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PubMed1982

Rapid migration of inositol phospholipids with axonally transported substances in the rabbit optic pathway.

Following an intraocular injection of myo-[2-3H]inositol, the axonal transport of labelled water-soluble substances and inositol phospholipids was investigated. Evidence was obtained for a rapid axonal transport of a relatively small amount of labelled inositol phospholipids. In contrast to other axonally transported phospholipids, there was no significant accumulation of labelled, rapidly transported inositol phospholipids in the nerve terminal region at later time intervals following the isotope administration.

Animals↗
PubMed2003

Neuropsychological outcome in children with optic pathway tumours when first-line treatment is chemotherapy.

Standard treatment of optic pathways gliomas consists of radiotherapy and surgery when feasible. Owing to the toxicity of irradiation, chemotherapy has emerged as an interesting therapeutic option, especially in young children. This study describes the neuropsychological profile of 27 children (aged between 1.5 and 15.7 years) with optic pathways gliomas treated with chemotherapy as first-line treatment. Eight of them also received radiotherapy as salvage treatment. Eight had neurofibromatosis type 1 (NF1). Intellectual outcome was preserved in children treated with chemotherapy only (mean=107+/-17) compared to children also receiving radiotherapy (mean IQ=88+/-24) or children having NF1 and treated with chemotherapy (mean IQ=80+/-13). Scores for abstract reasoning, mental arithmetic, chessboard/coding, perception, judgement of line orientation were lower in children irradiated than in those treated only by chemotherapy. Children with Nf1 showed subnormal IQ scores with marked impairment of short- and long-term memory. With respect to long-term neuropsychological outcome, our study shows that a chemotherapy-first strategy can preserve the intellectual outcome of these patients either by avoiding the need of radiotherapy or by delaying its use as much as possible.

Adolescent↗
PubMed2005

Bilateral congenital anophthalmos and agenesis of the optic pathways.

This report presents a rare example of a bilateral congenital anophthalmos and an agenesis of the optic pathways. The MR imaging studies revealed that the eyeballs, optic nerves, optic chiasm, optic tracts and optic radiation were absent. The chromosomal examination was normal. Mild mental retardation was also observed. Apart from the rarity of the anophthalmos and the total absence of the optic pathways, no etiologic reason for this pathology could be detected, which makes this case more significant.

Abnormalities, Multiple↗
PubMed1999

Proton radiation therapy (PRT) for pediatric optic pathway gliomas: comparison with 3D planned conventional photons and a standard photon technique.

PURPOSE: Following adequate therapy, excellent long-term survival rates can be achieved for patients with optic pathway gliomas. Therefore, avoidance of treatment-related functional long-term sequelae is of utmost importance. Optimized sparing of normal tissue is of primary concern in the development of new treatment modalities. The present study compares proton radiation therapy (PRT) with a three-dimensional (3D)-planned multiport photon and a lateral beam photon technique for localized and extensive optic pathway tumors. METHODS AND MATERIALS: Between February 1992 and November 1997, seven children with optic pathway gliomas underwent PRT. For this study, we computed proton, 3D photon, and lateral photon plans based on the same CT data sets, and using the same treatment planning software for all plans. Radiation exposure for normal tissue and discrete organs at risk was quantified based on dose-volume histograms. RESULTS: Gross tumor volume (GTV) ranged from 3.9 cm3 to 127.2 cm3. Conformity index (relation of encompassing isodose to GTV volume) was 2.3 for protons, 2.9 for 3D photons, and 7.3 for lateral photons. The relative increase of normal tissue (NT) encompassed at several isodose levels in relation to NT encompassed by the 95% proton isodose volume was computed. Relative NT volume of proton plan isodoses at the 95%, 90%, 80%, 50%, and 25% isodose level increased from 1 to 1.6, 2.8, 6.4, to a maximum of 13.3. Relative volumes for 3D photons were 1.6, 2.4, 3.8, 11.5, and 34.8. Lateral plan relative values were 6, 8.3, 11.5, 19.2, and 26.8. Analysis for small (<20 cm3) and larger (> 80 cm3) tumors showed that protons encompassed the smallest volumes of NT at all isodose levels. Comparable conformity and high-dose gradient were achieved for proton and 3D photon plans in small tumors. However, with increasing tumor volume and complexity, differences became larger. At the 50% isodose level, 3D photons were superior to lateral photons for small tumors; this advantage was equalized for larger tumors. At the lowest isodose level, 3D photons encompassed the highest amount of NT. Analysis of organs at risk showed that PRT reduced doses to the contralateral optic nerve by 47% and 77% compared to 3D photons and lateral photons, respectively. Reductions were also seen for the chiasm (11% and 16%) and pituitary gland (13% and 16%), with differences at clinically relevant tolerance levels. Furthermore, reduced dose exposure of both temporal lobes (sparing 39% and 54%) and frontal lobes was achieved with PRT. CONCLUSION: PRT offered a high degree of conformity to target volumes and steep dose gradients, thus leading to substantial normal tissue sparing in high- and low-dose areas. It is expected that this will result in decreased long-term toxicity in the maturing child. Advantages of proton versus 3D photon plans became increasingly apparent with increasing target size and tumor complexity. Even in small tumors, conformity of 3D photon irradiation came at the expense of a larger amount of NT receiving moderate to low radiation doses. Lateral photons resulted in inferior dose distribution with high radiation exposure of clinically relevant normal tissues.

