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Biomedical subjects

G R Duckwiler

Publications and source records attributed to G R Duckwiler.

At least 55 records · Page 3Linked to original sources
PubMed1993

Combined embolization and surgical treatment of arteriovenous malformation of the orbit.

We examined three patients with arteriovenous malformation of the orbit. At initial examination, all patients had a slowly progressive mass effect combined with congestive symptoms and clinical signs typical of an orbital vascular lesion. Arteriovenous malformation of the orbit was diagnosed on the basis of clinical and radiographic assessment, including the use of digital subtraction angiography and in one patient, magnetic resonance imaging. Treatment of each patient involved neuroradiologic embolization of the vascular lesion followed by surgical excision. Transient complications of endovascular management occurred. In one patient particulate emboli migrated into the central retinal artery after postembolization orbital surgical excision; consequent focal ischemic retinopathy contributed to short-term visual field deficits, which eventually resolved spontaneously. In another patient, spasm of the ophthalmic artery occurred during embolization, resulting in a transient afferent pupillary defect and loss in visual acuity to 20/60, which resolved over the subsequent week. High-flow orbital vascular lesions represent a considerable treatment challenge because of the complex anatomic and hemorrhagic characteristics of the malformation. Neuroradiologic characterization and embolization as a preoperative adjuvant is not without risk but offers an important advantage in the treatment of these formidable lesions. A combination of endovascular and surgical management may allow otherwise inoperable lesions to be treated successfully.

Adolescent↗
PubMed1993

Pathologic findings in a patient with a vein of Galen aneurysm treated by staged endovascular embolization.

Vein of Galen aneurysms are uncommon malformations that can be treated with a combination of endovascular embolization and surgery. Since the relevant techniques are new and innovative, their pathologic sequelae are not yet well described. A patient treated with staged embolization over a 15-month period developed evidence of cerebral venous hypertension on angiography. At necropsy, we observed marked myointimal proliferation of the aneurysm wall, dura, and cerebral vessels in addition to severe widespread encephalomalacia, calcinosis, and rare mural thrombi. These vascular changes have not been previously described in cases of vein of Galen aneurysm, and may, in part, be a consequence of embolization therapy.

Cerebral Veins↗
PubMed1993

Pediatric intracranial vascular malformations: evaluation of treatment results with color Doppler US. Work in progress.

To determine the value of color Doppler ultrasound (US) in the preoperative assessment and evaluation of treatment results in children with intracranial vascular malformations (VMs), the authors performed 36 color Doppler US studies in nine children who underwent endovascular embolization. Color flow imaging with spectral waveform analysis of feeding arteries, nidus, draining veins, and uninvolved cranial vasculature was performed, and correlation was made with other imaging findings. In most VMs, color Doppler US enabled the authors to map the lesion completely. Hemodynamic changes after embolization included improvement in blood supply to uninvolved portions of the brain and increase in caliber and flow of feeding vessels that were not occluded during embolization. Serial volume flow measurements were performed with Doppler US in major extracranial arteries. Success of embolization was indicated by substantial decrease of total carotid artery flow. Color Doppler US is a noninvasive modality that adds important imaging and hemodynamic data to those provided by angiography.

Cerebral Angiography↗
PubMed1993

True anatomical compartmentalization of the cavernous sinus in a patient with bilateral cavernous dural arteriovenous fistulae. Case report.

An unusual case of complete anatomical compartmentalization of the cavernous sinus in a patient with bilateral Type D cavernous dural arteriovenous fistulae is described. This anatomical anomaly isolated the anterior cavernous sinus and orbital venous system, which was primarily responsible for the patient's clinical presentation. The compartmentalization of the cavernous sinus also limited options for definitive endovascular therapy to a transvenous approach via the superior ophthalmic vein.

Adult↗
PubMed1992

Fluid equations applied to blood flow measurement using digital videodensitometry.

