Left Vertebral Artery to Common Carotid Artery Transposition in a Patient With Bilateral Vertebral Insufficiency: 3-Dimensional Operative Video.

Extracranial vertebral artery (VA) atherosclerosis is responsible for 14% to 32% of posterior circulation infarctions.1 In the posterior circulation, narrowing of the VA > 30% is significantly associated with strokes. Subclavian artery (SCA) atherosclerosis can produce subclavian steal. Retrograde VA flow around an occluded SCA decreases blood flow to the posterior circulation and causes vertebrobasilar insufficiency (VBI). Flow augmentation to the posterior circulation can be achieved by VA endarterectomy, arterial stenting, VA-common carotid artery (CCA) transposition, or bypass using an interposition graft.2,3 This video illustrates microsurgical revascularization of the proximal VA with VA-CCA transposition. A 58-yr-old man with a prior stroke and chronic right VA occlusion presented with dysarthria and gait instability. Angiographic evaluation confirmed complete midcervical right VA occlusion and left SCA occlusion proximal to VA origin, with subclavian steal. After obtaining patient consent and a failed attempt at endovascular recanalization of the left SCA, a left VA-CCA end-to-side transposition was performed. Neck dissection exposed the left CCA. The thyrocervical trunk served as a landmark to identify the SCA, which was traced proximally to the VA origin. After proximal occlusion, the VA was transected and "fish-mouthed" for end-to-side anastomosis to CCA. An intraluminal, continuous suture technique was used to sew the back walls of this anastomosis. Postoperative computed tomography angiography confirmed bypass patency. Collateral circulation through the thyrocervical and costocervical trunks likely supplied the left arm, and no cerebral, or limb, ischemic symptoms were noted on follow-up. VA-CCA transposition is an uncommon technique for safe and effective revascularization of symptomatic, medically refractory VBI caused by VA occlusion or, as in this case, SCA occlusion with secondary subclavian steal. Used with permission from Barrow Neurological Institute, Phoenix, Arizona.

Right Pretemporal-Transsylvian Approach for Resection of a Midbrain Cavernous Malformation: 3-Dimensional Operative Video.

Brainstem cavernous malformations (CMs) account for 15% to 18% of all intracranial CMs1 and 13% of all cerebrovascular pathology in the posterior fossa.1,2 This video demonstrates the resection of a pontomesencephalic CM through a pretemporal approach through the oculomotor-tentorial triangle (OTT).3 A 49-yr-old woman presented with an acute onset of left hemiparesis, diplopia, vertigo, partial oculomotor, and facial palsy. Neuroimaging revealed a 25-mm diameter right pontomesencephalic CM with evidence of prior hemorrhage. Institutional Review Board approval and patient consent were obtained for surgery. A right orbitozygomatic craniotomy was performed, and the lesion was exposed through a pretemporal-transsylvian approach. After a wide Sylvian fissure split, the oculomotor nerve (CN III) was dissected away from the temporal lobe, and the temporal lobe was mobilized posteriorly to access the OTT. The posterior cerebral and superior cerebellar arteries were visualized in this triangle, and the cerebral peduncle and the CM were accessed deep to these arteries. After hematoma evacuation, the CM was resected in a piece-meal fashion using an intracapsular technique. Postoperative imaging confirmed the gross total resection of the lesion. The patient had persistent right CN III palsy and a slight worsening of left hemiparesis, which had resolved completely at the 6-mo follow-up. The OTT provides access to the upper ventrolateral pontomesencephalic area.3 This triangular surgical workspace is entered through a pretemporal-transsylvian corridor and widened with posterior temporal lobe retraction. The OTT is an important working space for accessing midbrain and upper pontine CMs posterolateral to CN III.

An outcomes-based grading scale for the evaluation of cerebral aneurysms treated with flow diversion.

