Cervical Artery Dissection and Chiropractic in The Neurologist: What the STOP-CAD Subanalysis Shows, and Where Both Sides Overreach

The Study

STOP-CAD (Stroke Outcomes in Patients with Cervical Artery Dissection) is a large multinational registry of imaging-confirmed cervical artery dissections. This subanalysis, led by Aleyadeh and colleagues, asked a narrow question: among 4,023 registry patients, who had a documented cervical manipulation in the 30 days before the dissection was diagnosed, and how did those patients differ from the rest?

The design is observational and retrospective. It captures an antecedent event, manipulation in the prior month, not a controlled exposure. There is no denominator of total manipulations performed, so the study cannot produce an incidence rate or an absolute risk per adjustment. It can only describe the patients inside a pool of people who already had a dissection. That is an important constraint, and the authors are careful about it.

What They Found

Read the first two rows together before anything else. The headline of the paper, and of nearly every news write-up that followed, is the manipulation association. The actual finding is that 95% of confirmed dissections in this registry had no manipulation at all. A subanalysis built around the 5% can tell you about that subgroup. It cannot tell the average patient that an adjustment is what tore the artery, because in 19 of every 20 cases there was no adjustment.

In 19 of every 20 confirmed dissections, there was no manipulation anywhere in the story.

The subgroup differences are real and worth stating honestly. Patients whose dissection followed a manipulation were more likely to be younger and female, and more likely to have a vertebral artery tear than a carotid one. That fits the anatomy: the vertebral artery runs through the bony canals of the cervical spine and is the one mechanically engaged by rotational neck movement. None of that establishes cause. It describes who is in the subgroup, which is a different question from what put them there.

The most important sentence in the paper is the authors' own admission. They wrote that "whether manipulation acts as a precipitating trigger or patients with early CeAD symptoms seek manipulation remains unresolved." When the investigators who ran the study say the cause question is open, that is not a chiropractor spinning the result. That is the published conclusion.

After Is Not Because

The reason that admission matters is a problem this literature has never escaped: a dissection announces itself with exactly the symptoms that send a person looking for neck care. The early, in-progress phase of a cervical artery dissection commonly produces neck pain and headache days to weeks before any stroke. A person with a new, nagging neck ache does what people do. They book a massage, see their doctor, or visit a chiropractor.

The cleanest evidence on this is still Cassidy 2008, a population-based study of roughly 818 vertebrobasilar strokes across 9 million person-years in Ontario. Patients under 45 who had this kind of stroke were about three times more likely to have seen a chiropractor in the days before. That figure gets quoted everywhere. The other half of the same finding almost never does: those patients were also more likely, to a similar degree, to have seen a primary care physician beforehand. Primary care physicians do not perform cervical manipulation. If the visit to the doctor carries the same association as the visit to the chiropractor, the visit is not the cause. The reason for the visit is. The authors concluded there was no evidence of excess stroke risk from chiropractic care compared with primary care.

A 2016 systematic review (Church et al.) reached the same place from a different angle: a small association (OR 1.74, 95% CI 1.26 to 2.41) with no convincing evidence of causation, most plausibly explained by confounding from the neck pain that precedes the dissection. For background scale, cervical artery dissection accounts for roughly 2% of all ischemic strokes but 10% to 25% in younger and middle-aged adults, a figure the 2024 American Heart Association scientific statement puts at up to 25% under age 50.

The Rebuttal, and Where It Overreaches

The chiropractic profession answered STOP-CAD with a Letter to the Editor (Tuchin et al.). Read fairly, much of it is correct, and the field is right to make these points in the journal record rather than only on clinic blogs.

The valid critiques are these. The 30-day antecedent window is wide; most adverse-event studies in physical therapy, osteopathy, and pharmacology use a 24 to 72 hour window, because an event a month earlier is a weak candidate for a mechanical trigger. The subanalysis does not compare chiropractic sessions against primary care sessions inside the same window, which is exactly the comparison that made Cassidy interpretable. Confounding by indication is real and largely unaddressed: the manipulation subgroup carried far more neck pain and more headache than controls, which is the signature of care-seeking for a dissection that has already begun. A retrospective registry of confirmed cases cannot adjudicate whether manipulation is a trigger, a risk factor, or a marker of where a symptomatic patient happened to go. And the term "chiropractic manipulation" is applied even though the registry could not always establish the practitioner's profession, in countries where cervical manipulation is performed by many provider types.

Then the Letter goes one step too far. It suggests prior chiropractic care may reduce dissection risk. The data do not support that, and I will not repeat it. A registry that cannot prove harm cannot, by the same logic, prove protection. Reaching for a protective claim mirrors the exact error the profession is right to criticize in the alarmist direction. The honest position is symmetrical: this design cannot show that manipulation causes dissection, and it cannot show that manipulation prevents it.

A study that cannot prove harm cannot prove protection either. Honesty has to run in both directions.

What This Means Clinically

For a practicing chiropractor, this body of evidence does not read as permission and it does not read as a verdict. It reads as a mandate to screen. The signal that should change behavior is not the 5% association. It is the prodrome, the fact that a tearing artery produces neck pain and headache before it produces a stroke, which means some fraction of the patients who walk in with new neck pain are in the early window of something that belongs in an emergency department, not on my table.

The Mechanics

When Herzog and colleagues (2012) actually instrumented the vertebral artery and measured the strain a cervical manipulation imposes, the strain fell within the range of ordinary daily neck movement and below the artery's mechanical failure threshold in normal tissue. That does not make manipulation risk-free, and it does not speak to an artery that is already compromised. What it argues against is the intuitive picture that a single adjustment routinely tears a healthy artery. The mechanical story and the epidemiological story point the same way: the dominant risk is the artery that is already failing, not the force of a normal adjustment on normal tissue.

What This Looks Like in a $40 Walk-In Practice

I run a high-volume, low-overhead walk-in clinic in Brookside. Most patients are in and out quickly. None of that changes the screen, because the screen is the part that protects people, and it takes a history and a few honest questions, not a long appointment.

Before I adjust a neck, I ask what the pain is doing and how it started. A headache or neck pain that is sudden, severe, and unlike anything the person has felt before is a stop sign, not a chief complaint to treat. So is neck pain that arrived alongside any neurological symptom: double vision, slurred speech, one-sided weakness or numbness, severe unsteadiness, a new pulsing sound in one ear, or a drooping eyelid with a changed pupil. Those patients do not get adjusted. They get referred for medical evaluation and imaging, the same day. I also handle higher-risk histories with more caution: connective tissue conditions such as Ehlers-Danlos or Marfan, recent significant trauma, a recent severe new headache, or the postpartum period. As a US Navy veteran and a licensed chiropractor, I would rather lose a $40 visit than miss a dissection. That is the whole point of the screen, and it is why I would rather a nervous patient ask me about this study than avoid care and never get the question answered. The same conservative judgment shows up in how I think about whether chiropractic is safe in general, and it is why I keep gentler options on the table for an anxious patient who still needs neck pain relief in Tulsa.

The Wider Evidence Picture

This piece sits inside a larger conversation The Forward Review has been having about what manipulation does and does not do. The honest reading of the PACBACK trial in JAMA and of the 2026 Cochrane review on spinal manipulation is the same posture I take here: state what the data support, refuse to oversell, and let the honesty do the work. That standard also runs through the review of chiropractic safety in older adults. It matters in one practical way for this topic. Thoracic manipulation for neck pain is one way to help a stiff, painful neck without a high-velocity cervical thrust, which is the option I reach for when a patient is anxious or a cervical adjustment is not the right call. The full archive lives at The Forward Review.