Child↗
PubMed2001

Distribution in ocular structures and optic pathways of immunocompetent and glial cells in an experimental allergic encephalomyelitis (EAE) relapsing model.

Relapsing experimental allergic encephalomyelitis (EAE) was induced in DA rats and the ocular pathologic events were examined at the various phases of the illness. About 80% of EAE rats presented anterior uveitis (AU), even after complete EAE recovery. We studied the phenotype and localization of immunocompetent cells, the major histocompatibility complex (MHC) class I and II antigen expression, as well as the chemokine monocyte chemoattractant protein-1 (MCP-1) appearance. In control animals, there were many glial fibrillary acidic protein (GFAP)(+) cells and OX42(+) cells in the ciliary body, retina, optic nerve and chiasma. Except in retina, we observed constitutive MHC class I and II expression. During the EAE acute phase, there was up-regulation of MHC class II and GFAP antigens in iris, ciliary body, limbus, and optic pathways. MHC class I and ED2 antigens were expressed in meninges and in the prechiasmatic cisterna, by cells which could have a role in immune surveillance. MCP-1 mRNA was highly expressed in optic pathways during the acute phase and the protein was expressed by astrocytes, macrophages, and lymphocytes. During the relapsing phase, MCP-1 was weakly expressed to disappear almost completely during the final recovery phase. The expression of MHC class II on astrocytes was increased during the relapsing and final recovery phase in which the inflammatory lesions persisted. These findings suggest that ocular areas and optic pathways, mainly optic chiasma, are important targets in the relapsing EAE.

Animals↗
PubMed1988

Oxygen-induced retinopathy in newborn rats: orthograde axonal transport changes in optic pathways.

The aim of this study was to evaluate axonal transport along the optic pathways of neonatal rats in which oxygen-induced retinopathy had been experimentally produced. One group of 116 rats was exposed to an FiO2 of 80% for the first 5 days of life and then kept under room-air conditions for the following 10 days. A second group of 108 rats was maintained under room-air conditions for the first 15 days of life. On the 16th day of life, 1.5 microliter of [35S]taurine was injected into the vitreous of the right eye of each animal and radioactivity was measured, at various intervals from the injection, in the right optic nerve, the chiasma and the left optic tract. Statistically significant reductions in axonal transport were observed in all three segments of the optic pathways of the oxygen-supplemented animals compared with the control group. The authors discuss various explanations for their findings and hypothesize that the alterations observed in this study may have significant and more or less long-term effects on the normal maturation of the visual system.

Animals↗
PubMedDate not supplied

Prognostic factors and results of radiation therapy in optic pathway tumors.

