Fragmentations and reactions of the organophosphate insecticide Diazinon and its oxygen analog Diazoxon studied by electrospray ionization ion trap mass spectrometry.

The fragmentations and reactions of Diazinon and related compounds have been studied by electrospray ionization ion trap mass spectrometry. Several novel fragmentation and rearrangements have been observed, including an intramolecular thiono-thiolo rearrangement. The stability, in the gas-phase, of the protomers of 2-isopropyl-4-methyl-6-pyrimidinol has been demonstrated. The complexity of the gas phase ion processes observed suggest that, at present, caution should be exercised in using this approach for the analysis of environmental and other samples until our understanding of these processes increases considerably.

Snare retrieval of intracranial thrombus in patients with acute stroke.

Intravenous or intraarterial thrombolysis of intracranial emboli is becoming an accepted clinical treatment modality for acute ischemic stroke, but not all emboli respond to the lytic drug regimens available today. If drug therapy fails, mechanical retrieval seems warranted. Four patients whose condition was resistant to intravenous and intraarterial thrombolytic drug treatment underwent at least partial clot removal with use of a snare, and almost immediate clinical improvement was noted. A fifth patient's clot was removed before lytic drugs were administered. All five patients, who presented with a sudden onset of stroke, were evaluated by arterial angiography; then, after a failed trial of intraarterial fibrinolytic drugs, they were treated by passing a 2- or 4-mm snare through a microcatheter. The snare wire was guided around the thrombus, gently brought back toward the microcatheter-but not into it-and the entire microcatheter and snare assembly was then removed. In four of the five cases, follow-up angiography performed immediately after the retrieval showed wider distal branches than normal. Follow-up computed tomography results were abnormal in all cases, showing hyperdense material in the territory that was previously ischemic. This hyperdensity subsided within 48 hours in all but one patient who developed small parenchymal hemorrhages; however, he remained asymptomatic. The snare device offers an additional or alternative therapy until completely effective thrombolytic agents become available. Although use of a snare is not ideal, device improvements should make the retrieval less technically challenging and more effective. There is a need for improved mechanical extraction devices, especially in light of the patient improvement that occurred. This experience also suggests that immediate removal of a mature clot could reduce the total time of brain ischemia more quickly than administration of thrombolytic drugs.

Stent-assisted angioplasty of intracranial vertebrobasilar atherosclerosis: an initial experience.

OBJECT: Patients with intracranial vertebrobasilar artery (VBA) atherosclerotic occlusive disease have few therapeutic options. Unfortunately, VBA transient ischemic attacks (TIAs) herald a lethal or devastating event within 5 years in 25 to 30% of patients. The authors report their initial experience with eight patients in whom medically refractory TIAs secondary to intracranial posterior circulation atherosclerotic occlusive lesions were treated with stent-assisted angioplasty. METHODS: Eight patients (six men), ranging in age from 43 to 77 years, experienced signs and symptoms of VBA insufficiency despite combination therapy with warfarin and antiplatelet agents. Angiographic studies revealed severe distal vertebral (four patients), proximal basilar (one patient), or proximal and midbasilar stenoses (three patients). Aspirin and clopidogrel were administered for 3 days before primary angioplasty and stent placement, and this regimen was maintained by the patients on discharge. Patients underwent heparinization during the procedure and were given a bolus and 12-hour infusion of abciximab. A neurologist specializing in stroke evaluated all patients before and after the procedure. The VBAs in all patients were successfully revascularized with 7 to 28% residual stenosis. Six patients experienced no neurological complications. One patient died the evening of the procedure due to a massive subarachnoid hemorrhage. Two patients had groin hematomas, one developed congestive heart failure, and one had transient encephalopathy. All surviving patients are asymptomatic up to 8 months postoperatively. CONCLUSIONS: Although primary intracranial VBA angioplasty with stent insertion is technically feasible, complications associated with the procedure can be life threatening. As experience is gained with this procedure, it may be offered routinely as an alternative therapy to patients with medically refractory posterior circulation occlusive disease that may develop into catastrophic VBA insufficiency.

Percutaneous vertebroplasty for pain relief and spinal stabilization.

