[Adult choroid plexus papilloma of the posterior fossa: extraventricular location].

Choroid plexus papillomas (CPPs) are rare neuroectodermal neoplasms accounting for 0.4% of all intracranial neoplasms in adults. Most of them are located in the posterior fossa in adults. Although CPPs commonly arise from the 4th ventricle, they occasionally extend to extraventricular space. Furthermore some occur primarily in the extraventricular region. It is difficult to diagnose CPP preoperatively when the main portion of the tumor is not located in the 4th ventricle. We present a case of a 54-year-old male manifesting slurred speech, nystagmus and cerebellar ataxia. Magnetic resonance imaging demonstrated an intracerebellar solid tumor with multilocular cysts, extending towards both the right lateral medullary region and the foramen of Luschka. Computed tomography scans showed patchy calcification at the periphery of the solid component. Angiographically, via the right posterior inferior cerebellar artery revealed the tumor was faintly opacified. Preoperative diagnosis included meningiomas, low-grade astrocytomas, ependymomas or CPPs, but none of them had neuroradiologically decisive findings. Tumor was subtotally resected through a right suboccipital craniectomy. A calcified solid portion adhering to the lower cranial nerves was left unresected. The pathological finding was CPP. CPP should be considered among calcified and enhanced masses in the lateral medullary to cerebellopontine angle space in adults, even if the main portion of the tumor is not located in the 4th ventricle.

Gamma Knife radiosurgery for numerous brain metastases: is this a safe treatment?

PURPOSE: Gamma Knife (GK) radiosurgery has recently been employed in patients with numerous brain metastases (METs), even those with 10 or more lesions. However, cumulative irradiation doses to the whole brain (WB), with such treatment, have not been determined. METHODS AND MATERIALS: Since the GammaPlan ver. 5.10 (ver. 5.31 is presently available, Leksell GammaPlan) became available in November 1998, 92 GK procedures have been performed for 80 patients with 10 or more brain METs at our facility. The median lesion number was 17 (range: 10-43) and the median cumulative volume of all tumors was 8.02 cc (range: 0.46-81.41 cc). The median selected dose at the lesion periphery was 20 Gy (range: 12-25 Gy). Based on these treatment protocols, the cumulative irradiation dose was computed. RESULTS: The median cumulative irradiation dose to the WB was 4.71 (range: 2.16-8.51) Gy. The median brain volumes receiving >2 Gy, >5 Gy, >10 Gy, >15 Gy, and >20 Gy were 1105 (range 410-1501) cc, 309 (46-1247) cc, 64 (13-282) cc, 24 (2-77) cc, and 8 (0-40) cc, respectively. CONCLUSION: The cumulative WB irradiation doses for patients with numerous radiosurgical targets were not considered to exceed the threshold level of normal brain necrosis.

Acute epidural hematoma caused by contrecoup head injury--case report.

A 50-year-old woman presented with a rare case of contrecoup epidural hematoma (EDH) associated with coup EDH. She was hit by a car while riding a bicycle, and struck the left parietal region of her head on the ground. She was dazed for a few minutes. On admission, she complained of nausea but exhibited no neurological deficits. Skull radiography revealed a linear fracture of the left temporal bone. Computed tomography (CT) demonstrated acute EDH in the right frontal region due to contrecoup injury, and thin EDH in the left temporal region due to coup injury. She vomited repeatedly after admission. She became lethargic and exhibited right hemiparesis. CT, taken 2 hours later, revealed enlargement of the left coup EDH, but no enlargement of the right contrecoup EDH. An emergent evacuation of the enlarged coup EDH was performed. Immediately after the operation, she became alert and the right hemiparesis subsided. The contrecoup EDH was conservatively treated, in the absence of enlargement. She was discharged 12 days after the injury without neurological deficits.

Bilateral ophthalmic segment "kissing" aneurysms presenting with subarachnoid hemorrhage--case report.

