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Arvind Ahuja, Lee R. Guterman, and Leo N. Hopkins

✓ A case is presented of severe atherosclerosis of the basilar artery, successfully treated with percutaneous transluminal balloon angioplasty. Crescendo daily transient ischemic attacks consisted of alternating hemiplegia and were refractory to medical management, including anticoagulation therapy. The clinical course, endovascular treatment, and results are described. Prior published experiences with this condition are reviewed.

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Yiemeng Hoi, Hui Meng, Scott H. Woodward, Bernard R. Bendok, Ricardo A. Hanel, Lee R. Guterman, and L. Nelson Hopkins

Object. Few researchers have quantified the role of arterial geometry in the pathogenesis of saccular cerebral aneurysms. The authors investigated the effects of parent artery geometry on aneurysm hemodynamics and assessed the implications relative to aneurysm growth and treatment effectiveness.

Methods. The hemodynamics of three-dimensional saccular aneurysms arising from the lateral wall of arteries with varying arterial curves (starting with a straight vessel model) and neck sizes were studied using a computational fluid dynamics analysis. The effects of these geometric parameters on hemodynamic parameters, including flow velocity, aneurysm wall shear stress (WSS), and area of elevated WSS during the cardiac cycle (time-dependent impact zone), were quantified. Unlike simulations involving aneurysms located on straight arteries, blood flow inertia (centrifugal effects) rather than viscous diffusion was the predominant force driving blood into aneurysm sacs on curved arteries. As the degree of arterial curvature increased, flow impingement on the distal side of the neck intensified, leading to elevations in the WSS and enlargement of the impact zone at the distal side of the aneurysm neck.

Conclusions. Based on these simulations the authors postulate that lateral saccular aneurysms located on more curved arteries are subjected to higher hemodynamic stresses. Saccular aneurysms with wider necks have larger impact zones. The large impact zone at the distal side of the aneurysm neck correlates well with other findings, implicating this zone as the most likely site of aneurysm growth or regrowth of treated lesions. To protect against high hemodynamic stresses, protection of the distal side of the aneurysm neck from flow impingement is critical.

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Giuseppe Lanzino, Ajay K. Wakhloo, Richard D. Fessler, Mary L. Hartney, Lee R. Guterman, and L. Nelson Hopkins

Object. Results of previous in vitro and in vivo experimental studies have suggested that placement of a porous stent within the parent artery across the aneurysm neck may hemodynamically uncouple the aneurysm from the parent vessel, leading to thrombosis of the aneurysm. For complex wide-necked aneurysms, a stent may also aid packing of the aneurysm with Guglielmi detachable coils (GDCs) by acting as a rigid scaffold that prevents coil herniation into the parent vessel. Recently, improved stent system delivery technology has allowed access to the tortuous vascular segments of the intracranial system. The authors report here on the use of intracranial stents to treat aneurysms involving different segments of the internal carotid artery (ICA), the vertebral artery (VA), and the basilar artery (BA).

Methods. Ten patients with intracranial aneurysms located at ICA segments (one petrous, two cavernous, and three paraclinoid aneurysms), the VA proximal to the posterior inferior cerebellar artery origin (one aneurysm), or the BA trunk (three aneurysms) were treated since January 1998. In eight patients, stent placement across the aneurysm neck was followed (immediately in four patients and at a separate procedure in the remaining four) by coil placement in the aneurysm, accomplished via a microcatheter through the stent mesh. In two patients, wide-necked aneurysms (one partially thrombosed BA trunk aneurysm and one paraclinoid segment aneurysm) were treated solely by stent placement; coil placement may follow later if necessary.

No permanent periprocedural complications occurred and, at follow-up examination, no patient was found to have suffered symptoms referable to aneurysm growth or thromboembolic complications. Greater than 90% aneurysm occlusion was achieved in the eight patients treated by stent and coil placement as demonstrated on immediate postprocedural angiograms. Follow-up angiographic studies performed in six patients at least 3 months later (range 3–14 months) revealed only one incident of in-stent stenosis. In the four patients originally treated solely by stent placement, no evidence of aneurysm thrombosis was observed either immediately postprocedure or on follow-up angiographic studies performed 24 hours (two patients), 48 hours, and 3 months later, respectively.

