van Os HJA, et al. - In this investigation involving 113 ischemic stroke cases and 598 healthy controls, researchers sought to assess the potential connection of headache, ischemic stroke, and the intrinsic coagulation pathway. Investigators found that an increase in ischemic stroke risk was linked to the combination of headache and high intrinsic coagulation protein levels (all but FXII antigen level and both FXIa-inhibitors), and it was higher than anticipated based on their individual impacts. They suggested that headache and high levels of intrinsic protein coagulation might interact biologically, increasing the risk of ischemic stroke.