Vertebral Artery Testing

VBI Test (George’s Test) is positioning of the neck to screen for who is at risk of dissecting (tearing) of the vertebral artery during a neck adjustment, and/or who is at risk of having a stroke due to a neck adjustment.  It is not supported by science.

Continue to do this test until your State Board of Chiropractic, the malpractice insurance companies, and the risk management firms state you can stop.  This is a legal standard, but not a clinical standard of care.  The odd side of this is that, in the right patient, just doing this test could dissect (tear) the vertebral artery.1 

Before the VBI Test, studies were done by medical doctors.  About fifty years ago, medical researchers injected a contrast dye into the vertebral arteries of cadavers.  When the neck/head was faced straight ahead, the dye flowed through the cadavers’ arteries.  When the head was turned to either side, the opposite vertebral artery was pinched off.  Based on these findings, medical doctors came to the conclusion that patients should not have their necks adjusted by chiropractors, as patients may suffer strokes as a result.

One can see that this makes as much sense as the statement, “Did you walk to work, or did you take your lunch.”
Turning the head to one side, causing the vertebral artery to be physically occluded by an upper vertebrae in a cadaver is different than in a live person, as a live person has blood flow and “collateral circulation”; therefore, the blood can flow in from other arteries and make up for the temporary occlusion.  Medical science supports this.  Surgeons can even surgically close a vertebral artery (in the correct patient) and a stroke will not occur, due to “collateral circulation.”  Thus, medical doctors’ comparing of the cadaver studies to human ones is not even supported by their own medical practice.

VBI risk factors
based on:

 The following are VBI (Vertebro-basilar insufficiency) risk factors.
Special questions relating to these symptoms or signs , should be asked and the results recorded, as part of the VBI Test.

  • drop attacks, black outs, loss of consciousness
  • nausea, vomiting and general unwell feelings
  • dizziness or vertigo, particularly if associated with head positioning
  • disturbances of vision (e.g., decreased, blurred, diplopia)
  • unsteadiness in the gait (ataxia) and general feelings of weakness
  • tingling or numbness (especially, dysaethesia i.e., tingling around the lips, hemianaesthesia or any alteration in facial sensation)
  • difficulty in speaking (dysarthria) or swallowing
  • hearing disturbances (e.g., tinnitus, deafness)
  • headache
  • past history of trauma cardiac disease, vascular disease, altered blood pressure, previous cerebrovascular accident or transient ischaemic attacks
  • blood clotting disorders
  • anticoagulant therapy
  • oral contraceptiveslong term oral steroids
  • a history of smoking 
  • immediately post partum

(Kleynhans & Terrett, 1985; Grant, 1988; Hutchinson, 1989; Chapman-Smith, 1994; Kunnasmaa & Thiel, 1994; Rivett, 1994; Carey, 1995; Rivett,1995; Grant,1994; Kuether et al, 1997; Rivett, 1997; Kesson & Atkins, 1998; Di Fabio, 1999).

Using our own life experience, we know that, even on a common sense basis, the medical doctors’ conclusion of comparing the cadaver studies to human ones is flawed.  We all turn our heads to either side, and may even hold them in the turned position, yet we do not have strokes as a result.  Also, consider neck movement when driving cars, backing up cars, checking the blind spots, and turning our heads to look to the side.  By using the medical doctors’ logic, there should be a high frequency, or at least a regular occurrence, of vertebral artery related strokes.  We all know this just does not happen.  Shouldn’t the medical doctors warn the general public, “Do not turn your neck when driving; in fact, do not turn your neck at all!”  But, the medical doctors do not; they just say, “Do not have your neck turned in a chiropractor’s office!”

The medical research states there is an unidentified weakness in certain people’s vertebral arteries and they can dissect (tear) spontaneously or with simple neck motion.

Will the VBI Test help identify who is at risk to dissect an artery with the neck motion during a chiropractic adjustment.  No, as it does not identify the patients who have unidentifiable weaknesses in the arteries.  But, the VBI motion could actually dissect the vertebral artery in a patient that has this unidentifiable weakness of the artery.
Will the VBI Test help identify a patient that will have a stroke from the chiropractic adjustment?  The stroke can occur due to a thrombus (clot) or emboli (clot that breaks loose and goes further in the blood vessel before it gets stuck).

Again, without the dissection, or vasospasm, the clot would probably not form.  If the patient walked into the doctor’s office with the dissection and clot already, which is likely the occurrence, the collateral circulation (blood flow from other areas) would keep the neurological symptoms from happening.  The patient would have been turning the head in their every day activities.  The fact that there had been no identifiable neurological symptoms when the patient came to the office shows the VBI Test would not have made a difference.

Dr. Daniel P. Dock is a Board Certified Chiropractic Neurologist and a Board Certified Chiropractic Orthopedist.  He has written four books:  A False Claim:  Stroke From Manipulation; Whiplash Trauma; Records Documentation; and The Orthopedic Spinal Examination.  The recipient of the Minnesota Chiropractic Association-President’s Award, Washington State Chiropractic Association’s Volunteer of  the Year Award, Georgia Chiropractic Association’s Honorary Life Time Membership, Dr Dock lectures at over sixty continuing education seminars per year.  He also maintains an active practice in Minnesota.

For more about Dr. Dock call 218-525-2033 or  e-mail [email protected]


  1. Dock, DP.  Stroke & Chiropractic Adjustments.  The American Chiropractor, V25, I6, p.52.

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