Conventional fractionated radiation therapy was used in 15 patients to treat arteriovenous malformations (AVMs) of the brain deemed inoperable or incompletely obliterated using endovascular or surgical techniques. The AVMs measured from 0.8 to 85 cm3 (mean 28.2 cm3; median 24 cm3). Angiography in 12 patients 1–21 years following radiation therapy demonstrated no significant change in 7, slight reduction in 2, near complete obliteration in 1, and complete obliteration in 2. Magnetic resonance imaging further demonstrated apparent obliteration in one other case. Three irradiated AVMs were available for pathological examination following fatal recurrent hemorrhage after 21 years in case 1 and following surgery after 5 years in cases 2 and 3. Doses of 20 and 45 Gy were delivered to the area of the AVM in 10 and 15 fractions with a 6-MV linear accelerator in case 1 and in cases 2 and 3, respectively. A blinded histopathological comparison was made of the latter cases and three AVMs removed at surgery that were not previously irradiated and that were comparable in size, number of arterial feeders, and location within the brain. Segmental hyalinization of some blood vessels was seen in both irradiated and nonirradiated cases. The single postmortem specimen showed extensive thrombosis but a patent nidus. The findings are in keeping with the clinical impression that conventional fractionated radiation therapy fails to alter the natural history of cerebral AVMs. The favorable outcome of radiosurgery on small- to medium-sized AVMs appears attributable to the shorter duration of therapy using relatively high-dose prescriptions to the nidus.
Ureterocele calculi are developed in cavities with urinary retention but far from the upper renal cavities. The structural features of three ureterocele calcium oxalate stones were observed by scanning electron microscope coupled with X ray microanalysis. The urinary parameters of the three patients were also determined. The stone A consisted of loose structure of large calcium oxalate dihydrate crystals and small spheres of hydroxyapatite. The interior contains disorganized plate-like calcium oxalate monohydrate crystals. The stone B was formed by a compact outer layer of calcium oxalate monohydrate columnar crystals. The structure of stone interior was similar to the stone A. The stone C was formed by concentric layers composed of either calcium oxalate monohydrate columnar crystals or hydroxyapatite. The core consisted of agglomerated calcium oxalate monohydrate crystals, hydroxyapatite and organic matter. From the urinary biochemical data it was deduced that two ureterocele patients (who formed A and B stones) were hypercalciuric (calcium > 300 mg/24 h), being 6.5 the urinary pH value of the patient that formed the A stone, and 7.0 the urinary pH of the patient that formed the C stone. The rest of urinary parameters for the three patients were normal. Thus, one of the requisite conditions for unattached stone development is the existence of a place inside the urinary tract where the solid particles that act as calculus initiator of the stone can be retained enough time to exert this action.
We report the case of a unilateral traumatic thrombosis of the renal artery. Revascularization was not performed because the diagnosis was made more than 24 h after the injury. Early diagnosis and prompt surgical repair are the keys to successful management of this complication.
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