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Biomedical subjects

G Duckwiler

Publications and source records attributed to G Duckwiler.

At least 37 records · Page 2Linked to original sources
PubMed1996

Management of cavernous sinus-dural fistulas. Indications and techniques for primary embolization via the superior ophthalmic vein.

OBJECTIVE: To describe indications and surgical techniques for embolization of cavernous sinus-dural fistulas (CDF) by passing platinum coils through a cannulated superior ophthalmic vein based on our clinical experience. DESIGN: Retrospective clinical review. SETTING: University tertiary referral hospital and eye institute. PATIENTS: Over a 3-year period, 10 consecutive patients with CDF and progressive orbital congestion underwent transvenous embolization. All patients had a dilated superior ophthalmic vein. All 10 patients had indications for treatment of fistulas on the basis of progressive glaucoma refractory to medical management, venous stasis retinopathy with retinal ischemia, optic neuropathy, diplopia, exophthalmos with exposure keratopathy, cortical venous congestion with risk for intracranial hemorrhage, or a combination of these findings. INTERVENTION: Nine of the 10 patients underwent anterior orbitotomy via a lid-crease or sub-brow incision with cannulation of the ipsilateral superior ophthalmic vein and embolization of the cavernous sinus with platinum coils, following an unsuccessful transarterial embolization. One patient underwent a primary transvenous embolization. MAIN OUTCOME MEASURES: Successful closure of the fistula on angiography, return of baseline visual acuity, normalization of postoperative intraocular pressure, and cosmetically acceptable cutaneous scar. RESULTS: All 10 patients had prompt resolution of symptoms and halt of progressive visual loss following occlusion of the fistulas. Two patients had no flow in the anterior superior ophthalmic vein on angiography suggesting thrombosis, yet the superior ophthalmic vein was easily accessed in the anterior orbit, and transvenous embolization was successfully performed. In 2 additional patients with nondilated superior ophthalmic veins, we were unable to gain surgical access and in 1 case severe bleeding occurred during attempted access of the small vein. CONCLUSIONS: When performed by an experienced orbital surgeon and neuroradiology team, transvenous embolization of CDF via a dilated anterior superior ophthalmic vein is a technically straightforward, safe, and effective treatment for CDF and perhaps should be employed as primary therapy in cases with progressive orbital congestive symptoms. If the superior ophthalmic vein is not dilated or if it is located deep in the orbit, transorbital venous access may not be possible.

Adult↗
PubMed1995

Correlation of the angioarchitectural features of cerebral arteriovenous malformations with clinical presentation of hemorrhage.

Superselective angiography is the most accurate technique in the analysis of brain arteriovenous malformation (AVM) angioarchitecture. Therefore, we reviewed the selective and superselective angiograms of 100 consecutive patients with intracerebral AVMs. Our purpose was to determine which parameters of angioarchitecture were significantly correlated with a clinical presentation of hemorrhage. The vascular characteristics evaluated on the angiograms were the size of the AVM, the location of the AVM, the type of nidus, the type of feeders, the characteristics of venous drainage, and the number and location of aneurysms. The parameters found to correlate with hemorrhage were deep venous drainage (P = 0.01), feeding by perforators (P = 0.01), intranidal aneurysm(s) (P = 0.004), multiple aneurysms (P = 0.001), feeding by the vertebrobasilar system (P = 0.002), and location in the basal ganglia (P = 0.04). Six parameters of AVM angioarchitecture were correlated with a clinical presentation of hemorrhage. Among these parameters, three (feeding by perforators, number of aneurysms, and presence of intranidal aneurysms) were well displayed by superselective angiogram.

Adolescent↗
PubMed1995

High-flow, small-hole arteriovenous fistulas: treatment with electrodetachable coils.

