Normal perfusion pressure breakthrough in arteriovenous malformation surgery: The concept revisited with a case report

The pathophysiological mechanisms and the salient features of normal perfusion pressure breakthrough (NPPB) are discussed on the basis of an operated case of arteriovenous malformation

Contralateral Approach to Unruptured Superior Hypophyseal Artery Aneurysms

Objective To evaluate the feasibility and limitations of the contralateral approach to unruptured superior hypophyseal artery (SHA) aneurysms. Methods Data regarding eight cases of superior hypophyseal artery aneurysms operated on by a contralateral pterional approach at our center from January 2008 to September 2010 were collected and evaluated retrospectively. Of these eight cases, six were male and two were female. The mean age was 57.1 years (range 28 years to 77 years). All the aneurysms were unruptured; five were on right side and three were on left side. The surgical technique and outcome of patients were reviewed. Results All aneurysms were successfully clipped without complication and patency of all superior hypophyseal arteries was preserved. Postoperative three-dimensional computed tomography angiography revealed residual aneurysm in only one case. None of the patients had deterioration of visual acuity or field after surgery. The contralateral pterional approach was found to be appropriate for fully exposing the aneurysmal dome and neck without retraction of the optic nerve or the carotid artery in five cases. Slight retraction of the optic nerve was required in two cases, and significant manipulation of the optic nerve was required in one case. Conclusions The contralateral pterional approach for clipping of unruptured superior hypophyseal artery aneurysms is technically feasible and safe in a select group of patients where optimal results can be achieved without significant retraction of near by neurovascular structures

The role of intraoperative micro-Doppler ultrasound in verifying proper clip placement in intracranial aneurysm surgery

Aneurysmal subarachnoid hemorrhage constitutes a clinical entity associated with high mortality and morbidity. It is widely accepted that improper clip placement may have as a result of incomplete aneurysm occlusion and/or partial or complete obstruction of an adjacent vessel. Various modalities, including intraoperative or postoperative digital subtracting angiography, near-infrared indocyanine green angiography, micro-Doppler ultrasonography (MDU), and neurophysiological studies, have been utilized for verifying proper clip placement. The aim of our study was to review the role of MDU during aneurysmal surgery. A literature search was performed using any possible combination of the following terms: "aneurysm," "brain," "cerebral," "clip," "clipping," "clip malpositioning," "clip repositioning," "clip suboptimal positioning," "Doppler," "intracranial," "microsurgery," "micro-Doppler," "residual neck," "ultrasonography," "ultrasound," and "vessel occlusion". Additionally, reference lists from the retrieved articles were reviewed for identifying any additional articles. Case reports and miniseries were excluded. A total of 19 series employing intraoperative MDU during aneurysmal microsurgery were retrieved. All studies demonstrated that MDU accuracy is extremely high. The highest reported false-positive rate of MDU was 2 %, while the false-negative rate was reported as high as 1.6 %. It has been demonstrated that the presence of subarachnoid hemorrhage, specific anatomic locations, and large size may predispose to improper clip placement. Intraoperative MDU's technical limitations and weaknesses are adequately identified, in order to minimize the possibility of any misinterpretations. Intraoperative MDU constitutes a safe, accurate, and low cost imaging modality for evaluating blood flow and for verifying proper clip placement during microsurgical clipping