SEARCH · PubMed Health

Results for “OPTIC PATHWAY”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 487 records · Page 27Linked to original sources

PubMedDate not supplied

Monitoring tumor activity in low grade glioma of childhood.

Chemotherapeutic or radiotherapeutic regimens are being increasingly used in low grade glioma of childhood. These protocols require methods to monitor tumor activity. We report our experience in eleven patients. The tumors were localized in the optic pathway (3), cerebral cortex (4) and thalamus/hypothalamus (4). Histological diagnoses included low grade astrocytoma (6), gliofibroma (1) and ganglioglioma (2). Two children with neurofibromatosis type 1 (NF-1) and typical optical tumors were not biopsied. 13 episodes of progression were noted including 3 altered diagnoses. This was evident from clinical symptoms in 11/13 episodes, computed tomography (CT) or magnetic resonance imaging (MRI) in 10/13 situations, iodine-123-alpha-methyltyrosine (123I-IMT) single-photon emission computed tomography (SPECT) in 10/10 situations, fluorine-18 fluorodesoxyglucose (18F-FDG) positron emission tomography (PET) in 0/3 and thallium-201 (201Tl) SPECT in 1/1. Seven responses to chemotherapy were recorded. Clinical symptoms indicated this in 7/7 situations, MRI in 5/7, 123I-IMT SPECT in 1/2 and 201Tl SPECT in 1/1. These data suggest that 123I-IMT SPECT is a valuable addition to low grade glioma diagnostic and stress the need for a prospective study.

Adolescent↗

PubMed1979

[The optic nerve in the cat. II. Qualitative aspects of maturation in the adult cat].

54 healthy cats were studied. In almost all cases, two types of degenerative signs could be seen: in the primary optic pathways, but also in the posterior funiculi and the spinal-cerebellar tracts, lesions of wide-diameter axons seen by their initial demyelination, accompanied by intense neuroglial reactions, and, on the other hand, a Wallerian degeneration of smaller axons situated in the axial part of the nerve. The percentage of these abnormalities must still be evaluated. Their eventual consequences and nature are discussed.

Age Factors↗

PubMed1992

Slow axonal transport of soluble proteins and calpain in retinal ganglion cells of aged rabbits.

The rate of slow axonal transport of soluble proteins in retinal ganglion cells of the rabbit decreased with approximately 25% in aged (6 years) compared to previous estimates in adult (2 years) animals. Immunobinding of calpain to microtiter plates coated with a monoclonal antibody to mu-calpain was used to isolate labelled axonally transported mu-calpain from the nerve extracts. It was found that the distribution of labelled mu-calpain in the retrobulbar optic pathway was similar to the distribution profile of the slowly migrating phase of soluble proteins.

Aging↗

PubMed2005

Electrophysiological evaluation of visual pathways in paclitaxel-treated patients.

As paclitaxel may induce positive spontaneous visual symptoms or persistent visual loss, we carried out this electrophysiological study in an attempt to clarify the underlying pathophysiological mechanisms of visual pathway involvement. The study involved 30 breast cancer patients: 14 were treated with paclitaxel alone (group A) and 16 with paclitaxel and adriamycin (group B). Pattern visual evoked potentials (VEPs), and transient, 30 Hz flicker (FLK) and oscillatory potential (OP) white flash electroretinograms (ERGs), were recorded before treatment, after the third and sixth therapeutic cycle, and at the end of the programmed regimen. Pretreatment: Abnormal VEP and OP and FLK changes occurred more than 75% of patients; transient ERGs were normal in more than 90%. Serial recordings: VEPs remained unchanged in both goups. In group A, ERG b-wave latency significantly increased (ANOVA P<0.005), and OP and FLK were characterised by non-significant mild attenuation. Several combinations of ERG, OP, FLK and VEP changes occurred in 50% of the patients. The association between transitory lightining scotoma or blurred vision (reported by 12 patients) and VEP, ERG and FLK was poor, whereas that with OP was satisfactory. A few patients showed stable and persistent subclinical electrophysiological changes. Electrophysiological changes during treatment revealed the involvement of both the retina and anterior optic pathway. There was only a weak correlation between visual symptoms and electrophysiology. We suggest that the most likely mechanism of visual symptoms and electrophysiological changes during paclitaxel administration is vascular dysregulation in the retina, or ischemic mechanisms when the optic nerve is involved.

