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Biomedical subjects

F Viñuela

Publications and source records attributed to F Viñuela.

144 records · Page 8Linked to original sources
PubMedDate not supplied

Adjusting the polymerization time of isobutyl-2 cyanoacrylate.

Isobutyl-2 cyanoacrylate (IBCA) polymerizes by an anionic mechanism. The initiation of polymerization depends on an alkaline medium and can be inhibited with the addition of small amounts of acid. Using small amounts of glacial acetic acid (3.7%-7.1% by volume), the polymerization time was prolonged from 2.3 sec to 7.8 sec. In vivo experiments in dogs demonstrated no additional inflammatory reactions to the mixture of IBCA, iophendylate, and tantalum powder when acetic acid was added. Glacial acetic acid offers a safe and effective way, without increase in viscosity, to manipulate the polymerization time of IBCA.

Acetates↗
PubMedDate not supplied

Magnetic resonance imaging of small medullary infarctions.

Small infarctions of the medulla produce typical neurologic deficits and can be clinically recognized fairly reliably. High-field magnetic resonance imaging with a 1.5 T prototype scanner successfully demonstrated very tiny medulla infarctions in three of five patients. These lesions were imaged readily by a fairly rapid (approximately 1-2 min scan time) partial-saturation technique and confirmed on multiple spin-echo images. In addition, in two cases vertebral occlusion ipsilateral to the infarction was suggested by high signal on T2 weighted spin-echo images.

Aged↗
PubMedDate not supplied

Angiographic follow-up of large cerebral AVMs incompletely embolized with isobutyl-2-cyanoacrylate.

This study evaluated the long-term angiographic results in large cerebral arteriovenous malformations (AVMs) partially embolized with isobutyl-2-cyanoacrylate. Preembolization, immediate postembolization, and long-term follow-up angiograms were performed in 30 large, partially embolized brain AVMs. Particular attention was paid to the relative size of the residual AVM nidus and the embolized arterial feeders, to recruitment of new feeders, to the size of residual draining veins, and to the speed of arteriovenous shunt. Nine cases with less than 50% AVM nidus obliteration showed no significant morphologic changes. In 18 cases with 50-75% obliteration of the AVM nidus, 11 (61.1%) showed no significant changes, six (33.3%) showed enlargement of the AVM nidus, and one (5.5%) evolved to complete angiographic obliteration. In three cases with 75-99% AVM nidus obliteration, one remained unchanged, one showed an increase in the size of the AVM nidus, and one evolved to complete obliteration. Evaluation by plain film, CT, and cerebral angiography of the isobutyl-2-cyanoacrylate deposits showed that when the polymer was positioned predominantly in arterial feeders there was invariably reconstitution of the AVM nidus through leptomeningeal, deep medullary, and/or dural collaterals. This phenomenon did not occur when the isobutyl-2-cyanoacrylate was deposited mainly in the AVM nidus.

Arteriovenous Malformations↗
PubMedDate not supplied

Saccular aneurysms in basilar artery fenestration.

Of 59 cases of vertebrobasilar junction aneurysms diagnosed and treated from January 1977 to April 1986, 21 (35.5%) saccular aneurysms arose in a fenestration of the proximal basilar artery. Defects of the media at the junctures of the fenestrated segments, as well as the possible presence of turbulent flow at the vertebrobasilar junction, may explain the high incidence of vertebrobasilar aneurysms associated with proximal basilar artery fenestration.

Adult↗
PubMedDate not supplied

Preoperative embolization of brain AVMs with isobutyl-2 cyanoacrylate.

The role of embolization in the management of brain arteriovenous malformations remains controversial. The benefits of embolization alone are not clear and surgical removal may be technically difficult or impossible in many cases. In an attempt to facilitate surgical removal, we performed preoperative embolization in 15 cases using a mixture of isobutyl-2 cyanoacrylate and glacial acetic acid. In one case, a mixture of polyvinyl alcohol particles, microfibrillar collagen, and 30% ethanol was used. In 10 of these cases the surgeon felt that the embolization significantly aided the operative removal by decreasing blood loss, reducing the size of draining veins, and removing portions of the nidus itself. In no patient did the embolization result in an unanticipated significant neurologic deficit. The major role for embolization in the management of brain arteriovenous malformations may be as an aid to surgical removal.

Adult↗
PubMedDate not supplied

A comparison of iopamidol and iohexol in cerebral angiography.