RATIONALE AND OBJECTIVES: Time-dependent fluid flow is computed from projection radiographs without bolus tracking by applying the fluid equations of continuity and incompressibility. METHODS: The fluid equations are combined and integrated to yield an equation that describes instantaneous mass conservation within a vessel segment. The technique is demonstrated using phantom images and patient data obtained using a digital subtraction angiography (DSA) system. RESULTS: Instantaneous and mean flow rates are successfully computed with this algorithm, but the uncertainties are overestimated. In a 1.0-cm diameter tube, instantaneous and mean velocities corresponding to 7.3 cm per frame are computed within 13% uncertainty using a 4.0-cm segment length. Mean flow rates computed from standard diagnostic angiograms taken from three different projections agree within 16%. CONCLUSIONS: This technique can successfully compute time-dependent flow rates from DSA image sequences with large fluid displacements between frames. The accuracy is strongly dependent on the magnitude of the contrast density gradient.

Algorithms↗
PubMed1991

Meckel cave lesions: percutaneous fine-needle-aspiration biopsy cytology.

The authors describe the novel combination of two traditional methods to facilitate diagnosis of Meckel cave lesions, which may otherwise require craniotomy to obtain adequate tissue samples. Fine-needle-aspiration biopsy cytology was performed on tissue obtained with a percutaneous approach via the foramen ovale with use of fluoroscopic guidance and intravenous analgesia during an outpatient procedure. This new application of fine-needle-aspiration biopsy cytology results in decreased patient morbidity and significant cost reduction.

Adult↗
PubMed1990

Pre-operative micro-angioplasty of refractory vasospasm secondary to subarachnoid hemorrhage.

A patient with subarachnoid hemorrhage secondary to a basilar artery aneurysm developed severe bilateral middle and anterior cerebral artery vasospasm with extensive neurologic deficits. Microangioplasty of the middle cerebral artery segments bilaterally led to reversal of the neurologic deficits, allowing early operative treatment of the aneurysm in a previously inoperable patient.

Aged↗
PubMed1989

Neurovascular lesions and endovascular therapy: the role of MR.

Magnetic resonance imaging (MRI) studies were performed on 27 patients with vascular lesions of the central nervous system before and after embolization with either IBCA, polyvinyl alcohol foam particles, Avitene (microfibrillar collagen) or balloons. Thirteen pial brain arteriovenous malformations (AVMs), 3 brain AV fistulas, 2 giant aneurysms, 5 dural AVMs, 1 vertebro-vertebral fistula and 3 meningiomas were studied. The pre-embolization MR demonstrated the nidus and venous drainage of all pial AVMs. MR failed to detect 3 out of 5 dural AVMs using only spin echo sequences. A draining vein alone was seen in the remaining two cases. MR was superior to CT in detecting contiguous parenchymal changes such as atrophy, reversible ischemia, and mass effect in the pre-embolization studies. Following embolization, MR demonstrated partial or complete obliteration of the vascular nidus in all 13 pial AVMs. The embolized area was seen as an area of increased signal consistent with thrombus where previously there had been signal void. Ischemic or edematous changes in the brain parenchyma following embolization were seen on MR more easily than on CT scans. MR was accurate in the assessment of aneurysm patency, degree of thrombosis and balloon position in both giant aneurysms, and AV fistulae. These MR findings had an impact on patient management. MR will be an increasingly useful tool in the diagnosis and management of a number of neurovascular diseases requiring endovascular intervention.

Arteriovenous Malformations↗
PubMed1989

Extracranial lesions of the head and neck: preliminary experience with Gd-DTPA-enhanced MR imaging.

The authors report initial experience with magnetic resonance imaging enhanced with gadolinium diethylenetriaminepentaacetic acid (DTPA) in 27 patients with various extracranial lesions of the head and neck. Unenhanced T1- and T2-weighted images were compared with T1-weighted images obtained 3-30 minutes after Gd-DTPA administration. Overall, compared with precontrast T1- and T2-weighted images, Gd-DTPA improved the visibility of lesions in 11 and five of 27 patients, respectively. Gd-DTPA particularly improved the conspicuity of tumors of the nasal cavity and paranasal sinuses and tumors having perineural or intracranial extension. Gd-DTPA-enhanced images were equivalent to precontrast T1- and T2-weighted images in five and 13 patients, respectively, and inferior to them in nine and eight patients, respectively. Mixed results were obtained in two patients and one patient when Gd-DTPA-enhanced images were compared with T1- and T2-weighted images, respectively. The authors conclude that Gd-DTPA has definite but limited uses in extracranial head and neck pathologic conditions and that more research is needed to evaluate particular applications.