AIMS AND BACKGROUND: The role of radiotherapy in the management of patients with optic pathway tumors remains controversial. This study analyzes the outcome of patients treated with radiotherapy and attempts to identify the groups of patients that may require early therapy. METHODS: We retrospectively reviewed 36 patients with optic pathway tumors treated with radiotherapy alone (26 patients) or with postoperative radiotherapy (10 patients). Seven patients had optic nerve tumors and 29 patients had chiasmal tumors. The actuarial progression free survival and observed survival probabilities were calculated using the Kaplan-Meier method and differences between curves were evaluated by the Mantel-Cox test. The obtained significant variables in the univariate analysis were analyzed using the Cox proportional hazards model. RESULTS: The 10-year actuarial progression-free survival (10-y PFS) rate was 86% for patients with optic nerve gliomas and 47% for patients with chiasmal tumors. The 10-year actuarial observed survival (10-y OS) rate was 75% for patients with optic nerve gliomas and 53% for patients with chiasmal gliomas. In the group of patients with chiasmal tumors, progression-free survival and observed survival rates were significantly lower in infants (10-y PFS: 30%; 10-y OS: 37%), in patients with neurological deficits (10-y PFS and 10-y OS: 23%), in patients with signs of elevated intracranial pressure (10-y PFS and 10-y OS: 9%), with hydrocephalus (10-y PFS and 10-y OS: 0%), or with impairment of consciousness (10-y PFS and 10-y OS: 17%). Evaluation by computed tomography scanning was associated with a significantly higher probability of PFS. Radiation doses lower than 50 Gy were associated with significantly lower PFS and OS rates. In the Cox multivariate analysis, presence of neurological deficits and radiation dose significantly influenced observed survival. Presence of hydrocephalus significantly influenced progression-free survival. CONCLUSIONS: The prognosis of patients with chiasmal gliomas presenting with neurologic deficits is poor and should be treated at diagnosis. A minimum tumor dose of 50 Gy is recommended.

Actuarial Analysis↗
PubMed2003

[A case of metastatic suprasellar tumor with edema along the optic pathway].

A rare case in presented of a patient with edema formation along the optic pathway, which was caused by metastatic suprasellar tumor mimicking craniopharyngioma. A 63-year-old female with visual disturbance, diabetes insipidus, and symptomatic panhypopituitarism was admitted to our hospital. CT images showed a suprasellar mass lesion. MR images demonstrated a heterogeneously enhanced tumor and edema along the optic nerve and tract. Although no cystic component is shown in radiological findings, these features are commonly observed in cases of craniopharyngioma. The patient underwent removal of the tumor by the transcranial approach. Since histological examination revealed adenocarcinoma, the tumor was diagnosed as metastatic brain tumor originating from non-recurrent rectal cancer operated on eight years previously. Conventional radiotherapy with a dose of 50GY was performed for the residual tumor. The tumor size was unchanged, but the edema had disappeared 7 months after the operation. Edema spreading along the optic tract was reported as a characteristic MR finding for diagnosis of craniopharyngiomas as distinguished from other common parasellar tumors. However, it is suggested that edema of the optic pathway seems to be caused not only by craniopharyngioma but also other suprasellar lesions. Even if there was a characteristic radiological finding for some specific diseases, metastasis should be kept in mind as a differential diagnosis, because of its various appearance in neuroimages.

Adenocarcinoma↗
PubMed2002

Demonstration of the optic pathway in large pituitary adenoma on heavily T2 weighted MR images.

The objective of the investigation was to understand preoperatively the detailed anatomical relationship of large pituitary adenomas to surrounding structures, using the heavily T2-weighted reversed (T2R) MR images. This study consisted of 28 patients with pituitary adenoma, presenting with visual disturbance. The MRI scanner used was a Gyroscan ACSNT 1.5T and the slice thickness of the image was 3 mm with 0.5 mm interslice gap. The relation of pituitary adenoma to optic pathway and to the degree of visual field defect was assessed. Relations of the optic chiasm to adenoma were classified into three types: anterior, superior and posterior. The optic chiasm was directly visualized and identifiable in all patients studied. It was located anterior in four cases, superior in 22 and posterior in two in relation to the adenoma. Its location was further confirmed by the anatomical delineation of surrounding structures such as anterior commissure and lamina terminalis. Optic nerve or tract was unidentifiable in one case, for each category. Detectability of each optic component was higher on T2R images than on conventional T1-weighted images. The adenoma extended into and in front of the third ventricle in anterior and posterior types, respectively. The anterior communicating artery complex and the optic pathway were relocated together in anterior and superior types, and were separated in the posterior type. In a case of the posterior type, the complex was sectioned to obtain a wider surgical field during anterior interhemispheric approach. While degrees of visual field defect were proportional to tumour size in the superior type, they were unrelated in the anterior and posterior types. On choosing a transcranial approach, the transcallosal route is unsuitable for an adenoma of posterior type, which extends in front of the third ventricle. This preoperative MRI information makes it possible to visualize directly the optic pathway even in huge adenomas, and is useful in predicting surgical anatomy and selecting a proper surgical approach.

