Stroke Due to Cervical Manipulation

"Cervical manipulation remains a safe, effective procedure with minimal side-effects when the standards of care are followed."

As an expert witness in the field of chiropractic negligence for over 10 years, I have been involved in more than 600 cases throughout the United States. Of the cases reviewed, more than 150 involved allegations of a cerebrobasilar injury caused by chiropractic cervical manipulation. In all but a few of these situations, the chiropractor violated the standard of care and a causal relationship to the treatment and resulting injury was apparent. A stroke or arterial dissection associated with chiropractic treatment is a tragic, life-altering situation for all parties involved.

Vertebrobasilar accidents account for just over 5 percent of the malpractice suits filed each year, but they are among the most serious. These injuries frequently result in permanent neurological deficit, psychological trauma, quadriplegia and/or death. Many of these lawsuits result in settlements well in excess of a million dollars. This alone is a compelling reason to maintain higher limits of liability coverage.

Overall, the chiropractic profession has downplayed the risk of stroke through cervical manipulation. Early studies and opinions held that the risk was minimal, and that cervical manipulation has not been conclusively proven to cause vascular accidents. More recent information and studies suggest the risk of stroke due to cervical manipulation is still very low, but higher than past information would indicate. One problem encountered researching this subject is the lack of complete, concise, data from which to draw accurate conclusions. The number of patients under chiropractic treatment has increased dramatically in recent years, without a corresponding rise in manipulation-induced strokes. Hopefully, this indicates that even with more exposure, improved chiropractic education, screening procedures and increased awareness may be starting to have a positive effect.

In 1972, Maigne suggested, "There is probably less than one death of this nature out of several tens-of-millions of manipulations." In 1982, Cyriak stated, "This risk works out to about one in ten million manipulations, and is no argument against manipulation reduction in suitable cases." In 1981, Hosek, et al., suggested, "We may form a conservative likelihood estimator by looking at the ratio of vertebrobasilar injuries to adjustments performed. This ratio would be 100 injuries per/100 million adjustments, about one in a million." In 1983, Gutmann concluded, "There are two to three serious incidents involving the vertebrobasilar system in one million manipulations to the upper cervical spine." In 1985, Dvorak and Orelli stated that "following an inquiry amongst the members of the Swiss Medical Group for Manual Medicine, it was calculated that there were slight neurological complications in one in 40,000; and one important complication in 400,000 cervical manipulations."

Current studies estimate that one out of every two practitioners may have a patient suffer a serious cerebrovascular injury in his or her professional lifetime. Recent high-publicity deaths of young adults in Canada from cervical manipulation prompted a population-based case-control study. The results from this study have prompted some medical experts to conclude that the risk of a vertebrobasilar injury from cervical manipulation may be as high as 1.3 incidents per 100,000 cervical manipulations. In March 2001, The New England Journal of Medicine estimated that the incidence of vertebral or carotid artery dissections may even be as high as one incident per 20,000 cervical manipulations. As more information is obtained, the risk factors have steadily increased.

My experience as a forensic expert leads me to conclude that the risk of stroke from cervical manipulation is greater than current literature suggests. In some cases I have reviewed, people died as a direct result of cervical spinal manipulation. In almost all of these cases dealing with vascular injuries, the incident could have been avoided or lessened with a proper history, vascular screening, avoidance of rotational manipulation, and/or closer monitoring of posttreatment progress.

Recognizing the increased risk is just the first step. The next question is, how do these vascular injuries occur, and what are some of the risk factors? The vertebral arteries are where the vast majority of cervical manipulation injuries occur, with a smaller number affecting the carotid arteries. Injuries occur either from direct trauma to the vessel wall or through subsequent vasospasm following treatment. Research and current data suggest that rotational manipulation of the upper cervical spine is the type of maneuver most likely to cause a stroke. Damage to the arterial wall through stretching, kinking, tearing or direct trauma can cause sufficient damage to disrupt vascular flow to certain areas of the brain, resulting in ischemia. Damage to the inner vessel wall, the intima, may result in a dissection or tearing of the wall. This damage can initiate the clotting response, with subsequent embolus formation altering blood flow to the brain. Signs and symptoms of ischemia usually occur during or shortly after upper cervical manipulation.

The demographics of cerebrovascular injury with cervical manipulation indicate that middle-age men and women in the 30-45 age range are in the highest risk group. For years, it was incorrectly assumed that this type of stroke risk was higher in the elderly, due to vascular degenerative changes and athrosclerosis. The most common presenting symptoms of patients suffering strokes are headache, neck pain and cervical muscle spasms.

In an excellent article,¹ Dr. Edward Sullivan recommended the following screening procedures be followed prior to performing cervical manipulation:

Part 1 - High-risk categories noted in the history

1. Hypertension
2. Transient ischemic attacks
3. Smoking (length of time is important)
4. Whiplash or cervical strain/sprain
5. Family history of strokes
6. Medications affecting hemodynamics (antihypertensives, oral contraceptives or regular aspirin use)
7. Arteriosclerosis
8. Cardiovascular disease
9. Diabetes
10. Cervical spine spondylosis or spurring.
11. Constant headaches (several days duration)
12. Migraines
13. Known congenital arterial cervical anomaly (absent vertebral artery, etc.)
14. Cervical arterial surgery
15. Radiographic evidence of atlanto-occipital ligament ossification or a cervical anomaly (spina bifida, posterior ponticle, etc.)

Part 2 - Symptomatic systems review

1. Diplopia
2. Bilateral blurred vision
3. Monocular blindness
4. Ataxia
5. Tinnitis
6. Hearing loss in one or both ears
7. Slurred speech
8. Dizziness
9. Difficulty in swallowing
10. Loss of consciousness
11. Temporary lack of understanding
12. Drop attacks without loss of consciousness
13. Numbness or loss of sensation anywhere in the body
14. Weakness, loss of coordination or strength anywhere in the body

Part 3 - Hypertension, subclavian, and carotid artery: stenosis/occlusion

• Checking bilateral blood pressures; noting significant discrepancy.
• Palpate and measure bilateral radial pulse; checking for weakness or absence.
• Auscultate for bruits and palpate; bilateral supraclavicular fossas and carotid bifurcations.

Part 4 - Vertebrobasilar artery functional maneuver test (George's Test)

Have the patient rotate his/her head as far to the right as possible and hyperextend the neck for 3-5 seconds. Observe for signs of ischemia; if negative, proceed to the left side.

The most common signs of vertebrobasilar ischemia include dizziness; nausea; nystagmus; blurred vision; syncope; slurred speech; weakness; paresthesia; and numbness.

If the patient has a positive George's Test, do not perform a cervical adjustment. If the history and review of systems place the patient in a high-risk category, referral to an appropriate medical specialist may be indicated. If the patient exhibits signs of ischemia during or following cervical manipulation, do not readjust the patient. Observe the patient closely, periodically monitoring vitals while checking the progression of the ischemic signs and symptoms. If the ischemia persists or becomes more pronounced, immediately transport the patient to the nearest hospital.

These screening procedures are highly effective in preventing cerebrovascular incidents, as evidenced by the experience at the outpatient clinics at my alma mater, National College of Chiropractic. Several millions of cervical adjustment has been given at the National College, without a single reported vertebrovascular incident. The obvious conclusion is that cervical manipulation remains a safe, effective procedure with minimal side-effects when the standards of care are followed.

Reference

1. Sullivan E. Screening prior to cervical adjustments can prevent strokes. Chiropractic Economics 1988.

Alan H. Bragman, DC
Atlanta, Georgia