We present one case of carotid-cavernous fistula caused by percutaneous treatment of trigeminal neuralgia and one case of vertebrovertebral fistula caused by percutaneous internal jugular vein cannulation. Each fistula had a small arteriovenous communication that prevented the use of detachable balloons. Endovascular transarterial treatment of these two iatrogenic fistulas with electrically detachable platinum coils was performed. Both fistulas were occluded with preservation of the parent artery, and the patients have fully recovered.

Aged↗
PubMed1995

Epilepsy associated with cerebral arteriovenous malformations: a multivariate analysis of angioarchitectural characteristics.

PURPOSE: To identify the morphological vascular characteristics of cerebral arteriovenous malformations (AVMs) that predict a clinical presentation of epilepsy. METHOD: Fifteen angioarchitectural characteristics of brain AVMs were selected for assessment in 100 consecutive patients referred to our institution for endovascular treatment. In this population, 47% of the AVMs were diagnosed as a consequence of epilepsy. The angioarchitectural characteristics and population demographics were statistically analyzed by means of multivariate analysis. RESULTS: The following six parameters were found to be the most predictive of epilepsy: cortical location of the AVM, feeding by the middle cerebral artery, cortical location of the feeder, absence of aneurysms, presence of varix/varices in the venous drainage, and association of varix and absence of intranidal aneurysms. Three factors were not among the most predictive factors of epilepsy but were significantly associated with the onset of seizures: AVM feeding by the external carotid artery, a temporal cortical location, and a parietal cortical location. CONCLUSION: Detailed analysis of the angioarchitecture of intracranial AVMs has helped us identify features that strongly correlate with epilepsy. This may aid in future understanding of the physiopathologic mechanisms in epilepsy associated with AVMs, and in identifying goals of treatment for epileptogenic AVMs.

Adolescent↗
PubMed1994

A nonlinear mathematical model for the development and rupture of intracranial saccular aneurysms.

Mathematical models of aneurysms are typically based on Laplace's law which defines a linear relation between the circumferential tension and the radius. However, since the aneurysm wall is viscoelastic, a nonlinear model was developed to characterize the development and rupture of intracranial spherical aneurysms within an arterial bifurcation and describes the aneurysm in terms of biophysical and geometric variables at static equilibrium. A comparison is made between mathematical models of a spherical aneurysm based on linear and nonlinear forms of Laplace's law. The first form is the standard Laplace's law which states that a linear relation exists between the circumferential tension, T, and the radius, R, of the aneurysm given by T = PR/2t where P is the systolic pressure. The second is a 'modified' Laplace's law which describes a nonlinear power relation between the tension and the radius defined by T = ARP/2At where A is the elastic modulus for collagen and t is the wall thickness. Differential expressions of these two relations were used to describe the critical radius or the radius prior to aneurysm rupture. Using the standard Laplace's law, the critical radius was derived to be Rc = 2Et/P where E is the elastic modulus of the aneurysm. The critical radius from the modified Laplace's law was R = [2Et/P]2At/P. Substituting typical values of E = 1.0 MPa, t = 40 microns, P = 150 mmHg, and A = 2.8 MPa, the critical radius is 4.0 mm using the standard Laplace's law and 4.8 mm for the modified Laplace's law.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Ruptured↗
PubMed1994

A nonlinear mathematical model for the development and rupture of intracranial fusiform aneurysms.

