Hi Eric
My Dr's stated mine is always Idiopathic but then stated I was born with it. Well which is it Ugh, I think the Idiopathic means they don't know how it occurred do that is what they call it. This condition has so many unanswered questions but together I believe we are figuring them out. My prayers are with you so happy you syrinx is shrinking. Your sound so similar to mine I had the decompression in 2009 in 2011 pain increased by 2013 had to have another surgery had arachnoid cyst plus tethering of the spinal cord. Now my cord is back tethered and my NS is unable to do anything more for me or I may not walk again. Tough choices we have God Bless