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1/13. De novo development of a cavernous malformation of the spinal cord following spinal axis radiation. Case report.

    Analysis of recent reports has suggested that cavernous malformations (CMs) of the brain may have an acquired pathogenesis and a dynamic pathophysiological composition, with documented appearance of new lesions in familial cases and following radiotherapy. The authors report the first case of demonstrated de novo formation of an intramedullary CM following spinal radiation therapy. A 17 year-old boy presented with diabetes insipidus and delayed puberty. Evaluation of endocrine levels revealed hypopituitarism, and magnetic resonance (MR) imaging demonstrated an infundibular mass. The patient underwent a pterional craniotomy and removal of an infundibular germinoma. The MR image of the spine demonstrated normal results. The patient received craniospinal radiation therapy and did well. He presented 5 years later with acute onset of back pain, lower-extremity weakness and numbness, and difficulty with urination. An MR image obtained of the spine revealed an intramedullary T-7 lesion; its signal characteristics were consistent with a CM. The patient was initially managed conservatively but developed progressive myelopathy and partial brown-sequard syndrome. Although he received high-dose steroids and bed rest, his symptoms worsened. He underwent a costotransversectomy and excision of a hemorrhagic vascular lesion via an anterolateral myelotomy. Pathological examination confirmed features of a CM. The patient has done well and was walking without assistance within 4 weeks of surgery. De novo genesis of CMs may be associated with prior radiation therapy to the spinal cord.
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2/13. Contribution of clinical teratologists and geneticists to the evaluation of the etiology of congenital malformations alleged to be caused by environmental agents: ionizing radiation, electromagnetic fields, microwaves, radionuclides, and ultrasound.

    Analysis of these six clinical problems demonstrates the value of a complete clinical evaluation of a child with congenital malformations by an experienced and well-trained physician who is familiar with the fields of developmental biology, teratology , epidemiology, and genetics. Too often, the entire emphasis is placed on epidemiological data that may be meager or insufficient for a rational conclusion when clinical findings that are readily available can provide definitive answers with regard to the etiology of a child's malformations or the merits of an environmental etiology.
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3/13. Moyamoya syndrome after radiation therapy for optic pathway glioma: case report.

    We present a 4-year-old girl with neurofibromatosis-1 who developed moyamoya syndrome characterized by bilateral stenosis or occlusion of the distal internal carotid arteries and their branches, leading to the development of an abnormal vascular network. In light of a literature review, the postradiation vasculopathy of the moyamoya type and its relationship with neurofibromatosis-1 are discussed.
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4/13. Multiple patterns of resistance to fluconazole in candida glabrata isolates from a patient with oropharyngeal candidiasis receiving head and neck radiation.

    candida glabrata has emerged in recent years as a significant cause of systemic fungal infection. We have previously reported on the first three patients receiving radiation for head and neck cancer to develop oropharyngeal candidiasis due to C. glabrata. The goal of this study was to track the development of increased fluconazole resistance in C. glabrata isolates and to evaluate previously described genetic mechanisms associated with this resistance from one of these three patients. The patient was a 52-year-old man with squamous cell carcinoma treated with radiation. At week 7 of his radiation, he developed oropharyngeal candidiasis, which was treated with 200 mg of fluconazole daily for 2 weeks. Serial cultures from this and three subsequent time points yielded C. glabrata. Isolates from these cultures were subjected to antifungal susceptibility testing, dna karyotyping, and evaluation of the expression of genes previously associated with C. glabrata resistance to fluconazole, CgCDR1, CgCDR2, and CgERG11. Two strains (A and B) of C. glabrata were identified and found to display different patterns of resistance development and gene expression. Strain A developed resistance over a 2-week period and showed no overexpression of these genes. In contrast, strain B first showed resistance 6 weeks after fluconazole therapy was discontinued but showed overexpression of all three genes. In conclusion, development of resistance to fluconazole by C. glabrata is a highly varied process involving multiple molecular mechanisms.
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5/13. radiation-induced ostial stenosis of the coronary artery as a cause of acute coronary syndromes: a novel mechanism of thrombus formation?

    Mediastinal irradiation can induce coronary artery disease characterized by fibrous lesions developing in the absence of lipid/foam cell accumulation. We document several consecutive cases of acute coronary artery occlusion developing over radiation-induced lesions in patients who were relatively young, without evidence of classical risk factors for atherosclerosis, and in whom the coronary vasculature was otherwise apparently free of disease. The finding of acute coronary artery occlusion at the site of a fibrous lesion lends further support to the hypothesis that acute coronary syndromes may not necessarily be identifiable with ulceration/disruption of the atherosclerotic plaque as the underlying mechanism of acute thrombus formation.
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6/13. Carotid stenting for symptomatic radiation-induced arteritis complicated by recurrent aneurysm formation.

