Cerebral hyperperfusion syndrome following carotid endarterectomy

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Abstract
Extracranial internal carotid artery stenosis accounts for 15–20% of ischaemic strokes and carotid endarterectomy (CEA) is the most frequently performed surgical intervention in stroke prevention.1 The risk of stroke and death associated with the operation has been estimated at about 5.6% (95%CI 4.4–6.9).2 Neurological complications following CEA are usually ischaemic in nature, due to embolization or occlusion of the carotid artery. However, in a small subset of patients, cerebral hyperperfusion or reperfusion causes post-operative neurological dysfunction,3 characterized by ipsilateral headache, focal seizure activity, focal neurological deficit and ipsilateral intracerebral haemorrhage or oedema. Although rare, it can lead to significant morbidity and mortality if not correctly recognized and treated.4 The haemodynamic changes following CEA are complex and vary between patients.5–7 The main reason to perform CEA is removal of the source of emboli originating from carotid plaques. However, following successful endarterectomy there is increased blood flow in the ipsilateral carotid artery in almost all patients, related to the degree of pre-operative stenosis and hypoperfusion. In patients without pre-operative hypoperfusion, flow velocities generally peak on the first post-operative day and return to pre-operative values after 4–5 days. However, in patients with pre-operative hypoperfusion, flow velocities may remain high for many weeks.8,,9 Although cerebral blood flow (CBF) and perfusion increase in almost all patients following CEA, hyperperfusion is usually defined as a >100% increase in CBF compared to the pre-operative baseline.3 Hyperperfusion following CEA occurs in some 9–14% of patients, but only a minority develop symptoms as a result.10–12 Cerebral hyperperfusion syndrome (CHS) is a clinical triad of ipsilateral headache, seizure and focal neurological symptoms occurring in the absence of cerebral ischaemia.3,,11 It is accompanied by post-operative hypertension in almost all patients. The earliest description of CHS is a case …