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L N Hopkins

Publications and source records attributed to L N Hopkins.

At least 19 recordsLinked to original sources
PubMed1999

Neurosurgery at the State University of New York at Buffalo.

WALLACE HAMBY STARTED the first practice dedicated to neurosurgery in Buffalo in 1933. Several years later, he was able to establish a residency program and became nationally known for his treatments of cerebral aneurysms and arteriovenous malformations. It was up to Louis Bakay to create an academic department within the State University of New York system and to incorporate an active and successful research program. This tradition has been expanded and enriched under the present leadership of L. Nelson Hopkins. The department is now well recognized, has 10 full-time staff members, and performs approximately 2000 procedures annually. There are numerous research opportunities available, at both the resident and fellowship levels.

Curriculum↗
PubMed1998

Saccular aneurysm induction by elastase digestion of the arterial wall: a new animal model.

OBJECTIVE: To develop a rabbit aneurysm model that is more realistic in gross appearance and histological features than previous models and to enable the development of a larger animal model. METHODS: Ten rabbits received porcine pancreatic elastase, five at the right common carotid artery bifurcation and five others at the right superior thyroid artery origin. One control animal received collagenase and another received papaverine, each at the right superior thyroid artery origin. The agents were topically delivered to the arterial adventitia with a microsyringe after surgical exposure of the targeted arteries. The arteries were monitored for aneurysm growth with a video camera for up to 3 hours and were then removed and processed for histology. RESULTS: Saccular aneurysms developed in one of five animals after elastase application at the carotid bifurcation and in all five animals receiving elastase at the superior thyroid artery origin. Among the six aneurysms, recurrent minor hemorrhages occurred in four, thrombosis of the aneurysm sac in three, and rupture causing severe bleeding in one. Histological sections revealed thin-walled aneurysms composed only of collagen fibers and some cellular elements. No saccular dilation resulted from papaverine application. Collagenase application resulted in a hemorrhagic-thrombotic lesion in the arterial wall but no aneurysm formation. CONCLUSION: Arterial saccular aneurysms were induced in rabbits by topical application of elastase with an easy and efficient method. These aneurysms are histologically similar to natural aneurysms, and their arterial nature renders them more authentic than those of surgical models. This aneurysm model may serve as a foundation for further aneurysm research.

Animals↗
PubMed1998

Stenting and secondary coiling of intracranial internal carotid artery aneurysm: technical case report.

OBJECTIVE AND IMPORTANCE: Endovascular stents have been successfully used in the treatment of fusiform and dissecting aneurysms of the peripheral circulation and extracranial carotid and vertebral arteries. Technical limitations related to the inability to navigate the stent and the delivery system through tortuous vascular segments has limited their application with intracranial lesions. Availability of new flexible and pliable stent systems might overcome these difficulties. CLINICAL PRESENTATION: A 49-year-old woman presented with a dissecting pseudoaneurysm of the horizontal portion of the petrous internal carotid artery that increased in size, as revealed by serial angiographic studies. INTERVENTION: The aneurysm was treated by deploying a new flexible stent across the aneurysm neck and by then packing the aneurysm sac with Guglielmi detachable coils that were delivered by a microcatheter positioned through the stent struts into the aneurysm lumen. CONCLUSION: New flexible stents can be used to treat intracranial internal carotid artery aneurysms in difficult-to-access areas, such as the horizontal petrous segment. The stent may disrupt the aneurysm inflow tract, thereby inducing stasis and facilitating intra-aneurysmal thrombosis. In addition, the stent acts as an endoluminal scaffold to prevent coil herniation into the parent artery, which allows tight packing of even wide-necked and irregularly shaped aneurysms. The stent may also serve as a matrix for endothelial growth. We think this new generation of flexible stents and the use of this described technique will usher in the next era of endovascular management of intracranial aneurysms.

Aortic Dissection↗
PubMed1998

Delayed aneurysm regrowth and recanalization after Guglielmi detachable coil treatment. Case report.

