A Case of Cerebral Hyperperfusion Showing Unique Characteristics on Susceptibility-weighted MR Imaging after Carotid Endarterectomy

Cerebral hyperperfusion syndrome (CHS) is a potentially devastating complication of carotid endarterectomy (CEA). Early detection and treatment of hyperperfusion are important before the condition develops into CHS. We herein present a case involving a 65-year-old female with severe right internal carotid artery (ICA) stenosis, who experienced hyperperfusion after right CEA. During the postoperative course, changes in the resting cerebral blood flow (rCBF) were evaluated using single-photon emission computed tomography (SPECT), and were found to correlate with the changes in the signal intensity of cortical arteries, cortical veins, and perilateral ventricular veins of the right middle cerebral artery (MCA) territory on susceptibility-weighted imaging (SWI). SWI showed a prominent hyperintensity of cortical arteries in the right MCA territory at postoperative day 1 (POD1), but the hyperintensity gradually decreased over time and became indistinct by POD48. As for cortical veins and perilateral ventricular veins, SWI showed an increased signal intensity of these veins during the peak of rCBF on POD1, but later, the signal intensity decreased as rCBF decreased on POD5. The signal intensity of cortical veins and perilateral ventricular veins finally returned to normal on POD9. Those SWI findings could be related to an impairment of cerebral autoregulation and the resulting hyperperfusion. SWI could be potentially useful as an additional tool in the evaluation of hyperperfusion.