OBJECT: Despite the popularity of flow-diverting stents for the treatment of cerebral aneurysms, there is no widely accepted scale for the characterization of results. We present an outcomes-based grading scale that considers factors related to failure of flow diversion. METHODS: The grading scale was developed using the results from consecutive patients at two institutions who were treated with flow diversion for a cerebral aneurysm. The initial treatment results were graded on patient, aneurysm, and treatment characteristics. A 6-point grading scale was developed based on these data. RESULTS: One hundred and seventy-one patients were included in the patient cohort. When compared by multivariate analysis with patients without residuals, patients with aneurysm residuals were found to be older (age ≥60 years, p=0.01, OR 1.17, 95% CI 1.03 to 1.33), to have larger aneurysms (size ≥15 mm, p<0.01, OR 1.38, 95% CI 1.17 to 1.62), to have aneurysms with associated side branches (p=0.02, OR 1.17, 95% CI 1.03 to 1.33), and to have a post-treatment Raymond score of 2 or 3 (p=0.01, OR 1.28, 95% CI 1.06 to 1.56). Using the Raymond score (1-3) as the foundation for the grading scale, additional points (0 or 1) were given for the other three identified factors, creating a 6-point scale. We found that patients with residual aneurysms had statistically higher final tabulated scores (p<0.01). CONCLUSIONS: We propose a novel straightforward outcomes-based scale to characterize results after flow diversion treatment of cerebral aneurysms. This scale may provide the basis for the common reporting of results in future studies.

Volumetric classification of pituitary macroadenomas predicts outcome and morbidity following endoscopic endonasal transsphenoidal surgery.

Endoscopy in combination with extended approaches allow for resection of large pituitary adenomas via a transsphenoidal route. The objective of the current study was to determine a volumetric threshold for lesions with high perioperative morbidity and high rate of subtotal resection following endonasal endoscopic surgery. Thus, we analyzed a prospectively collected database of 71 patients who underwent endoscopic transsphenoidal approaches for macroadenomas (diameter >1 cm). Extend of resection (EOR) was calculated based on volumetric analysis of pre-and post-operative contrast-enhanced MRI. Average EOR was 97.8% and a gross total resection (GTR) was achieved in 76.1% of all patients. GTR was accomplished in 92.0% versus 38.1% of adenomas either without or with CS invasion, respectively. Likewise, GTR was accomplished in 90.2% versus 40.0% of lesions less than or greater then 10 cm(3) respectively. However, even if only subtotal resection was achieved, 90.3% of tumor volume was removed. At 17 months follow-up, visual field defects improved in 80.8% of patients. Complications included permanent diabetes insipidus (5 patients), panhypopituitarism (4 patients), injury to the ophthalmic artery (1 patient) and CSF leak (1 patient). On multivariate logistic regression, two factors negatively predicted GTR: invasion of the CS and volume greater than 10 cm(3). A 10 cm(3) threshold was a stronger predictor of EOR and complication risk than diameter-based measurements. A volume greater than 10 cm(3) and CS invasion may help to identify pituitary lesions associated with a higher likelihood of subtotal resection and post-operative morbidity.

Understanding the role of tumor stem cells in glioblastoma multiforme: a review article.

It has been hypothesized that cancer stem cells (CSC) may account for the pathogenesis underlying various tumors, including GBM. Markers of these CSCs can be potentially used as therapeutic targets. In this review, we discuss the most recent information regarding CSCs, their molecular biology and their potential role in GBM.

Electron transfer to nitrite reductase of Rhodobacter sphaeroides 2.4.3: examination of cytochromes c2 and cY.

The role of cytochrome c(2), encoded by cycA, and cytochrome c(Y), encoded by cycY, in electron transfer to the nitrite reductase of Rhodobacter sphaeroides 2.4.3 was investigated using both in vivo and in vitro approaches. Both cycA and cycY were isolated, sequenced and insertionally inactivated in strain 2.4.3. Deletion of either gene alone had no apparent effect on the ability of R. sphaeroides to reduce nitrite. In a cycA-cycY double mutant, nitrite reduction was largely inhibited. However, the expression of the nitrite reductase gene nirK from a heterologous promoter substantially restored nitrite reductase activity in the double mutant. Using purified protein, a turnover number of 5 s(-1) was observed for the oxidation of cytochrome c(2) by nitrite reductase. In contrast, oxidation of c(Y) only resulted in a turnover of approximately 0.1 s(-1). The turnover experiments indicate that c(2) is a major electron donor to nitrite reductase but c(Y) is probably not. Taken together, these results suggest that there is likely an unidentified electron donor, in addition to c(2), that transfers electrons to nitrite reductase, and that the decreased nitrite reductase activity observed in the cycA-cycY double mutant probably results from a change in nirK expression.