Regarding "Carotid endarterectomy with routine electroencephalography and selective shunting: influence of contralateral internal carotid artery occlusion and utility in prevention of perioperative strokes".

Abstract

The excellent paper by Dr Schneider and his colleagues (J Vasc Surg 2002;35:1114-22) confirms, along with other reported studies, that contralateral internal carotid artery (ICA) occlusion does not represent a perioperative stroke risk with carotid endarterectomy provided hemodynamic compromise is detected in their patients by electroencephalographic (EEG) monitoring and shunting is used with care and expertise. The authors refer to our work using high-dose barbiturate cerebral protection without shunting and with continuous EEG monitoring1Frawley JE Hicks RG Gray LJ Neische JW. Carotid endarterectomy without a shunt for symptomatic lesions associated with contralateral severe stenosis or occlusion.J Vasc Surg. 1996; 23: 421-427Abstract Full Text PDF PubMed Scopus (57) Google Scholar and correctly state that this technique requires further clinical confirmation before it should be generally adopted. They also express a reluctance to depend on barbiturate cerebral protection in patients with contralateral ICA occlusion, particularly if EEG monitoring detected an ischemic change after clamping. We have recently reported 1000 consecutive carotid endarterectomies using high-dose barbiturate cerebral protection without shunting, 940 of these in symptomatic patients, 193 with previous stroke, 315 with contralateral ICA stenosis >70%, and 98 with contralateral occlusion.2Frawley JE Hicks RG Hicks RG Woodforth IJ. Risk factors for peri-operative stroke complicating carotid endarterectomy: selective analysis of a prospective audit of 1000 consecutive operations.Aust N Z J Surg. 2000; 70: 52-56Crossref PubMed Scopus (25) Google Scholar Like Dr Schneider's group, we experienced no intraoperative ischaemic strokes, despite EEG changes in 155 patients. We were also able to define the causes of perioperative stroke in this prospective series of patients, and although it is painful to have to admit it, complications of the surgery itself accounted for eight of 15 strokes (53%). The other seven strokes were secondary to medical events producing prolonged hypotension (four cases; 26.5%), uncontrolled hypertension (two cases; 13.25%), and postoperative thrombotic occlusion of a contralateral 90% ICA stenosis in one case. In our experience, high-dose barbiturate cerebral protection has been associated with a perioperative stroke rate of 1.5% in high-risk patients and has safely replaced intraoperative shunting. Spetzler, Bailes, and Apostolides3Spetzler RF Bailes JE Apostolides PJ. Rationale and protocol for microsurgical carotid endarterectomy.in: Microsurgical carotid endarterectomy. Lippincott-Raven, Philadelphia1996: 105-139Google Scholar have produced results equivalent to ours using high-dose barbiturate protection without shunting in their first 200 reported cases. However, in their most recent experience, they have used shunts in patients with persistent ischemic EEG changes with high-dose barbiturate anesthesia (7% of 327 patients), again with excellent results. We are in a position to compare barbiturate protection with routine shunting and selective shunting based on EEG monitoring, techniques we had used for some 12 years before changing to routine barbiturate protection. Because of an improvement in our perioperative nontransient stroke rate from 2.9% to 1.5% with the change in our own technique, we are no longer in a position that would ethically allow us to conduct a randomised trial comparing barbiturate protection with shunting but would certainly welcome such a study. It does seem, however, that results around the world have improved remarkably over the last decade, and the results achieved in the NASCET and ECST together with the advised acceptable perioperative stroke rates for symptomatic lesions (<6%) and asymptomatic lesions (<3%) are no longer acceptable, with many units reporting rates of less than 2%.