Chronic paroxysmal hemicrania, not intractable [G44.049], Reason for Study: ^Reason: headache etiology History: change HA frequency No evidence of acute ischemic or hemorrhagic lesion on the scan.There is about 5mm downward displacement of cerebellar tonsil through the foramen magnum.The ventricles, sulci and cisterns are symmetric and unremarkable. The gray-white matter differentiation is normal. There is no mass, mass effect, edema, midline shift, intra or extra-axial fluid collection/hemorrhage, or restricted diffusion/acute ischemia. The midline structures and cranial-cervical junction are normal. Normal flow voids are identified in the major intracranial vessels. The paranasal sinuses and mastoid air cells are clear.
No evidence of acute ischemic or hemorrhagic lesion.About 5mm cerebellar tonsilar herniation through the foramen magnum. 