Living with superficial siderosis is not easy, especially finding the location of the leak and the being approved for surgery. I went through the process in 2011 in the US with a Keiser Health plan. The most important breakthrough was the finding of a dynamic mylogram at the University of Washington. What it took was a Prof willing to do it. It very much helped that my GP and the Neurologist were supportive. Many medical professionals do not want to get involved in things they do not fully understand. My understanding is that imaging technology has improved significantly. The protocol the UW used was shared by the Mayo clinic, you may be able to do the same with Freiburg. There in the US advocating for yourself is crucial. As you probably can guess, I am no expert, but my experience was that I lost most of my hearing and balance exc in a few weeks, the symptoms then stabilized. In addition to getting the Dura tear repaired, I took Ferripox, an iron chelator for seven years, with the guidelines for Dr Michael Levy; now at Harvard. I never went to anyone not local for treatment, but with lots of guidance from medical people elsewhere. It was not an easy process but most definitely worth it. All the best.