Hi and welcome fellow Ozzie,
I honestly think you need to get a second opinion with the best specialist in your state on your CNS vasculitis diagnosis, your test results should not of all been negative and with CNS being one of the rarer forms of vasculitis it would be in your best interest to have the diagnosis confirmed.
I understand you've seen two different neurologist and if they disagree on the dx, what was the other neurologists opinion on what you had instead of CNS Vasculitis?
The international vasculitis foundation list 'Flinders medical centre' in SA on their website, so it might be worth considering contacting Flinders and asking their clinic which specialist they'd recommend for you to see and where you can get some support.
This is a very interesting resource on the various types of Vasculitis, it has a lot of other links that you might find worth reading too... http://www.uptodate.com/contents/vasculitis-beyond-the-basics
In regards to MS, there are many medical explanations and medical conditions that cause the same or similar symptoms, neurologically abnormal clinical signs and brain lesions, and all the specific details help identify the different types of lesions and more likely causation's.....if for example you had 4-5 tiny (1-3mm) non specific white matter lesions in a common brain location, they would more likely be the most common type of ischemic micro vascular bleeds but also keep in mind that CNS Vasculitis is associated with Transient Ischemic Attacks (TIA's), so the MRI evidence you have may be very suggestive or consistent with your diagnosis and not the type of brain lesions that MS causes.
The relationship you have with your diagnosing and treating physician is very important with chronic medical conditions, so if you are very frustrated with the limited information, support, treatment options etc that your getting from your neurologist, it would be in your best interest to find one that suits you better, so please consider seeking out a CNS Vasculitis specialist so you can at least be confident in your dx, dr and treatment for the future of your health..
Hope that helps.....JJ
I would see a MS Specialist. I wasted six months with a neurologist who missed the MS even though all my tests were positive for MS. She was not a MS Specialist.