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Cameron G McDougall

Publications and source records attributed to Cameron G McDougall.

At least 19 recordsLinked to original sources
PubMed2006

The evolution of endovascular treatment for intracranial arteriovenous malformations.

Endovascular therapy for arteriovenous malformations (AVMs) remains a relatively new approach. Beginning in the 1960s with the use of flow-directed techniques for selective embolization, hemodynamic alterations have been used to treat these lesions. In every aspect of treatment, technological advances, including catheters, embolic materials, angiography suites, and pharmacological agents, have improved outcomes while lowering the risk to patients. In this article, the authors review the technical evolution of endovascular AVM therapy. Developments in embolic materials, beginning with foreign bodies and autografts and continuing through to highly engineered contemporary substances, are discussed. Finally, changes in treatment paradigms that have occurred over the years are traced. Within neurosurgery, this specialty has shown some of the fastest growth and development in recent decades. As minimally invasive approaches are embraced in all areas of medicine, it is clear that this treatment modality will continue to be refined.

Embolization, Therapeutic↗
PubMed2006

Durability of aneurysm embolization with matrix detachable coils.

OBJECTIVE: Matrix detachable coils (MDC; Boston Scientific/Target, Fremont, CA) are platinum coils coated with a bioabsorbable polymeric material (polyglycolic-polylactic acid). In animal models, the introduction of polyglycolic-polylactic acid-coated coils into experimental aneurysms resulted in a cellular reaction which promoted stable intra-aneurysmal scar tissue formation. The current study was undertaken to assess the durability of aneurysm occlusion after embolization with MDC. METHODS: All patients undergoing embolization were prospectively enrolled in an endovascular database at our institution. All coils used for embolization were recorded in the operative notes for the procedure. Only aneurysms embolized with 50% or greater length of MDC were included. All patients with Neuroform stents (Boston Scientific/Target, Fremont, CA) were excluded from the study. Patients were followed with conventional angiography and magnetic resonance angiography. RESULTS: During a 20-month period, 131 aneurysms were embolized with MDC. Follow up data (average, 6.9 mo; range, 1.5-22 mo) were available for 82 aneurysms (61 with conventional angiography, 21 with magnetic resonance angiography only). Of the aneurysm patients with follow-up available, 65 had small aneurysms with small necks, three were small aneurysms with wide necks, 12 were large aneurysms, and two were giant aneurysms. Overall, there were 30 (36.6%) recanalizations, 19 (23.1%) of which required retreatment. In two additional patients, retreatment was either recommended (n = 1) or attempted unsuccessfully (n = 1). Fifty-two aneurysms were unchanged or demonstrated progressive thrombosis (63.4%). The recanalization rate for small aneurysms with small necks was 26.1% (17 out of 65) with a 13.8% retreatment rate (9/65). The recanalization rate for large aneurysms was 75% (9 out of 12) with seven requiring retreatment. CONCLUSION: In the absence of Neuroform stent support, aneurysms embolized with the MDC system demonstrated a significant rate of recanalization. Many of the recanalizations were of sufficient size to warrant retreatment. The rates of recanalization observed in the present series were comparable to, or worse than, those reported for bare platinum coils.

Adult↗
PubMed2006

Postembolization neurological deficits in cerebral arteriovenous malformations: stratification by arteriovenous malformation grade.

OBJECTIVE: To stratify the risk of embolization during the treatment of cerebral arteriovenous malformations (AVMs) by grade and to assess its impact on the overall treatment risk. METHODS: Patients with cerebral AVMs treated with embolization between 1995 and 2004 were retrospectively reviewed. Age, sex, AVM grade, location of lesion, number and location of embolized arteries, and number of embolization sessions were analyzed with respect to neurological or vascular complications after embolization. RESULTS: Embolization was performed in 153 patients: 508 vessels were embolized during 203 sessions (mean, 3.3 vessels per patient). The mean angiographic and clinical follow-up periods were 1.7 and 2.1 years, respectively (range, 3-60 mo). The periprocedural morbidity and mortality rate was 11.8%, but at the last follow-up examination, only 2% of survivors were significantly disabled (modified Rankin score > 2). One (0.7%) patient died, and 17 patients experienced unexpected neurological deficits immediately after embolization. Five of these patients demonstrated near or total recovery during follow-up. The number of branches embolized was the only variable significantly related to neurological deficit (P < 0.017). The long-term rates of neurological deficits after embolization were 0, 5, 7, 10, and 18%, respectively, for AVM Grades I through V. Among 114 patients who underwent preoperative embolization, follow-up deficit rates of Grades I through V were 0, 5, 6, 6, and 25%, respectively. Long-term permanent deficits from embolization occurred in 8.6% of patients. CONCLUSION: Endovascular treatment carries a procedural risk related to AVM grade and number of branches treated. This risk should be weighed carefully in the context of overall treatment morbidity and mortality.

