Subarachnoid hemorrhage associated with clival chordoma--case report.
(65/258)
A 66-year-old man presented with clival chordoma associated with subarachnoid hemorrhage. Computed tomography showed subarachnoid hemorrhage in the right ambient cistern and a well-enhanced tumor in the petroclival region. Surgical exploration performed on the day of admission showed a clot in the tumor. The tumor was totally removed. Histological examination showed hemorrhage between the tumor and the dura. The diagnosis was clival chordoma. Subarachnoid hemorrhage in chordoma seems to occur by spreading of intratumoral hemorrhage into the subarachnoid space due to dural invasion. (+info)
Rhombencephalosynapsis: CT and MRI findings.
(66/258)
An unusual disorder of cerebellar development, rhombencephalosynapsis is a unique entity which presents with cerebellar fusion and absence of cerebellar vermis on imaging studies, often associated with supratentorial findings. No specific clinical syndrome has been described in these patients so far, and most cases are found in infancy and childhood. MRI and its multiplanar capabilities and high spatial and contrast resolution increased its recognition. Two cases are reported, with emphasis on imaging findings. (+info)
Pediatric cerebellar cystic oligodendroglioma: case report and literature review.
(67/258)
Oligodendrogliomas rarely occur in the posterior fossa of childhood and constitute approximately 1% of pediatric brain tumors. Only six pediatric posterior fossa oligodendroglioma cases have been reported to date and none of them were cystic. The authors present a seven-year-old girl with cystic, cerebellar midline localized tumor. A standard suboccipital craniectomy was performed and the tumor was histologically confirmed as oligodendroglioma. After operation the patient underwent radiation therapy and at one the-year follow-up, no recurrence of the tumor was observed. (+info)
Detailed MR imaging anatomy of the abducent nerve: evagination of CSF into Dorello canal.
(68/258)
BACKGROUND AND PURPOSE: The abducent nerve is difficult to identify reliably and consistently with conventional radiologic techniques. In this study, a 3D fast asymmetrical spin-echo MR imaging technique was used to obtain detailed images of the abducent nerve in normal volunteers. METHODS: The 3D fast asymmetrical spin-echo MR protocol was used to image the abducent nerves in 24 normal volunteers by using a 1-mm section thickness in the tilted axial and parasagittal planes. The microanatomy of the abducent nerve within Dorello's canal was also demonstrated in a cadaver study. RESULTS: In 24 normal volunteers, the anatomy of 47 abducent nerves was clearly depicted on MR images. The length of the cisternal segment of the abducent nerve, extending from the brain stem to its dural foramina, ranged from 6.7 to 19.6 mm (mean, 13.1 mm). The abducent nerves were at an angle of 5 to 90 degrees (mean, 24.5 degrees) to the clivus. CSF evagination was detected in the region of Dorello's canal in 36 (77%) of 47 abducent nerves. The length of CSF evagination varied: 0.9 mm in five nerves, 1.0 to 1.9 mm in 18 nerves, 2.0 to 2.9 mm in eight nerves, and 3.0 mm or more in five nerves. Histologic examination of serial sections of the abducent nerve revealed that the petroclival segment of the nerve was covered by an envelope composed of an arachnoid cell layer. CONCLUSION: The course of the abducent nerve was reliably identified using the 3D fast asymmetrical spin-echo MR protocol and a histologically proven arachnoid envelope around the petroclival segment of the nerve was shown as CSF evagination into Dorello's canal by MR imaging. (+info)
Multiple neurenteric cysts in the posterior fossa and cervical spinal canal--case report.
(69/258)
A 46-year-old woman presented with multiple neurenteric cysts in the posterior fossa and spinal canal. Neuroimaging demonstrated neurenteric cysts in the interspace between the left cerebellar hemisphere and vermis, the lateral side of the right cerebellar hemisphere, and the ventral side of the spinal cord at the C-2 and C-4 levels. Total resection of the paravermian cyst and partial removal of the spinal cyst at the C-4 level were performed. Histological examination showed the cyst wall consisted of single or multiple layers of columnar epithelial cells with secretory granules, with mucin secretion verified by periodic acid-Schiff staining. Immunohistochemical staining showed the walls were positive for the cytokeratin, epithelial membrane antigen, and carcinoembryonic antigen, and negative for glial fibrillary acidic protein and S-100 protein. These findings confirmed the endodermal origin. The diagnosis was neurenteric cyst. The paravermian cyst disappeared, but the spinal cyst at the C-4 level recurred 8 months later. Reoperation became necessary 16 months later. The other two cysts also showed enlargement at 6 or 15 months. Total removal of neurenteric cyst is recommended if possible. (+info)
Chronic subdural hematoma of the posterior fossa associated with cerebellar hemorrhage: report of rare disease with MRI findings.