Laplace's law, which describes a linear relation between the tension and the radius, is often used to characterize the mechanical response of the aneurysm wall to distending pressures. However, histopathological studies have confirmed that the wall of the fully developed aneurysm consists primarily of collagen and is subject to large increases in tension for small increases in the radius, i.e., a nonlinear relationship exists between the tension within the aneurysm wall and the radius. Thus, a nonlinear version of Laplace's law is proposed to accurately describe the development and rupture of a fusiform saccular aneurysm. The fusiform aneurysm was modelled as a thin-walled ellipsoidal shell with a major axis radius, Ra, minor axis radius, Rb, circumferential tension, S0, and meridional tension, S phi, with phi defining the angle from the surface normal. Using both linear and nonlinear models, differential expressions of the volume distensibility evaluated at 90 degrees were used to determine the critical radius of the aneurysm along the minor axis from S0 and S phi in terms of the following geometric and biophysical variables; A, elastic modulus of collagen; E, elastic modulus of the aneurysm (elastin and collagen); t, wall thickness; P, systolic pressure; and Ra. For typical physiological values of A = 2.8 MPa, E = 1.0 MPa, T = 40 microns, P = 150 mmHg, and Ra = 4Rb, the linear model yielded critical radii of 4.0 mm from S phi and 2.2 mm from S0. The resultant critical radius was 4.56 mm. Using the same values, the critical radii from the tension components of the nonlinear model were 3.5 mm from S phi and 1.9 mm from S0.(ABSTRACT TRUNCATED AT 250 WORDS)

Aneurysm, Ruptured↗
PubMed1994

Aneurysms related to cerebral arteriovenous malformations: superselective angiographic assessment in 58 patients.

PURPOSE: To report the comprehensive superselective angiographic characteristics of aneurysms associated with cerebral arteriovenous malformations. METHOD: One hundred consecutive patients referred for cerebral arteriovenous malformation embolization underwent preembolization superselective angiography. Superselective angiograms were obtained after microcatheterization of arteriovenous malformation pedicles, and assessed for number and location of aneurysms related to the malformation. A chi 2 test was conducted to correlate these parameters with the onset of intracranial hemorrhage. RESULTS: Aneurysms were demonstrated in 58 of 100 patients. Single aneurysms were found in 24 patients and multiple aneurysms in 34. Presence and number of aneurysms were found to correlate significantly with a clinical presentation of hemorrhage. CONCLUSION: Superselective angiography was found to be of paramount importance in elucidating the precise and detailed angioarchitecture of brain arteriovenous malformations.

Adolescent↗
PubMed1994

Technical feasibility and performance studies of a Doppler guide wire for potential neuroendovascular applications.

PURPOSE: To conduct technical feasibility and performance studies on a new Doppler-tipped, 0.014-inch micro-guide wire for potential neuroendovascular applications. METHODS: In vivo microcatheterizations of brachiocephalic arteries were performed in two swine using the 0.014-inch Doppler guide wire and a commonly used microcatheter. A standardized, bench-top method of evaluating basic mechanical properties of micro-guide wires was also used to compare the 0.014-inch Doppler guide wire with a commonly used micro-guide wire. RESULTS: The 0.014-inch Doppler guide wire had similar steerability, tractability, torque control, and distal tip flexibility to the commonly used micro-guide wire in the in vivo simulations. Frequent micro-guide wire exchanges were possible without loss of superselective positioning of the microcatheter. Bench-top testing showed the 0.014-inch Doppler guide wire to have comparable distal tip flexibility and stiffness to the commonly used micro-guide wire. CONCLUSION: The comparable subjective and objective mechanical properties of the 0.014-inch Doppler guide wire to that of a commonly used micro-guide wire further establishes the possibility of clinical implementation of the device.

Animals↗
PubMed1993

Monitoring carotid test occlusions with continuous EEG and clinical examination.

We routinely monitor invasive neuroradiologic carotid balloon test occlusions with continuous polygraph and quantitative EEG along with repeated detailed clinical examinations. Four of 17 consecutive cases showed changes during carotid occlusion. In one instance, an immediate delta increase was accompanied by slurred speech and aphasia. Another showed alpha attenuation without clinical change. A third patient had significant clinical change without EEG change. Nine of the 17 cases underwent permanent therapeutic carotid occlusion as treatment of an intracerebral vascular abnormality. Seven of these nine had no EEG or clinical changes during monitoring and have had no functional abnormalities on follow-up. The patient with focal alpha attenuation had an accidental balloon detachment but has had no functional or structural neurologic abnormalities. The patient with minor regional increased delta received a permanent carotid occlusion and went on to develop clinical signs 24 h later. We believe that continuous EEG monitoring and repeated clinical examinations provide useful ways of evaluating cerebral circulation during carotid test occlusions.

