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

ObjectivesIntra-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. MethodsThis 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 (MCA Vmean) was measured pre-operatively, intra-operatively, and post-operatively at two and 24 h. Intra-operative MCA Vmean increase was compared with MCA Vmean increase two and 24 h post-operatively in relation to CHS. Cerebral hyperperfusion (CH) was defined as MCA Vmean 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. ResultsOf 257 CEA patients, 25 (9.7%) had CH intra-operatively, 45 (17.5%) 2 h post-operatively, and 34 (13.2%) 24 h post-operatively. Of nine patients (3.5%) who developed CHS, intra-operative CH was diagnosed in two and post-operative CH in eight (after 2 h [ n = 5] or after 24 h [ n = 6]). This resulted in a PPV of 8%, 11%, and 18%, and a NPV of 97%, 98%, and 99% for intra-operative, 2 h and 24 h post-operative TCD, respectively. ConclusionsTCD measurement of the MCA Vmean 24 h after CEA under general anaesthesia is most accurate to identify patients who are not at risk of CHS.