Iopamidol and iohexol, the new nonionic low-osmolality contrast agents, have both been shown to be safe, effective, and better tolerated than conventional ionic agents for cerebral angiography. In this randomized, double-blind study involving 40 patients, these two agents were compared for adverse effects, radiographic quality, and patient tolerance. No significant differences were observed in 220 injections. Because we found iopamidol and iohexol to be equally safe and effective for cerebral angiography, the choice of which contrast agent to use should be based on other considerations.

Adult↗
PubMedDate not supplied

Unruptured intracranial arteriovenous malformations do cause mass effect.

Sixty patients with clinically unruptured intracranial arteriovenous malformations were studied with high-resolution computed tomography. In 33, local and distant mass effects were evidenced by compression, distortion, and displacement of normal anatomic structures by the malformation, its afferent and efferent vessels, and the surrounding edema.

Brain Edema↗
PubMedDate not supplied

Rolandic arteriovenous malformations: improvement in limb function by IBC embolization.

Three patients with arteriovenous malformations in the rolandic region and significant limb deficit showed virtually complete functional recovery after awake operative embolization of most of the malformations using isobutyl-2 cyanoacrylate. Two of these patients, with functionally useless hands, had sustained the deficits months earlier as the result of a specific brain-damaging event: one as a result of surgery and the other as a result of a hemorrhage. Both of these showed significant return of function during the awake operative embolization procedure. The other patient had had progressive leg weakness over a 2 year period. The theory of steal phenomenon as an explanation for progressive neurologic deficits in association with large arteriovenous malformations must be extended to explain apparently stable deficits after some brain trauma (surgery or hemorrhage). These results suggest that some patients with arteriovenous malformations and without clinical deficits who are near a critical level of "near ischemia" may be thrown out of balance by an acute interceding event.

Adolescent↗
PubMedDate not supplied

Delayed metrizamide CT enhancement of syringomyelia: postoperative observations.

Delayed metrizamide computed tomography (CT) was performed both preoperatively and postoperatively in 11 syringomyelia patients. Change of syrinx size between the studies was easily assessed on CT. The morphologic change of the syrinx gave useful information about its continuity. One of our cases had reoperation as a result of this CT information. All cases with Chiari I malformation still showed filling of the syrinx cavity by metrizamide after posterior fossa decompression and obex plugging. This supports the idea that the abnormal fluid circulation maintaining syringomyelic cavities is more than just the flow through the obex to the central canal but may also be from fluid passage through the cord substance.

Humans↗
PubMedDate not supplied

Stenosis of afferent vessels of intracranial arteriovenous malformations.

Four women are described with stenoses of the feeding arteries to cerebral arteriovenous malformations. These stenoses were hemodynamically significant in that the nidus malformations filled late in the arterial phase of angiography and the draining veins did not fill much earlier than the usual venous phase. In two of these patients, who were referred for possible embolization, the stenosis served as an impediment to balloon navigation in the feeding vessel in one and served as a partial contraindication to embolization in the other. It is possible that if these stenoses progress, they may lead to thrombosis of the arteriovenous malformations.

Adult↗
PubMedDate not supplied

Delayed CT metrizamide enhancement of syringomyelia secondary to tumor.

Six cases of syringomyelia associated with intramedullary tumor were examined by metrizamide myelography and delayed computed tomography. All cases showed opacification of syringomyelic cavities 7-24 hr after myelography. This finding suggests that metrizamide can pass through the cord substance from the subarachnoid space into a syrinx cavity in noncommunicating types of syringomyelia. It supports the theory of transneural passage of fluid as part of the origin of such cavities. These cases also support the thesis that, in patients with cord cavities, tumor can be excluded only if the cavity is demonstrated within all areas of cord enlargement.

Adult↗
PubMedDate not supplied

Progressive thrombosis of brain arteriovenous malformations after embolization with isobutyl 2-cyanoacrylate.

Embolization of brain arteriovenous malformations (AVMs) with isobutyl 2-cyanoacrylate (IBCA) is an alternative to surgical treatment when dealing with large AVMs with multiple arterial feeders. The deposition of IBCA in the nidus of the AVM may produce an active and progressive thrombosis that may lead to complete occlusion of the nidus and/or to progressive thrombosis of the draining veins. Four clinical examples of progressive thrombosis after IBCA embolization are demonstrated, including two cases in which late follow-up angiography showed complete obliteration of a partly embolized AVM.

Adult↗
PubMedDate not supplied

Clinical trial of Iohexol vs. Conray 60 for cerebral angiography.