Adult↗
PubMed1993

Therapeutic alternatives for vein of Galen vascular malformations.

From September, 1986, to March, 1990, the authors treated 28 children harboring a vein of Galen vascular malformation. Eleven (39.3%) of the patients were neonates, 13 (46.4%) were 1 to 2 years old, and four (14.3%) were more than 2 years old. Fifteen patients (53.6%) presented with severe congestive heart failure, six (21.4%) had seizures, four (14.3%) had hydrocephalus, and three (10.7%) presented with intraventricular hemorrhage. Based on the Yaşargil classification of malformations, 10 lesions (35.7%) were Type I, seven (25%) were Type II, eight (28.6%) were Type III, and three (10.7%) were Type IV. In 11 patients (39.3%), a combined transfemoral, transarterial, and transvenous embolization of the vein of Galen malformation was performed. A pure transtorcular approach was utilized in eight patients (28.6%), and postembolization surgical clipping of arterial feeders was performed in two cases with intractable congestive heart failure. Complete anatomical occlusion of the galenic malformation was achieved in 13 patients (46.4%). An immediate postembolization improvement in the patient's clinical status was obtained in 23 (82.1%) of 28 patients and a good long-term clinical outcome was seen in 17 patients (60.7%). Five deaths (17.9%) occurred in this series of 28 patients; three (10.7%) were related to a transtorcular embolization and two (7.1%) to the unchanged natural history of the disease.

Cerebral Veins↗
PubMed1992

Carotid-cavernous fistula caused by a ruptured intracavernous aneurysm: endovascular treatment by electrothrombosis with detachable coils.

A case of carotid-cavernous fistula caused by a ruptured intracavernous aneurysm is reported. The fistula was treated with electrothrombosis by the detachment of two platinum coils into the aneurysm via an endovascular transvenous approach; the fistula was closed, and the patient has recovered completely. The advantages of using electrodetachable platinum coils include thrombogenicity, controllable deposit, radiopacity, and biocompatibility.

Adult↗
PubMed1992

Endovascular treatment of posterior circulation aneurysms by electrothrombosis using electrically detachable coils.

In a multicenter study, 120 patients with intracranial aneurysms presenting a high surgical risk were treated using electrolytically detachable coils and electrothrombosis via an endovascular approach. The results of treatment in patients with posterior fossa aneurysms (42 patients with 43 aneurysms) are presented. The most frequent clinical presentation was subarachnoid hemorrhage (24 cases). The clinical follow-up periods ranged from 1 week to 18 months. Complete aneurysm occlusion was obtained in 13 of 16 aneurysms with a small neck and in four of 26 wide-necked aneurysms. A 70% to 98% thrombosis of the aneurysm was achieved in 22 of 26 aneurysms with a wide neck and in three of 16 small-necked aneurysms. One aneurysm could not be treated due to a technical complication. Two cases required postprocedural surgical clipping of a residual aneurysm. One patient (originally in Hunt and Hess Grade V) experienced procedural rupture of the aneurysm requiring an emergency parent artery occlusion. He eventually died 5 days later. Another patient (originally in Grade IV) had coil migration and posterior cerebral artery territory ischemia. A third patient developed a permanent neurological deficit (hemianopsia) after complete occlusion of a wide-necked basilar bifurcation aneurysm. One patient, harboring an inoperable giant basilar bifurcation aneurysm, died from aneurysm bleeding 18 months after partial occlusion. Overall morbidity and mortality rates related to treatment were 4.8% (two cases) and 2.4% (one case), respectively (2.6% and 0% if considering only patients in Hunt and Hess Grades I, II, and III). It is suggested that this technique is a viable alternative in the management of patients with posterior fossa aneurysms associated with high surgical risk. Longer angiographic and clinical follow-up study is necessary to determine the long-term efficacy of this recently developed endovascular occlusion technique. Close postoperative angiographic and clinical monitoring of patients with wide-necked subtotally occluded aneurysms is mandatory to check for potential aneurysmal recanalization, regrowth, and rupture.

