Medulloblastomas of the cerebellopontine angle.
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It is unusual for a medulloblastoma to occur in the cerebellopontine angle (CPA). Four of the total 63 cases of medulloblastoma managed in our department between 1988 to 1998, presented with a mass in the cerebellopontine angle. There were two children amongst these four patients, aged eight and nine years. The other two patients were young adults. Three patients had primary CPA medulloblastoma, while the fourth case had a recurrence in this region, following the excision of the primary vermian tumour. All the four cases were managed by gross total microsurgical excision and craniospinal irradiation. One of the two children, developed subfrontal recurrence after 1 year and 8 months of initial treatment, while the other child developed a large recurrence at primary site, within three months of post-operative irradiation. However, the adult patient developed CPA recurrence and subsequent cervical intramedullary metastasis within two and a half years of diagnosis. These three cases succumbed to their disease, between three months to thirty months of their initial management. However the fourth patient, a 20 years female with desmoplastic variant, was well at two and a half years of follow up. (+info)
Intracranial germinoma with syncytiotrophoblastic giant cells in the cerebellopontine angle--case report.
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A 23-year-old man presented with a 3-week history of left hearing disturbance and left facial nerve paresis. T1-weighted magnetic resonance (MR) imaging showed an iso-intense mass in the left cerebellopontine angle (CPA), with homogeneous enhancement with gadolinium-diethylenetriaminepenta-acetic acid. T2-weighted MR imaging showed the mass as heterogeneously iso- to hyperintense. Gross total removal of the tumor was achieved. Histological examination revealed that the tumor was a germinoma with syncytiotrophoblastic giant cells. Whole central nervous system irradiation with cisplatin-etoposide chemotherapy was performed postoperatively. He has been in good condition with no sign of recurrence for 7 years. Intracranial germ cell tumors in the CPA are very rare. Total surgical removal followed by irradiation and chemotherapy will provide a good outcome. (+info)
Neurenteric cyst in the cerebellopontine angle with xanthogranulomatous changes: serial MR findings with pathologic correlation.
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We report serial MR findings in a middle-aged woman with a neurenteric cyst involving the cerebellopontine angle cistern with xanthogranulomatous changes. On the initial gadolinium-enhanced T1-weighted MR images, the solid portion of the lesion had homogeneously strong enhancement. Follow-up MR images obtained 6 months later showed that the mass had increased in size; however, the solid portion decreased in size. The enhancing solid portion corresponded to the xanthogranulomatous changes on pathologic correlation. (+info)
Cerebellopontine angle epidermoid tumor presenting with 'tic convulsif' and tinnitus--case report.
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A 22-year-old female presented with a cerebellopontine angle epidermoid tumor manifesting as a rare combination of hemifacial spasm, trigeminal neuralgia, and tinnitus. Magnetic resonance imaging demonstrated the tumor distorting the brainstem and the fourth ventricle. The tumor was almost completely resected and the seventh-eighth cranial nerve complex was decompressed by mobilizing the anterior inferior cerebellar artery loop. No arterial loop was related to the trigeminal nerve. The patient was completely relieved of the "tic convulsif" and tinnitus after the surgery. The inflammatory nature of epidermoid tumor may be involved in the etiology of the syndrome. Microvascular decompression may be needed in addition to tumor removal in such cases. (+info)
Mass screening for retrocochlear disorders: low-field-strength (0.2-T) versus high-field-strength (1.5-T) MR imaging.
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BACKGROUND AND PURPOSE: In patients with clinical symptoms suggestive of a retrocochlear disorder, contrast-enhanced T1-weighted spin-echo (SE) high-field-strength MR imaging is considered the criterion standard in assessing vestibular schwannoma. However, only 10-20% of its findings are pathologic. Our purpose was to prospectively compare the performance of low-field-strength MR imaging in screening for retrocochlear disorders, with high-field-strength MR imaging as the criterion standard. METHODS: A total of 287 patients with suspected retrocochlear disease underwent axial 1.5-T MR imaging with a T1-weighted SE sequence before and after contrast enhancement and with a high-resolution T2-weighted construction interference in steady state sequence. At immediate follow-up, the same patients underwent axial 0.2-T T1-weighted SE imaging without additional contrast enhancement. Results were classified as negative, positive, or uncertain and were analyzed in light of the patients' clinical symptoms. RESULTS: MR imaging at 1.5 T depicted 63 disorders (21.95%), including 53 schwannomas, three other tumors, and seven other disorders (ie, gadolinium-enhancing inner ear, facial nerve, or meninges). MR imaging at 0.2 T showed evidence of 58 disorders; five disorders were not detected, although all schwannomas and other tumors were seen, including those smaller than 2 mm, and only two (28.6%) of the other disorders were detected. When correlated with clinical data, results showed that the five undetected disorders occurred in patients with unusual clinical signs. CONCLUSION: MR imaging at 0.2 T provided high sensitivity in detecting vestibular schwannoma of the internal auditory canal or cerebellopontine angle; it can be used for mass screening for this disease. Positive and uncertain imaging findings should be followed up with high-field-strength MR imaging. (+info)
Clear-cell meningioma: CT and MR imaging findings in two cases involving the spinal canal and cerebellopontine angle.
