Cerebral reserve and indications for shunting in carotid surgery.

The aim of this study was to establish whether a preoperative evaluation of cerebral haemodynamic reserve, carried out by means of transcranial Doppler and single photoemission computed tomography with a provocative test (acetazolamide) is able to select those patients who require carotid shunting to avoid cerebral ischaemia during clamping. All patients were monitored during operation by means of somatosensitive evoked potentials. Those patients who required shunting because of abnormal evoked potentials were also those who had a poor cerebral reserve with a perfusion and velocity increase below 15%. Only one neurological deficit developed in patients who were not shunted.