Adolescent↗
PubMed1987

MR imaging of the knee. Part II. Chronic disorders.

Sixty patients with symptoms of chronic disease of the knee joint were evaluated with high-resolution, thin-section magnetic resonance (MR) imaging. MR imaging depicted a wide variety of knee joint abnormalities including osteochondritis dissecans, medullary infarcts, epiphyseal osteonecrosis, intraarticular osteochondral fragments, synovial cysts, joint effusions, intraarticular soft-tissue tumors, synovial disease, leukemic infiltration of bone marrow, Osgood-Schlatter disease, and nonossifying fibroma. In two cases MR imaging depicted bone infarcts not seen on both radionuclide bone scans and standard radiographs. The highly detailed depiction of the articular cartilage was of particular importance in predicting arthroscopic findings in cases of osteochondritis dissecans. In two cases, a soft-tissue mass (pigmented villonodular synovitis) and a large osteochondral fragment undetected at arthroscopy were accurately localized with MR imaging. The results indicate that MR imaging is capable of providing information that might otherwise require multiple, sometimes invasive diagnostic procedures.

Chronic Disease↗
PubMed1986

Meniscal injuries: detection using MR imaging.

Both retrospective and blinded analyses of thin-section, high-resolution magnetic resonance (MR) images of the knee joint, produced using a solenoid surface coil, indicate that MR imaging is an effective technique for evaluating meniscal injuries. Images of 49 patients were evaluated, and the results were correlated with those of subsequent arthroscopy. A grading scale was developed to rate the index of suspicion of a meniscal tear based on the MR images. Overall, approximately 80% of menisci rated grade 4 (definite tear) or 3 (probable tear) were found to have corresponding tears at arthroscopy. In many other patients with a grade 4 or 3 meniscus in whom a corresponding tear was not found arthroscopically, meniscal tears at other sites or other abnormalities were correctly diagnosed using MR. A majority of the false-positive MR images involved the posterior horns of the menisci, the sites of most false-negative arthroscopic diagnoses. The predictive value of a negative MR image was almost 100%. Even in patients with moderate-to-large effusions, the menisci were accurately evaluated. The results imply that MR imaging is useful in the preoperative evaluation of suspected meniscal tears.

Adolescent↗
PubMedDate not supplied

Development of the biologically active Guglielmi detachable coil for the treatment of cerebral aneurysms. Part II: an experimental study in a swine aneurysm model.

