The exact pathophysiology of TACs is not well understood; current investigations suggest the involvement of the trigeminovascular system, the autonomic nervous system, and the hypothalamus. Recent functional and anatomic neuroimaging studies have demonstrated changes in the pain neuromatrix including the trigeminal nerve, trigeminovascular complex, and general pain system [30]. TACs are a primary headache disorder; however, the differential diagnosis includes structural lesions affecting the trigeminal autonomic reflex and pain pathways. Therefore, it is usually recommended to rule out a secondary cause of these headaches with neuroimaging. The most common structural lesions are primary pituitary lesions. Other reported lesions include parasellar meningiomas, posterior fossa lesions, vascular lesions such as carotid or vertebral artery dissection, cerebral AVMs, and sinus infections. Possible underlying causes of hemicrania continua include CVT and intracranial metastases [30-33]. Arteriography Cervicocerebral There is no relevant literature to support the use of cervicocerebral arteriography in the initial imaging evaluation of TACs. CT Head With IV Contrast There is no relevant literature to support the use of CT head with IV contrast in the initial imaging evaluation of TACs. Headache CT Head Without and With IV Contrast There is no relevant literature to support the use of CT head without and with IV contrast in the initial imaging evaluation of TACs. CT Head Without IV Contrast There is no relevant literature to support the use of CT head without IV contrast in the initial imaging evaluation of TACs. CTA Head With IV Contrast There is no relevant literature to support the use of CTA head with IV contrast in the initial imaging evaluation of TACs; it may have utility in follow-up evaluation after initial neuroimaging. Vascular lesions including carotid/vertebral dissections, AVMs, and aneurysms are a rare, secondary cause of TACs [30,31,33].
Headache PCAs. The exact pathophysiology of TACs is not well understood; current investigations suggest the involvement of the trigeminovascular system, the autonomic nervous system, and the hypothalamus. Recent functional and anatomic neuroimaging studies have demonstrated changes in the pain neuromatrix including the trigeminal nerve, trigeminovascular complex, and general pain system [30]. TACs are a primary headache disorder; however, the differential diagnosis includes structural lesions affecting the trigeminal autonomic reflex and pain pathways. Therefore, it is usually recommended to rule out a secondary cause of these headaches with neuroimaging. The most common structural lesions are primary pituitary lesions. Other reported lesions include parasellar meningiomas, posterior fossa lesions, vascular lesions such as carotid or vertebral artery dissection, cerebral AVMs, and sinus infections. Possible underlying causes of hemicrania continua include CVT and intracranial metastases [30-33]. Arteriography Cervicocerebral There is no relevant literature to support the use of cervicocerebral arteriography in the initial imaging evaluation of TACs. CT Head With IV Contrast There is no relevant literature to support the use of CT head with IV contrast in the initial imaging evaluation of TACs. Headache CT Head Without and With IV Contrast There is no relevant literature to support the use of CT head without and with IV contrast in the initial imaging evaluation of TACs. CT Head Without IV Contrast There is no relevant literature to support the use of CT head without IV contrast in the initial imaging evaluation of TACs. CTA Head With IV Contrast There is no relevant literature to support the use of CTA head with IV contrast in the initial imaging evaluation of TACs; it may have utility in follow-up evaluation after initial neuroimaging. Vascular lesions including carotid/vertebral dissections, AVMs, and aneurysms are a rare, secondary cause of TACs [30,31,33].