As promised, here is a link to the Spine 2008 article which examined neck pain associated disorders:

http://www.spinejournal.com/pt/re/spine/fulltext.00007632-200802151-00004.htm;jsessionid=HSQHcPMSkxnTnTkyrPTzcK6LHhry8QKLFyzlh2L2h08vVBxnfBf2!2092430889!181195628!8091!-1?index=1&database;=ppvovft&nav;=reference

Of particular importance is the following passage:

Vertebrobasilar Stroke Study Findings
There was an association between chiropractic services and subsequent vertebrobasilar artery stroke in persons under 45 years of age, but a similar association was also observed among patients receiving general practitioner services. This is likely explained by patients with vertebrobasilar artery dissection-related neck pain or headache seeking care before having their stroke.

Hence, there is no difference in association between stroke and DC and MD visits.  This suggests that VB strokes are not necessarily caused by SMT or a visit to the DC but that they are already in progress prior to the visit.  It should also be noted that there are 2 MDs involved in this study in case the argument of bias comes up.  It will be interesting what CynRN and the stroke fear mongers have to say now that the evidence disputes their beliefs.