Adult↗

PubMed1995

Interactive events subserving the pupillary light reflex in pigmented and albino rats.

The consensual pupilloconstrictor response requires the intensity information that is delivered to each eye to be integrated to produce an averaged response such that the pupillary diameter in each eye is equal. Here we have examined how luminance information from each eye is integrated in the rat and where the integration occurs, using a pupillometry system to record pupillary diameter after illumination of one or both eyes. In albino rats the size of the uncrossed optic pathway to the pupilloconstrictor centre, the olivary pretectal nucleus, is reduced three-fold and there is a concomitant but less dramatic reduction in the size of the consensual response. Unilateral lesions of the olivary pretectal nucleus in pigmented rats restrict all optic input to the opposite pretectum. Stimulation of one or both eyes in these animals suggests that integration occurs not only at the level of the olivary pretectal nucleus, but also downstream in the Edinger-Westphal nucleus. Parallels with human studies and the opportunity to perform secondary lesions suggests the rat may provide a good model in which to study the substrates of the pupilloconstrictor response and mechanisms of integration of convergent parallel inputs in general.

Animals↗

PubMed1989

Distribution of neurohypophysial peptides in the guinea pig brain. II. An immunocytochemical study of oxytocin.

Oxytocin immunoreactivity was mapped in the brain of adult guinea pigs. Emphasis was laid on cells and pathways other than those directed toward the neurohypophysis. Immunoreactive cell bodies were only detected in the hypothalamus and preoptic region. Compared to the rat, several differences were noted: there was no equivalent in the guinea pig, of the parvocellular neurones in the lateral and posterior parts of the paraventricular nucleus which are at the origin of caudally directed oxytocinergic pathways in the rat. There was also no equivalent to the rat anterior commissural nucleus. In contrast to the rat, numerous oxytocin-immunoreactive cell bodies were detected ventrally to the optic pathways, in retrochiasmatic and subchiasmatic areas and in the median preoptic nucleus. The close proximity of many oxytocin-containing cell bodies and dendrites to ventricular and subarachnoid spaces suggests that oxytocin could reach some of its targets following release into cerebrospinal fluid. Immunoreactive axons and presumptive axon terminals were found in the subfornical organ, in the dorsal motor nucleus of the vagus nerve and in the laterodorsal tegmental nucleus. Labelling was present, but weaker, in the following other areas: the dorsal parabrachial nucleus, the central nucleus of the amygdala and the nucleus of the solitary tract.

Animals↗

PubMed1981

Progressive visual loss due to glioblastoma: normal neuroroentgenorgraphic studies.

A case of progressive bilateral visual loss of abrupt onset an rapid course is described. Extensive neurorentgenographic evaluation was normal, and the results of exploratory craniotomy were unremarkable, except for a slight ovality of the left optic nerve. A biopsy of the left optic nerve showed a glioblastoma, apparently originating in the anterior optic pathways.

Blindness↗

PubMed1999

Alterations of the retino-cortical conduction in patients affected by classical congenital muscular dystrophy (CI-CMD) with merosin deficiency.

