I ended up with migraines 24/7....it's like having a permanent migraine & they have no idea what the cause is. I never had even a headache before being put on anti-depressants that had the side effect of migraines.
According to my pain specialist, I am one of the lucky people with migraines where pain medication helps completely. He said in the pain specialist world, it's a known fact that narcotic pain medication is not usually a treatment that even helps with migraines for some unknown reason.
Maybe the same situation you are talking about...with those who get no relief from the head pain after the surgery vs those who do.
I can only imagine what horrible pain you must have experiences with how bad my migraines were without relief.
Praying that the Dr's over these last years have become more knowledgable about what they see when they do your tests.