TRANSCRANIAL PULSED DOPPLER IN CAROTID-AR TERY SURGERY - A COMPARISONOF CLINICAL, PARACLINICAL AND OPERATIVE FINDINGS

Blood flow in the middle cerebral artery was monitored during carotid artery surgery under loco-regional anaesthesia by plexus block in awak e patients in order to assess the value of transcranial pulsed Doppler in understanding the embolic or haemodynamic mechanisms of peroperati ve cerebrovascular accidents. Blood flow changes in the middle cerebra l artery ipsilateral to the operated carotid artery were compared with clinical, paraclinical and operative findings. Sixty-two patients wer e included in the study, 34 with symptomatic carotid artery lesions an d 28 with very severe, progressive but asymptomatic stenosis. Thirteen patients (9 with symptomatic and 4 with asymptomatic lesions) suffere d one or more neurological events during surgery. The blood flow veloc ities were studied at different stages during surgery and compared bet ween the two groups-symptomatic and asymptomatic to try and assess the mean systolic velocities predictive of cerebral hypoperfusion. Three events occurred during carotid artery dissection, 7 at clamping, 3 dur ing clamping; 9 shunts were installed, one of which at the twelfth min ute of clamping. A shunt was not installed in 4 cases : two events occ urred at the end of the operation (muscle weakness, diplopia), one eve nt occurred during an episode of hypotension, another at clamping whic h resulted in aborting the operation as transluminal pulsed Doppler su ggested an embolism during dissection. Two events were attributed to a n embolic phenomenon and 16 to cerebral hypoperfusion. Peroperative mi ddle cerebral arterial flow recording enables detection of an embolism , monitoring of a shunt and the prediction of a neurological event sho uld the mean systolic velocities fall to less than 15 cm/s and the red uction in velocity attain 70 % (sensitivity 87.5 %, specificity 91 %).