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Craig Kilburg, Philipp Taussky, M. Yashar S. Kalani and Min S. Park

The use of flow-diverting stents for intracranial aneurysms has become more prevalent, and flow diverters are now routinely used beyond their initial scope of approval at the proximal internal carotid artery. Although flow diversion for the treatment of cerebral aneurysms is becoming more commonplace, there have been no reports of its use to treat flow-related cerebral aneurysms associated with arteriovenous malformations (AVMs). The authors report the cases of 2 patients whose AVM-associated aneurysms were managed with flow diversion. A 40-year-old woman presented with a history of headaches that led to the identification of an unruptured Spetzler-Martin Grade V, right parietooccipital AVM associated with 3 aneurysms of the ipsilateral internal carotid artery. Initial attempts at balloon-assisted coil embolization of the aneurysms were unsuccessful. The patient underwent placement of a flow-diverting stent across the diseased vessel; a 6-month follow-up angiogram demonstrated complete occlusion of the aneurysms. In the second case, a 57-year-old man presented with new-onset seizures, and an unruptured Spetzler-Martin Grade V, right frontal AVM associated with an irregular, wide-necked anterior communicating artery aneurysm was identified. The patient underwent placement of a flow-diverting stent, and complete occlusion of the aneurysm was observed on a 7-month follow-up angiogram. These 2 cases illustrate the potential for use of flow diversion as a treatment strategy for feeding artery aneurysms associated with AVMs. Because of the need for dual antiplatelet medications after flow diversion in this patient population, however, this strategy should be used judiciously.

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Jaechan Park, Wonsoo Son, Ki-Su Park, Min Young Kim and Joomi Lee


The Ghajar Guide technique is used to direct a ventricular catheter at a 90° angle to the skull surface at Kocher’s point. However, the human calvaria is not completely spherical. Lateral to the sagittal midline, the calvaria slopes downward with individual variation and thereby affects the accuracy of ventricular catheter placement. Accordingly, the authors investigated the accuracy of the orthogonal catheter trajectory using radiographic simulation and examined the effect of the calvarial slope on this accuracy.


A catheter trajectory orthogonal to the skull surface at Kocher’s point and the ideal catheter trajectory to the foramen of Monro were drawn bilaterally on coronal head images of 52 patients with hydrocephalus. The correction angle, the difference between the 2 catheter trajectories, was then measured. Meanwhile, the calvarial slope was measured around Kocher’s point by using a coronal head image. The correlation between the correction angle and factors such as the calvarial slope and bicaudate index was then assessed using a Pearson correlation analysis.


The ventricular catheter trajectory orthogonal to the skull at Kocher’s point in the patients with hydrocephalus led to a catheter trajectory into the ipsilateral (70.2%) or contralateral (29.8%) lateral ventricles. The correction angles ranged from −3.3° to 16.4° (mean ± SD 5.7° ± 3.7°). In 87 (83.7%) head sides, lateral deviation from the orthogonal trajectory was required to approximate the ideal trajectory, and the correction angle ranged from 2.0° to 16.4° (mean 6.7° ± 2.9°). The calvarial slope in the 104 head sides ranged from 15.6° to 32.5° (mean 24.2° ± 3.1°). Pearson correlation analysis revealed a strong positive correlation (r = 0.733) between the calvarial slope and the correction angle.


The accuracy of ventricular catheter placement using the Ghajar Guide technique is affected primarily by the calvarial slope around Kocher’s point. A radiographic analysis of a preoperative coronal head image can be used to estimate the accuracy of ventricular catheter placement and enable adjustment to approximate the ideal catheter trajectory.

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Daniel M. S. Raper, Nasser Mohammed, M. Yashar S. Kalani and Min S. Park

The preferred method for treating complex dural arteriovenous fistulae of the transverse and sigmoid sinuses is via endovascular, transarterial embolization using liquid embolysate. However, this treatment approach mandates access to distal dural feeding arteries that can be technically challenging by standard endovascular approaches. This video describes a left temporal craniotomy for direct stick microcatheterization of an endovascularly inaccessible distal posterior division of the middle meningeal artery for embolization of a complex left temporal dural arteriovenous fistula. The case was performed in the hybrid operative suite with biplane intraoperative angiography. Technical considerations, operative nuances, and outcomes are reviewed.

