There's an article about primary CNS vasculitis in The Lancet in August 2012 (volume 380, issue 9843, pp. 767-77). It's written by Carlo Salvarani, Robert D Brown Jr, Gene G Hunder. Behind a publisher's paywall of course, though digital copies can be bought from thelancet.com/. I will have a look at it soon. I'm lucky to have access to this journal's electronic version through my honorary research fellowship at Dundee University.