Transcranial Doppler

Using Transcranial Doppler & Extracranial Doppler Ultrasound Testing at the Hauser Neck Center

Transcranial doppler (TCD) has been called the stethoscope for the brain. It can track moment to moment changes in blood flow to the brain, allowing us to assess the effect of interventions, such as changes in neck positioning, on brain blood flow. TCD can be used to monitor the brain blood flow for extended periods of time. Yes, we can be monitoring your brain blood flow while you walk around the office or move your neck!

Adequate blood flow is a prerequisite for the normal neurological function of the brain, spinal cord, vagus nerve, and other important nervous tissues. Any type of stenosis of a blood vessel causes an increase in velocity, whether it be from atherosclerosis plaque or thrombus, excessive stretch due to cervical instability, or bony compression (osteophyte or instability). If blood supply is compromised, so will neurologic function. If the blood flow is intermittently compromised, such as only when the neck is in certain positions, it will be difficult to catch and diagnose. To assess proper blood flow to the body's most important nerves and nervous tissue (the brain), especially with head and neck motions, the Hauser Neck Center at Caring Medical Florida performs transcranial doppler (TCD) and extracranial doppler (ECD) ultrasound examinations.


It is sometimes overlooked that all the blood supply to the brain, brainstem, cervical spinal cord and nerves, as well as cranial nerves including the vagus nerve runs through the neck. Specifically, the vertebral arteries run within the transverse foramina of the lower cervical vertebrae (C2-C7) and the carotid sheath houses the internal carotid artery actually runs right on (or in front of) the anterior portion of the cervical vertebrae. Approximately 70% of the brain blood flow comes from the internal carotid artery and 30% from the vertebral arteries.  Depending on the study, 60-70% of the internal carotid artery blood flow goes to the middle cerebral artery and 30-40% to the anterior cerebral artery.

One of the mechanisms by which cervical dysstructure (destruction of the cervical supporting structures and loss of cervical lordosis) and cervical instability cause symptoms is by compromising blood supply. It is through dynamic transcranial doppler (TCD) and extracranial doppler (ECD) ultrasound analysis that this decrease in blood supply can be documented.

What symptoms can be caused by a loss of circulation to the brain?

Symptoms and diagnoses such as dizziness, lightheadedness, fainting (drop attacks), imbalance, dysarthria (slurred speech), facial dropping, transient ischemic attacks (weakness or sensory deficits on one side of body/face that resolve completely within an hour), as well as strokes (weakness or sensory deficits on one side of the body/face that last greater than one hour) imply a loss of circulation to the brain or other vital nervous tissue. Patients may complain of “weird” symptoms such as a swishing sound in their ear, numb tongue, numb lips, visual distortions, poor balance, and other symptoms that come and go.

Commonly, a person’s history will clearly indicate that their symptoms/conditions occur when they are upright and/or while they were moving their neck, versus when they are lying flat. Any symptom that is worsened with a specific neck position or movement most likely is due to cervical instability or another neck issue. Even symptoms such as blurry vision, changes in vision, tinnitus, vertigo, poor balance, brain fog, dystonia, tremors, decreased memory, swallowing difficulty, hearing impairment, and ear fullness, as well as any type of cranial nerve issue, can be from cervical instability. One of the troubling similarities amongst the wide array of symptoms is how many patients tell us that no one else has been able to find the cause, despite being seen at some of the most prestigious medical centers in the world. Often, patients say they’ve tried telling their providers that they feel it is coming from the neck, but that “no one will listen to me” or “I was told my MRI was fine.” However, what we see every day at Caring Medical Florida is that patients are usually correct when they feel there is something wrong in the neck. They just did not have a provider who understood cervical instability! Anyone with dizziness, syncope or seizures should have a thorough dynamic TCD and extracranial doppler examination.


When a person wracked with chronic pain and other symptoms, especially if they feel it is coming from their neck, they want to know the real story of what is going on, and to have testing available that can show what is truly representative of what is happening in their neck. Every day, we see cases of people who have been through every static MRI, X-ray, CT and other tests that showed nothing that would account for their horrific symptoms. It is one of the most devastating and frustrating positions a person can be in to have a real and disabling medical condition, yet all the “experts” dismiss them or begin to make the patient feel crazy. When there is a legitimate concern in the neck, it will show up on the right dynamic testing. The Hauser Neck Center at Caring Medical Florida is dedicated to determining the real story of a patient’s neck! If there is something to be found, we want to find it and determine if it is treatable with Prolotherapy or if there is another preferable treatment course. Ultimately, we want to help find out what is best for YOU!

