Vad är den förväntade livslängden för någon med Stiff person syndrome (SPS)?

I read that there is 6-29 years from onset of symptoms for a life span which was done in a clinical trial. There are always improvements but there needs to be more research done. Complications of SPS can be severe and in the end stages it is sad and hard to watch and cope with (my father died in 2010 of SPS and I watched him slowly and it was painful). I am currently doing my own clinical trial with a combination of certain medications and therapies to see if it will help with symptoms.