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Biomedical subjects

R T Higashida

Publications and source records attributed to R T Higashida.

At least 127 records · Page 7Linked to original sources
PubMed1988

Treatment of vertebral arteriovenous fistulas.

Twenty patients with vertebral arteriovenous fistulas (eight spontaneous, six traumatic without vertebral artery transection, and six traumatic with vertebral artery transection) were treated by transvascular embolization techniques, resulting in complete fistula closure in all patients. The fistulas were located at C1-C2 in 45%, C2-C3 in 25%, C4-C5 in 15%, C5-C6 in 10%, and C6-C7 in 5%. Trauma was the most common cause: 30% followed knife wounds, 20% followed gunshot injuries, and 10% followed blunt trauma. Eight patients had spontaneous fistulas, two associated with fibromuscular dysplasia. Three patients-all with large, long-standing fistulas-developed neurologic deficits coincident with the abrupt closure of the fistula, which resolved with reestablishment of fistula flow. Two of these patients were treated by staged closure; the other one by gradual closure. In all three cases the result was complete fistula closure without neurologic sequelae. The remaining spontaneous fistulas were all closed by balloon embolization with preservation of the vertebral artery and without deficits. The six patients with traumatic fistulas without transection were cured by balloon embolization, without deficits; in four there was also preservation of vertebral flow. The other six patients had traumatic fistulas with transection and were all cured by balloon embolization with preservation of flow in two. Four patients required bilateral approaches to the fistula to achieve complete fistula closure. The only complication was a mild residual Wallenberg syndrome after occlusion of the posterior inferior cerebellar artery in the treatment of a transection located at C1. In our opinion, transvascular techniques are the treatment of choice for vertebral arteriovenous fistulas.

Adult↗
PubMed1988

MR evaluation of large intracranial aneurysms using cine low flip angle gradient-refocused imaging.

MR imaging has proved to be useful in evaluating large intracranial aneurysms. The parent artery and patent lumen can be identified as flow voids and differentiated from thrombus. However, in the presence of slow flow, even-echo rephasing, and motion artifact, increased intraluminal signal may be present, which may be difficult to distinguish from thrombus. Aneurysms are also dynamic lesions and exert pulsatile mass effect on adjacent structures. Further definition of vascular anatomy and physiology may aid in therapeutic planning and assessment. Cine MR is a new technique using a movie loop of sequential GRASS (gradient-recalled acquisition in the steady state) images obtained during various points in the cardiac cycle. The combination of GRASS images and cardiac gating thus allows cinegraphic display of vascular structures. A comparison of this method with routine T1- and T2-weighted MR imaging and angiography was made in a group of 13 patients with intracranial aneurysms greater than 1.5 cm in diameter. Eight of these patients underwent transvascular detachable balloon occlusion. With cine MR, flowing blood has high intensity due to flow-related enhancement. Turbulent and high-velocity flow can be recognized on the basis of signal loss, which occurs during systole. Thrombus demonstrated variable signal intensity, which remained unchanged during the cardiac cycle. Compared with routine MR sequences, there was less image degradation from phase-encoding artifacts and improved visualization of the neck of the aneurysm. Pulsatile mass effect was uniquely assessed. After transvascular embolization, cine MR demonstrated improved conspicuity of acute thrombus and higher contrast between flowing blood and the occlusion balloon when compared with routine MR. Confirmation of flow within the parent vessel, residual aneurysm lumen, and distal arterial branches is possible. If the parent vessel was occluded, cine MR yielded greater information than angiography. Cine MR provides additional anatomic and physiologic data in the evaluation and assessment of therapy of intracranial aneurysms. Information can be obtained that is not available with either routine MR or angiography. The inherent limitations of this new technique include partial-volume artifacts, less than optimal flow-related enhancement or spatial resolution, and poor data acquisition due to cardiac arrhythmias.

Adolescent↗
PubMed1987

Radiation dose enhancement therapy with iodine in rabbit VX-2 brain tumors.