Some of the questions we seek answers to for our patients:

  • Does the structure of the neck look good, or is it terrible?
  • Which nerves are not transmitting nerve impulses correctly?
  • Are nerve impulses being blocked? 
  • How do the vagus nerves look? 
  • Is there are an imbalance between the sympathetic and parasympathetic nervous systems? 
  • Is cervical instability present, and to what extent?
  • Is there a blood flow problem to the brain, and which neck position causes it?
  • Does the overall hemodynamic picture make sense?
  • Can the changes in blood flow explain some or all of the symptoms?
  • Can the blood flow changes be explained solely by the cervical instability and dysstructure (destruction of cervical supporting structures) that was found on Digital Motion X-ray?

We do the testing to obtain the real story of your neck. Dr. Hauser and our team wants the story to end with…after their neck condition was finally understood, treated, and resolved, they lived happily ever after. This is our hope for all of the people who come to the Hauser Neck Center!


Pulsed doppler ultrasound transmits and receives bursts of ultrasound waves at regular intervals enabling the recording of blood velocity. It can also tell the direction of blood flow. There are various places that the blood flow can be checked including thin bones of the temporal bone to view the anterior and middle cerebral areas (and sometimes the posterior cerebral arteries), occipital bones to check the vertebral and basilar arteries (and sometimes the posterior cerebral arteries), the eyes (ophthalmic and distal portion of internal carotid arteries) through the orbital bones and the neck (internal and external carotid arteries and branches).

Blood flow velocities at Caring Medical are done by two different methods, one involves visually seeing the blood vessels (called duplex or color imaging) and then taking a cross-sectional view of the area of insonation (area within the blood vessel that is imaged) and one in which the sound waves are heard within the blood vessel and the wave is then seen on the screen. Both methods give accurate results. The Hauser Neck Center testing method is unique in that during part of the examination the neck vessels are screened at the same time the brain blood vessels are while the neck is put through various motions. This real-time examination can reveal hidden areas of vascular compromise or vasospasm and determine where in the neck it is happening. This can then be compared to finding on digital motion x-ray (DMX) and other diagnostic studies to determine what is the underlying pathology in the neck leading to the decrease in blood flow.


Transcranial doppler (TCD) ultrasound provides real-time measurements of the blood flow in the arteries that go to the brain. It is done with a 2MHz frequency ultrasound probe that can send a sound wave many inches within the skull to measure the blood flow to the deep brain arteries. The blood supply to the eye can also be determined.

This blood flow can be determined while the person moves their head and neck in various positions to see if the flow decreases and thus is compromised. When these conditions affect the vertebrobasilar arteries it is called vertebrobasilar artery insufficiency, or when a significant symptom appears and then resolves completely within an hour it is called a vertebrobasilar insufficiency transient ischemic attack. Many people have symptoms that are actually “mini strokes” or ischemic attacks (brain angina) and don’t even realize what has happened. Symptoms such as double vision, dysarthria, dysphagia, loss of balance, vertigo, sensory symptoms on one part of the body, disequilibrium, drop attacks, ataxia, alternating paresthesia, tinnitus, perioral numbness and other symptoms that last less than one hour are suggestive of significant compromise of brain flow through the vertebrobasilar symptom. TCD is a noninvasive test that is done at the Hauser Neck Center at Caring Medical Florida to diagnose vertebrobasilar insufficiency or ischemia, as well as analyze compromises in the carotid arterial system.

The blood supply to the brain, brainstem, and even the eye can be checked right in a doctor’s office. In general, there are four main places that the sound waves can penetrate deep within the skull: (1) temporal bone, (2) orbit, (3) submandibular, and (4) occipital bone. Basically, the arteries in the Circle of Willis can be found by pulsating sound waves (insonation) in these areas toward the arteries. What can be determined is: (1) direction of blood flow, (2) depth of the artery, (3) flow velocity, (4) change in flow velocity with a change in neck motion or position, (5) change in flow velocity with change in neck support (with collar or supine),  (6) change in flow velocity to changes in brain CO2 levels (hyperventilation or holding breath),  (7) change in flow velocity to changes in muscles contraction or light exposure, and the most important factor (8) which blood vessel(s) are involved causing the symptoms!

The testing protocol at our facility involves baseline measurements of some of the arteries of the Circle of Willis while supine and upright. Then the patient is put through various neck motions such as flexion, extension, rotation and then a combination of motions while the TCD prone is fixated in position of measurement. Various stressors besides neck position can be tested, including cerebral vasoreactivity to changes in CO2 levels by holding one's breath or hyperventilating. As one hyperventilates, the CO2 levels in the brain decrease, which causes arterial vasoconstriction (pulsatile index to increase) and a decrease of up to 50% in cerebral blood flow velocities. Holding one’s breath causes the arteries to dilate and increases the brain artery blood flow (i.e. middle cerebral artery). Changes of CO2 levels can be used to bring out vasospasms when checking the blood flow to the brain with various neck positions. When blood vessels are healthy and not under spasm, they can quickly and appropriately change diameter to increases or decreases in blood flow. Changes in blood flow are noted to neck motions (and other stressors including CO2 levels), along with any symptoms that are provoked (pain, dizziness, loss of balance, headache).


