Cervical SMT and STROKE..

Across 25 years of comparative research, one pattern holds consistently: in the period before a stroke or artery dissection is diagnosed, patients were statistically just as likely to have seen a medical doctor as a chiropractor for the same neck pain or headache. The type of provider made no measurable difference to what followed — strong evidence that the symptoms themselves were an early sign of a dissection already in progress, not something either provider caused.

Evidence Timeline

A 25-Year Timeline: What the Research Actually Shows About Chiropractic Neck Care and Stroke Risk

By Dr Silver Esho | Chiropractor  |  25 September 2026

Concern about stroke and neck manipulation is one of the oldest and most persistent questions in this field, and it deserves a straight answer built from the actual research rather than a reassuring one-liner. Below is every major comparative study on this question published between 2001 and 2026, in the order it appeared. Scroll down through the timeline, tap any year to expand what that study actually found, and read the pattern that emerges by the end.

Early design — no active medical comparator

Comparator-controlled, self-controlled, or large-scale real-world design

2001

Rothwell, Bondy & Williams — Stroke

Case-control study, no active medical comparator · Ontario administrative data

Design gap identified

⌄

Found that people who had a stroke were more likely to have seen a chiropractor in the week beforehand. But the study had no comparison group of people who'd seen a family doctor for the same kind of symptoms — so there was no way to tell whether the manipulation caused the stroke, or whether the stroke's own warning signs (neck pain, headache from a dissection already under way) were what sent the patient to a chiropractor in the first place.

This gap — no active comparator — is exactly what the next generation of research was built to close.

2003

Smith, Johnston, Skalabrin et al. — Neurology

Case-control study · California stroke registries

Design gap identified

⌄

Reported spinal manipulation as an independent risk factor for vertebral artery dissection. It's one of the few studies in this timeline with a genuinely positive finding, and it's included for that reason — a fair review doesn't skip the results that complicate the story.

Worth noting: when the same broader registry data was later examined specifically for carotid artery dissection (26 cases), no association with neck manipulation was found at all. Even within this one research effort, the signal wasn't consistent across the two types of dissection.

2008

Cassidy, Boyle, Côté et al. — Spine

Population-based case-control + case-crossover · Ontario, 9 years, 100M+ person-years

Landmark comparator study

⌄

The study that changed how this question gets studied. Instead of simply asking whether stroke patients had seen a chiropractor, the researchers also asked how often the same patients had seen a family doctor for the same symptoms in the same time window.

The result: chiropractic visits and doctor visits carried statistically similar associations with vertebrobasilar stroke. Neither one caused it. The most plausible explanation — a dissection developing in the neck already causes headache and neck pain, and patients seek care for that pain from whichever provider they'd normally see, before the stroke becomes obvious.

2015

Kosloff, Elton, Tao et al. — Chiropractic & Manual Therapies

Case-control study · US commercial & Medicare Advantage claims

⌄

No significant association was found between chiropractic visits and vertebrobasilar stroke in this large US claims dataset — one of the largest insurance-based comparisons attempted on this question at the time.

2015

Whedon, Song, MacKenzie et al. — J Manipulative Physiol Ther

Retrospective cohort · Medicare beneficiaries aged 66–99 with neck pain

⌄

Tracking over a million older adults who sought care for neck pain from either a chiropractor or a primary care physician, this study found no meaningful increase in stroke risk after a chiropractic visit compared with a medical visit for the same complaint. Absolute stroke incidence following either type of visit was very low in both groups.

2016

Church, Sieg, Zalatimo et al. — Cureus

Systematic review + meta-analysis of the accumulated literature

⌄

Applying formal causation criteria (Bradford Hill) directly to the pooled evidence, this review found only one of nine causation criteria was clearly satisfied, and rated the overall certainty of the evidence as very low. Their stated conclusion: no evidence for a causal link between chiropractic care and cervical artery dissection.

2017

Cassidy, Boyle, Côté, Hogg-Johnson, Bondy & Haldeman — J Stroke Cerebrovasc Dis

Case-crossover, chiropractor vs. doctor comparator · Ontario, 15,523 carotid stroke cases

⌄

The same comparator logic as 2008, applied specifically to carotid stroke. Result: no excess risk of carotid stroke after chiropractic care. Chiropractor and doctor visits carried statistically indistinguishable risk at every time window tested (1, 3, 7, and 14 days).

In patients 45 and older — 98.6% of all cases in the study — there was no positive association with chiropractic care at all.

2023

Chu, Trager, Lee & Niazi — Scientific Reports

Real-world safety surveillance, medical-record verified · Hong Kong, 960,140 SMT sessions, 54,846 patients

⌄

Rather than inferring risk from population-level associations, this study tracked actual adverse events across nearly a million real chiropractic treatment sessions, each one corroborated against medical records.

Result: zero cases of stroke, TIA, or cervical/carotid artery dissection. The only serious (grade 3) events recorded across the entire dataset were two rib fractures, both in older women with pre-existing osteoporosis, from thoracic — not cervical — technique.

2023

Whedon, Petersen, Schoellkopf, Haldeman, MacKenzie & Lurie — European Spine Journal

Case-control (two comparator groups) + case-crossover · US claims, 2,337 VAD + 2,916 CAD cases Mixed finding

⌄

The most methodologically thorough study in this timeline, testing the question three separate ways with three different control groups. Two of the three approaches — comparison against the general population, and comparison against the same patients' own history — found reduced or no increased risk of cervical artery dissection with chiropractic care.

