A 68-year-old woman presented with headache and seizures, 5  days after a right carotid endarterectomy. In the month before surgery, she had experienced three transient episodes of left arm weakness; the last was 15 days before surgery. A preoperative MR scan of brain showed a few small ischaemic lesions within the cerebral white matter but no acute infarction. MR angiography showed >95% stenosis in the right internal carotid artery, with a small calibre distal internal carotid artery, suggesting poor distal flow. The left internal carotid and vertebral arteries showed no significant stenosis. Her blood pressure was controlled on medication, recorded at 120/65 mm Hg preoperatively but 156/86 mm Hg immediately before surgery. Postoperative blood pressure was monitored with an arterial line, aiming for below the preoperative level (figure 1). Following 48 h of uneventful observation, she was discharged home.