The video can be found here:

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Sung Hun Park, Woo Min Park, Cheul Woong Park, Kwan Soo Kang, Young Keun Lee and Sang Rak Lim


The purpose of this study was to determine whether anterior lumbar interbody fusion (ALIF) followed by percutaneous translaminar facet screw fixation is effective in elderly patients with degenerative spinal disease.


Twenty-nine patients > 60 years old who underwent ALIF with percutaneous translaminar facet screw fixation from January to June 2004 were studied. The radiological and clinical data of these patients were collected and analyzed. The mean follow-up period was 14.6 months (range 12–17 months).


The mean preoperative, immediate postoperative, and 6- and 12-month postoperative posterior disc heights were 7.1, 11.6, 9.8, and 9.8 mm, respectively. Subsidences of posterior disc height > 20% developed in 9 patients (30%). The significant risk factor for subsidence was found to be 2-level operations (p = 0.023). The mean preoperative Oswestry Disability Index score and visual analog scale scores for the back and leg were 24.4, 6.6, and 7.5, respectively, and improved postoperatively to 14.2, 1.5, and 1.8, respectively.


Minimally invasive ALIF followed by percutaneous translaminar facet screw fixation was performed as a minimally invasive surgical technique in elderly patients. However, in certain circumstances such as multilevel operations or in patients with severe osteoporosis, significant cage subsidence can develop.

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Vijay M. Ravindra, Jayson A. Neil, Marcus D. Mazur, Min S. Park, William T. Couldwell and Philipp Taussky

The craniocervical junction (CCJ) functions within a complicated regional anatomy necessary to protect and support vital neurovascular structures. In select instances, vascular pathology can be attributed to this complicated interplay of motion and structure found within this narrow space. The authors report 3 cases of complex vascular pathology related to motion at the CCJ and detail the management of these cases. Two cases involved posterior circulation vascular compression syndromes, and one case involved a vascular anomaly and its relation to aneurysm formation and rupture. The patient in Case 1 was a 66-year-old man with a history of syncopal episodes resulting from the bilateral vertebral artery becoming occluded when he rotated his head. Successful microsurgical decompression at the skull base resulted in patent bilateral vertebral artery V3 segments upon head movement in all directions. The patient in Case 2 was a 53-year-old woman who underwent elective resection of a right temporal meningioma and who experienced postoperative drowsiness, dysphagia, and mild right-arm ataxia. Subsequent MRI demonstrated bilateral posterior inferior cerebel-lar artery (PICA) strokes. Cerebral angiography showed a single PICA, of extradural origin, supplying both cerebellar hemispheres. The PICA exhibited dynamic extradural compression when the patient rotated her head; the bilateral PICA strokes were due to head rotation during surgical positioning. In Case 3, a 37-year-old woman found unconscious in her home had diffuse subarachnoid hemorrhage and evidence of a right PICA aneurysm. A right far-lateral craniectomy was performed for aneurysm clipping, and she was found to have a dissecting aneurysm with an associated PICA originating extradurally. There was a shearing phenomenon of the extradural PICA along the dura of the foramen magnum, and this microtraumatic stress imposed on the vessel resulted in a dissecting aneurysm. This series of complex and unusual cases highlights the authors’ understanding of vascular pathology of the CCJ and its management.