Conclusions. A new generation of flexible stents can be used to treat complex aneurysms in difficult-to-access areas such as the proximal intracranial segments of the ICA, the VA, or the BA trunk. The stent allows tight coil packing even in the presence of a wide-necked, irregularly shaped aneurysm and may provide an endoluminal matrix for endothelial growth. Although convincing experimental evidence suggests that stent placement across the aneurysm neck may by itself promote intraluminal thrombosis, the role of this phenomenon in clinical practice may be limited at present by the high porosity of currently available stents.

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Amos O. Dare, Kevin J. Gibbons, Matthew D. Gillihan, Lee R. Guterman, Thom R. Loree, and Wesley L. Hicks Jr.

Object

To evaluate the reliability of balloon test occlusion with hypotensive challenge (BTO and HC) as a predictor of neurological complications before internal carotid artery (ICA) sacrifice in patients with advanced head and neck cancer, the authors retrospectively reviewed the medical records of patients presenting to their institutions between 1992 and 1997 in whom this preoperative assessment was performed.

Methods

Eleven patents who were candidates for extended comprehensive neck dissection (ECND) and potential ICA sacrifice were included in the study. Eight patients tolerated the test and underwent endovascular occlusion or surgical ligation of the ICA before ECND (four patients), preservation of the ICA at the time of surgery (three patients), or palliative therapy (one patient). Of three patients in whom BTO and HC failed, one patient received palliative treatment only; the other two underwent ECND with preservation of the ICA. In the group of patients who passed the test and underwent ICA occlusion or ligation before ECND, fatal thromboembolic stroke occurred within 24 hours of permanent balloon occlusion in one patient, resulting in a combined neurological morbidity/mortality rate of 25% in this subset of patients and an overall complication rate of 9% in this series.

Conclusions

The authors found that BTO and HC offers a simple and reliable method of preoperative risk assessment when ICA resection is planned for regional control of disease in advanced head and neck cancer. This management option, however, is associated with a potential for neurological complication that must be weighed against the natural course of the disease and the risks and benefits of other treatment modalities.

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Elad I. Levy, Robert D. Ecker, James J. Thompson, Peter A. Rosella, Ricardo A. Hanel, Lee R. Guterman, and L. Nelson Hopkins

Recent advances in carotid artery (CA) stent placement procedures have propelled this technology into the forefront of treatment options for both symptomatic and asymptomatic patients with CA stenosis. Until recently, endarterectomy was the only surgical option for patients with CA occlusive disease. For high-risk surgical candidates, periprocedural stroke rates remained unacceptable and were significantly higher than those associated with the natural history of the disease. Advances in stent technology and improvements in antiplatelet and antithrombotic regimens, in conjunction with distal protection devices, have significantly lowered the risk of periprocedural complications for high-risk surgical candidates requiring CA revascularization. In this paper the authors review data gleaned from the important recent CA stent trials and address questions concerning the safety, efficacy, and durability of stent-assisted angioplasty for extracranial CA occlusive disease. Additionally, they review the role of noninvasive imaging modalities for the diagnosis and surveillance of CA disease in these high-risk patients.

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Richard D. Fessler, Ajay K. Wakhloo, Giuseppe Lanzino, Adnan I. Qureshi, Lee R. Guterman, and L. Nelson Hopkins

Symptoms of vertebrobasilar insufficiency may precede neurological sequelae in up to 50% of patients. Although select patients may benefit from microsurgical revascularization, combined perioperative morbidity and mortality rates can be as high as 20%. The authors present their preliminary clinical experience using stent placement for symptomatic vertebral artery (VA) occlusive disease.

