It is my understanding that there at many causes of sciatica pain. When I had it the cause was a synovial cyst that was pushing on the sciatica nerve. I had this two times with two different cysts. I had surgery to remove the cysts (twice) and have not had a problem since. I was told this was a very rare cause and my doctor was especially surprised at the second one. These were about 12 years ago. I think I’m written up in some medical book!