Adenoma↗
PubMed1999

MR imaging anatomy of the optic pathways.

Imaging in neuro-ophthalmology is a major, developing field. Visual and motor ocular symptoms and signs are of diagnostic and localizing significance, and occur frequently in patients with brain space-occupying lesions. Knowledge of the anatomy of the optic pathways extending from the retina to the calcarine fissure throughout the brain is crucial. Multiplanar high resolution MR imaging permits the physician to depict the visual path with exquisite detail. This article provides a correlative regional anatomic and imaging atlas of the brain following the optic pathways, with reference to the most accurate technical imaging procedures.

Anatomy, Artistic↗
PubMedDate not supplied

Anterior optic pathways gliomas. The dilemma of treatment.

Anterior optic pathways gliomas are classifiable histologically and clinically with other pilocytic gliomas of the midline (of hypothalamus and brainstem), especially of childhood. The very slow course, sometimes imperceptible over the years, that characterizes the majority of them should not be taken to mean lack of growth. Tumultuous courses and acute episodic deteriorations are both possible. Hence the need for therapy. Indefinite abstention cannot be upheld, at least in the great majority of cases. In gliomas of a nerve only the object of surgery is usually removal, using the intraorbital, intracanalicular and intracranial approaches, but in gliomas of the chiasm or chiasm-hypothalamus the object is more exploratory and decompressive. Radiotherapy is generally accepted as affective only in the latter cases. No single standard protocol is possible: treatment had to be individualized case by case.

Adult↗
PubMed1982

Transfer of axonally transported phospholipids into myelin isolated from the rabbit optic pathway.

The contribution of the axonal transport to the biosynthesis of myelin phospholipids was investigated in the rabbit optic pathway. A double labeling technique was used. The same animals were injected with one isotope intravitreally and the other intraventricularly. This procedure allows double labeling of the optic nerves, optic tracts, lateral geniculate bodies (LGB), and superior colliculus (SC). The precursors simultaneously injected were: [1-14C]palmitate (15 microCi intravitreally in both eyes or 50 microCi intraventricularly) and [2-3H]glycerol (50 microCi intravitreally in both eyes of 100 microCi intraventricularly). Twenty four hours and 10 days after the injections, myelin was purified from pooled optic nerves and optic tracts as well as from pooled LGBs or SCs. The phospholipids were extracted and then separated by thin-layer chromatography; the specific radioactivity of the various classes of phospholipids was determined. Using both administration routes of C- or 3H-precursors, the distribution of label and specific radioactivity of myelin phospholipids in the retina and in all other optic structures were very similar. Phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine + phosphoinositol were preferentially labeled with both precursors. These results suggest that, in the rabbit optic pathway the phospholipids synthesized in the retinal ganglion cells and transported along the axons, could undergo transaxonal transfer into myelin.

Animals↗
PubMed1983

The role of crossed and uncrossed optic pathways mediating black-white discrimination in rats with one eye enucleated at birth.

It has been reported that rats with one eye enucleated at birth (OEB) are able to relearn a black-white discrimination task originally learned with both the visual cortices intact faster than rats monocularly enucleated at three months of age (OET) when relearning is made after the visual cortex contralateral to the remaining eye is destroyed. Two experiments examined the hypothesis that functional enhancement of uncrossed optic pathways produced by monocular enucleation at birth might be the sole factor to produce such a phenomenon. The results showed that faster relearning in OEBs could not be totally explained by the hypothesis, and suggest that only when (1) there is a learning effect in the visual cortex ipsilateral to the remaining eye produced by interaction of visual information through the callosal fibers with an increased amount of information through uncrossed optic pathways during original learning and (2) relearning is mediated by enhanced functioning of uncrossed optic pathways, would such phenomenon be produced.

Animals↗
PubMed1981

Gliomas of the intracranial anterior optic pathways in children. The role of computed tomography, angiography, pneumoencephalography, and radionuclide brain scanning.

Twenty-two gliomas of the anterior optic pathways in children were reviewed, and the relative merits of computed tomography (CT), pneumoencephalography (PEG), angiography, and radionuclide brain scanning were assessed. Contrast-enhanced CT scans proved to be superior in demonstrating the full extracranial extent of the lesions and spread along the optic pathways; however, PEG was more reliable with small chiasmatic lesions. Angiography rarely provided a specific diagnosis of intracranial optic glioma, but in was diagnostic when the intracanalicular or intraorbital portion of the optic nerve was involved. A protocol for neuroradiological investigation of suspected cases is proposed.

