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At least 757 records · Page 42Linked to original sources
PubMed1988

Neuro-imaging of cerebral visual disturbances in children.

The present study comprises the neuroradiological examination (computertomography++, magnetic resonance imaging) of 26 children--9 of them were premature, 16 were full-term and in one patient, no details of the pregnancy were known--all suffering from: a) visual disturbance, not caused by ocular disease or afflictions of the optic nerve b) infantile encephalopathy The examination revealed characteristic lesions of the retrochiasmatic part of the visual system. These consisted of white matter abnormalities located periventricularly and just below the striate area, and of grey matter abnormalities of the striate cortex. The demonstration of these abnormalities may advance the diagnosis of the visual handicap and may facilitate early adjustment of developmental stimulation.

Adolescent↗
PubMed1985

[Computerized tomography in endocrine ophthalmopathy with malignant exophthalmos].

CT scanning was done in 16 patients with deterioration of sight in endocrine ophthalmopathy. The assessment involved muscular changes and density of retrobulbar fat. Evaluation of muscular changes was staged. In addition, exophthalmus was graded and evaluated by staging. More than two thirds of patients showed pronounced muscular thickening whereas the remaining patients showed few or no muscular changes. Likewise, in a number of patients exophthalmus could hardly be demonstrated according to Hertel's values. Thus, clinical presentation in a number of patients is relatively mild. Pathophysiologic considerations as to the development of deterioration of sight mainly involve myogenic compression of the optic nerve at its orbital entry. This does not seem to hold true for patients without muscular thickening. In such patients optic nerve affection could be caused by increase of the volume of the fat body.

Adipose Tissue↗
PubMed1994

Cerebral visual impairment in cerebral palsy: relation to structural abnormalities of the cerebrum.

In patients with cerebral palsy (CP), cerebral visual impairment (CVI) is frequently found in addition to ophthalmological disorders. Lesions in the visual areas are found in CT scans of CP patients with CVI. The aim of the present study was to determine the prevalence of these specific findings in CP patients with CVI. CT scans of 49 cerebral palsy patients were studied; CVI was diagnosed in 36 patients; in 13 patients, visual acuity was normal. In 8 patients, comparison with an MRI scan was possible (6 with CVI, 2 with normal acuity). The CT scans were scored according to the criteria used by Van Nieuwenhuizen (1987): normal, abnormalities of the white matter adjacent to the posterior horns of the lateral ventricles, abnormalities of the white matter located under the visual cortex, abnormalities of the visual cortex and abnormalities elsewhere. Abnormalities in the visual areas were found in 15% of the normal acuity group and in 53% of the CVI group. In 17 of the 19 CVI patients with abnormalities in the visual areas, the lesions were located in the white matter surrounding the posterior horns (89%). MRI imaging revealed the same abnormalities as the CT scans in 6 patients, but in one patient the abnormality was seen in more detail and in one patient the lesion in the occipital area was seen only on MRI. MRI examination seems to detect at least as many, but in some cases even more specific lesions in CVI patients compared to CT scanning, but the numbers were too small to allow any definitive conclusions to be drawn.

Adolescent↗
PubMed1994

Follow-up of optic pathway gliomas in children with neurofibromatosis type 1.

Optic pathway gliomas (OPG) are found in about 15% of patients with neurofibromatosis Type 1 (NF-1). The natural history of OPG is not yet well documented. Treatment in cases with growing tumors is still controversial. Twenty-one patients with NF-1 and OPG, diagnosed over a 20-year period, and followed neuroradiologically and ophthalmologically for at least two years, were reevaluated. The diagnosis of OPG was made at a mean age of 7.1 years (range 0-14.5 years); six children were asymptomatic, 15 were symptomatic. The mean follow-up was 9.0 years (2.0-18.5 (years). In eight initially operated or biopsied patients (three optic nerve and five chiasmal gliomas) tumor regrowth was found in one patient without progression on subsequent follow-up. Improvement of visual acuity occurred in one child after operation of a large suprasellar tumor and deterioration in one patient after biopsy of a chiasmal glioma. The neuroradiological follow-up of the 13 not-operated and not-radiated patients (four optic nerve and nine chiasmal gliomas) was stable in 10, progressive in three, resulting in visual loss in one patient. In 11 children (52%) a second tumor outside the optic pathway was found at a mean age of 4.0 years after the diagnosis of an OPG. Until now they are mostly asymptomatic. Second site tumors were operated in two children because of rapid tumor growth, one child died of a brainstem tumor. OPG are a frequent complication in children with NF-1, appearing within the first decade.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2003

"Balanced" orbital decompression for severe Graves' orbitopathy: technique with treatment algorithm.

