you have an abnormal
opening inside your heart
TCDs and bubble studies are very safe.
Risks include:
•Minor pain or infection at the IV site
(during a bubble study)
• Stroke or blood clot in the lungs
(extremely rare)
Alternatives to TCD may include:
•MRI, CT scan
Alternatives to bubble study may include:
• Echocardiogram, MRI
• Cardiac catheterization

Talking with your doctor about the test
The listsbelow are the most common potential benefits, risks and alternatives for TCD and bubble studies, but other
benefits or risks may apply in your unique medical situation. Talking with your doctor is the most important part of learning
about the test. If you have questions, be sure to ask.

Potential Benefits:

A TCD or bubble study can:
• Identify whether spasms, clots, or plaque are blocking blood flow to the brain
• Identify whether you have an abnormal opening inside your heart

Risks and potential complications:

TCDs and bubble studies are very safe.
Risks include:
•Minor pain or infection at the IV site
(during a bubble study)        

Alternatives:

Alternatives to TCD may include:
•MRI, CT scan
Alternatives to bubble study may include:
• Echocardiogram, MRI
• Cardiac catheterization


@2018 Arizona Neurology and Sleep Center. The content presented here is for your information only. It is not a substitute for professional medical advice, and it should not be used to diagnose or treat a health problem or disease. Please consult your healthcare provider if you have any questions or concerns.

Indications for a TCD ultrasound examination of children and adults include but are not limited to:

          1. Evaluation of sickle cell disease to determine stroke risk.

  2. Detection and follow-up of stenosis or occlusion in a major intracranial artery in the circle of Willis or   vertebrobasilar system, including monitoring and potentiation of thrombolytic therapy for acute stroke patients.

          3. Detection of cerebral vasculopathy.

  4. Detection and monitoring of vasospasm in patients with spontaneous or traumatic subarachnoid    hemorrhage.

          5. Evaluation of collateral pathways of intracranial blood flow, including after intervention.

          6. Detection of circulating cerebral microemboli or high-intensity transient signals (HITS)

          7. Detection of right-to-left shunts.

          8. Assessment of cerebral vasomotor reactivity (VMR).

          9. As an adjunct to the clinical diagnosis of brain death.

  10. Intraoperative and periprocedural monitoring to detect cerebral thrombosis, embolization, hypoperfusion, and hyperperfusion.

          11. Assessment of arteriovenous malformations, before and after treatment.

          12. Detection and follow-up of intracranial aneurysms.

          13. Evaluation of positional vertigo.

 

Additional applications in children include but are not limited to:

1. Assessment of intracranial pressure and hydrocephalus.

2. Assessment of hypoxic-ischemic encephalopathy.

3. Assessment of dural venous sinus patency.

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