BACKGROUND AND PURPOSE: Ion implantation is a surface-modification technology that creates a borderless surface on protein-coated platinum; this change in physical and chemical properties on the surface of Guglielmi detachable coils (GDCs) appears to enhance cell proliferation and adhesion. Our purpose was to evaluate the effect of ion implantation on GDCs in an experimental aneurysm model. METHODS: GDCs were coated with either type I collagen, fibronectin, vitronectin, laminin, or fibrinogen. Using He+ or Ne+ 1 x 10(14-15) ions/cm2, ion implantation was performed on these protein-coated GDCs (GDC-Is). A total of 56 experimental aneurysms were constructed microsurgically in the common carotid arteries of 28 swine. These experimental aneurysms were embolized with standard GDCs (n = 23), collagen GDC-Is (n = 11), vitronectin GDC-Is (n = 6), laminin GDC-Is (n = 4), fibrinogen GDC-Is (n = 6), and fibronectin GDC-Is (n = 6). The animals were sacrificed at day 14 after coil embolization. The physical properties of the new coils (friction on delivery, deployment into aneurysms, trackability, etc) and the development of tissue scarring and neoendothelium across the aneurysm's orifice were evaluated macroscopically and microscopically. RESULTS: No evidence of increased coil friction/stiffness was observed during delivery of GDC-Is through microcatheters in this aneurysm model. A more intense scar formation and neoendothelium at the neck of aneurysms were observed macroscopically when treated with GDC-Is. Significant differences in the proportion of neck coverage between standard GDCs (48.3% +/- 20.5%) and all GDC-I groups were observed (collagen GDC-I-89.4% +/- 14.9%, P < .01; vitronectin GDC-I-71.5% +/- 7.0%, P < .05; laminin GDC-I-76.5% +/- 11.0%, P < .05; fibrinogen GDC-I-74.8% +/- 13.9%, P < .05; fibronectin GDC-I-87.5% +/- 15.0%, P < .01). Light microscopy showed a well-organized fibrous tissue bridging the aneurysm's neck when using GDC-Is, whereas only a fibrin-like thin layer covered the standard GDC surfaces. CONCLUSION: GDC-Is indicated a more intense inflammatory response in the aneurysm body and dome and faster re-endothelial coverage of the neck of the aneurysm. This accelerated histologic response may decrease the chances of coil compaction and aneurysm recanalization. This technology may improve anatomic and clinical outcomes in patients harboring intracranial aneurysms.

Animals↗
PubMedDate not supplied

Dural arteriovenous fistula in children: endovascular treatment and outcomes in seven cases.

BACKGROUND AND PURPOSE: Dural AVF is a vascular anomaly that rarely occurs in children and is best treated by endovascular embolization. We report our experience using various endovascular embolization techniques in the treatment of dural AVF in a pediatric population. METHODS: Seven children with angiographically proven dural AVF were treated with endovascular embolization using microcoils, N-butylcyanoacrylate, detachable balloons, and/or silk suture. All imaging studies, embolization procedures, and patient charts were retrospectively reviewed. RESULTS: Seven children had been treated for dural AVF at our institution since 1987. Three newborns presented with congestive heart failure. Four older children (10 months-10 years) presented with signs referable to venous hypertension, including seizures, hydrocephalus, and proptosis. Embolization approaches included transarterial, transvenous, and direct puncture after neurosurgical exposure of a dural sinus. The number of embolizations ranged from 1 to 13 sessions per patient. All patients experienced symptomatic improvement after each embolization session. The three newborns showed marked improvement in cardiac function that allowed discharge to home. Clinical follow-up ranged from 3 weeks to 9 years (mean, 4.1 years). Two children with partially embolized dural AVF died, and one was lost to follow-up. Four children are alive after complete embolization of their dural AVF; two are developmentally normal, and two have mild developmental delay. CONCLUSION: Endovascular embolotherapy is the current treatment of choice for dural AVF. Embolization therapy may be life saving in the setting of cardiac failure and curative in cases of small or simple fistulae. Multiple, complex dural AVF are usually not curable, and treatment is aimed at symptomatic relief. Treatment strategies focus on the location and/or complexity of the fistula, the patient's clinical status, and the neurologic prognosis.

Central Nervous System Vascular Malformations↗
PubMedDate not supplied

Delayed venous occlusion following embolotherapy of vascular malformations in the brain.

PURPOSE: To describe the nature and features of delayed venous thrombosis following embolization of arteriovenous fistulae. METHODS: Retrospective review of the available clinical history, details of embolization procedures, and results of follow-up angiography were carried out on all embolization procedures performed on high-flow vascular malformations of the brain done at our institution since 1987. RESULTS: Four patients were identified who had delayed (greater than 1 week) venous thrombosis/occlusion after embolization of the malformation associated with neurologic complications. Two patients had arteriovenous fistula and two had vein-of-Galen malformations. These patients had no untoward embolization of the venous outlet as a cause of the venous occlusion. CONCLUSIONS: It is postulated that thrombosis in the arteriovenous fistula group was induced by conversion (due to embolization) of a patulous high flow venous outlet into a slow flow system; in the vein-of-Galen group, the occlusion was thought to be due to high-flow venopathy.