The third approach, comparing against people who'd had an unrelated ischemic stroke, produced one complicating result for vertebral artery dissection specifically. This is worth stating plainly rather than smoothing over. But the authors themselves note the finding was highly sensitive to which control group was used, disappeared under the other two methods in the very same study, and — even taken entirely at face value as a real causal effect — would represent an increase in absolute risk from roughly 1 to 3 cases per 5 million person-weeks. They conclude the association is more likely explained by differences in how patients with underlying vascular disease seek care than by manipulation itself causing harm.

2026

Trager, Baumann, Labak et al. — Chiropractic & Manual Therapies

Propensity-matched retrospective cohort, active-comparator design · 431,492 patients per arm, SMT vs. ibuprofen

⌄

The largest and most tightly matched study to date, and the first to benchmark against a common over-the-counter pain reliever instead of another provider visit. After propensity matching, patients who received chiropractic neck manipulation for neck pain or headache had a lower incidence of cervical artery dissection than patients prescribed ibuprofen for the same complaint (relative risk 0.53).

The authors are careful about how they frame this — they treat it as evidence that chiropractic care is not riskier than a common medical alternative, not as proof that manipulation actively protects against dissection. The most likely explanation for the lower observed rate is that chiropractors already tend to avoid manipulating necks they judge to be higher risk, rather than manipulation itself lowering risk.

The Pattern, After 25 Years

Read in order, these ten studies tell a coherent story about how this question got answered, not just what the answer is.

The earliest studies (2001, 2003) simply noticed that people who'd had a stroke had often seen a chiropractor recently. On its own, that observation can't distinguish two very different explanations: either the manipulation caused the stroke, or the stroke was already brewing — via an artery quietly tearing in the neck — and the headache and neck pain it produced sent the patient looking for care, of any kind, before anyone knew what was actually happening. This is called protopathic bias, and it's a well-known trap in this kind of research.

Every major study from 2008 onward was built specifically to tell those two explanations apart — by comparing chiropractic visits to doctor visits for the same symptoms, by comparing each patient to their own history before and after the event, or by comparing against an active medical alternative like ibuprofen. In every one of those better-designed studies, the excess risk attributed to chiropractic care specifically disappeared, reversed, or came out statistically indistinguishable from ordinary medical care for the same complaint. A near-million-session, medical-record-verified safety study recorded not a single stroke or dissection. The most recent and largest matched comparison found chiropractic care statistically safer than a common over-the-counter medication.

The one exception worth naming: the 2023 Whedon study's finding for vertebral artery dissection against stroke-patient controls didn't disappear as cleanly as the others, and a fair timeline doesn't pretend it did. But that same study found the opposite result under its other two designs, the authors attribute it most plausibly to how sicker patients seek care rather than to manipulation causing harm, and even a literal causal reading implies a genuinely tiny absolute risk. One complicated result inside an otherwise consistent 25-year pattern is a reason for honesty, not a reason to throw out everything else.

Put simply: across four countries and healthcare systems, several independent research teams, and a quarter-century of steadily improving methods, NO study capable of separating cause from coincidence has shown that chiropractic neck manipulation independently increases the risk of stroke or cervical artery dissection BEYOND the risk of simply having neck pain or a headache and going to get it looked at — by ANYONE.

Sources

1. Rothwell DM, Bondy SJ, Williams JI. Chiropractic manipulation and stroke: a population-based case-control study. Stroke. 2001;32:1054–1060.
2. Smith WS, Johnston SC, Skalabrin EJ, et al. Spinal manipulative therapy is an independent risk factor for vertebral artery dissection. Neurology. 2003;60:1424–1428.
3. Cassidy JD, Boyle E, Côté P, et al. Risk of vertebrobasilar stroke and chiropractic care: results of a population-based case-control and case-crossover study. Spine (Phila Pa 1976). 2008;33:S176–S183.
4. Kosloff TM, Elton D, Tao J, et al. Chiropractic care and the risk of vertebrobasilar stroke: results of a case-control study in U.S. commercial and Medicare Advantage populations. Chiropr Man Therap. 2015;23:19.
5. Whedon JM, Song Y, Mackenzie TA, Phillips RB, Lukovits TG, Lurie JD. Stroke after chiropractic spinal manipulation in Medicare B beneficiaries aged 66 to 99 years with neck pain. J Manipulative Physiol Ther. 2015;38:93–101.
6. Church EW, Sieg EP, Zalatimo O, Hussain NS, Glantz M, Harbaugh RE. Systematic review and meta-analysis of chiropractic care and cervical artery dissection: no evidence for causation. Cureus. 2016;8:e498.
7. Cassidy JD, Boyle E, Côté P, Hogg-Johnson S, Bondy SJ, Haldeman S. Risk of carotid stroke after chiropractic care: a population-based case-crossover study. J Stroke Cerebrovasc Dis. 2017;26(4):842–850.
8. Chu EC-P, Trager RJ, Lee LY-K, Niazi IK. A retrospective analysis of the incidence of severe adverse events among recipients of chiropractic spinal manipulative therapy. Sci Rep. 2023;13:1254.
9. Whedon JM, Petersen CL, Schoellkopf WJ, Haldeman S, MacKenzie TA, Lurie JD. The association between cervical artery dissection and spinal manipulation among US adults. Eur Spine J. 2023;32(10):3497–3504.
10. Trager RJ, Baumann AN, Labak CM, Lewis KL, Perez JA, Goertz CM, Schuster A. Association between spinal manipulative therapy and cervical artery dissection in patients with neck pain or headache: a retrospective cohort study. Chiropr Man Therap. 2026;34:53.