Dilatation of Cerebral Blood Vessels as a Factor in Headache

Although headache is one of the most common ailments of humanity, surprisingly little experimental work has been reported in the effort to elucidate the factors involved in its appearance. As a preliminary approach to the problem, the following considerations may be of interest. First, in regard to the anatomic position of the nervous elements responsible for the sensation of pain in the cranial cavity, it may be said that they apparently lie along the blood vessels, and not in the brain substance or in the meninges. In operating on the brain under local anesthesia, with the dura mater exposed but not itself anesthetized, surgeons 1 have observed that the patient feels little pain when the meningeal coverings or the brain tissue are manipulated, unless a blood vessel is cut or traumatized. It has been noted experimentally in this laboratory, 2 in anesthetized dogs, that faradic stimulation will cause reflex augmentation