Activation of the trigeminovascular system by mechanical distension of the superior sagittal sinus in the cat.

Distension of dural sinuses in man produces migraine-like pain. In eight alpha-chloralose anaesthetized cats mechanical distension of the superior sagittal sinus with a small intraluminal device was used to activate single units in the dorsolateral C2 spinal cord. Units in this region have been shown to respond to electrical stimulation of the superior sagittal sinus in the cat model. Linked responses to mechanical dilatation could only be obtained with very rapid stretching stimuli or high amplitudes of distension of the vessel. Lower thresholds for transduction of distension in the vessel wall may depend on transferral to the dura or biochemical or neural pre-sensitization of the superior sagittal sinus. These data are consistent with the view that migraine is not primarily a vascular disorder but requires at least humoral or neural facilitation.