    We describe a 56-year-old male who underwent successful carotid stenting (CS) with adjuvant distal protection in response to symptomatic radiation-induced carotid disease. During the CS procedure, it was incidentally noted that the lesion yield pressure was surprisingly low (2 atm). The patient returned with local symptoms from common carotid aneurysmal dilation at the proximal edge of the stent that was successfully treated with a stent graft. A second aneurysm developed proximal to the stent graft and, based on intravascular ultrasound mapping, he ultimately underwent venous bypass covered by a free-muscle graft. We believe the low lesion yield pressure in this case reflected loss of vessel integrity and it may be prudent to avoid oversizing the stent in such patients.
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7/13. Treatment of unstable fractures of the pelvic ring in pregnancy.

    Unstable fractures of the posterior pelvic ring during pregnancy are rare. pregnancy increases the high demands on the therapy of these types of fractures. The aim of the therapeutic strategy in such a situation is a good functional outcome of the mother without influencing the fetal health. Some osteosynthetic techniques result in good functional outcomes, but they are associated with high amounts of ionizing radiation. We report the case of a pregnant woman who sustained a vertical unstable fracture of the posterior pelvic ring as a result of a traffic accident. The fracture was treated surgically by open reduction and internal fixation with two transiliac reconstruction plates with minimal radiographic exposure to the fetus. One year later, a good functional result concerning the mother was shown. The child was healthy without any signs of prenatal impairment. Surgical treatment of an unstable fracture of the pelvic ring during pregnancy is possible with a justifiable risk to the mother and the child. Consideration of the expected fetal radiation exposure in the course of the therapy is particularly recommended. Using minimal doses of ionizing radiation, the described method results in a good clinical outcome of the mother while simultaneously reducing the radiation exposure of the fetus to an acceptable level.
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8/13. Uterine radiation dose from open sources: the potential for underestimation.

    The evaluation of the risk of radiation damage to the unborn child as the result of the administration of radionuclides remains a subject for discussion (Mountford 1989). Lack of information concerning the biodistribution of radiopharmaceuticals in the early stages of pregnancy, before organogenesis has occurred, has greatly restricted the objective assessment of fetal doses. Recent observations on the biodistribution of a therapeutic dose of sodium iodide 131 in a patient with an unsuspected early pregnancy lead us to suspect that current dose estimates with respect to uterine exposure (ARSAC 1988) may seriously underestimate the actual exposure of the developing fetus.
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keywords = radiation
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9/13. The effect of embryonic and fetal exposure to x-ray, microwaves, and ultrasound: counseling the pregnant and nonpregnant patient about these risks.

    The term radiation evokes emotional responses both from lay persons and from professionals. Many spokespersons are unfamiliar with radiation biology or the quantitative nature of the risks. Frequently, microwave, ultrasound, and ionizing radiation risks are confused. Although it is impossible to prove no risk for any environmental hazard, it appears that exposure to microwave radiation below the maximal permissible levels present no measurable risk to the embryo. Ultrasound exposure from diagnostic ultrasonographic-imaging equipment also is quite innocuous. It is true that continued surveillance and research into potential risks of these low-level exposures should continue; however, at present ultrasound not only improves obstetric care, but also reduces the necessity of diagnostic x-ray procedures. In the field of ionizing radiation, we have a better comprehension of the biologic effects and the quantitative maximum risks than for any other environmental hazard. Although the animal and human data support the conclusion that no increases in the incidence of gross congenital malformations, IUGR, or abortion will occur with exposures less than 5 rad, that does not mean that there are definitely no risks to the embryo exposed to lower doses of radiation. Whether there exists a linear or exponential dose-response relationship or a threshold exposure for genetic, carcinogenic, cell-depleting, and life-shortening effects has not been determined. In establishing maximum permissible levels for the embryo at low exposures, refer to tables 4, 5, 6, 8, and 9. It is obvious that the risks of 1-rad (.10Gy) or 5-rad (.05Gy) acute exposure are far below the spontaneous risks of the developing embryo because 15% of human embryos abort, 2.7% to 3.0% of human embryos have major malformations, 4% have intrauterine growth retardation, and 8% to 10% have early- or late-stage onset genetic disease. The maximal risk attributed to a 1-rad exposure, approximately 0.003%, is thousands of times smaller than the spontaneous risks of malformations, abortion, or genetic disease. Thus, the present maximal permissible occupational exposures of 0.5 rem for pregnant women (see Table 10) and 5 rem for medical exposure, are extremely conservative. Medically indicated diagnostic roentgenograms are appropriate for pregnant women, and there is no medical justification for terminating a pregnancy in women exposed to 5 rad or less because of a radiation exposure.(ABSTRACT TRUNCATED AT 400 WORDS)
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10/13. Failure of root development of human permanent teeth following irradiation.

    Complete absence of root formation of the upper incisors, canine and first premolar was reported in a 27-year-old female who had received radiation therapy for a retinal glioma of the right eye at age of 3 years 1 month. Ground and decalcified sections showed no remarkable changes in enamel and dentin of the crowns, but the pulp floor was closed by irregular dentin deposit despite the absence of root formation. The outer surface of the irregular dentin was covered by acellular cementum, and the periodontal membrane was undeveloped. A slight degree of fibrosis was seen in the pulp, but the coronal part of the dentin was lined by odontoblasts. The theory that tooth eruption is caused by the growth of the root is not substantiated by the observation in this case.
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