STUDY DESIGN: This was a retrospective review of 47 consecutive patients (1995-1998) in whom percutaneous intraosseous methylmethacrylate cement injection (percutaneous vertebroplasty) was used to treat osteoporotic vertebral compression fractures and spinal column neoplasms. OBJECTIVES: To present initial results regarding pain relief, spinal stabilization, and complications after treatment with percutaneous vertebroplasty. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty was developed in France in the late 1980s. Several European reports have described excellent results for treatment of compression fractures and neoplasms. The procedure was not performed in the United States until 1994. Only a single series of 29 patients treated in the United States has been reported. METHODS: A retrospective review was conducted of 47 consecutive patients with 84 vertebrae treated with percutaneous vertebroplasty. Thirty-eight patients with 70 vertebrae had symptomatic, osteoporotic fractures and had failed medical therapy. Eight patients with 13 vertebrae had primary or metastatic neoplasms. One patient had a hemangioma. Immediate and long-term pain response, spinal stability, and complications were evaluated. RESULTS: Among the 38 patients treated for osteoporotic fractures, 24 (63%) had marked to complete pain relief, 12 (32%) moderate relief and 2 (5%) no significant change. Only 4 of the 8 patients with malignancies had significant pain relief. In 7 of these patients, no further vertebral compression occurred, and spinal canal compromise was prevented. The patient with the hemangioma had no significant pain reduction. Minor complications occurred in 3 (6%) patients. CONCLUSIONS: Percutaneous vertebroplasty provided significant pain relief in a high percentage of patients with osteoporotic fractures. The procedure provided spinal stabilization in patients with malignancies but did not produce consistent pain relief. Complications were minor and infrequent. Percutaneous vertebroplasty is a promising therapy for patients with osteoporotic fractures and for selected vertebral column neoplasms.

Pharmacologic testing as an adjunct to neuroendovascular procedures.

Pharmacologic testing is a method that may be employed to predict the permanent outcome of arterial embolization. Various drugs used for these tests and their differential indications are discussed. Pharmacologic testing provides an additional margin of safety and is useful as an adjunctive tool when performing embolizations of vessels supplying the head, brain, or spinal cord.

Temporary and permanent occlusion of cerebral arteries: indications and techniques.

Permanent occlusion of the carotid and vertebral arteries has long been used as a treatment for certain aneurysms, tumors, arteriovenous fistulae, and traumatic injuries. Temporary occlusion of these vessels often is used to predict patient tolerance before permanent vessel occlusion. When inadvertent arterial occlusion or injury is considered to be a significant risk of an open or endovascular surgical procedure, temporary arterial occlusion may be used to assess tolerance for permanent occlusion. The results of temporary arterial occlusion testing are often used to determine the need and type of bypass graft to augment cerebral blood flow. Temporary arterial occlusion also may be used to arrest proximal blood flow during open or endovascular surgery.

Endovascular arterial occlusion accomplished using microcoils deployed with and without proximal flow arrest: results in 19 patients.

BACKGROUND AND PURPOSE: Prior to their relatively recent FDA approval, detachable balloons for endovascular arterial occlusion had been available on only a limited basis. We evaluated the feasibility of permanent endovascular carotid and vertebral artery occlusion using microcoils deployed with and without proximal flow arrest in 19 patients. METHODS: Permanent endovascular occlusion was performed in 19 arteries of 19 patients. The treated lesions included nine aneurysms, one carotid-cavernous fistula/pseudoaneurysm, seven neoplasms, and two dissections. Nondetachable balloons were used to arrest proximal blood flow during occlusion of only six arteries. Anticoagulation (heparin, 5000 U IV) was used during occlusion of 18 arteries. Three to 88 coils were used per lesion. Complex fibered platinum microcoils were used for all cases, and GDCs were also used in two patients. RESULTS: Sixteen patients had no new neurologic deficits after arterial occlusion. No patient had an acute event that suggested an embolic complication. Coils provided rapid and durable arterial occlusion in 17 patients. In both patients with acute carotid artery rupture, large numbers of coils placed during flow arrest failed to produce complete occlusion, which was accomplished subsequently with detachable balloons. One of these patients incurred a fatal hemispheric infarct after occlusion. One patient treated for a ruptured posterior inferior cerebellar artery aneurysm by vertebral artery occlusion continued to have progressive neurologic deficits. One patient with a cavernous aneurysm had upper extremity weakness and mild dysphasia 24 hours after internal carotid artery occlusion. CONCLUSION: In our small series, microcoils were found to be safe and effective for neurovascular occlusion. When both intravenous heparin (5000 U IV bolus) and heparinized catheter flush solutions (5000 U/L) are used, flow arrest during coil placement is unnecessary to prevent clinically apparent embolic complications.

