Pre- and intraoperative methods of controlling cerebral circulation in giant aneurysm surgery

The surgical treatment of giant aneurysms usually requires temporary clipping of the aneurysmatic vessel. In planning the surgical approach and in applying temporary clips, the surgeon must consider collateral circulations. The functional integrity of the collateral vessels frequently decides the patient's outcome. In 8 patients with internal carotid artery giant aneurysm, measurements of blood flow velocities in the ipsilateral middle cerebral artery were performed preoperatively with transcranial Doppler ultrasound (TCD) during manual occlusion of the carotid artery at the neck. Three different perfusion patterns were established, and each collateral capacity was rated as insufficient, temporarily sufficient, or long-term unproblematic. Surgical strategies were conceived. In one patient with giant aneurysm of the middle cerebral artery the temporary occlusion test was not carried out preoperatively. Intraoperatively, collateral circulation was controlled using microvascular Doppler sonography (MVD). In 8 cases cortical blood flow (CoBF) was monitored by thermal diffusion flow probe and/or laser Doppler. In some cases, the complex pathological anatomy required a change in surgical strategy and a new MVD determination of collateral capacity. Despite these precautions 2 patients suffered ischemia of the basal ganglia and the white matter.