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Alim P. Mitha, John H. Wong, Michael D. Hill and Mayank Goyal

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John H. Wong, Alim P. Mitha, Morgan Willson, Mark E. Hudon, Robert J. Sevick and Richard Frayne

Object

Digital subtraction (DS) angiography is the current gold standard of assessing intracranial aneurysms after coil placement. Magnetic resonance (MR) angiography offers a noninvasive, low-risk alternative, but its accuracy in delineating coil-treated aneurysms remains uncertain. The objective of this study, therefore, is to compare a high-resolution MR angiography protocol relative to DS angiography for the evaluation of coil-treated aneurysms.

Methods

In 2003, the authors initiated a prospective protocol of following up patients with coil-treated brain aneurysms using both 1.5-tesla gadolinium-enhanced MR angiography and biplanar DS angiography. Using acquired images, the subject aneurysm was independently scored for degree of remnant identified (complete obliteration, residual neck, or residual aneurysm) and the surgeon's ability to visualize the parent vessel (excellent, fair, or poor).

Results

Thirty-seven patients with 42 coil-treated aneurysms were enrolled for a total of 44 paired MR angiography–DS angiography tests (median 9 days between tests). An excellent correlation was found between DS and MR angiography for assessing any residual aneurysm, but not for visualizing the parent vessel (κ = 0.86 for residual aneurysm and 0.10 for parent vessel visualization). Paramagnetic artifact from the coil mass was minimal, and in some cases MR angiography identified contrast permeation into the coil mass not revealed by DS angiography. An intravascular microstent typically impeded proper visualization of the parent vessel on MR angiography.

Conclusions

Magnetic resonance angiography is a noninvasive and safe means of follow-up review for patients with coil-treated brain aneurysms. Compared with DS angiography, MR angiography accurately delineates residual aneurysm necks and parent vessel patency (in the absence of a stent), and offers superior visualization of contrast filling within the coil mass. Use of MR angiography may obviate the need for routine diagnostic DS angiography in select patients.

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Michael B. Avery, Ahmed Alaqeel, Amy B. Bromley, Yong-Xiang Chen, John H. Wong, Muneer Eesa and Alim P. Mitha

OBJECTIVE

Reliable animal models are an important aspect of translational research, especially for relatively uncommon clinical entities such as fusiform aneurysms. While several animal models exist, very few are tailored to cerebral fusiform aneurysms, which have unique attributes compared to abdominal fusiform aneurysms. The authors aimed to build from previous models to create a cerebral fusiform aneurysm model that is simple to use and reliable.

METHODS

Twelve female New Zealand White rabbits were assigned to 3 groups: group E, elastase only; group C, CaCl2 only; group EC, elastase + CaCl2. All rabbits underwent surgical exposure of the right common carotid artery (CCA) and 20 minutes of peri-carotid incubation with their respective chemicals. Angiography was performed 6 weeks later for arterial dilation measurements, with 50% increase in diameter being defined as fusiform aneurysm formation. The arterial segments, along with the contralateral CCAs, were harvested and assessed histologically for wall component measurements and elastin semiquantification. A separate rabbit underwent aneurysm creation per the group EC protocol and was treated with an endovascular flow-diversion device.

RESULTS

All of the group EC rabbits developed fusiform aneurysms (mean dilation of 88%), while none of the group E or group C rabbits developed aneurysms (p = 0.001). Histological analysis revealed increased internal elastic lamina fragmentation in the group EC aneurysms, which also had less tunica intima hyperplasia. All aneurysms exhibited thinning of the tunica media and reduction in elastin content. The use of an endovascular flow-diverting stent was successful, with complete parent vessel remodeling, as expected, 4 weeks after deployment.

CONCLUSIONS

The peri-arterial application of combined elastase and CaCl2 to the CCA appears sufficient to reliably produce fusiform aneurysms after 6 weeks. Exposure to elastase or CaCl2 individually appears insufficient, despite the observed histological changes to the arterial wall. The proposed fusiform aneurysm model is able to accommodate endovascular devices, simulating the tortuous pathway experienced in using such devices in human cerebral aneurysms and thus is a satisfactory model to use in translational research.

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Aaron Hockley, Michael K. Tso, Mohammed A. Almekhlafi, Abhay K. Lodha, Robin Clegg, Jeremy Luntley, Muneer Eesa and John H. Wong

OBJECTIVE

Vein of Galen aneurysmal malformations (VGAMs) in infancy have a poor natural history if left untreated. Their high-flow nature can preclude safe and accurate therapeutic vessel occlusion and the risk of inadvertent pulmonary embolism is predominant. The authors describe the technique of rapid cardiac ventricular pacing for inducing transient hypotension to facilitate the controlled embolization of VGAMs.

METHODS

Initial transjugular venous access was obtained for placing temporary pacing leads for rapid cardiac ventricular pacing immediately prior to embolization. Definitive transarterial embolization procedures for the VGAMs were then performed in the same setting in which liquid embolic agents or coils were used.

