The age of patients at presentation with meningioma and the latency period of radiation-induced meningiomas are dose related. These tumors are more aggressive and are certain to recur, have a higher histopathological grade, and are associated with complex cytogenetic aberrations particularly involving 1p and 6q.

No abstract

Gamma radiation is known to cause serious damage in the brain, and many agents have been used for neuroprotection. In this study, lipid peroxidation levels and histopathological changes in brain tissues of whole-body irradiated rats with likely radiation injury were compared to those with melatonin and vitamin E protection. Forty rats in four equal groups were used. The control group received neither radiation nor medication. The remaining groups received doses of 720 cGy in two equal fractions 12 h apart. The second group received radiation but no medication, the third received radiation plus 100 mg/kg per day of vitamin E i.p., and the fourth received radiation plus 100 mg/kg per day of melatonin i.p. over 5 days. On the 10th postoperative day, all the rats were decapitated and specimens from parietal cortices were analyzed for tissue malondialdehyde (MDA) levels and histopathological changes. Increases in MDA were relatively well prevented by melatonin treatment but less so with vitamin E therapy. On histopathological examination, melatonin significantly reduced the rates of edema, necrosis, and neuronal degeneration, whereas vitamin E reduced only necrosis. Neither substance was capable of preventing vasodilatation. In conclusion, melatonin may be useful in preventing the pathological changes of secondary brain damage as a result of free oxygen radicals generated by irradiation.

The fundamental goal of skull base surgery is tumor removal with preservation of neurological function. Injury to the lower cranial nerves (LCN; CN 9-12) profoundly affects a patient's quality of life. Although intraoperative cranial nerve monitoring (IOM) is widely practiced for other cranial nerves, literature addressing the LCN is scant. We examined the utility of IOM of the LCN in a large patient series. One hundred twelve patients underwent 123 skull base operations with IOM between January 1994 to December 1999. The vagus nerve (n=37), spinal accessory nerve (n=118), and the hypoglossal nerve (n=83) were monitored intraoperatively. Electromyography (EMG) and compound muscle action potentials (CMAP) were recorded from the relevant muscles after electrical stimulation. This data was evaluated retrospectively. Patients who underwent IOM tended to have larger tumors with more intricate involvement of the lower cranial nerves. Worsening of preoperative lower cranial nerve function was seen in the monitored and unmonitored groups. With the use of IOM in the high risk group, LCN injury was reduced to a rate equivalent to that of the lower risk group (p>0.05). The immediate feedback obtained with IOM may prevent injury to the LCN due to surgical manipulation. It can also help identify the course of a nerve in patients with severely distorted anatomy. These factors may facilitate gross total tumor resection with cranial nerve preservation. The incidence of high false positive and negative CMAP and the variability in CMAP amplitude and threshold can vary depending on individual and technical factors.

A 35-year-old woman presented with a solitary neurofibroma in an unusual presacral location without neurofibromatosis manifesting as bilateral chronic sciatica for 2 years. She was initially considered as having a giant right ovarian mass, but was referred with a prediagnosis of solitary giant sacral nerve sheath tumor. The initial differential diagnosis was based on neuroimaging. A right-sided J incision with the extraperitoneal approach provided good exposure and handling of the tumor bed. Almost total excision without neurological deficit was possible. The histological diagnosis was neurofibroma. Benign retroperitoneal neural sheath tumors in patients without von Recklinghausen's disease are quite rare. Intrapelvic tumors are often diagnosed at a later stage. Neuroimaging is very helpful to delineate this unusual site and the extent of tumor development, and to determine the appropriate surgical intervention. A clear understanding of retroperitoneal anatomy is essential for safe removal of such tumors. Complete resection is preferred to prevent local recurrence and malignant transformation. Although root section is inevitable, neurological deficit is unlikely.