BACKGROUND: Graves' orbitopathy can produce proptosis, compressive optic neuropathy, and extraocular motility abnormalities; symptoms result from an increase in orbital volume due to expansion of intraorbital fat, with or without extraocular muscle involvement. STUDY DESIGN: We conducted a chart review of patients who underwent orbital decompression to treat Graves' orbitopathy. Twenty-two orbits (13 patients) underwent orbital bone decompression, of which 17 orbits (9 patients) underwent the combined medial and lateral "balanced" decompression. RESULTS: All patients had significant improvement with an average decrease in proptosis of 5.9 mm in the balanced decompression group. Restoration of normal optic nerve function was achieved in all patients with compressive optic neuropathy. Diplopia was noted in 4 patients (30.7%) preoperatively. Two patients had new postoperative diplopia (15.35%). CONCLUSION: In our experience, "balanced" decompression results in a reduction of proptosis and improved optic nerve function and has a low incidence of complications.

Adult↗
PubMed2001

Orbital wall approach with preoperative orbital imaging for identification and retrieval of lost or transected extraocular muscles.

PURPOSE: To report the results of an anterior approach along the orbital wall to recover a lost or transected extraocular muscle. METHODS: This is a retrospective review of lost or transected muscles retrieved by an anterior orbitotomy approach to the adjacent orbital wall because they were unable to be recovered by a standard conjunctival approach. Magnetic resonance imaging or computed tomography was performed on all subjects before surgery. RESULTS: Six patients underwent anterior orbitotomy via an orbital wall approach; all had undergone an attempted retrieval from a standard transconjunctival approach that failed. Five muscles had been lost from surgical or traumatic transection, and 1 muscle had been lost during strabismus surgery. The muscle location at retrieval ranged from 20 to 25 mm (mean, 23 mm) posterior to the limbus. The duration that these muscles were disinserted ranged from 7 days to 7.5 years (mean, 24 months). Preoperative deviation in primary gaze ranged from 15 to 50 PD, whereas first day postretrieval deviations all measured less than 8 PD. After a mean follow-up of 162 weeks, the mean deviation in primary gaze was 2 PD (range, orthotropia to 7 PD of esotropia). CONCLUSIONS: Anterior orbitotomy along the orbital wall with preoperative orbital imaging of extraocular muscle anatomy and function combine to create a valuable approach for retrieval of a lost or transected muscle. This technique may successfully retrieve lost or transected muscles that previously were irretrievable when using a standard transconjunctival approach.

Humans↗
PubMed2002

Differential activation of the human orbital, mid-ventrolateral, and mid-dorsolateral prefrontal cortex during the processing of visual stimuli.

There is considerable uncertainty about the precise functional contribution of the different parts of the prefrontal cortex to mnemonic processing. Changes in regional cerebral blood flow were measured with positron emission tomography in normal human subjects exposed to abstract visual designs under various conditions. It was demonstrated that the processing of stimuli that deviate from expectations involves selectively the orbitofrontal cortex, namely the part of the frontal cortex that is preferentially linked with the limbic system. By contrast, when the subject is making an explicit decision on the contents of memory (e.g., judgments of relative stimulus familiarity), the mid-ventrolateral prefrontal cortex is involved. The mid-dorsolateral prefrontal cortex is engaged when monitoring of information within working memory is required.

Adult↗
PubMed1987

Deficits in human visual spatial attention following thalamic lesions.

There has been speculation concerning the role that thalamic nuclei play in directing attention to locations in visual space [Crick, F. (1984) Proc. Natl. Acad. Sci. USA 81, 4586-4590]. We measured covert shifts of visual attention in three patients with unilateral thalamic hemorrhages shortly after the lesion and after a 6-month recovery period. The experiment measured reaction time to targets that occurred at locations to which attention had been cued (valid trials) or at a currently unattended location (invalid trials). Although the patients showed no deficits in visual fields with perimetry and no neglect in the 6-month follow-up, we found slow reaction times for targets on the side contralateral to the lesion whether or not attention had been cued to that location. Deficits have also been found in this task with cortical and midbrain lesions, but the patterns of performance are quite different. The results with thalamic patients suggest they have a specific deficit in the ability to use attention to improve the efficiency of processing visual targets contralateral to the lesion (engage operation). This finding is in accord with hypotheses of a thalamic link between cortical visual attention and pattern recognition systems proposed by Crick.

Aged↗
PubMed1994

Binocular disparity discrimination in human cerebral cortex: functional anatomy by positron emission tomography.

Neurobiological studies in higher primates indicate that the processing of stereoscopic information takes place at early levels in the visual cortex. To map the anatomical structures in the human brain participating in pure stereopsis based upon binocular disparity, we measured with positron emission tomography the changes in regional cerebral blood flow as an indicator of metabolic activity in 10 healthy young men during visual discrimination of binocular disparity. The data demonstrate that the discrimination of pure stereo-optic disparity information takes place in the polar striate cortex and the neighboring peri-striate cortices, as well as in the parietal lobe, the prefrontal cortex, and the cerebellum. The discrimination of stereoscopic depth is dependent on a network composed of multiple functional fields localized in occipital- and parietal-lobe visual areas as well as in the dorsolateral and mesial prefrontal cortex. The findings support the importance of coactivated occipitoparietal visual areas in the processing and analysis of binocular depth information in humans.

