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At least 253 records · Page 14Linked to original sources
PubMed2004

Clinico-pathological features of pilomyxoid astrocytoma of the optic pathway.

Five cases of pilomyxoid astrocytoma (PmA) characterized by a monophasic pattern with a myxoid background were selected for a clinicopathological study from 23 cases previously diagnosed as pilocytic astrocytoma (PA). All PmA patients were either infants or young children (mean age 2.1 years), and all tumors were located in the optic chiasm/hypothalamus region. All cases received chemotherapy, which reduced tumor size, and the location of the tumor became confined to the optic chiasm. In two cases, tumor recurrence occurred 3 and 7 years after chemotherapy. Histology of the recurrent tumors showed the biphasic pattern of classical PA. Hence, we conclude that PmA might be an infantile form of PA and speculate that a subset of PmA in the optic pathway/hypothalamus originates from the optic chiasm, possibly derived from radial glia existing in the embryonic optic chiasm.

Astrocytoma↗
PubMed1980

The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye.

The projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which one eye is of reduced size while the other is normal). In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.

Animals↗
PubMed1988

[Microangioma and optochiasmatic apoplexy. Description of an anatomo-clinical entity associating spontaneous hemorrhages of the anterior optic pathways and rupture of cryptic vascular anomalies].

A 39 year-old women presented for the third time in 9 years, with an acute chiasmal syndrome caused by hemorrhage within a ruptured intra-chiasmatic cryptic angioma. We have reviewed this entity described as "chiasmal apoplexy" and defined its clinicopathological characteristics. Sub-frontal microsurgical approach to the optic chiasm is recommended to confirm the diagnosis and to decompress the optic chiasm. However, surgery does not prevent the possibility of recurrences. We have precised the concept of cryptic vascular malformation.

Adult↗
PubMed1997

MRI of the anterior optic pathways following enucleation.

We examined five patients who had enucleation of one eye for inflammatory or neoplastic disease, using MRI at 1.5 Tesla. None had symptoms referable to the enucleated orbit. In addition, age- and-sex matched individuals were imaged as control subjects, and a further 15 subjects, referred for other than orbital disease, were reviewed. Measurements were made retrospectively of the dimensions of the optic chiasm to establish normal values. All five patients showed abnormalities on MRI following enucleation: abnormal signal within the optic nerve remnant on short tau inversion recovery (STIR) images, and atrophy of the nerve remnant and the chiasm. These findings were not apparent in the control or normal subjects. Such findings are to be expected following enucleation and should not be interpreted as indicating active pathology.

Aged↗
PubMed1998

Clinical and radiologic evaluation of optic pathway lesions.

The clinical evaluation can often suggest the level of a visual pathway lesion; however, several different types of pathological processes, can produce the same visual field deficit. Imaging evaluation with CT and/or MRI can help to localize and characterize these diverse types of pathology. A radiological differential diagnosis can then be suggested which, in turn, facilitates patient management. In certain instances, the specific cause of a visual field defect can be identified with the radiological evaluation.

Brain Diseases↗
PubMed2005

Manganese-enhanced MRI of the optic visual pathway and optic nerve injury in adult rats.

PURPOSE: To evaluate manganese (Mn2+)-enhanced MRI in a longitudinal study of normal and injured rat visual projections. MATERIALS AND METHODS: MRI was performed 24 hours after unilateral intravitreal injection of MnCl2 (150 nmol) into adult Fischer rats that were divided into four groups: 1) controls (N = 5), 2) dose-response (N = 10, 0.2-200 nmol), 3) time-response with repeated MRI during 24-168 hours post injection (N = 4), and 4) optic nerve crush (ONC) immediately preceding the MnCl2 injection (N = 7). Control and ONC animals were reinjected with MnCl2 20 days after the first injection, and MRI was performed 24 hours later. RESULTS: In the control group, the optic projection was visualized from the retina to the superior colliculus, with indications of transsynaptic transport to the cortex. There was a semilogarithmic relationship between the Mn2+ dose and Mn2+ enhancement from 4 to 200 nmol, and the enhancement decayed gradually to 0 by 168 hours. No Mn2+-enhanced signal was detected distal to the ON crush site. In the control group, similar enhancement was obtained after the first and second MnCl2 injections, while in the ONC group the enhancement proximal to the crush site was reduced 20 days post lesion (20 dpl). CONCLUSION: Mn2+-enhanced MRI is a viable method for temporospatial visualization of normal and injured ON in the adult rat. The observed reduction in the Mn2+ signal proximal to the ONC is probably a result of retrograde damage to the retinal ganglion cells, and not of Mn2+ toxicity.

Animals↗
PubMedDate not supplied

Platelet-derived growth factor (PDGF) receptors in the developing mouse optic pathway.

The molecules which control the patterns of cell division, growth, and precise interconnections characteristic of the central nervous system still remain largely unidentified. The protein platelet-derived growth factor (PDGF) has been shown to mediate interactions among glial cells in vitro. More recent evidence has indicated that PDGF may also be involved in controlling communication between neurons and glial cells and among neurons. The presence of receptors for PDGF on neurons of the developing nervous system is an essential piece of evidence in this chain of events. Ganglion cells are labeled with antibodies to PDGF receptor only during the period of active process outgrowth. These findings suggest that PDGF is used as a mediator of intercellular signaling during neuronal development.

Animals↗
PubMed1996

Increased expression of specific recognition molecules by retinal ganglion cells and by optic pathway glia accompanies the successful regeneration of retinal axons in adult zebrafish.

Retinal ganglion cells (RGCs) in adult zebrafish can regenerate their axons. We show that successful axonal regeneration is accompanied by the re-expression by RGCs of mRNAs encoding specific recognition molecules that are expressed at high levels in the larval retina but are down-regulated in the adult. Message levels for 11.1 and 11.2 (two homologs of mammalian L1), n-cam (homologous to mammalian N-CAM), beta 3 (related to the beta 3 and beta 2 subunits of mammalian Na,K-ATPase), and tn-c (homologous to mammalian tenascin-C) were high in larval RGCs undergoing axonogenesis and low in adult RGCs. After an optic nerve crush, axotomized adult RGCs showed increased levels of 11.1, 11.2 and n-cam mRNA expression, whereas the levels of beta 3 and tn-cmRNA remained unchanged. The optic nerve crush also induced the expression of some of these mRNAs in the optic nerve and tract where they are not normally detectable. This lesion induced up-regulation by presumptive glia was observed for 11.1, 11.2, n-cam and beta 3 but not for tn-c. The combination of a neuronal (intrinsic) response to axotomy with an environmental (extrinsic) response may be an important determinant allowing for the successful axonal regeneration.

Animals↗