Loading tissue with iodine enhances the radiation dose absorbed from low energy X-rays. In order to test whether this is a useful procedure for treating brain tumors, we infused radiographic contrast media into rabbits carrying VX-2 brain tumors and delivered 15 Gy of 120 kVp X-rays in 3 fractions to the tumor. From CT scans we estimated that the dose enhancement was approximately 30%. The median survival times, after tumor detection on CT, of untreated rabbits, treated with radiation alone, and treated with radiation plus contrast media were 3, 25.5, 38.5 days, respectively. The repeated infusion of contrast media, 3.5 g of iodine per kg of body weight, did not affect kidney function as measured by serum creatinine levels. This method of enhancing radiation dose in brain tumors therefore appears promising.

Animals↗
PubMed1987

Dural fistulas involving the cavernous sinus: results of treatment in 30 patients.

Thirty symptomatic indirect carotid cavernous fistulas were treated between 1978 and 1986 with a variety of treatment modalities. Combined carotid artery and jugular vein compression resulted in a complete cure in seven of 23 patients (30%) and improvement in one additional patient. There were no complications from this treatment, which is performed by the patient on an outpatient basis. Patients in whom carotid jugular compression therapy failed or who demonstrated cortical venous drainage or visual decline were treated with intravascular embolization. Embolization resulted in complete cure in 17 of 22 (77%) and improvement in four of 22 (18%). One patient required surgical excision of the involved dura after embolization to achieve complete cure. There was one permanent complication (stroke), which resulted in mild weakness caused by clot formation on a catheter.

Adult↗
PubMed1987

Dural fistulas involving the transverse and sigmoid sinuses: results of treatment in 28 patients.

Twenty-eight symptomatic dural fistulas involving the transverse and sigmoid sinuses were treated between 1978 and 1986 with a variety of treatment modalities. Occipital artery compression therapy resulted in a complete cure in two of nine patients (22%) and improvement in three of nine (33%). There were no complications from this treatment. Patients who were excluded or in whom compression therapy failed were treated with embolization alone or in conjunction with surgery. Of the 17 patients who underwent embolization alone, ten were cured and six were improved. Six patients had a combination of embolization and surgery; four patients were cured and two improved. There were three complications in this series, one related to surgery and two related to embolization.

Adult↗
PubMed1987

Carotid cavernous fistulae: indications for urgent treatment.

Angiographic and clinical data from 155 patients with carotid cavernous fistulae were retrospectively reviewed to determine angiographic features associated with increased risk of morbidity and mortality. These features included presence of a pseudoaneurysm, large varix of the cavernous sinus, venous drainage to cortical veins, and thrombosis of venous outflow pathways distant from the fistula. Clinical signs and symptoms that characterized a hazardous carotid cavernous fistula included increased intracranial pressure, rapidly progressive proptosis, diminished visual acuity, hemorrhage, and transient ischemic attacks. Cortical venous drainage from the carotid cavernous fistula is secondary to occlusion or absence of the normal venous outflow pathways and is associated with signs and symptoms of increased intracranial pressure and an increased risk of intraparenchymal hemorrhage. Angiographic demonstration of a cavernous sinus varix, with extension of the sinus into the subarachnoid space, is associated with an increased risk of fatal subarachnoid hemorrhage. Identification of these high-risk features provides a basis for making decisions about treatment.

Arteriovenous Fistula↗
PubMed1987

Intravascular balloon embolization of a large mid-basilar artery aneurysm. Case report.

A patient who presented with multiple episodes of subarachnoid hemorrhage was diagnosed as having a large mid-basilar artery aneurysm that had no definable surgical neck. Balloon embolization was performed utilizing two detachable silicone balloons to occlude the mid-basilar artery and the aneurysm. The procedure was carried out with the patient fully awake and alert. One day after the procedure, the patient developed pontine and cerebellar ischemia which completely resolved after 5 days on heparin therapy. A follow-up angiogram performed immediately after the procedure and at 3 months demonstrated complete occlusion of the mid-basilar artery and the aneurysm. The patient was intact neurologically upon discharge 5 days after the embolization procedure and has since resumed his normal activities. Balloon embolization therapy may offer some advantages over surgical methods for the treatment of such therapeutically challenging aneurysms.

Adult↗
PubMed1987

Variants of radiculomeningeal vascular malformations of the spine.

