Hypertension and the post-carotid endarterectomy cerebral hyperperfusion syndrome

Cerebral hyperperfusion syndrome is a preventable cause of stroke after carotid endarterectomy (CEA). It manifests as headache, seizures, hemiparesis or coma due to raised intracranial pressure or intracerebral haemorrhage (ICH). There is currently no consensus on whether to control blood pressure, blood pressure thresholds associated with cerebral hyperperfusion syndrome, choice of anti-hypertensive agent(s) or duration of treatment.

A systematic review of the PubMed database (1963-2010) was performed using appropriate search terms according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

A total of 36 studies were identified as fitting a priori inclusion criteria. Following CEA, the incidence of severe hypertension was 19%, that of cerebral hyperperfusion 1% and ICH 0.5%. The postoperative mean systolic blood pressure of patients, who went on to develop cerebral hyperperfusion syndrome, was 164 mmHg (95% confidence interval (CI) 150-178 mmHg) and the cumulative incidence of cases rose appreciably above a postoperative systolic blood pressure of 150 mmHg. The mean systolic blood pressure of cerebral hyperperfusion cases was 189 mmHg (95% CI 183-196 mmHg) at presentation. The incidence of cerebral hyperperfusion in the first week was 92% with a median time to presentation of 5 days (interquartile range (IQR) 3-6 days). 36% of patients presented with seizures 31% with hemiparesis and 33% with both. The proportion of patients with severe hypertension was significantly higher in cases than in post-CEA controls (p < 0.0001, Odds ratio 19 (95% CI 9-41)). Three large case-control studies identify postoperative hypertension as a risk factor for ICH.

There is currently level-3 evidence for the prevention of ICH through control of postoperative blood pressure. From the available data, we suggest a definition for cerebral hyperperfusion syndrome, blood pressure thresholds, duration of monitoring and a postoperative blood pressure control strategy for validation in a prospective study. The implications of this are that one in five patients would need intravenous anti-hypertensives and home blood pressure monitoring for 1 week.