A 31-year-old woman presented with bilateral ophthalmic segment "kissing" aneurysms causing subarachnoid hemorrhage manifesting as sudden severe headache and nausea 3 days before admission. Cerebral angiography demonstrated bilateral internal carotid-superior hypophyseal artery aneurysms, both projecting medially from the medial surface of the internal carotid arteries and appearing to touch each other. Both aneurysms had to be clipped in the same operation, because of uncertainty over which aneurysm had bled. She underwent bilateral frontotemporal craniotomy on the day after admission. Intraoperatively, the two aneurysms were in contact with each other in the suprasellar cistern. Each aneurysm was clipped through the ipsilateral approach without any incident. The patient returned home a month after the operation and has since resumed her previous work. Identification of this rare entity of bilateral ophthalmic segment "kissing" aneurysms is important for surgical planning. Closely situated, bilateral ophthalmic segment aneurysms require a modified surgical strategy for proximal arterial control and the approach to each aneurysm.

Rapid regrowth of intracranial clear cell meningioma after craniotomy and gamma knife radiosurgery--case report.

A 24-year-old woman underwent craniotomy for falx meningioma (5 cm in diameter) on October 24, 1995. The deepest part of the tumor was located in the anterior horn of the lateral ventricle, which was not resected. The histology was clear cell meningioma (CCM), aggressive in nature. The MIB-1 labeling index was high (11%). She underwent gamma knife (GK) radiosurgery for the residual tumor with an irradiation dose of 16 Gy at the tumor periphery on May 24, 1996. The postradiosurgical course was uneventful. The residual intraventricular tumor gradually decreased in size, but the peripheral portion gradually grew into the diencephalic region. The patient remained in good condition for 5 years until September 2001, when she exhibited memory disturbance and lethargy. Magnetic resonance imaging demonstrated a large tumor (4.5 cm in diameter) in the diencephalon, compressing the optic nerves and fornix. The calculated tumor doubling time was 120 days. A second craniotomy was performed on October 9, 2001. The tumor was totally resected through the anterior transcallosal approach. The histology and the MIB-1 labeling index of the tissue from the second operation did not differ markedly from those of the first operation. Neither tumor recurrence nor metastasis has been observed to date. GK radiosurgery contributed to control of the residual intraventricular tumor, but the peripheral portion of the tumor, which received a relatively low radiation dose (16 Gy), grew rapidly. This suggests that a marginal dose of 16 Gy may not be sufficient for control of CCM.

Pseudoaneurysm formation at the rupture site of a middle cerebral artery aneurysm--case report.

A 42-year-old man suffered subarachnoid hemorrhage manifesting as sudden severe headache one month before admission. On admission, his headache had subsided and he had no neurological deficits. Cerebral angiography demonstrated an aneurysm originating from the bifurcation of the right middle cerebral artery. The aneurysm was irregular, with a snowman-like shape. Neck clipping of the aneurysm was carried out through a right pterional approach. Intraoperatively, a red, pulsating sac mimicking a blood clot (the snowman's "head") was located over the yellowish, thick-walled portion of the aneurysm. Exploration around the aneurysm detached the red sac from the thick-walled portion of the aneurysm. There was a small tear in the apex of the thick-walled aneurysm sac. A Sugita clip was applied to the neck of the true aneurysm. The postoperative course was uneventful and he was discharged one month later without neurological deficits. Histological examination of the red-colored sac showed the features of pseudoaneurysm. The red sac may have been a pseudoaneurysm covering the rupture site of the true aneurysm.

Aneurysm of the distal posterior inferior cerebellar artery originating from the extracranial and extradural vertebral artery.

A 42-year-old woman presented with a ruptured aneurysm of the distal posterior inferior cerebellar artery (PICA), which had a rare extracranial and extradural origin. Medial suboccipital craniectomy and C-1 laminectomy were performed. The aneurysm had adhered to the right cerebellar tonsil, but was successfully clipped without difficulty. Intraoperatively, the PICA origin was recognized in the extracranial and extradural space between the dorsal roots of the C-1 and C-2 nerves. The origin of the PICA from the vertebral artery (VA) may occur at any portion of the VA from the site of penetration of the dura to the vertebrobasilar junction, but an extradural origin is uncommon. A ruptured aneurysm of the PICA branching from the VA at a site proximal to the vertebrobasilar junction and below the foramen magnum may be overlooked by three-vessel angiography if the contrast medium cannot reflux to the contralateral PICA origin.