Excellent News: Chiropractic, Elderly, and Stroke

One of the more exciting aspects of chiropractic care is the low risk of side effects. In general, chiropractic care can be provided to thousands of patients by thousands of chiropractors, with the most common side effects occurring at a low rate and including muscle ache or stiffness. There have been some reports over the years, however, of very rare but more concerning side effects including a certain type of stroke called vertebrobasilar stroke, which occurs due to the disruption of an artery carrying blood through the neck to the brain. It has been proposed that chiropractic adjustments, which are often performed to alleviate neck conditions, might cause these types of strokes.

Stroke, which is one of the leading causes of death to all adults, occurs in about 700,000 individuals per year with about 160,000 of those incidents being fatal. Of all these annual strokes, about 18 of them are vertebrobasilar strokes, indicating the rarity of this type of stroke. (A stroke is the loss of blood flow to either a portion of the brain or the entire brain, causing neurological dysfunction.)

Past studies of the correlation of chiropractic adjustments with possible strokes have repeatedly emphasized the rarity of stroke associated with chiropractic care. A large chiropractic malpractice insurance company notes that "a causative relationship between chiropractic manipulation and stroke is unlikely. There is an associative relationship between the two because people may go to chiropractors for relief of stroke-related symptoms." Indeed, a famous study from 2008 indicated that "our population-based case-control and case-crossover study shows an association between chiropractic visits and VBA strokes. However, we found a similar association between primary care physician visits and VBA stroke. This suggests that patients with undiagnosed vertebral artery dissection are seeking clinical care for headache and neck pain before having a VBA stroke. " And this table shows, in a humorous way, the relative safety of the chiropractic adjustment compared with neurovascular events from, say, canoeing or drinking one bottle of wine a day, or, more seriously, with gastrointestinal bleeding due to over-the-counter pain medication or smoking or surgery.

Now there is a new study that has examined the risk of stroke after chiropractic adjustment in older adults, using the vast statistics available from Medicare. This is a numbers-based analysis that was published earlier this year. For further study into the topic, it is highly recommended that you read the whole study and follow the citation links, but here's a quick summation of the paper:

This is the first population-based study in the United States on risk of stroke after spinal manipulation and the first such study to focus on older adults. Among Medicare B beneficiaries aged 66 to 99 years with neck pain, the incidence of vertebrobasilar stroke was too low to allow further analysis. Chiropractic cervical spine manipulation is unlikely to cause stroke in patients aged 66 to 99 years with neck pain. For patients who saw a chiropractic physician, the adjusted probability of any type of stroke was lower than those who saw a primary care physician at days 1 through 24 after office visit, but higher at days 25 to 30, but these temporal associations are of doubtful clinical significance.