Muscle contraction headache and migraine. Platelet activation and plasma norepinephrine during the cold pressor test.

For clarification of possible platelet activation in migraine and chronic muscle contraction headache (MCH) under stress, plasma platelet factor 4 (PF4), norepinephrine (NE), and free fatty acids (FFA) were investigated during the cold pressor test. Both PF4 and NE increased significantly, whereas FFA showed no remarkable changes. The increases of PF4 in MCH and migraine during this test were significantly greater than in healthy controls. The increase of PF4, however, was independent of NE increase and FFA changes. On the other hand, we observed decreased NE levels in both MCH and migraine, which might suggest peripheral sympathetic hypofunction. The platelets of MCH or migraine patients seem to be impaired, and the impairment may be caused by continuous sympathetic hypofunction. The behaviour of the above three substances in MCH was similar to that in migraine throughout the present study.