The frequency of meningiomas has been the topic of relatively few reports. Hospital-based brain tumor series indicate that the incidence is approximately 20% of all intracranial tumors; population-based studies indicate an overall incidence of 2.3/100,000. Although intracranial tumors as a whole show a higher prevalence in males than in females, meningiomas have a 2:1 female-to-male ratio. Between Caucasians and Africans, African-Americans, and Asians, certain differences also have been noted. Meningiomas in children are rare and differ from those in adults and other childhood tumors; they are even more rare in infants. Several features indicating etiologic factors have been identified, among which are ionizing radiation, head injury, hormones, and other receptor binding sites, genetic factors, and viruses. The most common source of exposure of the head to ionizing radiation is dental radiographic examination. Since 1922, head trauma has been considered a possible risk factor, but recent large studies do not support this link. Several factors have prompted studies of estrogens and progestogens as risk factors for meningiomas. Other studies have sought to determine if certain individuals have an inherited predisposition for developing a meningioma and/or if viruses, which may act alone or with other mutagens, figure into the formation of a meningioma. The most promising studies are those of cytogenetics, and future elucidation of factors associated with the loss of one copy of chromosome 22, another phenomenon that has been identified in meningiomas, may lead to screening tests and gene therapy.
A prospective study of 70 patients with intraparenchymal brain lesions (36 gliomas and 34 metastases) was performed to evaluate the efficacy of intraoperative ultrasound (IOUS) in localizing and defining the borders of tumors and in assessing the extent of their resection. Eighteen of the 36 glioma patients had no previous therapy. All of these 18 tumors were well localized by IOUS; margins were well defined in 15 and moderately defined in three. The extent of resection was well defined on IOUS in all 18 patients, as confirmed by measurements taken on postoperative magnetic resonance (MR) images (p = 0.90). The remaining 18 patients with gliomas had undergone previous surgery and/or radiation therapy; five had recurrent tumors and 13 had radiation-induced changes. The extent of resection of the recurrent tumors was well defined in all but one patient, as confirmed by postoperative MR imaging. The extent of resection was poorly defined in all 13 patients whose pathology showed radiation effects. All 34 metastatic lesions were well localized and had well-defined margins. In addition, IOUS accurately determined the extent of resection in all cases, the results were confirmed with postoperative MR imaging. In conclusion, IOUS is not only helpful in localizing and defining the margins of gliomas and metastatic brain lesions, it also accurately determines the extent of resection, as confirmed by postoperative MR imaging. This assessment does not apply, however when the lesion is due primarily to radiation effect.
A mysterious disease was reported on May 24, 2003, when the Wisconsin Division of Public Health (DPH) received notice of a 3-year-old girl who had been hospitalized in central Wisconsin with cellulites and fever after being bitten by a prairie dog on May 13. The laboratory isolated a gram-negative bacillus, raising concerns that it might be tularemia or plague; ultimately, it was identified as an acinetobacter species and was considered to be a contaminant. Because no other such cases were reported at the time, the case was thought to be merely an isolated event. However, within two weeks, on June 2, 2003, evidence of a much wider scenario began to emerge. On that date, the Wisconsin DPH received notice from the Marshfield Laboratory that the mother of the first patient had become ill on May 26 and that electron-microscopic evidence of a poxvirus was found in a skin lesion. On that same day, another report, this time from the Milwaukee Health Department, of a strange illness was received at the DPH and described the case of a meat inspector who resided in southeastern Wisconsin and also was a distributor of exotic animals. By July 30, 2003, 72 confirmed or suspected cases of monkeypox had been reported in Wisconsin, Illinois, and Indiana and represented a large outbreak. The peak in the onset of illness occurred between May 29 and June 9, 2003, and no further cases of illness have been reported in humans since June 22, 2003. Traceback investigations from the child and other patients followed the route of introduction of monkeypox into Wisconsin to a distributor in Illinois, who had received a shipment of exotic animals imported into the United States through Texas from Ghana, West Africa.
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