Immunocytochemical analysis of the laminin alpha-2 (merosin) chain in the muscle of patients with Classic Congenital Muscular Dystrophy (Cl-CMD) differentiates the types of the disease associated with a merosin deficit from those that are merosin positive. Patients with Central Nervous System involvement in merosin negative Cl-CMD always present alterations of the white matter at RMI, but usually these are not clinically significant. While ocular malformations (microphthalmia, alterations of the anterior chamber, of the retina, or of the angle and cataract) and damage to the Central Nervous System are described in some subtypes of CMD (Muscle Eye Brain disease, Walker Warburg Syndrome), ocular involvement and retino-cortical conduction in merosin negative Cl-CMD are not well known. This study reports on four patients affected by merosin negative Cl-CMD. All these patients presented important alterations of the white matter associated with ventricular enlargement and, in one case, with pachygyria and micropolygyria. Refraction, visual acuity, ocular motility, anterior segment and fundus were examined. ERG Maximal, Cone and Rod response, VEP transient pattern reversal was carried out as well. Significant alterations at the standard ophthalmologic examination or of the electroretinogram responses were not registered while, in all cases, important modifications in retino cortical conduction (reduction in amplitude, increase in latency, reduction in amplitude on the lateral derivations) were observed, demonstrating involvement of the optic pathway at different levels during the course of this disease.

Adolescent↗

PubMed1991

Suprachiasmatic nucleus and retinohypothalamic projections in moles.

The suprachiasmatic nucleus of the hypothalamus (SCN) and the retinohypothalamic projections were identified in one species of old-world moles, all of whom are blind as a result of natural loss of vision. A cyto-architectonic study revealed that the SCN is well developed, even though other visual nuclei in the dorsal thalamus and the midbrain are not. An immunohistochemical study showed that vasoactive intestinal polypeptide (VIP)-like immunoreactive cell bodies and fibers were distributed in the SCN, as has been reported in other mammals. Following intraocular injections of wheatgerm agglutinin conjugated to horseradish peroxidase (WGA-HRP), the central retinal projections were examined. The results indicated that the SCN receives a direct projection from the retina, as seen in many other mammals. In addition to the projection to the SCN, retinal fibers were seen to terminate in the anterior hypothalamic region and the retrochiasmatic area, as observed in some other mammals. In moles, retinohypothalamic projections are bilateral, with an ipsilateral predominance. Considering that the retinogeniculate and retinotectal projections are vestigial, it is highly probable that the optic pathway in moles primarily consists of retinohypothalamic projections, which are devoted to the entrainment of circadian and circannual rhythms.

Animals↗

PubMed1977

Visual electroencephalographic computer analysis (VECA). A new electrophysiologic test for the diagnosis of optic nerve lesions.

The function of optic pathways was studied by visual electroencephalographic computer analysis (VECA). Pattern and flash stimuli were used. The VECA profile was abnormal in two types of lesions: pathology involving the eye, and pathology involving the optic nerve. When ocular pathology is excluded, an abnormal profile indicates optic nerve dysfunction. Of the multiple sclerosis patients tested, 77 percent had an abnormal VECA profile. The test was always abnormal in patients with optic neuritis. Delayed visual evoked responses occurred in 18 of 29 multiple sclerosis patients judged to be clinically without visual deficits. VECA is reliable and sensitive for detecting clinical and subclinical optic nerve pathology.

Adult↗

PubMed2004

Multifocal VEP in children: its maturation and clinical application.

AIM: To study the maturation of multifocal visual evoked potentials (multifocal VEP) in normal children between the ages of 5 and 16 years and to apply the results clinically in selected cases to the diagnosis of optic pathway diseases. METHOD: 70 normal children were recruited from the community and multifocal VEP (Accumap ObjectiVision, Sydney, Australia) was recorded. The waveform of the evoked responses, the latency and amplitude were analysed. Using these data, an age matched comparison was made with three children with advanced optic nerve disease; two had optic nerve glioma and one had congenital glaucoma. RESULTS: The full field amplitude did not correlate with age and varied greatly within each age group (coefficient of variability 28%). When scaled with respect to the background electroencephalogram the intra-age group variability decreased to 15% and a sigmoid relation was found between amplitude and age. The scaled amplitude remained largely unchanged till 11 years, between 11 and 13 years there was a rapid increase (40%), and remained stable thereafter. This relation was seen at all eccentricities tested. The latency decreased gradually with age and plateaued at 13 years. In the three children with vision abnormalities this test was able to detect scotomas consistent with their condition. CONCLUSION: Multifocal VEP perimetry shows an age related maturation in the visual pathway, characterised by distinctive timeframe of development for amplitude and latency. It can be performed by children as young as 5 years of age and holds promise as a diagnostic test capable of documenting children's visual fields objectively, even before they are able to perform subjective field tests.

