RESUMO
Background: Lower cranial nerve schwannomas are rare and only 63 cases originating from the accessory nerve have been documented. Case Description: We report a 61-year-old man who presented with a 3-month history of dysmetria, ataxic gait, and frequent falls. Magnetic resonance imaging revealed a giant rim-enhancing cystic lesion at the right cerebellomedullary cistern, which markedly displaced the brainstem and caused a critical compression on surrounding structures and mild hydrocephalus. Even though the nature of this lesion was not clear, it received a radiological diagnosis of meningioma as first option. Surgery was performed through an extended far lateral retrosigmoid approach with C1 hemilaminectomy, with intraoperative neurophysiological monitoring. A near-total resection was achieved due to the adhesion of the lesion to the brainstem and to the cranial nerves VII, VIII, IX, X, XI, and XII. Intraoperatively, the tumor was found to arise from the accessory nerve. The histopathological analysis concluded with a final diagnosis of ancient schwannoma, a rare histological subtype characterized by degenerative changes, typical from long-standing tumors. Conclusion: Very few cases of intracranial ancient schwannomas have been described. To the best of our knowledge, this is the first report of this extremely rare histological variant arising from the intracisternal component of the XI nerve. The rarity of this disease at this location may lead to preoperative misdiagnosis.
RESUMO
Defining high-grade glioma resectability is a challenge; and currently, it is based on anatomical imaging. However, complete removal of contrast-enhancing tumor is difficult to define in MRI. We present three cases of patients diagnosed with high-grade glioma. Brain MRI and F-fluorocholine PET/CT were performed before and after surgery to establish the extent of resection (EOR) and residual volume. Postoperative brain MRI and PET parameters showed discordant results in all the reported cases. PET was able to assess properly the EOR; however, the rules for the EOR establishment and its prognostic implication should be validated in prospective studies.