Six patients with clinical symptoms of vertebrobasilar insufficiency in whom VA stents were placed from 1995 to 1998 were identified. Diagnostic four-vessel cerebral angiography identified causative stenotic, atherosclerotic lesions in all cases. A transfemoral or transradial artery approach after the patient had undergone full heparinization was chosen for endovascular stenting. Guidewire placement across the lesion followed by urokinase infusion preceded stenting. Prestent angioplasty was performed in two patients. Following the procedure, all patients were maintained on daily antiplatelet therapy.

Patient age ranged from 45 to 76 years (average 63 years). Four patients were men and two were women. Angiography revealed greater than 95% stenosis in five patients and greater than 70% stenosis in one. Three patients had complete occlusion of the contralateral VA; in one other, the VA supplied only the posterior inferior cerebellar artery; and the remaining two patients had VAs with greater than 70% stenosis. Ten stents were placed in six patients for five VA origin lesions and one distal VA stenosis. A VA dissection occurring poststenting was treated by placement of three additional stents. One patient had transient double vision. All had resolution of their presenting symptoms. Follow up ranged from 1 to 24 months (average 8.4 months). Angiograms obtained in four patients at least 3 months postprocedure have revealed stent patency in all cases without evidence of restenosis.

Vertebral artery stent placement can be safely performed and is a viable treatment option for carefully selected patients with vertebrobasilar insufficiency.

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Alan S. Boulos, Eric M. Deshaies, Richard D. Fessler, Shuta Aketa, Scott Standard, Lazlo Miskolczi, Lee R. Guterman, and L. Nelson Hopkins

Object. Animal aneurysm models are required for the study of the hemodynamics and pathophysiology of intracranial aneurysms in humans and so that experimental treatments can be tested prior to clinical trials. The authors developed a canine model that consistently produces up to three bifurcation aneurysms similar in morphological features and hemodynamics to human intracranial aneurysms.

Methods. In 10 mongrel dogs, a harvested segment of the external jugular vein was anastamosed to an external carotid artery (CA)—lingual artery bifurcation arteriotomy site to create a lateral bifurcation aneurysm. The surgery was repeated on the contralateral side in each animal to form a second lateral bifurcation aneurysm and, in five dogs, a CA—CA crossover anastomosis was also performed to create a terminal bifurcation aneurysm.

Nineteen of 20 lateral bifurcation aneurysms were confirmed in 10 dogs by diagnostic angiography 7 to 14 days after surgery. Aneurysm fundus-to-neck ratios ranged from 1 to 2, depending on the size of the arteriotomy. The terminal bifurcation aneurysms were confirmed in all five dogs by diagnostic angiography 7 to 14 days after the procedure. The authors later tested endovascular techniques for embolizing the aneurysms.

Conclusions. Three bifurcation aneurysms of sufficient size for endovascular access can be created in a reproducible fashion in the same animal. This model is useful for studying complex endovascular procedures in aneurysms that mimic the human condition and for testing new devices and techniques.

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Giuseppe Lanzino, Robert A. Mericle, Demetrius K. Lopes, Ajay K. Wakhloo, Lee R. Guterman, and L. Nelson Hopkins

Object. Treatment consisting of percutaneous transluminal angioplasty (PTA) and stent placement has recently been proposed as an alternative to surgical reexploration in patients with recurrent carotid artery stenosis following endarterectomy. The authors retrospectively reviewed their experience after performing 25 procedures in 21 patients to assess the safety and efficacy of PTA with or without stent placement for carotid artery restenosis.

Methods. The mean interval between endarterectomy and the endovascular procedures was 57 months (range 8–220 months). Seven arteries in five patients were treated by PTA alone (including bilateral procedures in one patient and repeated angioplasty in the same vessel in another). Early suboptimum results and recurrent stenosis in some of these initial cases prompted the authors to combine PTA with stent placement in the treatment of 18 arteries over the past 3 years. No major periprocedural deficits (neurological or cardiac complications) or death occurred. There was one periprocedural transient neurological event, and in one patient a pseudoaneurysm of the femoral artery (at the access site) required surgical repair. In the 16 patients who each underwent at least 6 months of follow-up review, no neurological events ipsilateral to the treated artery had occurred after a mean follow-up period of 27 months (range 6–57 months). Three of five patients who underwent PTA alone developed significant (> 50%) asymptomatic restenoses that required repeated angioplasty in one and PTA with stent placement in two patients. Significant restenosis (55%) was observed in only one of the vessels treated by combined angioplasty and stent placement.