Microcatheter adhesion of cyanoacrylates: comparison of normal butyl cyanoacrylate to 2-hexyl cyanoacrylate.

PURPOSE: To compare the catheter adhesion properties of 2-hexyl cyanoacrylate (Neuracryl M), a new agent, to those of normal butyl cyanoacrylate (Histoacryl), the most widely used liquid acrylic agent for microcatheter embolization. MATERIALS AND METHODS: 2-hexyl cyanoacrylate (Neuracryl M1) was tested in pure form and mixed with either a proprietary polymerization retardant/contrast agent (Neuracryl M2) or ethiodized oil (Ethiodol). Histoacryl was tested in pure form and mixed with Ethiodol. The cyanoacrylate mixtures were injected through microcatheters into wells partially filled with heparinized whole blood. The cyanoacrylates were allowed to polymerize around the microcatheter tips for 1-3 minutes. The microcatheters were then pulled at a constant rate until they were extracted from the polymerized cyanoacrylates. The peak forces required for extraction were recorded. RESULTS: The peak forces required to extract the microcatheters from either pure Histoacryl or Histoacryl mixed with 33% Ethiodol were significantly higher (P < .01; P < .05) than those for pure Neuracryl M1. When Neuracryl M1 and M2 were mixed together (as intended for clinical use), the force required for microcatheter extraction was significantly lower than that for either pure Histoacryl, Histoacryl mixed with 33% Ethiodol, or Neuracryl M1 alone (P < .01; P < .01; P < .01, respectively). The force required to extract microcatheters from the Neuracryl M1 and M2 mixture was not, however, significantly different from that of Histoacryl mixed with 50% Ethiodol. The force of extraction for the Neuracryl M1 and 50% Ethiodol mixture was below our ability to obtain precise measurements. CONCLUSION: When Neuracryl M1 was mixed with its proprietary polymerization retardant/contrast agent (Neuracryl M2), catheter adhesion was not significantly different from that of Histoacryl mixed with 50% Ethiodol, a mixture common in clinical use. When Neuracryl M1 was tested alone or mixed with Ethiodol (not intended by the manufacturer), catheter adhesion was significantly decreased relative to pure Histoacryl or equivalent mixtures of Histoacryl and Ethiodol.

Carotid artery balloon test occlusion: combined clinical evaluation and xenon-enhanced computed tomographic cerebral blood flow evaluation without patient transfer or balloon reinflation: technical note.

OBJECTIVE: Clinical evaluation was combined with xenon-enhanced computed tomographic (CT) cerebral blood flow (CBF) evaluation during carotid artery balloon test occlusion (BTO), without patient transfer from the angiography suite to the CT scanner or balloon reinflation. TECHNIQUE: Thirteen patients underwent carotid artery BTO. Placement of temporary occlusion balloons was performed with patients positioned on the CT scanner table. If neurological testing revealed no changes within 10 minutes after balloon inflation, patients were positioned within the CT scanner gantry for xenon-enhanced CT CBF evaluation. CBF evaluations were begun 12 to 15 minutes after balloon inflation and required 8 minutes for completion. After completion of CBF evaluation, neurological testing continued during 30 minutes of arterial occlusion. RESULTS: One patient did not tolerate BTO, with the development of reversible hemiparesis. Reliable CBF data were not obtained because of patient motion in one case. Eleven patients clinically tolerated BTO and completed CBF evaluation. For five patients, xenon-enhanced CT scanning revealed no regions with CBF of less than 30 ml/100 g/min. For four patients, xenon-enhanced CT scanning revealed small regions with CBF of less than 30 ml/100 g/min within the anterior frontal lobe on the occluded side. For two patients, ipsilateral CBF decreased dramatically during BTO, with CBF in many regions of less than 30 ml/100 g/min and in some of less than 20 ml/100 g/min. CONCLUSION: Xenon-enhanced CT CBF evaluation can be combined with clinical testing during BTO without patient transfer, balloon reinflation, or increases in the duration of the procedure. We recognize that the value of CBF evaluation during BTO remains to be proven; our technique does, however, eliminate abbreviated clinical neurological evaluation, patient transfer, and balloon reinflation, which were previously associated with the use of xenon-enhanced CT CBF evaluation during carotid artery BTO.

Isolated unilateral hypoglossal neuropathy caused by dural arteriovenous fistula.

