IS TRANSCRANIAL DOPPLER A WORTHWHILE EXAMINATION FOR PREOPERATIVE EVALUATION OF THE CIRCLE-OF-WILLIS - EVALUATION OF 137 CAROTID ENDARTERECTOMIES PERFORMED UNDER REGIONAL ANESTHESIA

Background. Transcranial Doppler is often proposed for evaluation of t he Circle of Willis prior to carotid endarterectomy. The purpose of th is study was to evaluate preoperative TCD before carotid surgery. Meth ods. This is a retrospective report of 137 carotid endarterectomies pe rformed under regional anesthesia operated between January 1992 on Jun e 1996. All patients have a thight stenosis between 70% on 99%, and 49 % were symptomatic. Forty-three patients of the 132 had a controlatera l hemodynamically significant carotid stenosis with none occlusion. Th e TCD examinations were all performed with ADMS Doppler Spectradop wit h 3-MHz and 2-MHz probes. Clinical evaluation during cross-clamping wa s compared to the preoperative TCD. In 14% of the patients, the TCD co uld not be performed because there are not temporal bone windows. Resu lts. When the patients could be tested the positive predictive value o f the TCD was 18% and the sensitivity was 33%. The negative predictive value was 94%. 8% of the patients were shunted. TCD had numerous diff iculties. The most common is the lack of the temporal bone window (40% of the patients). The compression test is often difficult when the le sion is calcareous. Preoperative TCD is not according to our results, a reliable enough examination to modify operative strategy during caro tid surgery. When coupled with arteriography it is a good way to study cerebral hemodynamics. Conclusions. Regional anesthesia with local su pplication remains the method of choice to select those patients who r equire a shunt during carotid surgery. It can be used routinely and it is less complex than the various methods.