From what I've read about severe headache pain, the nerve pathways themselves don't necessarily spasm. What happens is that the blood vessels spasm, and that constriction/dilation action (spasm) triggers nerve pain because the nerves travel right along the same path of the blood vessels. In headaches, it's the blood vessels in the scalp that spasm and set off headaches--often as a result of the dilation (relaxation) mechanism. That's why the best anti-migraine remedies nowadays are very powerful vasoconstrictors. Both constriction and relaxation of blood vessels can be a pain trigger.

I'm going to do some reading about tramadol. I wonder if that might help alleviate some of the wackiness that's happening in response to my spinal problem I'm about to have surgery for. I think the compression of my spine is making me have a sort of physical tension I've not had before, along with very uncharacteristic irritability. It's irritability about the strangest things, too, like tense dialogue in a movie. And uncharacteristic floods of adrenalin in response to surprise, anger, and even after eating. It's the strangest feeling, and it's only been happening as this spinal pressure has gotten worse. I'm convinced the adrenergic response is aggravating my heart rhythm problem, too. Sorry to sidetrack off your original topic, but what you've told me about tramadol makes me wonder if it might help alleviate some of these symptoms!