We report a case of isolated hypoglossal nerve paralysis caused by a dural arteriovenous fistula. Diagnosis is discussed with emphasis on conventional and MR angiography. The anatomy of the hypoglossal nerve is reviewed along with more common causes of pathologic conditions.

Polyvinyl alcohol foam particle sizes and concentrations injectable through microcatheters.

PURPOSE: Injection of different size ranges and concentrations of polyvinyl alcohol (PVA) foam particles was performed to determine the optimal and maximum size ranges and concentrations that may be injected reliably through microcatheters used for vascular embolization. MATERIALS AND METHODS: Eight different microcatheters were tested. Six different size ranges of PVA foam particles (three each from two manufacturers) at three different concentrations were tested with each catheter. All PVA foam particles were suspended in dilute low-osmolarity contrast material. For each size range and concentration of PVA foam particles, sixty 1-mL injections were made into each catheter tested. Continuous pressure monitoring was employed during all injections. RESULTS: For each catheter, the authors determined recommended maximum size ranges of PVA foam particles that may be injected with reasonable pressure and minimal risk of inadvertent catheter occlusion. Among the four catheters used with 0.014-0.016-inch guide wires, the authors found that PVA foam particles as large as 1,000-1,500 microm could be injected without catheter occlusion. PVA foam particles as large as 710-1,000 microm could be injected through one catheter used with 0.010-0.013-inch guide wires. Particles as small as 300-500 microm occluded the other catheter used with the same size guide wires. Both of the flow-directed microcatheters tested would allow injection of PVA foam particles as large as 355-500 microm. CONCLUSION: Given the recent proliferation of microcatheters, improved understanding of maximum PVA foam particle size ranges and concentrations that can be injected through them will help prevent inadvertent catheter occlusion during embolization. Because the authors' results are based on a simulated high-flow vascular lesion, they may not be applicable in all circumstances. Embolization of low-flow lesions, however, should not require use of the maximum possible size and concentration of PVA foam particles.

Extradural aneurysms.

Extradural aneurysms have distinct characteristics from their intradural counterparts. Most extradural aneurysms cannot be treated by direct surgical exposure and clip ligation or by direct endovascular means without parent vessel sacrifice. Arterial occlusion with or without bypass grafting remains the traditional treatment. Controversy about the "best" or "proper" technique of arterial balloon test occlusion is rivaled only by that of the necessity for bypass grafting when apparent tolerance for arterial occlusion has been demonstrated.

Reconstructed helical CT scans: improvement in z-axis resolution compared with overlapped and nonoverlapped conventional CT scans.

OBJECTIVE: This in vitro study was designed to assess the z-axis resolving capabilities of reconstructed helical CT scans obtained with various imaging parameters versus those of conventional CT scans and the effect of decreasing slice index on the z-axis resolution of helical CT. MATERIALS AND METHODS: A z-axis line-pair phantom was imaged using conventional nonoverlapped CT scans, conventional CT scans that overlapped by 50%, and helical CT scans with pitches of 1.0 and 1.5. All helical images were reconstructed at comparable slice indexes (image indexes of 2.0, 1.0, and 0.5 mm for pitch = 1.0, and image indexes of 3.0, 1.5, and 0.75 mm for pitch = 1.5). Midline coronal and sagittal reconstructed images were obtained to allow standardized visualization of line pairs. The reconstructed images were reviewed separately by 10 radiologists. RESULTS: The overall z-axis resolution of reconstructed helical CT scans equaled or exceeded that of nonoverlapped conventional CT scans in all cases and equaled that of 50% overlapped conventional CT scans in 75% of cases. The 1.0-pitch helical sequences showed improved z-axis resolution with decreasing slice index. No statistically significant improvement in z-axis resolution could be determined by the observers for 1.5-pitch sequences with decreasing slice index. CONCLUSION: The use of helical CT with a pitch of 1.0 or 1.5 and an increased slice index can improve the z-axis resolution of reconstructed images when compared with nonoverlapped conventional CT and frequently equals the resolution of 50% overlapped conventional CT. This improvement in z-axis resolution should improve the appearance of reconstructed images (as used in CT angiography and three-dimensional imaging) by reducing partial volume artifacts while affording faster scanning at a reduced skin-surface radiation dose.

Hemimegalencephaly and intractable epilepsy treated with embolic hemispherectomy.