Guglielmi detachable coil (GDC) treatment for complicated cerebral aneurysms is an attractive option that has become widely accepted in recent years. This technique is usually considered only if the patient harbors an aneurysm that is not a good candidate for surgical clipping. However, the definition of "surgical candidate" varies among institutions, and many patients worldwide are being treated with GDCs as primary therapy. Although most centers currently perform follow-up angiography at 6 months to 1 year, others do not routinely perform it after an initially good result. The authors present a case that indicates longer follow up may be necessary and illustrates some of the pitfalls of GDC treatment. This 56-year-old man presented to the emergency room with a Hunt and Hess Grade II subarachnoid hemorrhage and was found to have a wide-necked basilar apex aneurysm. Because of associated medical comorbidities, it was decided to treat the aneurysm with endovascular techniques. The patient did well on follow-up angiography at 1 year postprocedure. However, at approximately 2 years follow up, the aneurysm was demonstrated to have dramatically recanalized and regrown, requiring open surgical intervention. Endovascular coiling was insufficient to treat this aneurysm and complicated definitive surgical management because a large coil mass had been placed in the operative field. It can be inferred from this case that angiographic follow up of these types of lesions may be beneficial up to 2 years after GDC treatment.

Basilar Artery↗
PubMed1998

Correlation of intraluminal thrombosis in brain tumor vessels with postoperative thrombotic complications: a preliminary report.

OBJECT: Thrombotic complications (deep vein thrombosis and/or pulmonary embolization [DVT/PE]) occur in 18 to 50% of patients harboring brain tumors who undergo neurosurgical procedures. Such patients are at risk for DVT/PE because of immobility, paresis, hypovolemia, and lengthy surgery. The present study was undertaken to see whether tumor patients at highest risk for DVT/PE could be identified so that augmentation of prophylactic measures might be used to reduce the incidence of thrombotic complications. METHODS: The authors conducted a retrospective analysis of 488 patients enrolled in their brain tumor registries between 1988 and 1995, identifying 57 patients (12%) with recorded symptomatic DVT, PE, or both postoperatively. In 24 of these 57 cases histological specimens were retrievable for review, allowing an in-depth analysis. Forty-five patients were lost to follow-up review, and the remaining 386 patients had no record of systemic thrombosis. Slides of pathological specimens were retrievable in 50 cases in which there was no DVT/PE. From these 50 cases, 25 were selected at random to represent the control group by a blinded observer. Seventeen (71%) of the 24 brain tumor specimens obtained in patients with DVT/PE stained positively for intraluminal thrombosis (ILT) after hematoxylin and eosin had been applied. The odds ratio associated with the presence of ILT was 17.8, with a confidence interval ranging from 4 to 79.3. No evidence of ILT was found in 22 patients (88%) within the control group (p < 0.0001, Fisher's exact test). Other factors that may predispose patients with brain tumors to DVT/PE-limb paresis, extent of tumor removal, and duration of the surgery-were also analyzed and found not to be statistically significant. Therefore, these factors were not the basis for differences seen between the study and control groups. CONCLUSIONS: These preliminary observations suggest that the presence of ILT within malignant glioma or glioblastoma tumor vessels may represent a marker of tumor-induced hypercoagulability.

Adult↗
PubMed1998

A novel approach to flow quantification in brain arteriovenous malformations prior to enbucrilate embolization: use of insoluble contrast (Ethiodol droplet) angiography.

OBJECT: Successful therapeutic embolization of arteriovenous malformations (AVMs) of the brain with liquid polymers (glues) requires precise knowledge of highly variable AVM structure and flow velocities and transit times of blood through the AVM nidus. The goal of this study was to improve AVM flow measurement and visualization by the substitution of the insoluble Ethiodol (ethiodized oil) contrast agent for the soluble contrast media normally used in angiographic studies. METHODS: Before enbucrilate embolization of 24 AVM feeding pedicles in 13 patients, standard contrast medium was superselectively injected into each target pedicle, followed by infusion of 20 microl of Ethiodol microdroplets. Transport of contrast material was assessed using high-speed biplane pulsed digital subtraction angiography (DSA) operating at 15 frames per second. The mean blood flow transit times through AVMs after administration of Ethiodol were found to be approximately half as long as in those measured after injection of soluble contrast materials (0.22 +/- 0.10 seconds compared with 0.46 +/- 0.19 seconds [mean +/- standard deviation]; p < 0.0001). The discrete Ethiodol microdroplets travel with the core flow, more closely approximating the dynamic behavior of enbucrilate, allowing the AVM structure to be traced with high spatial and temporal resolution. There were no inadvertent vessel occlusions or pulmonary complications related to the use of Ethiodol for DSA. CONCLUSIONS: Because of diffusion and convection, forces that decrease concentration, visualization of the contrast front is reduced, often resulting in deceptively long transit times when soluble contrast materials are used. Overestimation may prove dangerous when planning embolizations. The Ethiodol droplet DSA method provides accurate transit time measurements and precise, detailed, and dynamic AVM visualization. Further development of this method will improve the safety and precision of AVM treatments.