In recent years, it has become evident that the most common form of arteriovenous malformation to involve the spinal cord in adults is a low-flow fistula with its nidus located on the dura in relation to the dorsal nerve root. This lesion, termed "radiculomeningeal fistula" (RMF), is drained by the intradural coronal venous system and most likely causes neurological deficits due to raised venous pressure within the spinal cord. The therapy that was formerly recommended was multilevel laminectomy with microsurgical stripping of the intradural vessels. However, that procedure focused on the draining veins rather than the nidus, and it has been replaced by direct treatment of the nidus or by disconnecting the nidus from the coronal venous system. This paper reports variants of RMF's that show a wider spectrum of the clinical and radiological findings than has been previously reported. Three patients presenting with extradural venous drainage, intraspinal hemorrhage, and/or sudden non-hemorrhagic neurological decline are reported. A more complete understanding of RMF facilitates the radiological and clinical evaluation of these patients and enables the surgeon to modify the therapy in a significant way.

Adult↗
PubMed1986

Balloon embolization of a large distal basilar artery aneurysm. Case report.

Interventional neurovascular techniques have advanced to a level where treatment of intracranial aneurysms by intravascular detachable balloon embolization therapy is now possible. A patient is presented who had a spontaneous subarachnoid hemorrhage from a large aneurysm of the distal basilar artery. The aneurysm arose at the bifurcation of the posterior cerebral arteries and measured 15 X 9 X 9 mm. With the patient fully awake, a detachable silicone balloon was passed into the basilar artery by a transfemoral arterial approach. Stenosis (greater than 60%) of the mid-section of the basilar artery, secondary to arterial vasospasm from the recent hemorrhage, was present. The stenosis was treated by transluminal angioplasty, after which the balloon was passed into the aneurysm and detached. A follow-up angiogram 3 months later demonstrated complete occlusion of the aneurysm and a widely patent basilar artery at the angioplasty site.

Adult↗
PubMed1986

Treatment of direct carotid cavernous sinus fistulae. Various therapeutic approaches and results in 148 cases.

From 1974 to 1986, 148 patients with carotid cavernous fistula (CCF) were evaluated for intravascular therapy. Four patients died from hemorrhage before treatment could be instituted and the CCF closed spontaneously in 5. Therapeutic approaches which resulted in complete occlusion in the remaining 139 cases were transarterial in 118, transvenous in 15 and external compression of the carotid artery and jugular vein in 6. The current treatment of choice of the direct CCF is intravascular embolization using detachable balloons, particulate emboli or liquid adhesive agents to occlude the CCF while attempting to preserve the carotid artery. In 15 patients it was technically too difficult to use the transarterial approach. The patients were therefore treated from a transvenous approach including access via the femoral vein, superior ophthalmic vein, intraoperatively from the inferior petrosal sinus or direct puncture of the cavernous sinus. Embolic agents used included detachable silicone balloons, steel minicoils, particulate emboli and isobutyl-2-cyanoacrylate. In 14 of these 15 patients total obliteration was achieved with marked improvement in symptoms. Complications occurred in 3 patients including perforation of the cavernous sinus resulting in subarachnoid hemorrhage, delayed pontine hemorrhage from subtotal occlusion of the fistula and transient increased proptosis.

Arteriovenous Fistula↗
PubMed1986

Closure of carotid cavernous sinus fistulae by external compression of the carotid artery and jugular vein.

From 1974-1986, 152 patients with carotid cavernous sinus fistulae (CCF) have been evaluated. Progressive closure of both dural and direct types of CCF have been noted utilizing intermittent external manual compression of the cervical carotid artery and jugular vein. In a group of 71 patients in whom this treatment was attempted, we have observed that 7 of 23 patients (30%) with dural CCF, and 8 of 48 patients (17%) with direct CCF had complete closure of their fistulae with no recurrence either clinically or at angiography done one year later. Closure occurred at varying times, from several minutes to 6 months (mean 41 days) following compression therapy. In those patients with CCF without rapidly progressive visual deterioration, cerebral ischemia, or other complicating factors, we recommend this technique with serial clinical follow-up and angiography before more definitive therapy is employed.

