Spinal manipulation and stroke
Spinal joint "thrust
has been practiced by manual therapists for centuries. It's a regulated
act in Ontario, practiced primarily by chiropractors but also by some
medical doctors and certified physiotherapists.
Thrust manipulation is an
effective method for the treatment of headaches (cervicogenic or neck
generated,1 tension,2 and
migraine3), post traumatic4
and chronic neck pain,5 mid-back pain,6
and lower back pain.7,8 Like any true therapy,
spinal manipulation is not without risk. Possible injuries with
manipulation, and most contact-type therapies which involve tissue
stretching and pressure, include muscle strains, ligament sprains,
intervertebral disk sprains, and joint capsule sprains, and bone
fractures. The incidence of these injuries is very low with the most
common complaint being temporary soreness and stiffness after the first
treatment,2 as would be expected with any type
of manual therapy.
The most serious injury
associated with cervical spinal manipulative therapy is stroke caused
directly by, or complications following from, the damage to the
vertebral and carotid arteries of the neck which supply blood to the
brain. This type of stroke is called a vertebrobasilar artery (VBA)
stroke—also called vertebrobasilar stroke (VBS)—or, more generally, a
cerebrovascular accident (CVA).
Here are the current
published and peer-reviewed (examined by experts in the field) facts
regarding the issue of chiropractic care, cervical spine thrust
manipulation, and stroke:
- VBA stroke is a very rare event. There is no difference in
the risk of such an event following a visit to a chiropractor or a
primary care physician (PCP). The incidence of VBA stroke
associated with chiropractic or PCP visits is likely due to patients
with headache or neck pain from existing VBA dissection seeking care
prior to their stroke. There is no evidence of excess risk
of VBA stroke associated with chiropractic care compared to PCP care.9 This
recent large study puts to rest a similar, but seriously
methodologically flawed study.10
- Motor vehicle accidents,
sports, cervical spine manipulation, and many activities of daily
living have been associated with injury to the arteries in the neck.11,12,13
These injuries can, very rarely, lead to VBA stroke.
- The best information at
this time indicates that the incidence of manipulation associated
stroke is 1 in 400,000 to 1 in 1.3 million treatment sessions and
generally acknowledged to be 1 in 1 million treatments (0.0001%).13
An article in the Canadian Medical Association Journal14
puts the risk at 1 in 5.85 million manipulations. There is indication
that these incidences are under-reported, however, the degree is
unknown. Because of the low number of incidences, the numbers are very
difficult to calculate with any degree of accuracy.
- There are no clear
indicators for who is at greater risk—the usual risk factors for stroke
(smoking, oral contraceptives, obesity, high blood pressure, and
diabetes) do not apply.13
- CVAs after manipulation
appear to be unpredictable and should be considered an inherent,
idiosyncratic, and rare complication of this treatment approach.15
The first scientific study16
of what actually happens mechanically to the vertebral artery during
cervical spine manipulation was published in late 2002. The authors
- Cervical spinal
manipulative therapy resulted in strains to the vertebral artery that
were almost an order of magnitude (10 times) lower than the strains
required to mechanically disrupt it.
- Under normal
circumstances, a single typical (high-velocity/low-amplitude) spinal
manipulative therapy thrust is very unlikely to mechanically disrupt
the vertebral artery.
In a commentary on the same
article,17 the authors stated:
- Vertebral artery
elongations (lengthening, not stretching) during neck manipulations are
always well within the elongations observed within the normal range of
- Vertebral artery
elongations during neck manipulation are always much smaller than the
elongations that cause first mechanical failure.
- For the elongations
observed during neck manipulation, there are no measurable forces
(stresses) acting on the vertebral artery.
They concluded again that
it was highly unlikely that a spinal manipulative treatment to the neck
can cause mechanical injury to a normal vertebral artery. The authors
also stated that someone severely predisposed to a vertebral artery
stroke could possibly have one following manipulation; however, the
same event would have also been triggered by a normal movement of the
neck, for example, when turning the head while backing out of a
- Nilsson N, Christensen
HW et al. The Effect of Spinal Manipulation in the Treatment
of Cervicogenic Headache. J Manipulative Physiol Ther.
- Boline P, Kassak K,
Bronfort G, Nelson C, Anderson A. Spinal Manipulation vs
Amitriptyline for the Treatment of Chronic Tension-Type Headaches.
J Manipulative Physiol Ther. 1995;18:148-154.
- Tuchin PJ, Pollard H,
Bonello R. A Randomized Controlled Trial of Chiropractic
Spinal Manipulative Therapy for Migraine. J Manipulative
Physiol Ther. 2000;23(2):91-95.
- Jensen OK, Nielsen FF et
al. An Open Study Comparing Manual Therapy with the use of
Cold Packs in the Treatment of Post-Traumatic Headache.
- Giles LGF, Muller R. Chronic
Spinal Pain Syndromes: A Clinical Pilot Trial Comparing Acupuncture, a
Nonsteroidal Anti-Inflammatory Drug, and Spinal Manipulation.
J Manipulative Physiol Ther. 1999;22(6):376-381.
- Schiller L. Effectiveness
of spinal manipulative therapy in the treatment of mechanical thoracic
spine pain: A pilot randomized clinical trial. J Manipulative
Physiol Ther. 2001;24:394-401.
- Waddell G, McIntosh A,
Hutchinson A, Feder G, Lewis M. Low Back Pain Evidence Review.
Royal College of General Practitioners. 1999.
- Management of
Acute Lower Back Pain - 343. The College of Physicians
& Surgeons of Manitoba. 1999
- Cassidy J, Boyle E, Cote
P, He H, Hogg-Johnson S, Silver F, Bondy S. Risk of Vertebrobasilar Stroke and
Chiropractic Care: Results of a Population-Based, Case-Control and
Case-Crossover Study. Spine. 2008;33(4S) Neck Pain
Task Force Supplement: S176-S183.
- Rothwell DM, Bondy SJ, Williams JI. Chiropractic
manipulation and stroke: A population-based case-control study.
- Rome PL. Perspective:
An overview of comparative considerations of cerebrovascular accidents.
Chiropractic Journal of Australia. 1999;29(3):87-102.
- Terrett AGL. Vascular
accidents from cervical spine manipulation. Journal of the
Australian Chiropractic Association. 1987;17:15-24.
- Haldeman S, Kohlbeck FJ,
McGregor M. Risk Factors and Precipitating Neck Movements
Causing Vertebrobasilar Artery Dissection After Cervical Trauma and
Spinal Manipulation. Spine. 1999;24(8):785-794.
- Haldeman S, Carey P,
Townsend M, Papadopoulos C. Arterial dissections following
cervical manipulation: the chiropractic experience. CMAJ.
- Haldeman S, Kohlbeck FJ,
McGregor M. Unpredictability of Cerebrovascular Ischemia
Associated With Cervical Spine Manipulation Therapy. Spine.
- Symons B, Leonard T,
Herzog W. Internal forces sustained by the vertebral artery
during spinal manipulative therapy. J Manipulative Physiol
- Herzog W, Symons B. Commentary:
The mechanics of neck Manipulation with special consideration of the
vertebral artery. J Can Chiropr Assoc. 2002; 46(3):135.