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Clear-cell meningioma is a rare subtype of meningioma which occurs at a younger age and has a higher recurrence rate than other subtypes. We report two cases of clear-cell meningioma, one in the thoracolumbar spinal canal and the other in the cerebellopontine angle. Though the CT and MR imaging findings were not different from those of ordinary meningioma, after surgical removal the condition recurred repeatedly in the patient with spinal canal involvement. (+info)
High-spatial-resolution MR cisternography of the cerebellopontine angle in 90 seconds with a zero-fill interpolated fast recovery 3D fast asymmetric spin-echo sequence.
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BACKGROUND AND PURPOSE: Although the 12-minute 3D fast asymmetric spin-echo (FASE) protocol for imaging the inner ear has been satisfactory, reducing imaging time to minimize patient discomfort and maximize system throughput is desirable. We therefore evaluated the performance of a zero-fill interpolated (ZIP) fast recovery 3D FASE sequence in screening for cerebellopontine (CP) angle lesions in 90 seconds. METHODS: Thirty consecutive patients known or suspected to have CP angle lesions underwent MR imaging at 1.5 T with use of bilateral quadrature phased-array coils designed for examination of the CP angle. Conventional 3D FASE images (4000/240/1 [TR/TE/NEX]) were obtained in 11 minutes 48 seconds with a field of view (FOV) of 16 cm, matrix of 512 x 512 x 40, section thickness of 0.8 mm, and echo train length of 80. Then, ZIP fast recovery 3D FASE images (2000/240/1) were obtained in 90 seconds by using the same FOV. Contrast-enhanced T1-weighted 3D spoiled gradient-echo (SPGR) images were obtained as the reference standard. Three radiologists evaluated the images independently. Conventional 3D FASE and ZIP fast recovery 3D FASE images were reviewed at separate sessions. RESULTS: On 3D SPGR images, 10 tumors were detected in 10 of the 30 patients. All lesions were depicted with both 3D FASE protocols. There were no false-positive results with either 3D FASE protocol. Both protocols showed 100% sensitivity and 100% specificity for all three reviewers. CONCLUSION: High-spatial-resolution MR cisternography with the ZIP fast recovery 3D FASE protocol in 90 seconds results in a substantial reduction (by a factor of about eight) in the time required for screening for CP angle lesions compared with the previously reported conventional 3D FASE protocol, while maintaining high sensitivity and specificity. (+info)
CT and MR imaging characteristics of intravestibular lipoma.
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BACKGROUND AND PURPOSE: Intracranial lipomas are uncommon congenital malformations that most often are asymptomatic. A rare subset of intracranial lipomas arises within the vestibule of the inner ear, which can cause sensorineural hearing loss. We present the CT and MR imaging characteristics of lipomas within the vestibule of the inner ear and propose a pathogenetic mechanism for this malformation. METHODS: We retrospectively reviewed five cases of vestibular lipoma. T1-weighted axial conventional spin-echo and T2-weighted axial fast spin-echo sequences were performed in all five cases. Four patients underwent T1-weighted fat-saturated imaging, and one underwent CT scanning with Hounsfield units measured. RESULTS: Four female patients ranging in age from 10 to 40 years and one 26-year-old male patient had sensorineural hearing loss. Two patients had progressive high-frequency loss; one, sudden-onset high-frequency loss; and two, congenital high-frequency loss. All had lesions within the vestibule that displayed hyperintensity on T1-weighted images, isointensity to slight hypointensity on T2-weighted fast spin-echo images, hypointensity with fat saturation, and fat attenuation on CT scans. Three of the cases were associated with lipoma of the cerebellopontine angle. In none of these cases were the cerebellopontine angle and labyrinthine lipomas contiguous. CONCLUSION: Intravestibular lipoma is considered when a focal hyperintense lesion is identified within the vestibule of the inner ear on T1-weighted MR images. Lesion hypointensity on fat-saturated T1-weighted MR images verifies its lipomatous nature and separates it from intralabyrinthine hemorrhage or highly proteinaceous fluid. (+info)