There is a lot of talk about this regarding chiropractic care.  With this in mind, I wanted to put out this article that was published in the Journal of Stroke & Cerebrovascular Diseases.  This research was done by MDs, PhDs and one Chiropractor.  

It is entitled "Risk of Carotid Stroke after Chiropractic Care: A Population-Based Case-Crossover Study".

In this article they state that patients with carotid artery dissection can present with neck pain and/or headache before experiencing a stroke. These are common symptoms seen by both chiropractors and primary care physicians (PCPs). This study aimed to find out what risks there are of a carotid artery stroke after chiropractic care by comparing association between chiropractic and PCP visits and subsequent stroke.

Here is the data on chiropractic and risk of stroke:

A population-based, case-crossover study was undertaken in Ontario, Canada. All incident cases of carotid artery stroke admitted to hospitals over a 9-year period were identified. Cases served as their own controls. Exposures to chiropractic and PCP services were determined from health billing records.

Results

We compared 15,523 cases to 62,092 control periods using exposure windows of 1, 3, 7, and 14 days prior to the stroke. Positive associations were found for both chiropractic and PCP visits and subsequent stroke in patients less than 45 years of age. These associations tended to increase when analyses were limited to visits for neck pain and headache-related diagnoses. There was no significant difference between chiropractic and PCP risk estimates. They found NO ASSOCIATION between chiropractic visits and stroke in those 45 years of age or older.

Conclusions

No excess risk of carotid artery stroke after chiropractic care was found in this study. Associations between chiropractic and PCP visits and stroke were similar and likely due to patients with early dissection-related symptoms seeking care prior to developing their strokes.