The patient reported in this case study developed a very severe headache during triple-H therapy after coiling of an aneurysm. The abnormalities that developed on MRI are those of edema that followed the pattern of involving gyri and their underlying white matter. I have seen this pattern in two other patients who developed severe migraine (Fig. 1) Each had a history of migraine. The findings in each of my patients and the patient reported by Huijgen et al.1 were fully reversible. I am confident that these findings represent an unusually severe migraine syndrome and not posterior reversible encephalopathy syndrome. These clinical and MR findings have not been sufficiently reported in the literature.