Adolescent↗
PubMed1998

Cavernous sinus syndrome during balloon test occlusion of the cervical internal carotid artery. Report of two cases.

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.

Abducens Nerve↗
PubMed1997

Microvascular surgical anatomy of the vertebrobasilar junction.

OBJECTIVE: We examined the pertinent microvascular anatomy of 28 formalin-fixed brains to develop anatomic guidelines for aneurysm surgery in the region of the vertebrobasilar junction. METHODS: Using a surgical microscope, the outer diameters were observed for the following main arteries: vertebral, basilar, posteroinferior cerebellar, and anteroinferior cerebellar. The number of lower brain stem perforating arteries was examined in relation to their course. The distance between the arteries and their perforators was measured with respect to anatomic landmarks. RESULTS: The anatomy of the main arteries was characteristically variable, whereas the anatomy of the perforators was constant, particularly in terms of their numbers and points of penetration into the brain substance. The four major points of entry were the lateral medullary area just caudal to the posterior olivary sulcus, the posterior olivary sulcus, the small lateral fossa at the superior olivary groove, and the foramen cecum. Each of these areas coincides with the origin of common vertebrobasilar aneurysms. CONCLUSION: The anatomy of the main arteries was variable. In contrast, the perforators penetrated the adjoining brain stem at specific locations, regardless of the caliber of the main artery. Despite a small vertebral artery or its major branches, perforators penetrating the brain are significant and may effect the outcome of aneurysm surgery or endovascular procedures.

Adult↗
PubMed1997

Rapid saccular aneurysm induction by elastase application in vitro.

OBJECTIVE: To develop a new saccular aneurysm model in vitro using elastase to study aneurysm initiation, growth, and rupture and to create a new in vivo aneurysm model to test endovascular therapies. METHODS: Seventeen common carotid arteries excised from freshly killed pigs and sheep were treated with seven different methods of elastase delivery. The arteries were mounted in a saline-filled flow chamber. They received pulsatile flow for 48 hours, or until the resulting aneurysms ruptured. Changes were continuously monitored with video camera recordings and validated with histological sections. RESULTS: All eight arteries treated topically, either on the intimal or on the adventitial surface, with elastase concentrations greater than 1 U/mm2, developed saccular aneurysms; five of them ruptured within 48 hours. All four arteries treated with surface concentrations of 0.1 U/mm2 via microcatheter infusion into the lumen developed fusiform aneurysms. None of the arteries that received surface concentrations less than 0.1 U/mm2 developed aneurysms. Histological sections revealed a reduced number of cellular element in a stretched collagen matrix at the dome of the saccular aneurysms. CONCLUSION: After empirically testing several methods of elastase delivery, we were able to induce saccular, bifurcation-type aneurysms in animal arterial specimens. These aneurysms are histologically similar and more authentic than surgical models. The procedure is easy and reproducible. Our results suggest a possible enzymatic role in aneurysm formation and highlight the dramatic effects of selective arterial elastic damage. Also, the rapid growth of our experimental aneurysms may reflect the speed of the natural process.

Aneurysm, Ruptured↗
PubMed1997

Temporary balloon protection as an adjunct to endosaccular coiling of wide-necked cerebral aneurysms: technical note.

