Neuroradiology case of the day. Medulloblastoma.
Explore the source record for details and available documents.
Adult↗
Biomedical subjects
J D Barr
Publications and source records attributed to J D Barr.
Neuroradiology case of the day. Dural arteriovenous malformation.
Explore the source record for details and available documents.
Cerebral Veins↗
Neuroradiology case of the day. Malignant melanoma.
Explore the source record for details and available documents.
Adolescent↗
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.
Animals↗
Transient severe brain stem depression during intraarterial papaverine infusion for cerebral vasospasm.
A 63-year-old woman had severe, symptomatic cerebral vasospasm secondary to subarachnoid hemorrhage. We initiated simultaneous infusions of papaverine into her left vertebral and left internal carotid arteries. Twenty-five minutes after the infusions had begun, the patient had a transient reaction of respiratory arrest followed by rapid, progressive loss of brain stem function.
Apnea↗
Therapeutic occlusion of major vessels, test occlusion and techniques.
Temporary and permanent cerebrovascular occlusion have become well-accepted endovascular tools. Temporary vessel occlusion and cerebral blood flow analysis help to predict the adequacy of cerebral collateral flow prior to vessel sacrifice. Permanent cerebrovascular occlusion remains a useful alternative endovascular tool when complex lesions of the cervical region, skullbase, and brain are not treatable by surgical or intralesional techniques.
Angioplasty, Balloon↗
Provocative pharmacologic testing during arterial embolization.
Provocative pharmacologic testing reliably predicts the safety of arterial embolization. Arteries with intra-axial destinations are tested with a barbiturates and arteries with extra-axial destinations are tested with lidocaine. Testing is quickly and easily performed, essentially risk-free, and reduces the incidence of complications. Despite extensive knowledge of microvascular anatomy, anatomic variations and branches below the limits of angiographic resolution make provocative pharmacologic testing essential to minimize complications during arterial embolization.
Adolescent↗
Glipizide treatment of pancreas autotransplantation: effects on alterations in glucose-insulin relationships.
Pancreas transplantation has been proven effective in supplying an endogenous insulin supply in diabetics. However, alterations in glucose metabolism after transplantation suggest a possible "insensitivity" to its action in the periphery. We hypothesized that sulfonylurea treatment of canines who had received segmental pancreas autotransplants would correct these alterations by altering peripheral insulin sensitivity. Glipizide therapy (5 mg p.o. b.i.d.) did appear, in fact, to enhance basal insulin sensitivity by lowering fasting glucose (100 +/- 3 to 81 +/- 11 mg/dl pre-treatment to post-treatment) while not affecting basal insulin levels. However, glipizide therapy was associated with decreased insulin response to challenge by either oral glucose (2 gm/kg) or sustained intravenous hyperglycemia (150 mg/dl above basal). We conclude that our model of pancreas autotransplantation documents alterations in glucose metabolism which are devoid of the effect of immunosuppression. Glipizide treatment appears to affect fasting sensitivity to insulin, but results in a decrement of insulin response to oral or intravenous glucose challenge.
Animals↗
In situ lithotripsy of ureteral calculi: review of 261 cases.
The authors report 261 cases of single ureteral calculi treated with in situ lithotripsy after retrograde manipulations had failed. Previous reports have indicated that extracorporeal lithotripsy of impacted ureteral calculi has not been highly successful. Two hundred five of the calculi were located in the proximal ureter, above the sacroiliac joint; 27 were in the presacral ureter, overlying the bony pelvis; and 29 were in the juxtavesicular ureter, below the inferior border of the sacroiliac joint. Retrograde ureteral catheters were in place during lithotripsy for 215 calculi. Two hundred fifty-four (97%) calculi were successfully treated with lithotripsy and, when necessary, with additional postlithotripsy radiologic and urologic interventions. Seven (3%) calculi were not successfully fragmented. Nephrostomy was performed in 13 (5%) patients. Retrograde ureteral catheters were not found to enhance calculus fragmentation. In situ lithotripsy of ureteral calculi has been shown to be feasible as an alternative to ureterolithotomy when retrograde manipulation has failed.