Adolescent↗
PubMed2006

Neuroform in-stent stenosis: incidence, natural history, and treatment strategies.

OBJECTIVE: Delayed in-stent stenosis is an important and well-characterized complication of angioplasty and stenting for the treatment of intra- and extracranial atheromatous disease. The current series describes the incidence and natural history of in-stent stenosis after the deployment of the Neuroform stent within the cerebrovasculature for the treatment of aneurysms. METHODS: The collaborative Cleveland Clinic Foundation-Barrow Neurological Institute endovascular database was reviewed to identify cases of delayed moderate or severe in-stent stenosis observed during the follow-up of cerebral aneurysms treated with the Neuroform stent. The hospital charts, clinic records, and operative reports for these patients were reviewed. RESULTS: Of a total of 156 patients with follow-up, nine (5.8%) cases of moderate or severe delayed (>2 mo) in-stent stenosis were identified, including two parent vessel occlusions. In two cases, patients presented 3 months after stent-supported aneurysm embolization with focal neurological symptoms. Both of these patients were treated with angioplasty. One eventually required surgical bypass. Of the seven asymptomatic patients, four demonstrated some degree of spontaneous resolution at follow-up, one progressed to complete occlusion, one is awaiting further follow-up, and one patient died of unrelated causes. Of the nine patients in the series, five were treated with "bioactive" coils (Matrix, Hydrocoil, Cerecyte), three were treated with bare platinum coils, and one was treated with stenting alone. The earliest time interval to diagnosis was 2.5 months and 3 months for asymptomatic and symptomatic patients, respectively. The earliest interval documented for spontaneous resolution was 9 months. CONCLUSION: Delayed Neuroform in-stent stenosis, occurring in 5.8% of cases, is not a rare phenomenon. The stenosis can be symptomatic and may require endovascular treatment or surgical bypass. In asymptomatic patients, a strategy of "watchful waiting" may be effective because many patients demonstrate partial or complete resolution at follow-up. The spontaneous resolution of delayed in-stent stenosis has not been previously described. This may be a phenomenon unique to the application of low radial force, self-expanding stents within the nonatheromatous cerebrovasculature.

Adult↗
PubMed2006

Low morbidity associated with use of n-butyl cyanoacrylate liquid adhesive for preoperative transarterial embolization of central nervous system tumors.

OBJECTIVE: To determine the safety and efficacy of preoperative embolization of central nervous system tumors with n-butyl cyanoacrylate (NBCA) liquid adhesive. METHODS: Over a 6-year period, 35 consecutive patients (12 women, 23 men; mean age, 42 yr; range, 6 mo-75 yr) with a central nervous system tumor underwent preoperative embolization with NBCA. Tumor type, location, endovascular and surgical treatment, percent of tumor embolization, estimated blood loss, and neurological deficits related to embolization were evaluated retrospectively. RESULTS: One hundred feeding arteries were embolized (mean, 3 vessels/patient). In only one (3%) case was a normal artery inadvertently occluded by the embolization. During the follow-up period, the resulting neurological deficit resolved completely. There were no neurological deficits or inadvertent embolization events in the remaining 34 cases. The mean percent of tumor embolized was 68%, but this did not significantly correlate with operative blood loss (Pearson's correlation coefficient, r = 0.049). CONCLUSION: In experienced hands, central nervous system tumors can be embolized with NBCA liquid adhesive with a high degree of safety and efficacy. We think that adroit embolization technique with NBCA and other embolisates should be part of the contemporary neuroendovascular armamentarium.

