Evaluation of collateral flow capacity in patients with vascular or tumorous lesions of the skull base by Doppler sonography

Accurate characterization of the main trunk of the anterior cerebral artery by means of intraoperative sononavigation with Doppler sonography: implications for brain tumor surgery

OBJECTIVE

Doppler sonography can be used for real-time intraoperative localization of arteries within or near brain tumors but is less useful for distinguishing between arteries with similar diameters, such as the main trunk and branches of the anterior cerebral artery (ACA). By contrast, sononavigation provides real-time information in alignment with magnetic resonance imaging scans and may be of use in characterizing the identity of individual arteries on Doppler sonographic images. The goal of this study was to determine whether sononavigation can distinguish the main trunk of the ACA from the branches of the ACA on Doppler sonographic images.

METHODS

Doppler sonography was used in 3 patients undergoing surgical resection of brain tumors involving the main trunk of the ACA. The location of the main trunk of the ACA was characterized by sononavigation.

RESULTS

With these data, tumor resection was performed with preservation of the main trunk of the ACA. Gross total resection was achieved in 1 case.

CONCLUSIONS

Intraoperative sononavigation with Doppler sonography accurately localized the main trunk of the ACA and enabled preservation of this structure during tumor resection. This method may be applicable to the characterization of other critical arteries and may allow tumor resection with decreased morbidity.

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.

Transcranial Doppler in neurosurgery

This chapter describes the use of the transcranial Doppler apparatus in neurosurgery. The principles of Doppler insonation, the techniques of recording and the use of activation techniques is described. The relationship between blood flow and blood velocity is discussed, and the interaction of various pharmacological agents. The establishment of normal values for the laboratory and various vessels insonated is emphasised. The use of indices particularly the pulsatility index is described together with its variations. Cerebral vascular reactivity measurements and the interaction of Doppler recordings with raised intracranial pressure, useful in assessment of cerebral perfusion pressure as in head injury and in terminal cases, is documented. The use of transcranial Doppler in management of head injury and subarachnoid haemorrhage is described. The latter is probably the most useful routine place for Doppler measurement in neurosurgical practice and the documentation of the onset and progress of vasospasm is the final portion of the chapter.