Conclusions. Endovascular PTA and stenting of recurrent carotid artery stenosis is both technically feasible and safe and has a satisfactory midterm patency. This procedure can be considered a viable alternative to surgical reexploration in patients with recurrent carotid artery stenosis.

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Giuseppe Lanzino, Robert A. Mericle, Demetrius K. Lopes, Ajay K. Wakhloo, Lee R. Guterman, and L. Nelson Hopkins

Percutaneous transluminal angioplasty (PTA) and stenting has recently been proposed as an alternative to surgical reexploration in patients with recurrent carotid artery stenosis following endarterectomy. The authors retrospectively reviewed their experience after performing 25 procedures in 21 patients to assess the safety and efficacy of PTA with or without stenting for carotid artery restenosis.

The mean interval between endarterectomy and the endovascular procedure was 57 months (range 8-220 months). Seven arteries in five patients were treated by PTA alone (including bilateral procedures in one patient and repeated angioplasty in the same vessel in another). Early suboptimum results and recurrent stenosis in some of these initial cases prompted the authors to combine PTA with stenting in the treatment of 18 arteries over the past 3 years.

No major periprocedural deficits (neurological or cardiac complications) or death occurred. There was one periprocedural transient neurological event. A pseudoaneurysm of the femoral artery (at the access site) required surgical repair. In the 16 patients who each underwent at least 6 months of follow-up review, no neurological events ipsilateral to the treated artery had occurred after a mean follow-up period of 27 months (range 6-57 months). Three of five patients who underwent PTA alone developed significant (> 50%) asymptomatic restenoses that required repeated angioplasty in one and PTA with stenting in two patients. Significant restenosis (55%) was observed in only one of the vessels treated by combined angioplasty with stenting. Endovascular PTA and stenting of recurrent carotid artery stenosis is both technically feasible and safe and has a satisfactory midterm patency. This procedure can be considered a viable alternative to surgical reexploration in patients with recurrent carotid artery stenosis.

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Demetrius K. Lopes, Robert A. Mericle, Ajay K. Wakhloo, Lee R. Guterman, and L. Nelson Hopkins

✓ The authors report the occurrence of ipsilateral transient cavernous sinus syndrome during balloon test occlusion (BTO) of the cervical internal carotid artery (ICA) and discuss the involved pathomechanisms.

The authors reviewed their series of 129 BTOs of the ICA performed between 1989 and 1996. Two patients developed facial paresthesias and transient palsies of the third through sixth cranial nerves during test occlusion of the cervical ICA. The tests were performed prior to planned permanent carotid artery occlusion for the treatment of a neck sarcoma in one patient and a giant cavernous carotid artery aneurysm in the other. The patients' symptoms resolved with deflation of the balloon. When the balloon was subsequently inflated above the inferior cavernous sinus artery (ICSA), one of the patients complained of mild facial discomfort. There was no contralateral weakness or mental status change during test occlusion in either patient. Angiography demonstrated good filling of the ipsilateral intracranial circulation via collateral vessels of the circle of Willis.

In these two cases, the cranial nerves in the cavernous sinus were likely supplied by the ICA via the meningohypophyseal trunk and the ICSA. In each case, there was excellent blood supply to the ipsilateral cerebral hemisphere; however, there was probably inadequate retrograde filling of the cranial nerve collateral vessels located where the meningohypophyseal trunk and ICSA originated. These cases emphasize the importance of a patent external carotid artery—ICA connection for successful cervical carotid artery occlusion. Neurological examination during BTO was critical to interpret the clinical manifestations caused by the hemodynamic changes.