Transcranial Doppler 24 Hours after Carotid Endarterectomy Accurately Identifies Patients Not at Risk of Cerebral Hyperperfusion Syndrome

Abstract

Intra-operative transcranial Doppler (TCD) is the gold standard for prediction of cerebral hyperperfusion syndrome (CHS) in patients after carotid endarterectomy (CEA) under general anaesthesia. However, post-operative cerebral perfusion patterns may result in a shift in risk assessment for CHS. This is a study of the predictive value of additional post-operative TCD measurements for prediction of CHS after CEA. This was a retrospective analysis of prospectively collected data in patients undergoing CEA with available intra- and post-operative TCD measurements between 2011 and 2016. The mean blood flow velocity in the middle cerebral artery (MCAVmean) was measured pre-operatively, intra-operatively, and post-operatively at two and 24h. Intra-operative MCAVmean increase was compared with MCAVmean increase two and 24h post-operatively in relation to CHS. Cerebral hyperperfusion (CH) was defined as MCAVmean increase≥100%, and CHS as CH with the presence of headache or neurological symptoms. Positive (PPV) and negative predictive values (NPV) of TCD measurements were calculated to predict CHS. Of 257 CEA patients, 25 (9.7%) had CH intra-operatively, 45 (17.5%) 2h post-operatively, and 34 (13.2%) 24h post-operatively. Of nine patients (3.5%) who developed CHS, intra-operative CH was diagnosed in two and post-operative CH in eight (after 2h [n=5] or after 24h [n=6]). This resulted in a PPV of 8%, 11%, and 18%, and a NPV of 97%, 98%, and 99% for intra-operative, 2h and 24h post-operative TCD, respectively. TCD measurement of the MCAVmean 24h after CEA under general anaesthesia is most accurate to identify patients who are not at risk of CHS.