Usefulness of posterior transpetrosal approach for the large solid cerebellopontine angle hemangioblastoma fed from multiple blood supplies: A technical case report.

Background: Extra-axial cerebellopontine angle (CPA) hemangioblastomas are rare clinical entity and surgical treatment is challenging due to the anatomical difficulties and multi-directional blood supplies. On the other hand, the risk of endovascular treatment for this disease has also been reported. Herein, we successfully applied a posterior transpetrosal approach to remove a large solid CPA hemangioblastoma without preoperative feeder embolization. Case Description: A 65-year-old man presented with a complaint of diplopia during downward gaze. Magnetic resonance imaging revealed a solid tumor with homogeneous enhancement measuring about 35 mm at the left CPA, and the tumor compressed a left trochlear nerve. Cerebral angiography disclosed tumor-staining fed by both left superior cerebellar and left tentorial arteries. After the operation, the patient's trochlear nerve palsy improved dramatically. Conclusion: This approach offers more optimal surgical working angle to the anteromedial part compared to the lateral suboccipital approach. In addition, the devascularization from the cerebellar parenchyma can be performed more reliably than the anterior transpetrosal approach. After all, this approach can be particularly useful when vascular-rich tumors receive blood supplies from multiple directions.

Transpetrosal Approach for a Giant Thrombosed P2 Segment Posterior Cerebral Artery Aneurysm.

OBJECTIVE: Posterior cerebral artery (PCA) aneurysms are extremely rare and can be difficult to treat. We report successful trapping and thrombectomy of a giant thrombosed P2 segment aneurysm via a transpetrosal approach. CASE PRESENTATION: A 62-year-old woman was admitted to our hospital with a progressive left hemiparesis. Magnetic resonance imaging (MRI) showed a 30 mm mass lesion in the right ambient cistern. On vertebral angiography, the right P2 trunk was deviated medially and inferiorly, and the right posterior temporal artery (PTA) was not visualized. We diagnosed a giant thrombosed aneurysm of the right PTA. Surgery was performed via a right posterior transpetrosal approach. The proximal P2 was identified above the oculomotor nerve in the ambient cistern, and a giant PTA aneurysm was found. After coagulating the distal PCA, a temporary clip was applied to the proximal P2, the aneurysm wall was incised, thrombus was removed, and a permanent titanium clip was applied to complete trapping. Postoperative MRI showed disappearance of the aneurysm. The patient's left hemiparesis was resolved 2 months after the operation, and she was discharged home. CONCLUSION: Although trans-sylvian and subtemporal approaches are often performed for P2 aneurysms, they have difficulty identifying the distal PCA and may require excessive brain retraction. The transpetrosal approach can also be effective for giant thrombosed P2 aneurysms.

[A Case of Primary Central Nervous System Lymphoma Originated from Optic Chiasma and Presenting Difficulty in Diagnosis].

We report a case of primary central nervous system lymphoma(PCNSL)originating from an optic chiasma, which was difficult to diagnose but was finally diagnosed by biopsy. A 62-year-old immunocompetent man presented with bilateral visual field disturbance, hypopituitarism, and diabetes insipidus;an optic chiasm lesion was detected on MRI. After starting steroid supplementation for adrenal insufficiency, visual field disturbance immediately improved. Since the lesion completely disappeared three months after its onset, it became the follow-up without histological confirmation. Six months after the onset, visual field disturbance progressed, and the lesion recurred. We performed a left optic nerve biopsy to maintain the right visual field, which remained partially. The pathology was PCNSL. We performed postoperative chemoradiotherapy, and the patient showed remission and improvement of the visual field. Isolated PCNSLs arising from optic chiasma are very rare. The diagnosis of optic chiasm lesions is difficult due to their similarity with a variety of inflammatory/autoimmune disease and neoplastic lesions. When a lymphoma is considered to be differentiated, early biopsy should be performed before administering a steroid. The approach and sampling site to prevent the function are also important for biopsy.