Current update on the endovascular management of intracranial aneurysms

Rapid technological advances in the endovascular field has revolutionized the treatment of intracranial aneurysms. Since the Food and Drug Administration approval of Guglielmi detachable coils in 1995, a variety of newer coils with different design and physical properties such as complex coils, stretch resistant and bioactive coils, have become available promising to increase packing density and decrease aneurysmal recurrence and recanalization rates. Treatment of wide neck intracranial aneurysms has improved with availability of compliant balloons and newer intracranial assist devices. Emerging technology such as flow diverters hold promise in treatment of large and difficult to treat intracranial aneurysms. Liquid embolic agent (Onyx HD 500) offer a novel, safe and effective adjunctive treatment option when used in combination with coils with stent and/or balloon assist technique. Endovascular treatment options have vastly expanded the armamentarium of neurosurgeons allowing safe and durable treatment of aneurysms previously amenable to clipping only.

Endovascular therapy of acute ischemic stroke: report of the Standards of Practice Committee of the Society of NeuroInterventional Surgery

OBJECTIVE

To summarize and classify the evidence for the use of endovascular techniques in the treatment of patients with acute ischemic stroke.

METHODS

Recommendations previously published by the American Heart Association (AHA) (Guidelines for the early management of adults with ischemic stroke (Circulation 2007) and Scientific statement indications for the performance of intracranial endovascular neurointerventional procedures (Circulation 2009)) were vetted and used as a foundation for the current process. Building on this foundation, a critical review of the literature was performed to evaluate evidence supporting the endovascular treatment of acute ischemic stroke. The assessment was based on guidelines for evidence based medicine proposed by the Stroke Council of the AHA and the University of Oxford, Centre for Evidence Based Medicine (CEBM). Procedural safety, technical efficacy and impact on patient outcomes were specifically examined.

Neurologic complications of inferior petrosal sinus sampling

BACKGROUND AND PURPOSE

Inferior petrosal sinus sampling (IPSS) is a useful diagnostic technique in adrenocorticotropic hormone (ACTH)-dependent hypercortisolism with normal or equivocal MR imaging. The procedure is believed to be safe, with mostly minor complications. However, there are rare, but severe, neurologic complications that need to be considered.

MATERIALS AND METHODS

We performed an institutional review board-approved retrospective review of our institutional IPSS experience from July 2001 to January 2007. IPSS was performed for the evaluation of Cushing disease. The end points of particular interest were the indications for IPSS and the incidence of associated complications.

RESULTS

During the study period of 5(1/2) years, 44 patients underwent IPSS for evaluation of Cushing disease. There were 33 women and 11 men with a mean age of 43.1 years. Because of equivocal imaging and endocrine testing, 36 of 44 patients underwent IPSS, and 8 of 44 underwent IPSS after failed transsphenoidal exploration. The only complication was injury to the brain stem that occurred after an unremarkable procedure in a 42-year-old woman. She developed clinical evidence of pontomedullary dysfunction with MR imaging consistent with brain stem infarction. The cause of this injury is unclear, but a venous variant leading to transient venous hypertension or thrombosis is suspected.

CONCLUSION

Neurologic injury is a rare but serious complication associated with IPSS. Despite this, if performed under a strict paradigm, IPSS is both accurate and safe and can be very useful in the management of Cushing disease.

Historical movements in transsphenoidal surgery

Over the past century pituitary surgery has undergone multiple revolutions in surgical technique and technological advancements that have resulted in what is now recognized as modern transsphenoidal surgery. Although the procedure is well established in the current neurosurgical literature, the historical maze that led to its development continues to be of interest because it allows us to appreciate better the unique contributions made by the pioneers of the technique as well as the innovative spirit that continues to fuel neurosurgery. The early events in the history of transsphenoidal surgery have already been well documented. Therefore, the authors summarize the major early transitions along the timeline and then further describe more recent advancements in transsphenoidal surgery such as the surgical microscope, fluoroscopy, endoscopy, intraoperative neuroimaging, frameless image guidance, and radioimmunoassay. The story of these innovations is unique because each was developed as a response to certain needs of the surgeon. An understanding of these more recent contributions coupled with the early history provides a more complete perspective on modern transsphenoidal surgery.

Disparity of isoflurane effects on left and right ventricular afterload and hydraulic power generation in swine

The interaction between myocardial and vascular effects of anesthetics has a potential impact on how these drugs influence performance of the heart. Most studies have focused on volatile anesthetic effects on the left ventricle (LV) and systemic circulation. Whether the right ventricle (RV) and pulmonary circulation respond in a similar fashion, however, is unclear. In the present study, we therefore examined the dose-related effects of isoflurane on LV and RV contractility and total afterload and related changes to simultaneous effects on the hydraulic power generated by each chamber. Two groups of swine were studied: one received no additional treatment before isoflurane (ISO, n = 6), and the other received hexamethonium, atropine, and propranolol to produce autonomic blockade before isoflurane administration (ISO+AB, n = 4). For each experiment, measurements were made of RV and LV regional segment lengths and pressures, along with proximal aortic and pulmonary arterial (PA) blood flow and pressure during the administration of 0, 0.5, 1.0, and 1.5 minimum alveolar anesthetic concentration (MAC) isoflurane. Contractility was assessed by calculating the regional preload recruitable stroke work slope (PRSW). Afterload was characterized in both nonpulsatile and pulsatile terms by calculating aortic input impedance magnitude (Z). From these data, total arterial resistance (R), characteristic impedance (ZC), and vascular compliance (C) were determined with reference to a three-element Windkessel model of the circulation. Additionally, steady-state (WSS), oscillatory (WOS), and total (WT) hydraulic power output of each ventricle was calculated. In the ISO group, isoflurane produced a nearly threefold greater decrease of peak systolic pressure in the LV than in the RV, yet the dose-related decrease of regional PRSW was virtually the same in both chambers. In the aorta, isoflurane produced a maximal 25% reduction in R at 1.0 MAC and doubled C without a significant change in ZC. Alternatively, PA R was increased from baseline at 1.0 and 1.5 MAC, whereas ZC was increased from all other values at 1.5 MAC. PA C was not altered by isoflurane. In ISO+AB pigs, PA ZC at baseline was higher than that evident in ISO animals but was not altered by isoflurane. In contrast, baseline aortic R was lower in ISO+AB pigs but was still modestly reduced by 1.0 MAC isoflurane. In ISO animals, WT and WSS from both ventricles demonstrated dose-related decreases, but the reductions in LV WTand WSS were greater than those for the RV at all doses. Accordingly, the power requirement per unit flow decreased for the LV but remained constant for the RV. WOS for both ventricles was also reduced by isoflurane. However, the LV WOS to WT ratio increased, which indicates that more power was lost to the system by pulsation. In contrast, reductions in RV WT and WOS were nearly parallel at all isoflurane doses, and the WOS to WT ratio was unchanged. In the ISO+AB group, isoflurane-induced alterations in LV and RV power characteristics were similar to those in the ISO group. These data indicate that, despite similar effects on biventricular contractility, isoflurane exerts qualitatively different effects on RV and LV afterload, in part via alteration in autonomic nervous activity, that influence the distribution of power output between steady-state and pulsatile components.

IMPLICATIONS

In this study, we examined the effects of isoflurane on cardiac performance in swine and found that, although the drug depresses contraction of both the left and right ventricles similarly, it has different effects on forces that oppose the ejection of blood. These findings demonstrate that the two interdependent pumps that comprise the heart can be influenced differently by anesthetic drugs.