Iohexol, a new nonionic contrast agent, and Conray 60 were compared in a double-blind clinical trial of 60 patients for safety, imaging effectiveness, and patient discomfort in cerebral angiography. There was no significant difference between the two agents in physiologic changes, film quality, or incidence of adverse effects in the 60 patients. One patient in the iohexol group suffered a cardiac arrest, which was clinically due to septic shock and was probably the result of inadvertent contamination of the iohexol used for test injections in this case. Bacterial growth can be supported in iohexol under certain circumstances, due to the lack of preservatives in this contrast material. The patients in the iohexol group experienced significantly less discomfort than the Conray 60 group. Iohexol is a safe, effective contrast agent when handled properly and causes less discomfort to patients than Conray 60.

Adult↗
PubMedDate not supplied

Preembolization superselective angiography: role in the treatment of brain arteriovenous malformations with isobutyl-2 cyanoacrylate.

Transfemoral and intraoperative embolization of arteriovenous malformations (AVMs) of the brain with isobutyl-2 cyanoacrylate may achieve complete and permanent occlusion of the AVMs. The preembolization superselective angiogram is an important source of information to decrease potential technical or clinical complications while seeking that goal. The information obtained from the angiogram of each individual feeder may be classified as anatomical, dynamic, and functional. This angiogram is performed either through a calibrated-leak balloon glued to a Silastic tubing, which is capable of negotiating cortical arterial curves, or through a short catheter directly placed into a feeder at surgery. In 64 patients, 175 preembolization superselective angiograms were obtained. Of those, 105 were obtained using the transfemoral technique, and 70 were obtained by direct catheterization after a craniotomy. Complications occurred in eight patients with only one permanent injury. Transient neurologic deficit occurred in five patients. One patient developed a permanent left monoplegia and one patient a subarachnoid hemorrhage without permanent neurologic deficit. In one patient, a delayed intracerebral hemorrhage produced a right hemiplegia and aphasia. The patient fully recovered in 6 months.

Bucrylate↗
PubMedDate not supplied

[CNS vasculitis after ophthalmic herpes zoster infection].

We present a case of cerebral vasculitis secondary to infection with Varicella Zoster Virus which appeared in a 27 year old patient after a latency period of eight weeks. We emphasize the usefulness of angioresonance as a fitting means of evolutive follow up without the need to carry out control cerebral angiography. We likewise point out the usefulness of acyclovir as the sole treatment necessary in non-complicated cases.

Acyclovir↗
PubMedDate not supplied

Endovascular treatment of fusiform aneurysms with stents and coils: technical feasibility in a swine model.

PURPOSE: To assess the biomechanical feasibility of treating experimental fusiform aneurysms endovascularly with a combination of stents and coils. METHODS: An experimental model was surgically constructed in the necks of nine swine to simulate intracranial fusiform aneurysms possessing important "perforators" or side branches. Balloon-expandable metal stents were positioned across the aneurysms in eight swine. In five of these, additional treatment was intraaneurysmal placement of detachable microcoils. Attempts were made to deposit these coils strategically away from the origin of the side branch. RESULTS: Stent placement was successful in seven swine but failed in one swine because of stent-aneurysm size mismatch. Two swine treated with only stents showed no significant alterations in blood filling of the aneurysm or side branch. Satisfactory coil placement (outside the stent, within the aneurysm sac, and away from the orifice of the side branch) was achieved in four of the five swine treated with stents and coils. Careful fluoroscopic monitoring and controlled coil delivery were necessary to avoid covering the sidebranch origin. These aneurysms could not be packed densely after detachment of the first coil because of the resultant radiographic overlap of multiple coil loops on the stent and its lumen in all projections. In one swine there was inadvertent untoward reentry of the coil tip into the expanded stent lumen during its delivery. CONCLUSION: Endovascular treatment of experimental fusiforms aneurysms using stents and coils is technically feasible. The stent maintains patency of the parent artery while allowing strategic coil placement in the aneurysm sac away from the origin of side branches. This technique may prove useful in the future treatment of intracranial fusiform aneurysms. However, potential sources of technical difficulties have been identified, and further longterm studies using an appropriate intracranial stent will be necessary before human application.

Animals↗
PubMedDate not supplied

[Sensitivity and efficiency of intrathecal IgG secretion in multiple sclerosis. Comparison of several indices and formulas using pre-established values of specificity].

To furnish greater specificity in the analysis of cerebrospinal fluid from patients suspected of having multiple sclerosis, we studied the sensitivity and efficiency of indices and formulas used to calculate intrathecal IgG synthesis in a group of 49 patients with clinically defined multiple sclerosis, using cutoff values based on preestablished levels of specificity (75 and 90%), and compared the findings to those for a control group of patients with other neurological diseases. The best results were obtained with the indices and formulas based on computer models of brain-blood barrier function set forth most recently, namely Reiber's formula and Ohman's index, which had the highest specificity with the least loss of sensitivity.

Adult↗