Adolescent↗

PubMedDate not supplied

The pathogenesis and pathway into the central nervous system after intraocular infection of herpes simplex virus type I in rabbits.

Herpes simplex virus (HSV) type I was injected into the right eye of 18-day-old New Zealand albino rabbits and the animals were killed on the fourth and eighth days after inoculation. Longitudinal section of the optic nerves and chiasma showed that both myelinated axons and neuroglial cells crossed at the chiasma. Semi-serial (1 micrometer) and ultrathin sections showed the presence of HSV in both astrocytes and oligodendrocytes, although no particles were seen in the myelinated axons; the infected cells were confined to the medial side of the right optic nerve. HSV travels centropetally along the optic pathway and slowly spreads laterally by cell-to-cell infection. The virus does not appear to kill the astrocytes and oligodendrocytes, and also does not directly damage the myelin sheath.

Animals↗

PubMed2005

The role of intensity modulated radiation therapy for favorable stage tumor of the nasal cavity or ethmoid sinus.

OBJECTIVES: To compare intensity-modulated radiation therapy (IMRT), 4-field conformal, and the standard 3-field conventional technique of radiotherapy for favorable stage tumors of the nasal cavity or ethmoid sinus. METHODS AND MATERIALS: We compared the 3 techniques in 3 patients with tumors of the nasal cavity or ethmoid sinus that did not involve the eye or optic pathways. We required that each plan deliver the prescription dose (70.2 Gy at 1.8 Gy per fraction) to 95% of the planning target volume. We compared the maximum point dose to critical normal structures (brainstem, optic chiasm, optic nerves, retina, lens). RESULTS: : IMRT and the 4-field conformal technique were clearly better than the 3-field conventional technique. The 4-field conformal plan was as good as IMRT. CONCLUSIONS: The conventional 3-field technique is not the best way to treat most patients with tumors between the eyes. A 4-field conformal plan is an excellent alternative to IMRT for some patients with tumors of the nasal cavity or ethmoid sinus. Conformal radiotherapy with a noncoplaner field that exits into the low neck may make it difficult to electively irradiate the neck lymphatics. IMRT may be a better option in this situation.

Ethmoid Sinus↗

PubMed1993

[Comparison of two laser scanning tomography systems for three-dimensional analysis of the optic papilla].

The Heidelberg retina tomograph (HRT) allows three-dimensional topographic analysis of the optic disc based on the same confocal laser tomographic scanning principle as the laser tomographic scanner (LTS). We evaluated the reproducibility attained with the HRT and compared the data acquired with the two instruments. To determine the reproducibility of the data acquisition with the HRT, we measured 27 glaucomatous discs five times each. The mean standard deviation was 0.075 mm2 for the cup area, 0.035 mm3 for the cup volume and 0.018 mm for the mean cup depth. In addition, 50 eyes were examined with both instruments. Measurements of the optic disc area and cup area demonstrated slightly increased values obtained with the HRT (mean difference 4.1% and 6.6%, respectively), while the values for cup volume and cup depth were 15.5% and 13.9% larger than those obtained with the LTS. The comparison between LTS and HRT demonstrates good agreement of the reproducibility concerning three-dimensional topometric data relating to the optic nerve head. The differences between the measurements may be due to a modified optical pathway enabling direct assessment of the intraocular focus position in the HRT. In conclusion, the improved and simplified method of laser scanning tomography as used in the HRT yields reproducible and reliable measurements of the optic nerve head. In addition, this instrument makes it possible to obtain high-quality images without pupil dilatation with a significantly shorter examination time.

Equipment Design↗

PubMed1995

Precocious puberty in children with neurofibromatosis type 1.

