I've added two new pages to the SM InfoSite, http://sm.cavaliertalk.com . One lists all the vet neurologists in the UK with contact details; the other lists all the US-board certified vet neurologists in the US, Canada and a few other countries. These are listed by state or country, but I don't have contact details for them. However it should not be hard to have your vet get the exact contact if they are not listed in the phone book for the given region.
Note that there will be many other neurologists in other countries with the certifications recognised in their own countries; the US list just includes foreign-based neuros with the American certification.
Also note that these listings do not indicate whether a given neurologist is familiar with syringomyelia.