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J R Soc Med. 2005 October; 98(10): 472–474.
PMCID: PMC1240105

Post-carotid endarterectomy cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome, a serious complication of carotid endarterectomy, is easily missed when the patient presents as a medical emergency.


Case 1

A man of 74 on long-term antihypertensive therapy underwent endarterectomy under general anaesthesia for symptomatic 490% left internal carotid artery stenosis. The right internal carotid artery was occluded. Readings from his arterial line showed mild postoperative hypertension that settled on his usual antihypertensive medication (Figure 1). On discharge after 24 hours his systolic pressure was 150 mmHg. He was readmitted on the 'medical take' after 8 days complaining of occipital headache, nausea, vomiting, and episodic right hemiparesis. He had not been taking all his antihypertensive medication. Systolic pressure was 180 mmHg and urgent carotid duplex showed a patent endarterectomy site. CT of the brain showed a left intracerebral bleed (Figure 2). Fifteen hours after scanning he developed sudden dense right hemiplegia, dysphasia, and recurrent seizures. He was medicated for seizures but no treatment was given for his hypertension. Neurological function did not recover and he died of complicating bronchopneumonia 32 days postoperatively.

Figure 1
Perioperative blood pressure. ♦ Case 1; An external file that holds a picture, illustration, etc.
Object name is graysqu.jpg case 2
Figure 2
Computerized tomography of brain, case 1

Case 2

A 78-year-old man, previously normotensive, underwent endarterectomy under general anaesthesia for symptomatic 490% right internal carotid artery stenosis. His left internal carotid artery was occluded. One dose of nifedipine (5 mg sublingual) was administered for control of postoperative hypertension in the recovery area. He was discharged after 24 hours on no medication, with a systolic pressure of 140 mmHg (Figure 1). He was readmitted on the 'medical take' after 5 days with severe occipital headaches, grand mal seizures and persistent left hemiparesis. Blood pressure was persistently high (240 mmHg systolic) but no antihypertensive medication was given, only repeated doses of diazepam. Following his chance recognition in hospital by the vascular team, hyperperfusion syndrome was diagnosed. He was transferred to the vascular high-dependency unit, where carotid duplex scanning showed a patent carotid endarterectomy site. Aggressive treatment was started with sublingual nifedipine, then glyceryl trinitrate infusion, and the seizures and hemiparesis resolved completely within 60 minutes of normotension being re-established. CT of the brain showed no acute changes. He was started on bendrofluazide and phenytoin and discharged after five days with complete neurological recovery. He remains well after 24 months.

Box 1 Precautions against hyperperfusion syndrome

Indications for emergency general practitioner referral to the vascular unit

Recent carotid surgery (within weeks) and

  • Hypertension + persistent headaches and/or nausea and vomiting
  • Seizures (general or focal)
  • Focal neurological signs (e.g. hemiparesis or dysphasia).

Patient advice to contact our vascular unit after carotid surgery

  • Headaches not settling with usual painkillers
  • Nausea and vomiting
  • Any unusual sensation, weakness or seizure.


Post-carotid-endarterectomy cerebral hyperperfusion syndrome consists of headache and hypertension, with or without seizures and focal neurological signs, developing within days of successful carotid endarterectomy.1,2 Patients with this complication commonly have a poor outcome.3 When patients are admitted to medical rather than vascular units, the focus tends to be on control of seizures rather than hypertension.4

The timing of seizures and hemiparesis differed in our two patients but they had in common headache and hypertension. Headache after carotid endarterectomy should trigger clinical suspicion of hyperperfusion syndrome with urgent treatment of hypertension irrespective of seizures and neurological deficit. Scrupulous perioperative blood pressure management may be important in preventing the syndrome but good adherence to antihypertensive therapy is also necessary after discharge (in patient 1 this was poor). Patient 2 was not previously hypertensive, but nifedipine was required in the early postoperative period to establish normotension. We can only speculate whether tighter control of peri-admission blood pressure would have averted the hyperperfusion syndrome. High-grade stenosis (combined stenoses of 4190%), present in both patients, reduces cerebral perfusion reserve and has been linked to the syndrome.3 General rather than local anaesthesia may be another predisposing factor; the effect of carotid shunting on hyperperfusion syndrome is unknown. Changes in middle cerebral arterial flow have been implicated but were not measured in our cases.

In both patients hypertension developed after discharge, and a policy of checking blood pressure in the community within 48 hours of discharge might have signalled the onset of hyperperfusion syndrome. We are now assessing this management approach but the rarity of this complication will make any benefit difficult to establish. Patients are advised to contact our vascular high-dependency unit if they develop persistent headaches, nausea and vomiting or any new neurological symptoms (Box 1). Medical colleagues who see these patients as emergencies need to appreciate the relevance of the recent carotid endarterectomy and treat hypertension aggressively.4


1. Naylor AR, Ruckley CV. The post-carotid endarterectomy hyperperfusion syndrome. Eur J Vasc Endovasc Surg 1995;9: 365-7 [PubMed]
2. Breen JC, Caplan LR, DeWitt LD, Belkin M, Mackey WR, O'Donnell RP. Brain edema after carotid surgery. Neurology 1996;46: 175-81 [PubMed]
3. Russell DA, Gough MJ. Intracerebral haemorrhage following carotid endarterectomy. Eur J Vasc Endovasc Surg 2004;28: 115-23 [PubMed]
4. Naylor AR, Evans J, Thompson MM, London NJM, Abbott RJ, Cherryman G, Bell PRF. Seizures after carotid endarterectomy: hyperperfusion, dysautoregulation or hypertensive encephalopathy? Eur J Vasc Endovasc Surg 2003;26: 39-44 [PubMed]

Articles from Journal of the Royal Society of Medicine are provided here courtesy of Royal Society of Medicine Press