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Adam S. Arthur, Philipp Taussky, Min S. Park, Michael F. Stiefel and Robert H. Rosenwasser

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Nam Yoon, Aatman Shah, William T. Couldwell, M. Yashar S. Kalani and Min S. Park

Skull base meningiomas are technically challenging tumors to treat because of their deep vascular supply that can preclude early devascularization during resection. Preoperative embolization of these arterial feeders is thought to decrease blood loss and facilitate resection; however, given the complex and varied anatomy of these skull base lesions, preoperative embolization is not without risk. It is essential for both endovascular and skull base neurosurgeons to understand these risks in light of the potential benefits. The authors review the vascular anatomy of skull base meningiomas, indications for preoperative devascularization, endovascular techniques, and published results regarding embolization of these lesions.

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Sung-Min Kim, T. Jesse Lim, Josemaria Paterno, Jon Park and Daniel H. Kim

Object. The stability of lateral lumbar interbody graft—augmented fusion and supplementary lateral plate fixation in human cadavers has not been determined. The purpose of this study was to investigate the immediate biomechanical stabilities of the following: 1) femoral ring allograft (FRA)—augmented anterior lumbar interbody fusion (ALIF) after left lateral discectomy combined with additional lateral MACS HMA plate and screw fixation; and 2) ALIF combined with posterior transpedicular fixation after anterior discectomy.

Methods. Sixteen human lumbosacral spines were loaded with six modes of motion. The intervertebral motion was measured using a video-based motion-capturing system. The range of motion (ROM) and the neutral zone (NZ) in each loading mode were compared with a maximum of 7.5 Nm.

The ROM values for both stand-alone ALIF approaches were similar to those of the intact spine, whereas NZ measurements were higher in most loading modes. No significant intergroup differences were found. The ROM and NZ values for lateral fixation in all modes were significantly lower than those of intact spine, except when NZ was measured in lateral bending. All ROM and NZ values for transpedicular fixation were significantly lower than those for stand-alone anterior ALIF. Transpedicular fixation conferred better stabilization than lateral fixation in flexion, extension, and lateral bending modes.

Conclusions. Neither approach to stand-alone FRA-augmented ALIF provided sufficient stabilization, but supplementary instrumentation conferred significant stabilization. The MACS HMA plate and screw fixation system, although inferior to posterior transpedicular fixation, provided adequate stability compared with the intact spine and can serve as a sound alternative to supplementary spinal stabilization.

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Michael Karsy, Andrea Brock, Jian Guan, Phillip Taussky, M. Yashar S. Kalani and Min S. Park

Stroke is a leading cause of disability in the US. Although there has been significant progress in the area of medical and surgical thrombolytic technologies, neuroprotective agents to prevent secondary cerebral injury and to minimize disability remain limited. Only limited success has been reported in preclinical and clinical trials evaluating a variety of compounds. In this review, the authors discuss the most up-to-date information regarding the underlying molecular biology of stroke as well as strategies that aim to mitigate this complex signaling cascade. Results of historical research trials involving N-methyl-d-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazole propionate receptor antagonists, clomethiazole, antioxidants, citicoline, nitric oxide, and immune regulators have laid the groundwork for current progress. In addition, more recent studies involving therapeutic hypothermia, magnesium, albumin, glyburide, uric acid, and a variety of other treatments have provided more options. The use of neuroprotective agents in combination or with existing thrombolytic treatments may be one of many exciting areas of further development. Although past trials of neuroprotective agents in ischemic stroke have been limited, significant insights into mechanisms of stroke, animal models, and trial design have incrementally improved approaches for future therapies.

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Nam K. Yoon, Al-Wala Awad, M. Yashar S. Kalani, Philipp Taussky and Min S. Park

Atherosclerotic disease of the cerebral vasculature is a major cause of stroke worldwide. Atherosclerosis that is refractory to best medical management may require revascularization. In these instances, endovascular treatment provides a popular and safe alternative to open surgical techniques. The authors provide an overview of stent technology in the treatment of ischemic stroke, discussing the major studies evaluating stenting for extracranial carotid artery, vertebral artery, and intracranial atherosclerotic disease. The authors describe the commonly used stents with respect to their individual characteristics and technical limitations. Current and future developments in stent technology are also discussed, with areas for further innovation and clinical research.