We investigated morphological and metabolic changes of radiation necrosis (RN) of the brain following bevacizumab (BEV) treatment by using neuroimaging. Nine patients with symptomatic RN, who had already been treated with radiation therapy for malignant brain tumors (6 glioblastomas, 1 anaplastic oligodendroglioma, and 2 metastatic brain tumors), were enrolled in this prospective clinical study. RN diagnosis was neuroradiologically determined with Gd-enhanced MRI and 11C-methionine positron emission tomography (MET-PET). RN clinical and radiological changes in MRI, magnetic resonance spectroscopy (MRS) and PET were assessed following BEV therapy. Karnofsky performance status scores improved in seven patients (77.8 %). Both volumes of the Gd-enhanced area and FLAIR-high area from MRI decreased in all patients after BEV therapy and the mean size reduction rates of the lesions were 80.0 and 65.0 %, respectively. MRS, which was performed in three patients, showed a significant reduction in Cho/Cr ratio after BEV therapy. Lesion/normal tissue (L/N) ratios in MET- and 11C-choline positron emission tomography (CHO-PET) decreased in 8 (89 %) and 9 patients (100 %), respectively, and the mean L/N ratio reduction rates were 24.4 and 60.7 %, respectively. BEV-related adverse effects of grade 1 or 2 (anemia, neutropenia and lymphocytopenia) occurred in three patients. These results demonstrated that BEV therapy improved RN both clinically and radiologically. BEV therapeutic mechanisms on RN have been suggested to be related not only to the effect on vascular permeability reduction by repairing the blood-brain barrier, but also to the effect on suppression of tissue biological activity, such as immunoreactions and inflammation.
The objective of this study was to investigate the factors that potentially lead to brain radionecrosis (RN) after micromultileaf collimator-based stereotactic radiosurgery (SRS) for brain metastases. We retrospectively evaluated 131 lesions with a minimum follow-up of 6 months, 43.5% of which received prior whole-brain radiotherapy (WBRT). The three-tiered location grade (LG) was defined, as follows, for each target by considering mainly the depth from the brain surface: grade 1 (superficial), involving the region at a depth of ≤5 mm from the brain surface; grade 2 (deep), located at a depth of >5 mm from the brain surface; and grade 3 (central), located in the brainstem, cerebellar peduncle, diencephalon, or basal ganglion. The predictive factors for RN, including high-dose irradiated isodose volumes (IIDVs) and LG, were evaluated by univariate and multivariate analysis. Symptomatic RN (S-RN) and asymptomatic RN (A-RN) were observed in 8.4% and 6.9% of cases, respectively. Multivariate analysis indicated that the significant factors for both types of RN were LG, V12 Gy, and V22 Gy in all cases; V22 Gy and LG for the non-WBRT cases; and V15 Gy and LG for the WBRT cases. For the non-WBRT cases, the cutoff values of V22 Gy were 2.62 and 2.14 cm(3) for S-RN and both RN, respectively. For the WBRT cases, the cutoff values of V15 Gy were 5.61 and 5.20 cm(3) for S-RN and both RN, respectively. In addition to the IIDV data, LG helps predict the risk of RN. High-dose IIDV, V22 Gy, was also significantly correlated with RN, particularly for patients treated with SRS alone.
A 33-year-old woman presented with a rare intracranial pial arteriovenous fistula manifesting as monoparesis and hypesthesia of the right lower extremity. Computed tomography demonstrated an approximately 10-mm diameter subcortical hematoma in the left postcentral gyrus. Two months after suffering the ictus, angiography demonstrated a pial arteriovenous fistula in the late arterial phase fed by the left paracentral artery and drained into the left precentral vein. No nidus or dural arteriovenous fistula was detected. Left parietal craniotomy was performed and the pial arteriovenous fistula was extirpated by electrocoagulation. Intraoperative angiography demonstrated disappearance of the fistula. She experienced no postoperative neurological deterioration, but hypesthesia of the right leg persisted. Obliteration of the pial arteriovenous fistula was reconfirmed by postoperative angiography. She suffered no rebleeding episodes during the 36-month follow-up period. Pial arteriovenous fistula causing mild symptoms should be treated by flow disconnection because the direct arteriovenous shunt and attendant high blood flow usually results in huge venous varices. To determine whether direct surgery or endovascular treatment is appropriate, the position and shape of the lesion must be known.
We report a very rare case of hemangioblastomatosis in a patient without von Hippel-Lindau disease (VHL). A 50-year-old woman had a history of surgical procedures for total removal of a cerebellar hemangioblastoma (HB). Twenty-one years after the last operation, she developed communicating hydrocephalus; computed tomographic (CT) scans of the brain showed no recurrence of HB in the posterior fossa. Subsequently, she underwent placement of a ventriculo-peritoneal shunt. One year later, she was readmitted because of progressive numbness and pain in the left lower limb. Magnetic resonance imaging (MRI) showed multiple Gd-enhancing tumors around the brain stem, in the cerebellum, and in the cervical and thoracolumbar regions of the spine. She underwent surgical removal of the tumors in the cerebellum and spinal cord. Although the extirpated tissues were histopathologically verified HB with less than 1% MIB-1 labeling index, surgery was followed by external beam radiation therapy with doses of 40 Gy to the whole brain, 10 Gy to the posterior fossa and 30 Gy to the whole spine. However, she subsequently developed quadriparesis and became bedridden.
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