To the Biomechanics List

I am forwarding a response to the following request from Darren A Rivett.

Stephen Perle, D.C.
Assistant Professor of Clinical Sciences
University of Bridgeport College of Chiropractic
Bridgeport, CT 06601

On 2/16/95 Darren A Rivett wrote:
> >> I am interested in determining the incidence of cerebrovascular
> >> complications caused by cervical manual therapy/manipulation. This
> >> includes
> >> all professions using such techniques eg physios, osteopaths,
> >> chiropractors etc.
> >> I understand that the Swiss Association of Manual Medicine
> >> retrospectively found the risk factor to be 1 in 400,000
> >> manipulations.
> >> Is anyone aware of any other studies or estimates of the incidence
> >> of strokes related to manual therapy (current or completed)?
> > Darren A Rivett
> > Dunedin, New Zealand

Forwarded message:
> Studies Estimating the Risk of Stroke from Cervical Manipulation:
> Every published which has estimated the incidence of stroke from cervical
> manipulation has agreed that the risk is 1 to 3 incidents per million
> treatments. Dvorak, (1) in a survey of 203 practitioners of manual medicine
> in Switzerland, found a rate of one serious complication per 400,000 cervical
> manipulations, without any reported deaths, among an estimated 1.5 million
> cervical manipulations. Jaskoviak (2) reported approximately 5 million
> cervical manipulations from 1965 to 1980 at The National College of
> Chiropractic Clinic in Chicago, without a single case of vertebral artery
> stroke or serious injury.
> Henderson and Cassidy (3) reported a survey done at the Canadian Memorial
> Chiropractic College outpatient clinic where more than a half-million
> treatments were given over a nine-year period, again without serious
> incident. Eder (4) offered a report of 168,000 cervical manipulations over a
> 28 year period, without a single significant complication. After an extensive
> literature review performed to formulate practice guidelines (5), the
> authors concurred that the risk of serious neurological complications from
> cervical manipulation] is extremely low, and is approximately one or two per
> million cervical manipulations.
> In another survey, based on a computerized registration system in Holland,
> Patjin (6) found an overall rate of one complication in 518,886
> manipulations. A survey of California neurologists (7), which inquired
> about the number of patients they had treated who had suffered a stroke
> within 24 hours of cervical manipulation, estimated the rate of stroke to be
> about one in 500,000 manipulations. Other experts on manipulation (8) have
> published opinions that the risk of stroke from cervical manipulation is two
> or three more-or-less serious incidents per million treatments.
> In addition to these published studies, data from the National Chiropractic
> Mutual Insurance Company (NCMIC), which insures over 50 percent of US
> chiropractors, is also useful for estimating the risk of cervial
> manipulation. Since chiropractors deliver over 80 percent of the spinal
> manipulation performed in the US, and this company insures about one-half of
> the profession in the US, this malpractice insurer is a good source of
> statistics on this subject. They reported that strokes accounted for about 5
> percent of the 700 claims settled against their 24,000 members in 1993.
> Using this figure, we calculate there are about 35 strokes per year among
> the chiropractors insured by NCMIC.
> However, we have learned that these published statistics are based upon the
> total amount of money paid for claims. Since claims for strokes tend to be
> more costly, the figures are skewed. According to a member of NCMIC Board
> of Directors (personal communication with Louis Sportelli, DC, Dec. 21,
> 1994), in the three years of 1991-92-93, NCMIC closed a total of 96 claims
> for CVA; of this total 61 were closed with payment, and 35 were closed
> without payment. If one concludes that there was little or no merit to the
> 35 claims which were closed without payment, this would represent an average
> of 20 CVA claims per year. If these NCMIC chiropractors are similar to the
> national average, they see approximately 120 patient visits per week (9).
> Curtis and Bove (10) report that rotary adjustments of the cervical spine
> comprise about 30% of the visits made to chiropractors. Therefore,
> chiropractors insured by NCMIC each performed some 1800 cervical
> manipulations in each of those three years. Considering these numbers, we
> calculate that NCMIC's 24,000 DCs perform some 43,000,000 cervical
> manipulations per year. If this leads to 20 strokes, that's a rate of less
> than one stroke per 2 million cervical manipulations.
> Based upon these studies, the most reasonable estimate of the risk of stroke
> from cervical manipulation is one-half to two incidents per million
> manipulations performed. Only a minority of these cases are fatal. About
> one-third of the cases of stroke following cervical manipulation reported in
> Terrett's review of 107 cases (11) resolved with mild or no residuals. In a
> later review, Terrett (12) found a total of 126 cases of vertebrobasilar
> accidents following manipulation reported in the international literature
> from 1934-1987, of which 29 cases resulted in death. This yields a mortality
> rate of 23% among the incidences reported in the literature. While it has
> been argued that the rate of strokes may be significantly under-reported in
> the literature, it is probable that the rate of deaths are proportionally
> over-reported, since it is likely the more serious and impressive cases would
> be described in the literature.
> * A reasonable estimate of the risks of stroke following cervical
> manipulation is 1/2 to 2 incidents per one million treatments.
> * About one-third resolve with mild or no residuals (probably more due to
> reporting bias).
> * About one-fourth prove fatal (probably less due to reporting bias).
> * Therefore, there are about 40-50 manipulation-caused strokes in the US per
> year, and perhaps a dozen deaths, out of some 80-90 million neck
> manipulations.
> Compare this risk to the 3-4% rate of complication for cervical spine
> surgery, and the 4,000-10,000 DEATHS per million neck surgeries (13) Or,
> compare it to the risk from the most conservative treatment of neck pain,
> prescription of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs). One author
> (14) estimates 32,000 hospitalizations due GI hemorrhage from NSAID use for
> musculoskeletal complaints and osteoarthritis per year in the US (a rate of
> 0.4%). He estimates 3,200 deaths from GI hemorrhage due to NSAID use for
> musculoskeletal complaints annually.
> Bill Lauretti, DC
> Bethesda, Maryland
> BillLaur@AOL.COM
> 1. Dvorak J, Orelli F. How dangerous is manipulation to the cervical spine?
> Manual Medicine 1985; 2: 1-4.

