The Value of Near-Infrared Spectroscopy Measured Cerebral Oximetry During Carotid Endarterectomy in Perioperative Stroke Prevention. A Review

Abstract

Transcranial Doppler (TCD) for identification of patients at risk for cerebral hyperperfusion syndrome (CHS) following carotid endarterectomy (CEA) cannot be performed in 10-15% of patients because of the absence of a temporal bone window. Near-infrared spectroscopy (NIRS) may be of additional value in these patients. We aimed to (1) compare the value of NIRS related to existing cerebral monitoring techniques in prediction of perioperative cerebral ischaemia and (2) compare the relation between NIRS and the occurrence of CHS. A systematic literature search relating to NIRS and CEA was conducted in PubMed and EMBASE databases. Those included were: (1) prospective studies; (2) on NIRS for brain monitoring during CEA; (3) including comparison of NIRS to any other intra-operative cerebral monitoring systems; and (4) on either symptomatic or asymptomatic patients. We identified 16 studies, of which 14 focussed on the prediction of intra-operative cerebral ischaemia and shunt indication. Only two studies discussed the ability of NIRS in predicting CHS. NIRS values correlated well with TCD and electroencephalography (EEG) values indicating ischaemia. However, a threshold for postoperative cerebral ischaemia could not be determined. Neither could a threshold for selective shunting be determined since shunting criteria varied considerably across studies. The evidence suggesting that NIRS is useful in predicting CHS is modest. NIRS seems a promising monitoring technique in patients undergoing CEA. Yet the evidence to define clear cut-off points for the presence of perioperative cerebral ischaemia or identification of patients at high risk of CHS is limited. A large prospective cohort study addressing these issues is urgently needed.