Adolescent↗
PubMed2006

Endovascular reconstruction with the Neuroform stent as monotherapy for the treatment of uncoilable intradural pseudoaneurysms.

OBJECTIVE: Intradural pseudoaneurysms have a malignant natural history and can be difficult to treat if parent vessel deconstruction is not feasible. These lesions often involve a long arterial segment and lack a defined saccular component that would safely accommodate the introduction of embolization coils. The current report describes the successful endovascular treatment of these lesions using a strategy of Neuroform stent reconstruction. METHODS: A retrospective review of the prospectively maintained Neuroform databases from our two institutions identified all intracranial aneurysms treated with the Neuroform stent alone, without embolization coils. The clinical charts, procedural data, and angiographic results were reviewed. RESULTS: Over a 38-month study period (10/02-2/06), 266 aneurysms were treated with the Neuroform stent. Of these, 10 were small "uncoilable" intradural pseudoaneurysms associated with subarachnoid hemorrhage. These lesions were treated using a strategy of endovascular stent reconstruction of the diseased vascular segment with one or more Neuroform stents (without concomitant coil embolization). Seven pseudoaneurysms were treated in the context of acute or subacute subarachnoid hemorrhage, and three were associated with a remote history of subarachnoid hemorrhage. Periprocedural complications occurred in two patients (clinically silent, intraprocedural thromboembolic event successfully treated with intra-arterial abciximab, symptomatic postprocedural stent thrombosis with successful thrombolysis, and excellent neurological recovery). Both complications occurred in patients with ruptured aneurysms and could be attributed to inadequate platelet inhibition at the time of the initial procedure. Follow-up conventional angiographic examinations were available for all 10 patients with pseudoaneurysms (1-18.5 mo; average, 9.0 mo). In nine cases, the aneurysms improved at follow-up, with either complete (n = 5) or near complete (n = 4) resolution. In one case, short-term follow-up (1 mo) demonstrated no significant change. No patient has rehemorrhaged after treatment. CONCLUSION: Endovascular Neuroform stent reconstruction represents an optimal strategy for the management of intradural pseudoaneurysms that require a constructive treatment strategy and are too small to accommodate the introduction of embolization coils. Nine out of 10 patients in the current series treated with this strategy demonstrated some degree of endovascular remodeling with either complete (n = 5) or partial (n = 4) angiographic resolution at follow-up. No rehemorrhages were encountered. Adequate antiplatelet therapy, even in the setting of acute subarachnoid hemorrhage, is prerequisite for the avoidance of thromboembolic complications.

Adolescent↗
PubMed2006

The role of neuroendovascular therapy for the treatment of brain arteriovenous malformations.

Neuroendovascular embolization represents a critical component of the multidisciplinary management of cerebral arteriovenous malformations. Safe and effective embolization may be performed only in the context of a well-designed, rational treatment plan that is fundamentally based on a clear understanding of the natural history of the lesion, as well as the cumulative risks of multimodality treatment. This article outlines the role of neuroendovascular embolization in arteriovenous malformation therapy with a specific emphasis on decision making in the context of formulating a treatment plan. The authors also provide a summary of the available embolic agents and their technical application, potential intraprocedural and periprocedural complications, and postprocedural management.

Blood Vessel Prosthesis↗
PubMed2006

Resolution of an infectious pseudoaneurysm in a cervical petrous carotid vein bypass graft after covered stent placement: case report.

OBJECTIVE AND IMPORTANCE: Covered stenting of the carotid artery has been used to treat aneurysms and dissections. We describe a unique case of covered stenting in the setting of an infected psuedoaneurysm in a previously placed cervical-to-petrous vein bypass graft. Operating in an infected field and reopening a surgical wound at the craniocervical junction that had previously been exposed to penetrating trauma created substantial risks to open surgical repair. We therefore chose an endovascular strategy to repair this lesion. CLINICAL PRESENTATION: A 57-year-old diabetic man with a previously placed cervical-to-petrous vein bypass graft presented with chronic otitis media and acute hemorrhage from his right external auditory meatus. Evaluation revealed an infectious pseudoaneurysm of the vein graft at the skull base. TECHNIQUE: The patient was treated with intravenous antibiotics and endovascular placement of an 8-mm x 25-mm polytetrafluoroethylene-covered stent across the pseudoaneurysm. Angiography obtained 8 months later confirmed successful obliteration of the lesion. CONCLUSION: The patient's clinical outcome was excellent. Despite the active infection, covered stenting of the pseudoaneurysm was an effective treatment strategy, obviating the need for open debridement and graft revision.

