Someone recently posted about the fact that they still occasionally get headaches following surgical decompression or excision (I cannot recall which). What was interesting about their post was the comment that their usual headache medication (whether abortive or preventative) seemed to work better. This comment was almost made in passing, but I think it is rather profound. I have heard this same refrain from patients many times and I believe there is a good explanation for this phenomenon.
Many people likely have chronic headaches secondary to a combination of chemical imbalances as well as mechanical compression. In this case, when you take a medication because of a severe headache, you are uncertain whether it is the mechanical compression or the chemical abnormality that is responsible for your symptoms at that time. If the latter, then the medication will likely have a beneficial effect; if the former, it will have little to no effect. I strongly believe that this scenario is why many people tell me when I first meet them that you can flip a coin as to whether their medication will be effective. “50% of the time it works and the other 50% of the time it doesn’t” is a phrase I’ve heard more times than I can remember.
So let’s say that this same person now undergoes decompression surgery. Following recovery, the only abnormality left is the chemical imbalance. Now this person typically has far fewer headaches, with far less severity and/or of much shorter duration. However, from time to time, they will still experience a bad headache because the chemical abnormalities still exist. Remarkably, these same people will now state that their usual medications are more effective and the reason is hopefully more obvious. This medication is now more effective because it’s treating the problem every time - the chemical wrong it is supposed to right.