WARNING: Conducting an Orchestra Can Cause Vertebral Artery Dissection and Stroke
During the past decade, the issues of cerebrovascular accidents [CVAs] and spinal manipulation have become linked in a debate of ever-increasing intensity. A copious number of studies have investigated spinal manipulation as a putative causative factor of CVAs; however, a common theme among these is the failure to adequately explore the possibility that the majority of CVAs may be spontaneous, cumulative, or caused by factors other than spinal manipulation itself. The problem is only exacerbated by the sometimes hysterical reactions apparent in the mass media over the past three years in reaction to these flawed investigations. 
Previous studies have shown that vertebral artery dissections (VADs) have been “caused” by things as innocuous as:
Overhead workCervical rotation while backing up a car
Roller coaster rides
Cervical extension for x-rays or CTS
Hanging out washing
Traction and short wave diathermy
I certainly don’t want to make light of the suffering caused by a VAD. At the same time it boggles the mind that certain elements continue to publish slander against chiropractic care, when repeated reviews of the incidence of VADs proximal to chiropractic care suggest that it is orders of magnitude safer than the usual medical nostrums provided for neck pain relief. 
In fact, the most recent credible study reviewing risk ruled our chiropractic care as a potential cause of VAD after exposing arterial specimens to 1000 strain impulses of the same magnitude measured in cervical manipulation.
A pathologist, blinded to the experimental groups, assessed microstructural changes in those arteries using quantitative histology. Pearson analysis (a = .05) was used to assess differences in tissue microstructure between the groups. Cadaveric arterial tissues of New Zealand white rabbit with similar size, structure, and mechanical properties of human vertebral artery did not exhibit histologically identifiable microdamage when exposed to repeated (1000!) mechanical loading, equivalent to the strains observed in human vertebral artery during chiropractic cervical spine manipulative therapy. 
There are many more substantive articles like these at the:
1. Cerebrovascular Accidents: The Rest of The Story
International Spinal Trauma Conference ~ Anthony L. Rosner, Ph.D.
2. Is Cervical Spinal Manipulation Dangerous?
J Manipulative Physiol Ther 2003 (Jan); 26 (1): 48–52
3. Microstructural Damage in Arterial Tissue Exposed to Repeated Tensile Strains
J Manipulative Physiol Ther 2010 (Jan); 33 (1): 14–19