RESULTS

Beginning in 2010, a total of five procedures were performed in three infants. Transvenous rapid cardiac ventricular pacing was successfully achieved to induce systemic transient flow arrest in all but two attempts, and facilitated partial embolization with n-butyl cyanoacrylate (n-BCA) and coils in all procedures. Ventricular fibrillation occurred twice in one patient and was successfully reversed with defibrillation on both occasions. One patient failed to improve and died from refractory heart failure. Two patients stabilized following staged embolization.

CONCLUSIONS

Rapid transvenous cardiac ventricular pacing can be considered to induce transient hypotension and facilitate controlled embolization in challenging high-flow VGAMs.

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Alim P. Mitha, John H. Wong, Jian-Qiang Lu, William F. Morrish, Mark E. Hudon and William Y. Hu

✓ To the authors' knowledge, only 1 case of communicating hydrocephalus after endovascular coiling of unruptured brain aneurysms has been reported previously. Here, they report on 2 such cases of delayed communicating hydrocephalus after treatment with hydrogel-coated coils and offer the first histopathological evidence of foreign material, presumably related to the coils, as the cause of hydrocephalus.

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Albert P. Wong, Zachary A. Smith, Alexander T. Nixon, Cort D. Lawton, Nader S. Dahdaleh, Ricky H. Wong, Brenda Auffinger, Sandi Lam, John K. Song, John C. Liu, Tyler R. Koski and Richard G. Fessler

OBJECT

Transforaminal lumbar interbody fusion (TLIF) has become one of the preferred procedures for circumferential fusion in the lumbar spine. Over the last decade, advances in surgical techniques have enabled surgeons to perform the TLIF procedure through a minimally invasive approach (MI-TLIF). There are a few studies reported in the medical literature in which perioperative complication rates of MI-TLIF were evaluated; here, the authors present the largest cohort series to date. They analyzed intraoperative and perioperative complications in 513 consecutive MI-TLIF–treated patients with lumbar degenerative disc disease.

METHODS

The authors performed a retrospective review of prospectively collected data on 513 consecutive patients treated over a 10-year period for lumbar degenerative disc disease using MI-TLIF. All patients undergoing either a first-time or revision 1- or 2-level MI-TLIF procedure were included in the study. Demographic, intraoperative, and perioperative data were collected and analyzed using bivariate analyses (Student t-test, analysis of variance, odds ratio, chi-square test) and multivariate analyses (logistic regression).

RESULTS

A total of 513 patients underwent an MI-TLIF procedure, and the perioperative complication rate was 15.6%. The incidence of durotomy was 5.1%, and the medical and surgical infection rates were 1.4% and 0.2%, respectively. A statistically significant increase in the infection rate was seen in revision MI-TLIF cases, and the same was found for the perioperative complication rate in multilevel MI-TLIF cases. Instrumentation failure occurred in 2.3% of the cases. After analysis, no statistically significant difference was seen in the rates of durotomy during revision and multilevel surgeries. There was no significant difference between the complication rates when stratified according to presenting diagnosis.

CONCLUSIONS

To the authors' knowledge, this is the largest study of perioperative complications in MI-TLIF in the literature. A total of 513 patients underwent MI-TLIF (perioperative complication rate 15.6%). The most common complication was a durotomy (5.1%), and there was only 1 surgical wound infection (0.2%). There were significantly more perioperative infections in revision MI-TLIF cases and more perioperative complications in multilevel MI-TLIF cases. The results of this study suggest that MI-TLIF has a similar or better perioperative complication profile than those documented in the literature for open-TLIF treatment of degenerative lumbar spine disease.

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Michael K. Tso, Myunghyun M. Lee, Chad G. Ball, William F. Morrish, Alim P. Mitha, Andrew W. Kirkpatrick and John H. Wong

OBJECTIVE

Blunt cerebrovascular injury (BCVI) occurs in approximately 1% of the blunt trauma population and may lead to stroke and death. Early vascular imaging in asymptomatic patients at high risk of having BCVI may lead to earlier diagnosis and possible stroke prevention. The objective of this study was to determine if the implementation of a formalized asymptomatic BCVI screening protocol with CT angiography (CTA) would lead to improved BCVI detection and stroke prevention.

METHODS

Patients with vascular imaging studies were identified from a prospective trauma registry at a single Level 1 trauma center between 2002 and 2008. Detection of BCVI and stroke rates were compared during the 3-year periods before and after implementation of a consensus-based asymptomatic BCVI screening protocol using CTA in 2005.