Aneurysm, False↗
PubMed2006

Surgical management of arteriovenous malformations in children.

OBJECT: Children compose 3 to 20% of the patients with arteriovenous malformations (AVMs); however, AVMs are responsible for 30 to 50% of intracranial hemorrhages in children. METHODS: The medical records of 82 children with 84 AVMs treated surgically between 1983 and 2005 were reviewed. Fifty-two patients (63%) presented with hemorrhage, 13.4% presented with seizures, and AVMs in 12% were found incidentally. Patients with brainstem lesions presented at a significantly younger age (p = 0.002) than those harboring lesions in other locations. Frontal lobe lesions were significantly smaller than those in other locations, and thalamic lesions were significantly larger (p = 0.012 and 0.005, respectively). Most patients with Spetzler-Martin Grades I to III lesions underwent craniotomy only. Half of the patients with Grade IV and V lesions underwent embolization, craniotomy, and radiosurgery. The mean follow-up period was 43 months. Postoperatively, the initial obliteration rate was 65%, with a long-term obliteration rate of 90%. The perioperative mortality rate was 3.7%. Altogether, 81% of patients had excellent outcomes, and patients with Grade I lesions had the best outcomes. Of the 52 patients who presented with hemorrhage, 17% had fair or poor outcomes. The recurrence rate was 5.6%. CONCLUSIONS: Children with AVMs may be more prone than adults to present with a hemorrhage and to experience recurrence of the lesion after treatment. The authors favor resection for most AVMs in children and use embolization as a preoperative strategy for Grades II to V lesions treated surgically. Prehemorrhagic Grade IV and V lesions may best be treated conservatively and observed carefully for the development of symptoms. Long-term follow up of all patients is essential.

Cerebral Hemorrhage↗
PubMed2005

Endovascular management of intracranial vertebral artery dissecting aneurysms.

OBJECT: Intracranial vertebral artery (VA) dissecting aneurysms often present with severe subarachnoid hemorrhage (SAH) and dramatic neurological injury. The authors reviewed the management of 23 cases in an effort to evaluate treatment efficacy and outcomes. METHODS: The records of 23 patients who underwent endovascular treatment were reviewed to determine symptoms, type of therapy, complications, and clinical outcomes. All patients were evaluated using records kept in a prospectively maintained database. Ten men and 13 women (age range 35-72 years; mean age 49 years) were treated over an 8-year period. Twelve patients presented with poor-grade SAH, five with good-grade SAH, three with headache, and two with stroke. The other patient's aneurysm was discovered incidentally. Treatment included coil occlusion of the artery at the aneurysm in 21 patients and stent-assisted coil placement in two. Parent artery sacrifice was successful in all cases, whereas both patients treated with stent-assisted coil insertion suffered recurrences. No patient sustained permanent complications as a result of treatment. Two patients died due to the severity of their original SAH. Findings were normal in 14 patients on follow-up review (including five of the 12 presenting with poor-grade SAH), five had fixed neurological deficits but were able to care for themselves, and one was permanently disabled. CONCLUSIONS: Despite their often aggressive neurological presentation, intracranial VA dissecting aneurysms can be managed safely with coil occlusion of the lesion and/or parent artery. Even patients presenting in poor neurological condition may improve dramatically.

Adult↗
PubMed2005

Training, competency, and credentialing standards for diagnostic cervicocerebral angiography, carotid stenting, and cerebrovascular intervention: a joint statement from the American Academy of Neurology, the American Association of Neurological Surgeons, the American Society of Interventional and Therapeutic Neuroradiology, the American Society of Neuroradiology, the Congress of Neurological Surgeons, the AANS/CNS Cerebrovascular Section, and the Society of Interventional Radiology.

