Spinal manipulative therapy is an independent risk factor for vertebral artery dissection

OBJECTIVE: To determine whether spinal manipulative therapy (SMT) is an independent risk factor for cervical artery dissection. METHODS: Using a nested case-control design, the authors reviewed all patients under age 60 with cervical arterial dissection (n = 151) and ischemic stroke or TIA from between 1995 and 2000 at two academic stroke centers. Controls (n = 306) were selected to match cases by sex and within age strata. Cases and controls were solicited by mail, and respondents were interviewed using a structured questionnaire. The medical records of interviewed patients were reviewed by two blinded neurologists to confirm that the patient had stroke or TIA and to determine whether there was evidence of arterial dissection. RESULTS: After interview and blinded chart review, 51 patients with dissection (mean age 41 +/- 10 years; 59% female) and 100 control patients (44 +/- 9 years; 58% female) were studied. In univariate analysis, patients with dissection were more likely to have had SMT within 30 days (14% vs 3%, p = 0.032), to have had neck or head pain preceding stroke or TIA (76% vs 40%, p < 0.001), and to be current consumers of alcohol (76% vs 57%, p = 0.021). In multivariate analysis, vertebral artery dissections were independently associated with SMT within 30 days (OR 6.62, 95% CI 1.4 to 30) and pain before stroke/TIA (OR 3.76, 95% CI 1.3 to 11). CONCLUSIONS: This case-controlled study of the influence of SMT and cervical arterial dissection shows that SMT is independently associated with vertebral arterial dissection, even after controlling for neck pain. Patients undergoing SMT should be consented for risk of stroke or vascular injury from the procedure. A significant increase in neck pain following spinal manipulative therapy warrants immediate medical evaluation.