We undertook a comprehensive study of children with neurofibromatosis type 1 (NF-1) cared for in a large multidisciplinary clinic to determine the prevalence of precocious puberty and its relationship to optic pathway tumors (OPTs). Precocious puberty was diagnosed in 7 of 219 children with NF-1 (5 boys and 2 girls) examined between Jan. 1, 1985, and April 20, 1993. All seven children had OPTs involving the optic chiasm; they represented 39% of children with NF-1 and chiasmal tumors (95% confidence interval, 17% to 64%). Eleven prepubertal children (aged 2 to 10 years) with NF-1 and OPTs, and age- and sex-matched NF-1 control subjects without OPTs, underwent luteinizing hormone-releasing hormone (LH-RH) stimulation tests. Two boys with OPTs had pubertal luteinizing hormone (LH) responses, and testosterone levels > 10 ng/dl. Basal LH levels were also elevated in these two boys when tested with a very sensitive immunochemiluminometric assay. None of the children without an OPT had either a pubertal response to LH-RH or an elevated basal LH level. We conclude that precocious puberty in children with NF-1 is found exclusively in those who have OPTs involving the optic chiasm; it is a common complication in those children. With the use of a highly sensitive LH assay, biochemical evidence of hypothalamic-pituitary-gonadal axis activation may be demonstrated, even without provocative testing.

Child↗

PubMed1981

Diagnostic value of objective campimetry.

The results obtained in ten normal subjects with a new method of pupillocampimetry are described and compared with those obtained with routine campimetry. Once the relationship between the two methods was established, ten subjects suffering from pregeniculate or postgeniculate lesions of the optic pathways were examined by pupillocampimetry. This study shows the value of this new method, particularly for the differential diagnosis of pre- or postgeniculate lesions.

Adaptation, Ocular↗

PubMed1989

Electrophysiological findings in anterior ischemic optic neuropathy.

Electroretinograms (ERG), oscillatory potentials (OP) and pattern reversal visual evoked potentials (VEP) were performed in nine patients (mean age 66 years) with unilateral long-standing anterior ischemic optic neuropathy (AION) and in an age matched control group. Normal ERGs but bilateral impaired OPs were observed in virtually all AION affected patients. Regardless of visual acuity, VEP amplitude reduction was found in all eyes with AION and in controlateral eyes of patients with associated systemic conditions such as diabetes mellitus, arterial hypertension and atherosclerosis. A normal latency of VEP was found bilaterally in AION affected patients; however no correlation between VEP latency and visual acuity or fields could be established. Our results seem to indicate moderate ischemic damage to the retina and to the axons of the optic pathways in patients with AION.

Aged↗

PubMed1999

[Unilateral visual field defect due to optic nerve compression by sclerotic internal carotid artery: a case report].

A case of unilateral visual field defect due to optic nerve compression by a sclerotic internal carotid artery was reported. A 71-year-old woman was admitted to our department because of constricted visual field of the right eye. MRI showed elevation of the right optic nerve compressed by an internal carotid artery. The right carotid angiography revealed elevation and distortion of the C1-2 portion. Frontal craniotomy was carried out and the optic nerve was visualized on this side. The right optic nerve was found to have been compressed by the sclerotic internal carotid artery. The optic canal was then unroofed. The post-operative course was uneventful. The visual field was improved. When last seen 6 months after surgery, her visual field remained in the improved condition. Nasal field abnormalities are most frequently encountered in retinal and anterior optic nerve pathology. Our success in improving the visual field disturbance may be accounted for by the fact that the preoperative period was short and the operation was performed before atrophy of ocular fundi occurred. Nasal field loss caused by intracranial lesions of the optic pathway is rare. It is probably impossible to determine degree of the symptomatology caused by direct-pressure compression as opposed to that caused by ischemia secondary to occlusion of small arterial supply branches. Vascular compressive neuropathy of optic nerve should not be diagnosed simply by the radiological finding of the optic nerve dislocation. However, optic nerve compression by surrounding arteries should be remembered as one of the possible causes of visual field defect which needs to be treated surgically.

Aged↗