A patient with hemimegalencephaly and intractable epilepsy underwent a preoperative embolic hemispherectomy. A seizure-free interval of 1 year followed the embolization procedure. In addition, the procedure was thought to be beneficial in limiting blood loss during a subsequent surgical hemispherectomy.

Temporary balloon test occlusion of the internal carotid artery: experience in 500 cases.

PURPOSE: To describe experience with 500 temporary balloon occlusions of the internal carotid artery, with particular emphasis on the techniques and complications. METHODS: Temporary occlusion of the internal carotid artery was accomplished endovascularly using various balloon-catheter combinations. These temporary balloon occlusions were combined, when possible, with cerebral blood flow analysis with stable xenon-enhanced CT. RESULTS: Complications related to this procedure occurred in 16 (3.2%) patients. Eight (1.6%) patients had asymptomatic complications. There were 8 who experienced neurologic changes. Six (1.2%) of these were transient; two (0.4%) were permanent. There were no deaths. CONCLUSIONS: Temporary balloon occlusion of the internal carotid artery, believed helpful in identifying patients at risk of stroke during abrupt carotid artery sacrifice, can be performed with an acceptably low complication rate.

Iatrogenic carotid-cavernous fistula occurring after embolization of a cavernous sinus meningioma.

A carotid-cavernous fistula developed in a 62-year-old woman during an attempt at embolization of a skull base meningioma. The cause is thought to be perforation by the guide wire during catheterization of the meningohypophyseal trunk at the sharp bend at its origin.

Intraoperative urokinase infusion for embolic stroke during carotid endarterectomy.

Embolic stroke is an infrequent complication of carotid endarterectomy. Somatosensory evoked potential monitoring detected delayed acute neurological deterioration during endarterectomy performed on a 71-year-old woman. Intraoperative arteriography performed via an indwelling shunt revealed thrombus within the middle cerebral artery and distal branches. A microcatheter was placed into the internal carotid artery via the arteriotomy and advanced into the middle cerebral artery. Urokinase was infused into and around the thrombus until almost complete thrombolysis had been achieved. The patient recovered quickly and was discharged without neurological deficit.

The efficacy of particulate embolization combined with stereotactic radiosurgery for treatment of large arteriovenous malformations of the brain.

PURPOSE: To evaluate the efficacy of combined particulate embolization and single-stage stereotactic radiosurgery in the treatment of large arteriovenous malformations (AVMs) of the brain. METHODS: Twenty-four patients with large brain AVMs (diameter > 3.0 cm; volume > 14 cm3), who had previously undergone particulate embolization and stereotactic radiosurgery, were retrospectively evaluated 2 or more years after radiosurgery. RESULTS: In 12 (50%) of these patients there was complete AVM obliteration, comparing favorably with a 58% obliteration rate in a group of AVMs having a 4- to 10-cm3 volume, treated by radiosurgery alone. Recanalization of embolized, but not radiated, AVM segments was identified in 3 (12%) patients. However, long-term occlusion was demonstrated in the embolized portions of most AVMs subsequently treated by radiosurgery. Complications included 1 (4%) patient with a mild upper extremity paresis after radiosurgery and 2 (8%) patients with transient neurologic deficits after embolization. CONCLUSION: Combined embolization and stereotactic radiosurgery was more efficacious than radiosurgery alone for large brain AVMs. Recanalization after embolization did occur but was a relatively minor cause of treatment failure.

Physical characteristics of balloon catheter systems used in temporary cerebral artery occlusion.

PURPOSE: To compare and contrast the physical characteristics of balloon catheter systems used for temporary cerebrovascular occlusion. METHOD: Commonly used temporary occlusion systems were evaluated to determine: (a) balloon compliance; (b) balloon diameter versus volume; (c) balloon pressure versus volume; (d) simulated vessel wall pressure versus volume; (e) balloon failure volume; and (f) balloon deflation rate. Observations were made concerning construction differences that affect the potential safety of a balloon system or the way it is used. RESULTS: The nondetachable balloon system demonstrating the best compliance characteristics and lowest radial pressure generation was the nondetachable silicone balloon (Interventional Therapeutics Corporation, San Francisco, Calif). Diameter versus volume curves for all systems reveal an initial nonlinear expansion that could contribute to vessel overexpansion during occlusion. CONCLUSION: Balloon systems vary in construction, method of introduction, and compliance. Knowledge of these characteristics, as well as of nonlinear balloon expansion, should aid balloon selection and appropriate use while helping to minimize complications.