Neurosurgery
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Proliferation and proto-oncogene expression in 19 meningiomas of typical and atypical histology were analyzed in an attempt to understand the mechanism of growth that characterizes the neoplastic process in these tumors. Proliferation was estimated as the proliferative index by the enumeration of S-phase cells in imprints of tumor tissue exposed to bromodeoxyuridine in vitro, and the gene expression of c-myc, c-fos, c-src, c-H-ras, N-myc, acidic and basic fibroblast growth factor, insulin-like growth factors I and II, platelet-derived growth factor-alpha, and epidermal growth factor was quantified by messenger ribonucleic acid dot-blot hybridization assay. Atypical and malignant tumors had significantly higher proliferative indexes than did their nonmalignant counterparts. ⋯ Positive correlations between proliferation and proto-oncogene/growth factor expression were found for c-myc in atypical/malignant tumors and for epidermal growth factor in fibroblastic meningiomas. Deregulated expression of c-myc and c-fos common to both typical and atypical tumors suggests that these are early events in the meningioma tumor process that may disturb the control of cell differentiation and together with fibroblast growth factors are likely to endow the transformed cell with a selective growth advantage by reducing the requirement for exogenous mitogens and by providing a niche for the growth of the tumor clone. Positive correlation of c-myc levels with proliferation in atypical/malignant meningiomas implies that this is a feature of malignancy and indicates continued disruption of the negative regulation of proto-oncogene expression, perhaps by tumor suppressor gene losses, during the course of tumor progression.
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The surgical anatomy of the temporal branch of the facial nerve was studied bilaterally in 10 embalmed cadaveric heads. Particular attention was paid to the relationships between the temporal branch, the galeal-fascial layers, and the fat pads of the temporal-zygomatic region. The temporal branch of the facial nerve pierces the parotidomasseteric fascia below the zygomatic arch. ⋯ Occasionally, a twig for the frontalis muscle may run in between the two layers of the superficial temporal fascia. Because of these findings (anteroposterior variability of temporal branch twigs and recurrent intrafascial twig), Yasargil's interfascial dissection may at times fail. A combined frontotemporal scalp/superficial temporal fascia dissection is anatomically suited to preserve the temporal branch of the facial nerve.
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Brain retraction is required for adequate exposure during many intracranial procedures. The incidence of contusion or infarction from overzealous brain retraction is probably 10% in cranial base procedures and 5% in intracranial aneurysm procedures. The literature on brain retraction injury is reviewed, with particular attention to the use of intermittent retraction. ⋯ Recommendations for operative management of cases involving significant brain retraction are made. These recommendations optimize the following goals: anesthesia and metabolic depression, improvement in cerebral blood flow and calcium channel blockade, intraoperative monitoring, and operative exposure and retraction efficacy. Through a combination of judicious retraction, appropriate anesthetic and pharmacological management, and aggressive intraoperative monitoring, brain retraction should become a much less common source of morbidity in the future.
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The aim of the present study was to analyze the clinical data on rebleeding in cerebral aneurysms during angiography and to evaluate the importance of the time interval between the latest rupture and angiography. Fourteen personal cases and 202 patients reported in the literature are reviewed. ⋯ The prognosis in such ruptures was poor, with a mortality of 79%. Intentional delay in angiography of at least 6 hours from the latest rupture is recommended if the associated hematoma is not large.