PMC5154203_01
Primary tumor and follow-up magnetic resonance imaging. (a) Gross-total removal of the medulloblastoma. (b) Radiotherapy at 32.4 Gy for the posterior fossa and 23.4 Gy for the whole brain and spine; consequently, 55.8 Gy was irradiated around the tumor cavity. (c) Image obtained 7 years later showing no evident aneurysmal formation. (d) The 5-mm hyperintense nodule (arrow) on the continuous wall of the resected cavity discovered 9 years later
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F1
A 17-year-old man was found to have a posterior fossa medulloblastoma when he was 8 years old [Figure 1a]. He had undergone gross-total tumor resection without complication followed by craniospinal radiotherapy (total dose, 55.8 Gy) [Figure 1b] and combination chemotherapy with ifosfamide, cisplatin, and etoposide as adjuvant treatment. He was monitored throughout the next 9 years with serial magnetic resonance (MR) imaging, and no new neurological deficit was found [Figure 1c]. At 17 years of age, Gd-enhanced T1-weighted MR image revealed a 5-mm hyperintense nodule on the continuous wall of the resected cavity [Figure 1d].
Radiological findings of aneurysm. (a, b) A three-dimensional computed tomographic angiogram showing that the nodule was a right posterior inferior cerebellar artery aneurysm (arrow). R, right and L, left. (c) Lateral and (d) anteroposterior digital subtraction angiographic views confirming the fenestrated vertebral artery and the aneurysm between the infratonsillar and supratonsillar loops
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F2
Three-dimensional computed tomographic angiography (3D-CTA) revealed that the nodule was an PICA aneurysm [Figure 2a and b]. A digital subtraction angiogram (DSA) demonstrated an irregular 5.2-mm saccular, multilobular aneurysm arising from the right PICA between the caudal and cranial loops [Figure 2c and d].
Intraoperative findings. (a) The aneurysmal dome buried in the medulla oblongata (asterisk). (b, c) The aneurysm neck was clipped to keep the parent artery flow
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F3
The wall of the parent artery and aneurysm was normal, and the neck of saccular aneurysm was clipped using a fenestrated L-shaped clip to maintain the parent-artery flow [Figure 3].