(70/258)
Chronic subdural hematoma of the posterior fossa is an uncommon entity, and spontaneous lesions are very rarely described, occurring mostly during anticoagulation therapy. The association of the posterior fossa chronic subdural hematoma with spontaneous parenchymal hemorrhage without anticoagulation therapy was never related in the literature, to our knowledge. We describe a case of a 64 year-old woman who suffered a spontaneous cerebellar hemorrhage, treated conservatively, and presented 1 month later with a chronic subdural posterior fossa hematoma. (+info)
Posterior fontanelle sonography: an acoustic window into the neonatal brain.
(71/258)
BACKGROUND AND PURPOSE: Sonographic brain studies are classically performed through the anterior fontanelle, but visualization of posterior supratentorial and infratentorial structures is poor with this approach. Posterior fontanelle sonography is recommended for better assessment of these structures. Our purpose was 1) to determine whether sonography of the brain through the posterior fontanelle (PF) improves visualization of brain lesions when added to the routine anterior fontanelle (AF) approach and 2) to describe standardized PF coronal and sagittal sections. METHODS: In this prospective study (conducted from February 1999 to January 2001), PF sonography was added to AF sonography in 165 consecutive premature neonates with a birth weight of < 2000 g. Sonograms were recorded in digital format for re-evaluation at the end of the study. Lesions were grouped as congenital, infectious, hemorrhagic, or hypoxic-ischemic. The chi2 test for paired data and the kappa coefficient were used to compare diagnoses with AF alone and diagnoses with AF plus PF. RESULTS: PF sonography was performed in 164 of 165 patients. Results were normal in 86 and abnormal in 78. The single posterior fossa malformation detected in this series was best delineated with the PF approach. PF sonography increased the diagnostic rate of grade II hemorrhage by 32%. Cerebellar hemorrhage (two patients) and cerebellar abscesses (one patient) were diagnosed by using the PF approach. PF sonography did not contribute to the diagnosis of periventricular leukomalacia. CONCLUSION: Study of the neonatal brain with the addition of PF sonography afforded greater accuracy in detecting intraventricular hemorrhage compared with AF sonography alone, especially when the ventricle was not dilated. The PF approach better defines posterior fossa malformations. (+info)
Retroclival ecchordosis physaliphora: MR imaging and review of the literature.
(72/258)
BACKGROUND AND PURPOSE: Ecchordosis physaliphora (EP), found in about 2% of autopsies, is a clinically inconspicuous notochordal remnant appearing at the dorsal wall of the clivus. To our knowledge, a systematic review of its MR features does not exist. The aim of this study was to describe the MR imaging findings of incidentally found retroclival EP with special respect to its differentiation from intradural chordomas. METHODS: We reviewed 300 consecutive 1.5-T MR imaging studies that included thin-section transverse T2-weighted images of the skull base for the presence of a retroclival EP. In cases in which an EP was identified, two neuroradiologists observed MR signal intensity characteristics, contrast enhancement, size, form, stalk of EP, and signal intensity changes of the adjacent clivus. RESULTS: Five cases with retroclival EP were found (incidence, 1.7%). In all cases, the ecchordoses was hyperintense on T2-weighted images and hypointense on T1-weighted images. Contrary to the reported findings in chordomas, none of the lesions showed contrast enhancement. In four cases, there were signal intensity changes in the adjacent clivus. A stalklike connection between clivus and EP was seen in three patients. CONCLUSION: Because of the benign character of EP and the difficulties in its histopathologic differentiation from chordomas, precise knowledge of the radiologic characteristics of EP is important. On the basis of these five cases and a review of literature, contrast enhancement and the presence of clinical symptoms seem to be highly reliable parameters in the differential diagnosis of intradural chordoma and EP. (+info)