RESULTS

A total of 5480 patients with trauma were identified. The overall BCVI detection rate remained unchanged postprotocol compared with preprotocol (0.8% [24 of 3049 patients] vs 0.9% [23 of 2431 patients]; p = 0.53). However, postprotocol there was a trend toward a decreased risk of stroke secondary to BCVI on a trauma population basis (0.23% [7 of 3049 patients] vs 0.53% [13 of 2431 patients]; p = 0.06). Overall, 75% (35 of 47) of patients with BCVI were treated with antiplatelet agents, but no patient developed new or progressive intracranial hemorrhage despite 70% of these patients having concomitant traumatic brain injury.

CONCLUSIONS

The results of this study suggest that a CTA screening protocol for BCVI may be of clinical benefit with possible reduction in ischemic complications. The treatment of BCVI with antiplatelet agents appears to be safe.

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Judith M. Wong, John E. Ziewacz, Allen L. Ho, Jaykar R. Panchmatia, Albert H. Kim, Angela M. Bader, B. Gregory Thompson, Rose Du and Atul A. Gawande

Object

As part of a project to devise evidence-based safety interventions for specialty surgery, we sought to review current evidence concerning the frequency of adverse events in open cerebrovascular neurosurgery and the state of knowledge regarding methods for their reduction. This review represents part of a series of papers written to consolidate information about these events and preventive measures as part of an ongoing effort to ascertain the utility of devising system-wide policies and safety tools to improve neurosurgical practice.

Methods

The authors performed a PubMed search using search terms “cerebral aneurysm”, “cerebral arteriovenous malformation”, “intracerebral hemorrhage”, “intracranial hemorrhage”, “subarachnoid hemorrhage”, and “complications” or “adverse events.” Only papers that specifically discussed the relevant complication rates were included. Papers were chosen to be included to maximize the range of rates of occurrence for the reported adverse events.

Results

The review revealed hemorrhage-related hyperglycemia (incidence rates ranging from 27% to 71%) and cerebral salt-wasting syndromes (34%–57%) to be the most common perioperative adverse events related to subarachnoid hemorrhage (SAH). Next in terms of frequency was new cerebral infarction associated with SAH, with a rate estimated at 40%. Many techniques are advocated for use during surgery to minimize risk of this development, including intraoperative neurophysiological monitoring, but are not universally used due to surgeon preference and variable availability of appropriate staffing and equipment. The comparative effectiveness of using or omitting monitoring technologies has not been evaluated.

The incidence of perioperative seizure related to vascular neurosurgery is unknown, but reported seizure rates from observational studies range from 4% to 42%. There are no standard guidelines for the use of seizure prophylaxis in these patients, and there remains a need for prospective studies to support such guidelines.

Intraoperative rupture occurs at a rate of 7% to 35% and depends on aneurysm location and morphology, history of rupture, surgical technique, and surgeon experience. Preventive strategies include temporary vascular clipping.

Technical adverse events directly involving application of the aneurysm clip include incomplete aneurysm obliteration and parent vessel occlusion. The rates of these events range from 5% to 18% for incomplete obliteration and 3% to 12% for major vessel occlusion. Intraoperative angiography is widely used to confirm clip placement; adjuncts include indocyanine green video angiography and microvascular Doppler ultrasonography. Use of these technologies varies by institution.

Discussion

A significant proportion of these complications may be avoidable through development and testing of standardized protocols to incorporate monitoring technologies and specific technical practices, teamwork and communication, and concentrated volume and specialization. Collaborative monitoring and evaluation of such protocols are likely necessary for the advancement of open cerebrovascular neurosurgical quality.

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Xiao Wu, David Durand, Vivek B. Kalra, Renu Liu and Ajay Malhotra

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Aaron Hockley, Michael K. Tso, Mohammed A. Almekhlafi, Abhay K. Lodha, Robin Clegg, Jeremy Luntley, Muneer Eesa and John H. Wong

OBJECTIVE

Vein of Galen aneurysmal malformations (VGAMs) in infancy have a poor natural history if left untreated. Their high-flow nature can preclude safe and accurate therapeutic vessel occlusion and the risk of inadvertent pulmonary embolism is predominant. The authors describe the technique of rapid cardiac ventricular pacing for inducing transient hypotension to facilitate the controlled embolization of VGAMs.

METHODS

Initial transjugular venous access was obtained for placing temporary pacing leads for rapid cardiac ventricular pacing immediately prior to embolization. Definitive transarterial embolization procedures for the VGAMs were then performed in the same setting in which liquid embolic agents or coils were used.

RESULTS

Beginning in 2010, a total of five procedures were performed in three infants. Transvenous rapid cardiac ventricular pacing was successfully achieved to induce systemic transient flow arrest in all but two attempts, and facilitated partial embolization with n-butyl cyanoacrylate (n-BCA) and coils in all procedures. Ventricular fibrillation occurred twice in one patient and was successfully reversed with defibrillation on both occasions. One patient failed to improve and died from refractory heart failure. Two patients stabilized following staged embolization.

CONCLUSIONS

Rapid transvenous cardiac ventricular pacing can be considered to induce transient hypotension and facilitate controlled embolization in challenging high-flow VGAMs.