OBJECTIVE: We present an endovascular technique for treating wide-necked cerebral aneurysms using Guglielmi detachable coils (Target Therapeutics, Fremont, CA) and simultaneous temporary balloon protection. The temporary balloon serves as a mechanical external force to mold the microcoils away from the parent artery. METHODS: Two illustrative cases of wide-necked cerebral aneurysms treated with Guglielmi detachable coils and a temporary balloon are presented. Emphasis is placed on the technical aspects of the approach, with several variations. The first case involves a left posterior cerebral artery aneurysm at the P1/P2 segment, and the second case involves a left paraclinoid internal carotid artery aneurysm. Both patients suffered from subarachnoid hemorrhage, but neither was a candidate for craniotomy. In each case, the coils, when used alone, protruded into the parent artery and were therefore removed. Then a temporary balloon was inflated for mechanical protection during coil deployment. RESULTS: The use of simultaneous temporary balloon protection allowed more dense intra-aneurysmal coil packing, especially in the neck, without parent artery compromise, than did the use of Guglielmi detachable coils alone. CONCLUSION: Endovascular treatment of wide-necked cerebral aneurysms can be facilitated by simultaneous temporary balloon protection.

Aneurysm, Ruptured↗
PubMed1997

Initial experience with collagen-filled Guglielmi detachable coils for endovascular treatment of experimental aneurysms.

PURPOSE: To evaluate the effectiveness of Guglielmi detachable coils (GDCs) filled with collagen threads in the permanent treatment of experimental aneurysms. METHODS: Seventeen side-wall aneurysms were surgically constructed in the canine common carotid artery; six were treated with conventional GDCs and 11 with collagen-filled GDCs. One aneurysms was removed at 1 week, the others were studied by digital subtraction angiography for a period of 8 to 12 weeks. Longitudinal sections of all aneurysms were examined by light microscopy. RESULTS: Angiograms obtained throughout the follow-up period showed no significant difference between aneurysms treated with conventional GDCs and those treated with collagen-filled GDCs. Light microscopy revealed a dense meshwork of newly formed collagen and fibroblasts near the collagen-filled GDCs, whereas a loose cellular meshwork surrounded the conventional GDCs at 8 and 12 weeks after treatment. CONCLUSION: Collagen threads within GDCs do not noticeably improve angiographic treatment of experimental aneurysms; however, these threads did induce local proliferation of fibroblasts and production of collagen within the aneurysmal cavities.

Aneurysm↗
PubMed1996

Endovascular treatment of experimental aneurysms with liquid polymers: the protective potential of stents.

Liquid polymers have previously been used to treat experimental and human aneurysms. However, the delivery of a liquid embolic material into the cerebral circulation involves a high risk of irreversible vessel occlusion and stroke. To evaluate methods for the safe and effective treatment of experimental aneurysms with liquid polymer injection, we tested four different techniques to deliver cellulose acetate polymer (CAP) or N-hexyl-cyanoacrylate into canine side-wall carotid artery aneurysms. The animals were observed for 1 to 10 weeks after treatment. Two aneurysms were treated without protection of the distal circulation, one with CAP and another with N-hexyl-cyanoacrylate. In four cases, an angioplasty balloon was inflated within the parent artery during endosaccular injection of CAP. In two of these cases, the balloon was placed adjacent to the aneurysm orifice, resulting in simultaneous occlusion of both the aneurysm and the parent artery, and in the other two cases, the balloon was positioned proximal to the aneurysm, resulting in temporary flow arrest. Three aneurysms were treated with either CAP or N-hexyl-cyanoacrylate after implantation of a balloon-expandable tantalum stent within the parent artery across the aneurysm orifice. Complete angiographic obliteration was achieved in all but one case. One aneurysm ruptured. Another partially occluded aneurysm reopened 10 weeks after treatment. In all cases treated without stents, distal migration of the polymer resulted in either stenosis or occlusion of the parent arteries. The combination of stent implantation and polymer injection resulted in permanent aneurysm occlusion without detectable polymer migration. An intravascular stent deployed within the parent artery across the aneurysm orifice acted as a safety net during endosaccular polymer injection by allowing blood to flow from the aneurysm cavity while preventing distal migration of liquid polymer.

Aneurysm↗
PubMed1996

Clinical application of region-of-interest techniques to radiologic imaging.