> 2. Jaskoviak P. Complications arising from manipulation of the cervical
> spine. J Manip Physiol Ther 1980; 3: 213-19.

> 3. Henderson DJ, Cassidy JD. Vertebral Artery syndrome. In: Vernon H. Upper
> cervical syndrome: chiropractic diagnosis and treatment. Baltimore: Williams
> and Wilkins, 1988: 195-222.

> 4. Eder M, Tilscher H. Chiropractic therapy: diagnosis and treatment
> (English translation). Rockville, Md: Aspen Publishers, 1990: 61.

> 5. Haldeman S, Chapman-Smith D, Petersen DM. Guidelines for chiropractic
> quality assurance and practice parameters. Gaithersburg, Md: Aspen Publishers
> 1993: 170-2.

> 6. Patijn J. Complications in Manual Medicine: A Review of the Literature.
> J Manual Medicine 1991; 6: 89-92.

> 7. Carlini W, Lee P, et al. Incidence of stroke following chiropractic
> manipulation. In press. Based on abstract and press release presented at
> American Heart Association's 19th International Conference on Stroke and
> Cerebral Circulation, San Diego, February 19, 1994.

> 8. Guttman G: Injuries to the vertebral artery caused by manual therapy
> (English abstract), Manuelle Medizin 1983; 21: 2-14.

> 9. Plamandon RL. Summary of 1992 ACA annual statistical survey. ACA J
> Chiropractic 1993; 30 (Feb): 36-42.

> 10. Curtis P, Bove G. Family physicians, chiropractors, and back pain. J
> Family Practice 1992; 35 (5): 551-5.

> 11. Terrett AG. Vascular accidents from cervical spine manipulation: Report
> of 107 cases. J Aust Chiro Assoc 1987; 17: 15-24.

> 12. Terret AG, Kleynhans AM. Cerebrovascular complications of manipulation.
> In: Haldeman S., ed. Principals and Practice of Chiropractic. Norwalk,CT:
> Appleton & Lang, 1992: 579-98.

> 13. The cervical spine research society editorial committee. The Cervical
> Spine, Second edition. Philadelphia: J.B. Lippincott Company 1990: 834.

> 14. Fries, JF. Assessing and understanding patient risk. Scand J Rheumatol
> 1992; Suppl. 92: 21-4.