I seem to be sending out warnings lately. This latest came to me from Medscape, which quoted an article from the International Journal of Clinical Studies. I had heard of similar studies earlier. Apparently there is a risk that chiropractic manipulation of the neck can lead to acute dissection of the vertebral artery, stroke, and death. The majority of these events occur in patients younger than 40 years.
The link to the abstract of the article (see Medscape for fuller details) can be seen at PubMed:
The danger seems to be in acute rotation of the neck, since this is done without an MRA study of the vertebral arteries.