Flow-diversion headaches in a patient with high-grade internal carotid artery stenosis.

Background: High grade stenosis of the internal carotid artery (ICA) may result in flow diversion to the external carotid artery (ECA) and its branches. Head and facial pain secondary to flow-diversion to ECA and increase in regional blood flow are under-recognized and unreported. Design/Methods: We report a patient with high grade ICA stenosis and recurrent ipsilateral headaches that resolved after revascularization. Results: A 69 yo woman presenting with right arm weakness had neuroimaging evidence of ipsilateral high grade ICA stenosis and left hemispheric ischemic stroke. Her history was significant for unilateral recurrent headaches that clinically resolved after left ICA angioplasty and stenting. With prior evidence supporting extracranial vasodilatation as the source of pain in migraine, and current clinical observation, we propose flow-diversion phenomenon as the connection between high grade ICA stenosis and ipsilateral headache. Conclusion: Recognition of flow-diversion into the ECA as a possible mechanism for headaches may help in further understanding of ICA disease, its progression, and the effects of carotid revascularization on quality of life. Headache as a likely surrogate marker of carotid stenosis with flow-diversion warrants more research, and may be critical in the early identification of significant ICA stenosis and prevention of TIA or stroke.