Adolescent↗
PubMed1991

Electrothrombosis of saccular aneurysms via endovascular approach. Part 2: Preliminary clinical experience.

Fifteen patients with high-risk intracranial saccular aneurysms were treated using electrolytically detachable coils introduced via an endovascular approach. The patients ranged in age from 21 to 69 years. The most frequent clinical presentation was subarachnoid hemorrhage (eight cases). Considerable thrombosis of the aneurysm (70% to 100%) was achieved in all 15 patients, and preservation of the parent artery was obtained in 14. Although temporary neurological deterioration due to the technique was recorded in one patient, no permanent neurological deficit was observed in this series and there were no deaths. It is believed that this new technology is a viable alternative in the management of patients with high-risk intracranial saccular aneurysms. It may also play an important role in the occlusion of aneurysms in the acute phase of subarachnoid hemorrhage.

Adult↗
PubMed1991

Combined endovascular embolization and surgery in the management of cerebral arteriovenous malformations: experience with 101 cases.

The authors describe their experience with 101 cerebral arteriovenous malformations (AVM's) treated by endovascular embolization followed by surgical removal. Fifty-three patients presented with intracranial hemorrhage and 35 had seizures. Based on the classification of Spetzler and Martin, two AVM's were Grade I, 13 were Grade II, 26 were Grade III, 43 were Grade IV, and 17 were Grade V. Fifty-six AVM's were in the right hemisphere, 28 were in the left hemisphere, 12 were in the corpus callosum, and five involved the cerebellum. In 50 cases, presurgical obliteration of 50% to 75% of the AVM nidus was achieved by embolization, and in 31 cases this percentage increased to between 75% and 90%. In 97 (96%) patients, complete surgical removal of the AVM was obtained. Morbidity resulting from preoperative endovascular embolization was classified as mild in 3.9% of the cases, moderate in 6.9%, and severe in 1.98%. The death rate related to embolization was 0.9%. The immediate postsurgical morbidity was classified as mild in 5.9% of the cases, moderate in 10.8%, and severe in 5.9%. The overall long-term morbidity was mild in 5.9% of the cases, moderate in 6.9%, and severe in 1.98%. Two patients (1.98%) died due to intractable intraoperative hemorrhage and two (1.98%) as a result of postsurgical pulmonary complications.

Adolescent↗
PubMed1990

Use of a new mixture for embolization of intracranial vascular malformations. Preliminary experimental experience.

The internal carotid artery system in swine has a special anatomic configuration similar to a brain "arterial-arterial malformation." The internal carotid artery breaks up into a multitude of fine channels (rete mirabile) situated at the base of the skull on the side of the hypophysis. This anatomic arterial model was used to analyze acute and chronic angiographic and histological changes after occlusion of the rete mirabile with I) avitene, II) avitene, and 50% ethanol, III) avitene, 30% ethanol and Polyvinyl alcohol, IV) avitene 50% ethanol and Polyvinyl alcohol, V) IBCA and VI) silk. Histopathological changes observed in the rete mirabile six weeks following occlusion demonstrated that a mixture of avitene, 30% ethanol and Polyvinyl alcohol and IBCA produced the best anatomic results. Embolization with avitene, PVA and ethanol induced a more bland histological reaction than the one observed with IBCA. Preliminary clinical experience with this mixture is reassuring in those cases in which the AVM was surgically resected. The partially thrombosed AVM was easily depressed and compressed by the neurosurgeon allowing for satisfactory hemostasis in and around the nidus of the AVM.

Animals↗