Follow-Up Studies↗
Effect of glipizide on the surgically altered pancreas.
Surgical alterations of the pancreas affect peripheral glucose, insulin, and glucagon levels with accompanying changes in carbohydrate metabolism. The sulfonylurea glipizide has been used to treat insulin-deficient states; however, its mechanism is not completely known. We hypothesized that glipizide would correct postoperative changes in glucose handling in a way that would allow more complete understanding of the drug's action. Two surgical groups (Group 1:80 percent proximal pancreatectomy; Group 2: proximal pancreatectomy plus splenocaval diversion) were compared with a healthy control group (Group 3). We have concluded that glipizide may have affected basal insulin sensitivity in the control group and Group 2 animals without affecting insulin secretion in response to oral or intravenous glucose stimulation. Glipizide does not correct the alterations in glucose handling or insulin secretion after reduction in beta-cell mass.
Animals↗
The role of radiology in extracorporeal shock wave therapy.
Extracorporeal shock wave lithotripsy was used for the treatment of 1,252 kidneys and ureters with calculi during a 10-month period at the authors' medical center. Before lithotripsy was performed, excretory urography, radiography, renography, computed tomography, and ultrasound studies were done, when necessary, to locate the calculi. Nine calculi in five kidneys could not be fragmented with lithotripsy. Of 895 patients with calculi less than 2.5 cm in diameter, only 13 (1.5%) required interventional procedures to clear the calculi, whereas of 161 patients with calculi greater than or equal to 2.5 cm, 36 (22.4%) required nephrostomies. A column of calculous debris in the mid and distal portions of the ureter (steinstrasse) was seen in 171 instances (13.6%) after lithotripsy; 62% required interventions. The most common intervention required for successful lithotripsy was retrograde ureteral catheterization. Evaluation and treatment of patients with urolithiasis were largely dependent on radiography and excretory urography.
Endoscopy↗
Letter: The Flixborough Nypro explosion.
Explore the source record for details and available documents.
Animals↗
Acute stroke intervention with intraarterial urokinase infusion.
PURPOSE: A preliminary evaluation of the efficacy and safety of treating patients with acute stroke with intraarterial urokinase infusions was performed. PATIENTS AND METHODS: Twelve patients with acute stroke were treated within 8 hours of symptom onset (average, 5 hours). Thrombolysis was performed within the middle cerebral (n = 10), internal carotid (n = 1), and basilar (n = 1) arteries. Urokinase (160,000-500,000 IU) was infused through microcatheters placed into or adjacent to the thrombi. RESULTS: Thrombolysis was angiographically successful in nine patients (75%), all of whom had long-term neurologic improvement. No or minimal neurologic deficits were present in six patients (50%). Thrombolysis failed in three patients (25%); one patient died and two developed severe permanent neurologic deficits. No hemorrhagic complications occurred. CONCLUSION: Preliminary results suggest that intraarterial urokinase infusion may be effective and safe for treating patients with acute stroke. Potentially devastating neurologic damage was averted or lessened in nine patients (75%). No additional neurologic damage was caused by intervention in the remaining three patients (25%).
Cerebral Angiography↗
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.
Catheterization↗
Filtration of cryoprecipitate: a microscopic assessment of filter depostion.
A recent survey indicated that many Canadian hemophiliacs and physicians did not consider it necessary to filter cryoprecipitate prior to infusion. Experiments were performed to demonstrate that no loss of factor activity resulted from filtration of cryoprecipitate through standard blood filters. Furthermore, examination of the material retained on standard and ultrafiltration elements using scanning and transmission electron microscopy demonstrated the presence of amorphous and fibrillar proteins that proved to be largely composed of fibrin. This was accompanied by cellular material including intact and disintegrating leukocytes, erythrocytes, and platelets. Nonbiologic material was also discovered, including cellulose and plastic debris. This study emphasizes the need for effective filtration of cryoprecipitate.
Chemical Precipitation↗