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Angioplasty↗
PubMed2005

Antiplatelet therapy in neuroendovascular therapeutics.

Our understanding of the pharmacology of antiplatelet therapy continues to evolve rapidly. Although the existing data are primarily generated in the setting of interventional and preventative cardiology studies, these data may be extrapolated to guide the rational application of these agents in neuroendovascular procedures. Platelet function testing represents an increasingly available and practical method by which to verify the adequacy of therapy and guide clinical decision making. The optimal application of these agents will undoubtedly improve the risk profile of neuroendovascular procedures, increase the success rate of acute stroke intervention, and facilitate more effective secondary stroke prevention.

Adult↗
PubMed2005

Bilateral ethmoidal dural arteriovenous fistulae: a previously unreported entity: case report.

OBJECTIVE AND IMPORTANCE: Ethmoidal dural arteriovenous fistulas (AVFs) are rare intracranial lesions associated with a high risk of intracranial hemorrhage. Reported hemorrhage rates have ranged from 62 to 91%, and an aggressive clinical course is more likely than a benign clinical course. We describe the first case of a patient with bilateral ethmoidal dural AVFs. CLINICAL PRESENTATION: A 50-year-old man presented with posterior fossa subarachnoid hemorrhage and cerebellar intraparenchymal hemorrhage. Angiography revealed a tentorial AVF and a complex anterior ethmoidal dural AVF. INTERVENTION: The tentorial AVF was treated with preoperative embolization and surgical obliteration. On follow-up angiography, the ethmoidal dural AVF was not considered amenable to embolization. A right modified orbitozygomatic approach was performed and the right-sided fistula was interrupted. Intraoperative angiography revealed obliteration of the right-sided fistula, but a persistent fistula on the left. Further surgical exploration revealed this contralateral anterior ethmoidal dural AVF, which was clip ligated. No residual fistula was noted on intraoperative angiography. CONCLUSION: Anterior ethmoidal dural AVFs may occur bilaterally. Given their complex angiographic appearance, their presence bilaterally may not be readily apparent on preoperative angiography. Intraoperative angiography is crucial to identify a contralateral fistula and to verify that ligation has been curative.

Carotid Artery, Internal↗
PubMed2005

Intra-arterial thrombolysis for acute ischemic stroke: preliminary experience with platelet glycoprotein IIb/IIIa inhibitors as adjunctive therapy.

OBJECTIVE: To evaluate the safety profile of platelet glycoprotein IIb/IIIa inhibitors administered as adjunctive therapy to patients with large-vessel occlusion and acute ischemic stroke refractory to pharmacological thrombolysis with recombinant tissue plasminogen activator (rtPA) and mechanical disruption, balloon angioplasty, or both. METHODS: Twenty-one patients (mean age, 62 yr; range, 29-88 yr) met the following criteria: 1) large-vessel occlusion and acute ischemic stroke syndrome at presentation, 2) failure to recanalize after administration of rtPA (intra-arterial and/or intravenous) with or without mechanical thrombolysis, and 3) subsequent treatment with IIb/IIIa inhibitors (intra-arterial or intravenous). RESULTS: Eleven patients had ischemia in the dominant hemisphere, 8 in the vertebrobasilar system, and 2 in the nondominant hemisphere. Twelve patients received intravenous rtPA without significant improvement; 9 patients were not candidates for intravenous rtPA. All patients received intra-arterial rtPA. The IIb/IIIa inhibitors were administered intravenously in 3 patients, intra-arterially in 16, and both intravenously and intra-arterially in 2. Balloon angioplasty was performed in 18 patients. Complete or partial recanalization was achieved in 17 of the 21 patients. After thrombolysis, 15 improved clinically. Three patients (14%) sustained an asymptomatic intracerebral hemorrhage after thrombolytic therapy. No patient was clinically worse after intervention. At last follow-up (mean, 8.5 mo), 13 patients were functionally independent (modified Rankin score, 0-3) and 8 were disabled or dead. CONCLUSION: IIb/IIIa inhibitors are an alternative for achieving recanalization. The risk of hemorrhage may be low. As part of an escalating protocol that includes pharmacological and mechanical thrombolysis, IIb/IIIa inhibitors may improve clinical outcomes.