Adult↗
PubMedDate not supplied

Transvenous treatment of spontaneous dural carotid-cavernous fistulas using a combination of detachable coils and Onyx.

Three patients with spontaneous dural carotid-cavernous fistulas were treated by using a combination of detachable coils and Onyx liquid embolic agent. Cavernous sinus was accessed via the superior ophthalmic vein or inferior petrous sinus approach. In all cases, a complete angiographic closure of the fistulas was achieved with full recovery from neuro-ophthalmologic symptoms. This report suggests that the controlled and excellent penetration of Onyx is superb for blocking the intricate communication of dural carotid-cavernous fistulas.

Aged↗
PubMedDate not supplied

Endovascular mechanical clot retrieval in a broad ischemic stroke cohort.

BACKGROUND AND PURPOSE: Our aim was to describe an expanded experience with endovascular mechanical embolectomy in a broad group of patients, including those not meeting entry criteria for the MERCI multicenter trials. METHODS: We performed an analysis of all patients with ischemic stroke treated with the Merci Clot Retrieval Device at a single academic center outside of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trials. RESULTS: Twenty-four patients were treated with the device. Nine were MERCI trial ineligible: 4 received intravenous (IV) tissue plasminogen activator (tPA), 1 received IV tPA and was younger than 18 years of age, and 4 had time-to-treatment of longer than 8 hours. Mean age was 64 years (range, 14-89 years; 42% women). Median National Institutes of Health Stroke Scale (NIHSS) score was 21 (range, 11-30). Median symptoms-to-procedure-start time was 303 minutes (range, 85-2385 minutes). Recanalization (Thrombolysis in Myocardial Infarction, 2-3) was achieved in 15/24 (63%). In device-only patients, recanalization occurred in 10/16. In patients who failed IV tPA undergoing rescue embolectomy, recanalization was achieved in 4/5. Three patients unresponsive to device therapy received rescue intra-arterial tPA/abciximab; recanalization was achieved in 2/3. Recanalization was achieved in 3/4 patients in whom treatment was started longer than 8 hours after symptom onset. Asymptomatic hemorrhage occurred in 38%; symptomatic hemorrhage, in 8%. Three device fractures occurred; none worsened clinical outcome. In-hospital mortality was 17%; 90-day mortality, 29%. Good 90-day functional outcome (modified Rankin Scale, <or=2) was achieved by 25% (6/24). CONCLUSIONS: Endovascular mechanical embolectomy is an effective means of achieving revascularization in patients with acute ischemic stroke, including patients with late treatment start and intravenous tPA failure. Device-based therapy achieved recanalization in nearly two thirds of patients and good clinical outcomes in one fourth, with symptomatic hemorrhage in less than one tenth.

Adolescent↗
PubMedDate not supplied

Angiographic diagnosis and management of head and neck schwannomas.

Schwannomas are tumors derived from nerve sheath cells, which are often located in the head and neck, including the CNS. Although a definitive vascular pattern has been previously characterized for these lesions, preoperative embolization of the more vascular schwannomas has not been described. In a review of eight patients with schwannomas who underwent angiography at our institution since 1987, a characteristic vascular pattern became apparent that helped distinguish these lesions from other lesions of the head and neck. The lesions were moderately vascular with tortuous tumor vessels. Scattered, small puddles of contrast medium seen in the mid-arterial, capillary, and venous phases were believed to be characteristic of these lesions. Multiple feeding vessels were noted in all but one case, but these were only minimally enlarged. No arteriovenous shunting or vascular encasement was identified. Six of eight lesions were embolized with significant devascularization and no morbidity or mortality. In patients with head and neck tumors whose angiographic findings include a pattern of moderate hypervascularity, tortuous tumor vessels, and, in particular, scattered contrast puddles without arteriovenous shunting or vascular encasement, schwannoma should be suspected. Embolization is a useful and safe presurgical adjunct in the treatment of vascular schwannomas.

Adult↗