1/4. glioblastoma multiforme occurring in a patient treated with gamma knife surgery. Case report and review of the literature.Stereotactic radiosurgery is being increasingly advocated as the primary modality for treatment of vestibular schwannomas (VS). This modality has been shown to arrest tumor growth, with few associated short-term morbidities, and with possibly better hearing and facial nerve preservation rates than microsurgery. radiation-induced oncogenesis has long been recognized, although stereotactic radiosurgery de novo induction of a secondary tumor has never been clearly described. The authors report on a patient with a VS who did not have neurofibromatosis Type 2 and who underwent gamma knife surgery (GKS). This patient required microsurgical removal of the VS within 8 months because of development of a tumor cyst with associated brainstem compression and progressive hydrocephalus. The operation resulted in clinical stabilization and freedom from tumor recurrence. Seven and a half years after undergoing GKS, the patient presented with symptoms of raised intracranial pressure. magnetic resonance imaging demonstrated a new ring-enhancing lesion in the inferior temporal lobe adjacent to the area of radiosurgery, which on craniotomy was confirmed to be a glioblastoma multiforme (GBM). Despite additional conventional external-beam radiation to the temporal lobe, the GBM has progressed. Whereas this first reported case of a GBM within the scatter field of GKS does not conclusively prove a direct causal link, it does fulfill all of Cahan's criteria for radiation-induced neoplasia, and demands increased vigilance for the potential long-term complications of stereotactic radiosurgery, and reporting of any similar cases.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
2/4. The value of enhanced magnetic resonance imaging in the evaluation of endocochlear disease.BACKGROUND: gadolinium-enhanced magnetic resonance imaging (GdMRI) is routinely used in the evaluation and management of suspected retrocochlear pathology such as vestibular schwannoma. However, its value in the evaluation and diagnosis of cochlear pathology associated with sensorineural hearing loss (SNHL) has been less clear. STUDY DESIGN: Retrospective review of case histories and imaging studies of patients with SNHL and cochlear enhancement on GdMRI diagnosed between 1998 and 2000. RESULTS: Five patients with SNHL who required gadolinium administration to establish the diagnosis of endocochlear disease were identified. Diagnosed lesions included an intralabyrinthine schwannoma, intracochlear hemorrhage, radiation-induced ischemic change, autoimmune labyrinthitis, and meningogenic labyrinthitis. In these illustrative cases, the GdMRI demonstrated intrinsic high signal or contrast enhancement within the cochlea and labyrinth in the absence of a retrocochlear mass. In one patient with meningogenic labyrinthitis, cochlear enhancement on MRI led to prompt cochlear implantation before the potential development of cochlear ossification. CONCLUSION: Our experience suggests that GdMRI plays a crucial role in the diagnosis of cochlear pathology associated with sensorineural hearing loss and may directly impact patient management.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
3/4. Facial neuropathy due to axonal degeneration and microvasculitis following gamma knife surgery for vestibular schwannoma: a histological analysis. Case report.Complete facial palsy (House-Brackmann Grade VI) developed in a 63-year-old man with a vestibular schwannoma 25 months after he had undergone two gamma knife surgeries performed 33 months apart and involving a cumulative dose of 24 Gy directed to the tumor margin at the 50% isodose line. magnetic resonance imaging demonstrated tumor enlargement with central nonenhancement, which initially had been recognized 21 months after the second radiosurgery. microsurgery was performed to achieve total removal of the tumor. Histological and immunohistochemical examinations of the facial nerve specimen removed from the edge of the tumor revealed a loss of axons, proliferation of schwann cells, and microvasculitis. In this case, microvasculitis and axonal degeneration were probably the major causes of the radiation-induced facial neuropathy.- - - - - - - - - - ranking = 1keywords = radiation-induced (Clic here for more details about this article) |
4/4. radiation-induced schwannomas of the neuraxis. Report of three cases.We report 3 cases of possible radiation-induced schwannomas observed in our Department. Their salient clinical and pathogenetic features are analyzed and the role of radiation therapy in the oncogenesis of these lesions is discussed. Several cases of radiation-induced tumors, including some of the nervous system, have been reported, but schwannomas have only occasionally been reported in connection with ionizing radiation. The possible adjuvant role of antineoplastic drugs is also discussed, and the literature on this topic is reviewed.- - - - - - - - - - ranking = 2keywords = radiation-induced (Clic here for more details about this article) |