Abciximab↗
PubMed2005

Calcium alginate gel as a biocompatible material for endovascular arteriovenous malformation embolization: six-month results in an animal model.

OBJECTIVE: We sought to expand our assessment of calcium alginate as an embolic agent in an animal model of a cerebral arteriovenous malformation (AVM). The objective of this study was to assess the long-term biocompatibility and stability of calcium alginate in AVM swine models that survived from 1 to 6 months. METHODS: The swine model included a carotid-jugular anastomosis to redirect flow to the rete mirabile (RM), thereby simulating flow to an AVM. Alginate and the reactive component, calcium chloride, were injected from double-lumen or concentric-tube microcatheters to form an occlusion of the RM feeding vessel and the inferior portion of the RM. RESULTS: Angiography and histology verified complete occlusion of the RM feeding vessel for up to 6 months in eight of nine swine. Blood flow remained open to the superior portion of the RM and the circle of Willis. No evidence of downstream calcium alginate gel was seen in the follow-up angiograms or the histological preparations of the circle of Willis. A minor bioactive response to the alginate gel was noted at 1 month, yet no degenerative or inflammatory response was seen. At 6 months, there was moderate fibrous tissue around the alginate, which further sealed off flow to the embolized areas of the RM. CONCLUSION: Over a period of 6 months, calcium alginate was an effective endovascular occlusion material that blocked blood flow to the inferior portion of the RM. The chronic AVM model verified the long-term stability and biocompatibility of calcium alginate.

Alginates↗
PubMed2005

Usefulness of the Neuroform stent for the treatment of cerebral aneurysms: results at initial (3-6-mo) follow-up.

OBJECTIVE: The Neuroform microstent, a flexible, self-expanding, nitinol stent specifically designed for use in the cerebral vasculature, became available in North America for aneurysm treatment in November 2002. The present report details our experience with the Neuroform stent over the past 2 years, with an emphasis on evolving treatment strategies and treatment durability at initial (3-6 mo) follow-up. METHODS: All patients included in this report were registered in a prospectively maintained database. We assessed the clinical history, indications for stent use, aneurysm dimensions, technical details of the procedures, degree of aneurysm occlusion, angiographic and clinical findings at follow-up, and complications. RESULTS: Over a 20-month period, 64 patients with 74 aneurysms were treated with 86 Neuroform stents. Of 64 patients, 16 (25%) were treated in the context of subarachnoid hemorrhage (8 acute, 7 subacute, 1 remote). Indications for stent use included broad aneurysm neck (n = 51 stents; average neck, 5.1 mm; aneurysm size, 8.2 mm), fusiform/dissecting morphology (n = 17), salvage/bailout for coils prolapsed into the parent vessel (n = 7), and giant aneurysm (n = 11). Sixty-one aneurysms were stented and coiled with complete or near complete (>95%) occlusion in 28 patients (45.9%) and partial occlusion (<95%) in 33 patients (54%). Follow-up angiographic (n = 43) or magnetic resonance angiographic (n = 5) data (average follow-up, 4.6 mo; median, 4 mo; range, 1.5-13 mo) for 48 aneurysms (46 patients) after stent-supported coil embolization demonstrated progressive thrombosis in 25 patients (52%), recanalization in 11 patients (23%) (8 of whom were retreated), and no change in 12 patients (25%). Follow-up angiography in 5 additional patients with dissecting aneurysms treated with stents alone demonstrated interval vascular remodeling with decreased aneurysm size in all patients. Delayed, severe, in-stent stenosis was observed in 3 patients, 1 of whom was symptomatic and required angioplasty and subsequently superficial temporal artery-to-middle cerebral artery bypass surgery. Using the second-generation Neuroform2 delivery system (n = 53), very few technical problems with stent delivery and deployment have been encountered (n = 2). CONCLUSION: The Neuroform stent facilitates adequate embolization of complex cerebral aneurysms, which would not otherwise be amenable to endovascular therapy. Initial follow-up data indicate favorable progressive thrombosis and recanalization rates for aneurysms after Neuroform stent-assisted embolization. These advantages of stenting were most evident for small aneurysms with wide necks.

Cerebral Angiography↗