Adolescent↗
PubMed2001

An implementation strategy for IMRT of ethmoid sinus cancer with bilateral sparing of the optic pathways.

PURPOSE: To develop a protocol for the irradiation of ethmoid sinus cancer, with the aim of sparing binocular vision; of developing a strategy of intensity-modulated radiation therapy (IMRT) planning that produces dose distributions that (1) are consistent with the protocol prescriptions and (2) are deliverable by static segmental IMRT techniques within a 15-minute time slot; of fine tuning the implementation strategy to a class solution approach that is sufficiently automated and efficient, allowing routine clinical application; of reporting on the early clinical implementation involving 11 patients between February 1999 and July 2000. patients and methods: Eleven consecutive T1-4N0M0 ethmoid sinus cancer patients were enrolled in the study. For Patients 1-8, a first protocol was implemented, defining a planning target volume prescription dose of 60 to 66 Gy in 30-33 fractions and a maximum dose (Dmax) of 50 Gy to optic pathway structures and spinal cord and limit of 60 Gy to brainstem. For Patients 9-11, an adapted (now considered mature) protocol was implemented, defining a (planning target volume) prescription dose of 70 Gy in 35 fractions and a Dmax to optic pathway structures and brainstem of 60 Gy and to spinal cord of 50 Gy. RESULTS: The class solution-directed strategy developed during this study reduced the protocol translation process from a few days to about 2 hours of planner time. The mature class solution involved the use of 7 beam incidences (20-37 segments), which could be delivered within a 15-minute time slot. Acute side effects were limited and mild. None of the patients developed dry eye syndrome or other visual disturbances. The follow-up period is too short for detection of retinopathy or optic nerve and chiasm toxicity. CONCLUSION: Conventional radiotherapy of ethmoid sinus tumors is associated with serious morbidity, including blindness. We hypothesize that IMRT has the potential to save binocular vision. The dose to the optic pathway structures can be reduced selectively by IMRT. Further enrollment of patients and longer follow-up will show whether the level of reduction tested by the clinical protocol is sufficient to save binocular vision. An adaptive strategy of IMRT planning was too inefficient for routine clinical practice. A class solution-directed strategy improved efficiency by eliminating human trial and error during the IMRT planning process.

Adenocarcinoma↗
PubMed2004

Delayed visual deterioration after pituitary surgery--a review introducing the concept of vascular compression of the optic pathways.

BACKGROUND: Delayed visual deterioration after pituitary surgery has been attributed to secondary empty sella syndrome and downward herniation of the optic nerves and chiasm, but the pathophysiological basis of this condition is still a matter of debate. REVIEW: According to the literature, prior radiation therapy, previous visual impairment and transcranial surgery constitute risk factors for delayed visual deterioration. Radiation-induced vascular changes and/or strangulation of the optic nerves or chiasm are thought to compromise local blood flow. Downward herniation of the optic pathways was present in the majority of cases, but did not correlate with visual symptoms and signs, while dense scarring of the chiasm was a reproducable finding in all surgically explored cases. Indentations in the upper margin of the optic nerves or chiasm caused by the A1 segments of the anterior cerebral arteries have been reported repeatedly. As perichiasmal scarring constitutes the most consistent finding, the intimate relationship between artery and nerve with consecutive pulsatile pressure may constitute a causative factor in delayed visual dysfunction after pituitary surgery. The authors therefore introduce the concept of vascular compression, which is illustrated with a personal case of a successful decompression procedure with teflon interposition between the A1 segment and the non-herniated optic nerve to treat visual loss eight months following removal of a hemorrhagic pituitary adenoma. CONCLUSIONS: Clinicians should be aware that surgical exploration via a transcranial approach is indicated in cases of progressive visual loss late after pituitary surgery, no matter whether downward displacement of the optic pathways is present on imaging studies or not. Special attention should be paid intra-operatively to the dissection of the intimate relationship between the anterior cerebral arteries and the optic nerves and chiasm.

Anterior Cerebral Artery↗
PubMed1996

Injury to anterior optic pathways.

Fourteen patients with injury to the anterior optic pathways have been presented and analysed. Their clinical profile, radiological data and problems involved therein have been discussed. Since an expectant policy has been the rule so far, an attempt has been made to define the role of surgery in such cases.

Adolescent↗