Adolescent↗
PubMed1986

Cervical carotid artery aneurysms and pseudoaneurysms. Treatment by balloon embolization therapy.

The treatment of high cervical carotid artery aneurysms and pseudoaneurysms is often difficult due to relative surgical inaccessibility. We are currently managing such lesions by detachable balloon embolization therapy. In 7 patients with acute cervical carotid pseudoaneurysms, the carotid artery was occluded by a trapping procedure above and below the lesion using detachable silicone balloons. In 3 patients with aneurysms that had well organized walls, a detachable balloon was placed directly within the aneurysm, inflated to exclude it from the circulation, and then detached. The carotid artery was therefore preserved.

Adult↗
PubMed1986

Intravascular detachable balloon embolization of intracranial aneurysms. Indications and techniques.

The treatment of intracranial aneurysms from a transvascular approach, with preservation of the parent vessel is now being performed in selected cases. From a transfemoral approach, a silicone detachable balloon is flow-directed up the carotid or vertebral-basilar artery, guided directly into the aneurysm and detached. The aneurysm is thus excluded from the circulation and the parent artery is preserved. Thus far, this technique has been successful in treating aneurysms in the cavernous carotid, carotid ophthalmic, posterior communicating, distal basilar, and posterior cerebral artery distributions. The indications and techniques of detachable balloon embolization therapy are presented.

Embolization, Therapeutic↗
PubMed1986

Percutaneous transluminal angioplasty of the subclavian and vertebral arteries.

Percutaneous transluminal angioplasty (PTA) for atherosclerotic lesions of the subclavian, vertebral, and brachiocephalic vessels is being performed in selected cases. Clinically patients presented with symptoms of vertebral basilar insufficiency, multiple transient ischemic attacks, subclavian steal syndrome, and motor weakness of the upper extremity. Thus far, 22 procedures have been performed with good results. This included 16 subclavian, 4 vertebral, and 2 innominate arteries. Follow-up has ranged from 8 to 26 months (mean 17 months). No permanent neurologic complications have occurred with this technique, and all patients had significant clinical and radiographic improvement following this procedure.

Aged↗
PubMed1985

Development of rabbit brain tumor model for radiologic research.

A rabbit brain tumor model using transplanted VX-2 carcinoma had an 85% rate of successful implantation. Rabbits lived 8.5 +/- 1.3 days. The tumor doubling time was 0.5 to 2.6 days. Some tumors were shown as early as four days after implantation and all tumors were seen by ten days after implantation. Two of three rabbits receiving radiation therapy to the tumor had significant extension of life. This model is a useful radiologic research tool.

Animals↗
PubMed1981

Pulmonary vasoconstrictor responses to graded decreases in precapillary blood PO2 in intact-chest cat.

The effects of graded changes in pulmonary lobar arterial blood PO2 and ventilatory hypoxia were investigated in the intact-chest cat under conditions of controlled lobar blood flow. A reduction in precapillary PO2 from systemic arterial levels to below 60 Torr increased lobar arterial pressure. Ventilation with 10% O2 increased lobar arterial pressure, and responses to ventilatory hypoxia and precapillary hypoxemia were independent but additive. The magnitude of the pressor response to precapillary hypoxemia was similar in experiments in which the lung was autoperfused with right atrial blood or cross-perfused with aortic blood from a donor cat breathing 10% O2. During retrograde perfusion of the ventilated lung, a reduction in pulmonary venous PO2 to 40 Torr did not affect inflow pressure. The present data suggest that sensor sites upstream to the alveolar-capillary region in segments of lobar artery unexposed to alveolar gas sense a reduction in precapillary blood PO2 and elicit a pulmonary vasoconstrictor response. The sensor site in the precapillary segment is independent of sensors in the alveolar-capillary-exposed segment region, and the effects of stimulation of both sensors on the pulmonary vascular bed are additive. In addition, the present data indicate that sensors in the pulmonary veins do not sense a reduction in PO2 in venous blood and elicit a vasoconstrictor response. These data suggest that the mixed venous blood PO2 may exert an important regulatory role in controlling pulmonary arterial pressure and pulmonary vascular resistance in the cat under normal and pathological conditions.

Animals↗