The blood flow to the brain ultimately comes from arteries that go from the heart through the neck to the brain. The blood flow velocity in the arteries in the neck including the common carotid, internal and external carotid and vertebral can be checked in the supine, upright and in various neck positions (or with movement). The various blood vessels are seen in gray-scale or B-mode imaging. This is the imaging that checks the vessels for atherosclerotic plaque and thrombus. Color doppler imaging is used to show areas of narrowing and abnormal flow to select areas for spectral analysis so the blood flow can be checked. Not only can blood flow velocities be checked but also the pulsatile index, a measure of the resistance to blood flow. The color blood flow can also identify the small branches of the arteries that may need to be checked.  There’s no telling what the test may find, and it is something that we’ve recommended for many people! For instance, Dr. Hauser was found to have a decrease in blood flow to his brain with neck extension with rotation, which explained his dizziness, brain fog and disconnected feeling with swimming and also a drop attack he experienced. He underwent a Prolotherapy treatment series himself and we’re happy to report that he’s improved greatly!

Transient vasospasms in the arteries of the neck (spasm causing vasoconstriction or a decrease in blood flow) can be so severe that they can even cause strokes. Vasospasms are real and need to be determined which is done by dynamic extracranial doppler ultrasound examination.

Click here to read more about Vagospams and Dynamic Blood Flow Testing


Hospital ultrasound technicians are experts in finding atherosclerosis plaque in arteries, such as the carotid artery. They do this using B-mode and color ultrasound scans. The combination of B-mode analysis and color doppler is called duplex scanning. This is excellent at showing the characteristics of arterial plaque and the degree of stenosis. Carotid duplex ultrasound scans are typically done with a person lying flat on an examination table.

Vascular testing at the Hauser Neck Center does screen for plaque but that is not its primary purpose. We aim to discover if a person has compromised arterial blood flow because of neck position or movement because this type of scanning is not typically done at hospitals. The simple reason it is not done in hospitals is that there is no longer a billing code for looking at the change in blood flow for neck movement, so there is no way for hospitals to get paid for the motion part of the scan. Thus, it is not done. For the person with cervical arthritis, pain, and/or instability, the neck motion part of the scan is the most important part because it can show carotid or vertebral artery ischemia, or so-called “brain ischemia.” Heart ischemia causes angina (or chest pain), thus compromise of carotid and/or vertebral artery ischemia can cause brain angina (headache)!

Extracranial doppler tests done at the hospital do not test the vertebral artery at its V3 segment by the atlantoaxial joint (C1-C2). In our experience, this is where much of the compression is located. The hospitals test the vertebral artery at its V2 segment where it runs within the transverse foramina of C6 to C2. At the Hauser Neck Center, we test the blood flow to the important arteries in the brain and neck  with the patient in the supine and upright positions and during various neck positions. Because many of our patients have upper cervical instability, we do a thorough job of assessing for vertebral artery compression as it emerges from the transverse process of the axis and goes laterally to pass through the transverse foramen of the atlas and then through the foramen magnum into the brain. Ultimately, our protocols for vascular testing involve motion testing and showing how the various arteries response to stretch and motion in real-time! It is in the extremes of flexion, extension, and rotation where compromises of blood flow are seen in patients with cervical instability.


Patients often contact us in a hopeless state because of previous healthcare experiences but leave the first visit at Caring Medical extremely hopeful. This hope is well-founded because for the first time the person has been put through dynamic testing and shown what is causing their symptoms and, equally important, what can be done about it. To truly understand if and how symptoms are associated with the neck, it is important to analyze the following data:

  • Neck instability with digital motion x-ray;
  • Neck structure and motion with digital motion x-ray;
  • Blood flow through major arteries (supine, upright, and with the neck in various positions);
  • Vagus nerve function (baseline and under stressful situations, including various neck positions);
  • Autonomic nervous system function at baseline and under duress.

Once the testing is complete, a diagnosis can be determined and an appropriate treatment plan can be created. The success for patients at the Hauser Neck Center, is based on individualized treatment plans which rely upon a thorough understanding joint instability and cervical dysstructure and how to resolve these conditions with Comprehensive H3 Prolotherapy and appropriate supportive therapies. For some patients, these supportive therapies may include bracing, exercises, improvement in sleep habits, postural changes, and numerous other techniques.

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