In region-of-interest (ROI) imaging, a filter with a central aperture is used to substantially reduce patient dose outside of an ROI while maintaining or improving image quality within the ROI. The benefits of ROI imaging can be realized by using standard imaging equipment. ROI imaging has been clinically applied to gastrointestinal radiology and interventional procedures. In gastrointestinal procedures, ROI fluoroscopy without image processing can be used without adversely affecting the procedure or interfering with spot radiography. ROI fluoroscopy can reduce the dose-area product by a factor of 1.7 for gastrointestinal procedures. In interventional neuroradiologic procedures, equalized display brightness is achieved with road mapping during fluoroscopy and with standard digital subtraction techniques during angiography. In interventional radiology, ROI filters can generally reduce the patient skin dose to levels below the threshold for skin effects, thus eliminating these effects across more than 85% of the field of view.

Central Nervous System↗
PubMed1996

Application of region-of-interest imaging techniques to neurointerventional radiology.

To reduce radiation exposure to patients and staff during neurointerventional procedures, region-of-interest (ROI) techniques were used with fluoroscopy, road mapping, and digital subtraction angiography in 19 patients. ROI filters, made of multiple layers of gadolinium, were attached to the collimators. Patient skin exposure was reduced by a factor of 3.3-10.0 across 85% of the field of view, and exposures were reduced to below thresholds for skin effects.

Angiography, Digital Subtraction↗
PubMed1996

Misdiagnosis of symptomatic cerebral aneurysm. Prevalence and correlation with outcome at four institutions.

BACKGROUND AND PURPOSE: It is not known what fraction of patients with symptomatic cerebral aneurysms are misdiagnosed at initial medical presentation. It is also not clear whether misdiagnosed patients more frequently deteriorate before definitive aneurysm diagnosis and therapy or achieve a poorer outcome than correctly diagnosed patients. METHODS: We reviewed records of consecutive patients with symptomatic cerebral aneurysms managed by four tertiary-care neurosurgical services during a recent 19-month period. Clinical course and outcome were analyzed according to misdiagnosis or correct diagnosis at initial medical evaluation. RESULTS: Fifty-four of 217 patients (25%) were misdiagnosed at initial medical evaluation, including 46 of 121 patients (38%) initially in good clinical condition (clinical grade 1 or 2). Forty-six of 54 patients (85%) in the misdiagnosis group were initially grade 1 or 2 compared with 75 of 163 patients (46%) with correct initial diagnosis (P < .01). Twenty-six of 54 misdiagnosed patients (48%) deteriorated or rebled before definitive aneurysm treatment compared with 4 of 165 correctly diagnosed patients (2%) (P < .001). Among patients initially presenting as clinical grade 1 or 2, overall good or excellent outcome was achieved in 91% of those with correct initial diagnosis and 53% of patients with initial misdiagnosis (P < .001). Deterioration before correct diagnosis accounted for 16 of 67 patients (24%) with poor or worse final outcome in this series. CONCLUSIONS: Patients in good clinical condition with symptomatic cerebral aneurysms were commonly misdiagnosed. Misdiagnosed patients were more likely than correctly diagnosed patients to deteriorate clinically and had a worse overall outcome. Misdiagnosed cases accounted for a significant fraction of overall poor outcomes among consecutive cases of symptomatic aneurysms.

Adult↗
PubMed1996

Vascular neurosurgery: aneurysms, arteriovenous malformations, subarachnoid hemorrhage, and intracranial hemorrhage.

Cerebrovascular disease continues to be a major source of morbidity and mortality in our aging population. Endovascular therapy for the treatment of cerebral aneurysms and associated vasospasm is gaining credibility. Some arteriovenous malformations considered inoperable in the past can now be successfully treated using multimodality therapy. Quantitative measurement of cerebral blood flow is helping to identify patients at risk of ischemic events and defining new guidelines for intervention. New noninvasive imaging modalities may replace conventional angiography for surgical disease. Advances in technology continue to improve our ability to treat cerebrovascular disease prior to irreversible ischemic events.

Cerebral Hemorrhage↗
PubMed1996

FasTRACKER-18.

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Catheterization, Peripheral↗