Adult↗
PubMed2005

Mucocele in an Onodi cell responsible for acute optic neuropathy.

An Onodi cell is defined as the most posterior ethmoid cell, which pneumatizes laterally and superiorly to the sphenoid sinus. A rare case of an isolated mucocele in an Onodi cell with unilateral acute visual disturbance is presented. MRI was imperative for the early and accurate diagnosis, and prompt surgical drainage resulted in dramatic visual recovery.

Acute Disease↗
PubMed1997

Traumatic haemorrhagic optic neuropathy: case report.

We report a case of visual loss following haemorrhage into the optic nerve sheath following head trauma. The patient showed improvement in visual function following decompression of the optic nerve sheath and evacuation of the haematoma.

Child↗
PubMed1998

Primary transsphenoidal microsurgery in the treatment of craniopharyngiomas.

Thirty craniopharyngiomas were operated on between 1983 and 1993. Eight patients underwent surgery solely via the transsphenoidal route. None of these had undergone surgery previously. The eight patients were followed up for a period of 120 months (mean 87.5 months). The tumour was removed totally in five and subtotally in three patients. All eight patients had one or more endocrine abnormalities prior to surgery. Five patients presented with visual field defects or decreased visual acuity, which improved postoperatively in all cases. Seven received radiotherapy, with one declining this treatment. No recurrences have occurred during follow-up in any of the group. Primary transsphenoidal surgery is a both safe and effective treatment for those craniopharyngiomas that are located within an enlarged sella, have no calcification and are not adherent to parasellar structures.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Pseudo-subarachnoid hemorrhage and cortical visual impairment as the presenting sign of gliomatosis cerebri.

A 49-year-old white male presented with a pseudo-subarachnoid hemorrhage and diffuse brain edema. Neuroimaging showed brain edema causing the unusual findings of a pseudo-subarachnoid hemorrhage and bilateral occipital lobe infarcts following herniation and compression of the posterior cerebral arteries. An enlarged corpus callosum was noted which led to a brain biopsy and a diagnosis of gliomatosis cerebri.

Biopsy, Needle↗
PubMed1997

Functional localization of the system for visuospatial attention using positron emission tomography.

PET was used to image the neural system underlying visuospatial attention. Analysis of data at both the group and individual-subject level provided anatomical resolution superior to that described to date. Six right-handed male subjects were selected from a pilot behavioural study in which behavioural responses and eye movements were recorded. The attention tasks involved covert shifts of attention, where peripheral cues indicated the location of subsequent target stimuli to be discriminated. One attention condition emphasized reflexive aspects of spatial orientation, while the other required controlled shifts of attention. PET activations agreed closely with the cortical regions recently proposed to form the core of a neural network for spatial attention. The two attention tasks evoked largely overlapping patterns of neural activation, supporting the existence of a general neural system for visuospatial attention with regional functional specialization. Specifically, neocortical activations were observed in the right anterior cingulate gyrus (Brodmann area 24), in the intraparietal sulcus of right posterior parietal cortex, and in the mesial and lateral premotor cortices (Brodmann area 6).

Attention↗
PubMed1997

Blindsight in hemispherectomized patients as revealed by spatial summation across the vertical meridian.

The present study provides a demonstration of blindsight in two hemispherectomy patients who showed a visual spatial summation effect across the vertical meridian despite their lack of visual awareness in one hemifield. Such an effect cannot be related to light diffusion onto the sighted hemifield because it was not present when one of the stimuli fell into the retinal blind spot of control subjects. We conclude that blindsight phenomena of the simple type described in the present study can be subserved by sub-cortical mechanisms and do not necessarily require cortical processing.

Adolescent↗
PubMed1999

Brain activation during maintenance of standing postures in humans.

The regulatory mechanism of bipedal standing in humans remains to be elucidated. We investigated neural substrates for maintaining standing postures in humans using PET with our mobile gantry PET system. Normal volunteers were instructed to adopt several postures: supine with eyes open toward a target; standing with feet together and eyes open or eyes closed; and standing on one foot or with two feet in a tandem relationship with eyes open toward the target. Compared with the supine posture, standing with feet together activated the cerebellar anterior lobe and the right visual cortex (Brodmann area 18/19), and standing on one foot increased cerebral blood flow in the cerebellar anterior vermis and the posterior lobe lateral cortex ipsilateral to the weight-bearing side. Standing in tandem was accompanied by activation within the visual association cortex, the anterior and posterior vermis as well as within the midbrain. Standing with eyes closed activated the prefrontal cortex (Brodmann area 8/9). Our findings confirmed that the cerebellar vermis efferent system plays an important role in maintenance of standing posture and suggested that the visual association cortex may subserve regulating postural equilibrium while standing.

Adult↗