Hi there, I am writing about my husband. He has been seen by a neuro surgeon about the possibility of spinal surgery at L4/5. After looking at the MRI and Xrays, Dr. thought he had already had spinal surgery, which he has not. My husband has had a rapid decline in his ability to walk without falling and says there are times when he actually has to tell his brain to move a leg. He is falling because he has a bad left knee that "goes out from under him" after a stabbing pain. The neuro surgeon is concerned that he may have an underlying disease process. I am an RN so know a little bit about those possibilities. Aside from MS or ALS what other disease processes could we be looking at?