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At least 145 records · Page 8Linked to original sources
PubMed1995

A brain-damaged patient with an unusual perceptuomotor deficit.

When interacting with objects, the pattern of movements is influenced by such object characteristics as size and position. Little is known about the effect of higher level categorical encoding of objects upon movements. Here we present evidence for an approval-for-action process which takes into account such encoding. For the brain-damaged subject L.P., the ability to complete actions involving two objects in central vision is influenced by the semantic or functional relationship between the objects. Even though she perceives only one object, she can integrate two related objects into a coordinated action. If the objects are not related she is unable to integrate them into a single motor act. We propose that selection-for-action systems include processes which gate conceptually the behavioural disposition to action.

Aged↗
PubMedDate not supplied

Vision despite tomographic absence of the occipital cortex.

A 14-month-old boy with developmental delay showed microcephaly, spastic diplegia, central visual fixation and an esotropia. A head tomographic scan disclosed absence of normal occipital cortex and electroencephalography showed markedly reduced voltages over the occipital region. Visual development in this patient may be related to heterotopic occipital cortex of a functioning non-striate system of visual processing. Visual function cannot be predicted when severe developmental anomalies of the occipital cortex are detected with computerized tomography.

Abnormalities, Multiple↗
PubMed1988

Suprasellar meningiomas: the effect of tumor location on postoperative visual outcome.

The authors reviewed 38 cases of suprasellar meningioma to determine the correlation between tumor site and postoperative visual outcome. Progressive visual loss, the most frequent initial complaint (94.7%), occurred over a mean of 24 1/2 months, was most often unilateral (18 patients) or bilateral but asymmetrical (14 patients), and was severe (20/200 vision or worse) in 23 patients; 24 patients had visual field abnormalities. Computerized tomography or magnetic resonance studies clearly delineated the lesions but did not appear to permit earlier diagnosis. Eleven patients had tumors limited to the tuberculum sellae; the tumor extended from the tuberculum sellae onto the planum sphenoidale in nine patients, into one optic canal in eight, onto the diaphragma sellae in seven, and onto the medial sphenoid wing in three. Patients with tumors affecting the optic canal had severe unilateral visual loss more often than those with tumors at other sites. Tumors limited to the tuberculum sellae were most often completely resected; postoperative recovery of vision was also most frequent in patients with tumors at this site. Tumors involving the diaphragma sellae or the medial sphenoid wing were least often completely removed and most likely to be associated with postoperative visual deterioration. Overall, 42% of patients had improved vision postoperatively, 30% remained unchanged, and 28% were worse. After a mean follow-up period of 38 months, 24 patients are doing well, four have significant visual disability, and three are blind or doing poorly. Two patients died of causes unrelated to their tumor. Three patients have had tumor recurrence.

Adult↗
PubMed1984

[Eye symptoms in hypophyseal adenomas, craniopharyngiomas and meningiomas of the anterior and middle cranial fossa].

Among 181 inpatients suffering from pituitary adenoma, craniopharyngioma, or meningioma of the anterior or middle cranial fossa, 112 had ocular symptoms initially or during the course of the disease. Patients' histories were analyzed with regard to ophthalmological, neurological, and radiological diagnostic procedures carried out, and the conclusions drawn from these. Initial symptoms and signs were often misinterpreted and appropriate investigations consequently delayed. The mean duration of the history was 2.67 years (0-13 years) for the pituitary adenomas, 1.44 years (3 months-6 years) for the craniopharyngiomas and 3.73 years (1 month-24 years) for the meningiomas. Typical initial eye symptoms were progressive loss of vision with or without optic nerve atrophy, visual field defects, extraocular nerve palsies, and exophthalmus, the last two occurring if parasellar extension of the tumor was present. Plain skull X-rays were abnormal in nearly all cases of pituitary adenomas, but the incidence of abnormalities was less frequent with cases of craniopharyngiomas and meningiomas. The tumor was demonstrated by computerized tomography in all cases of pituitary adenomas, in 5 out of 6 cases with craniopharyngiomas and, where the examination was performed before and after administration of contrast medium, in all cases of meningiomas. Introduction of CT, however, shortened the duration of the history only in the meningioma group; the mean dropped from 4.38 years to 3.04 years. The chance of achieving a cure by surgical intervention lessened with both increasing length of history and tumor size. Out of 90 patients (15.6%) operated on, 14 died in the postoperative period. Vision improved postoperatively in only 26 patients whereas it remained unchanged or decreased further in 40 patients. In 10 cases there were no postoperative data available. These results emphasize the necessity of making an early diagnosis. This can nearly always be achieved if a careful clinical examination and adequate additional diagnostic procedures are carried out.

Adenoma↗
PubMed1990

Reversible visual loss caused by fibrous dysplasia.

Fibrous dysplasia is a developmental anomaly of bone, often affecting the facial bones. We treated a patient who had fibrous dysplasia involving the right maxillary and sphenoid bones. The patient had a sudden loss of visual acuity to R.E.: counting fingers. Visual fields demonstrated a central scotoma, and retrobulbar neuritis was diagnosed. When vision failed to improve spontaneously, however, radiologic studies were performed. These showed compromise of the optic canal by bony proliferation and an apparent mucocele at the orbital apex. Surgical exploration disclosed fibrous dysplastic bone and a cystic structure overlying the optic nerve. Successful surgical excision of the cyst and debulking of the fibrous dysplasia resulted in visual acuity returning to R.E.: 20/25.

Adult↗
PubMed1985

[Visual field defects in hydrocephalus].

Eight patients representing visual field defects associated with hydrocephalus are reviewed. Seven cases had aqueductal stenosis and one had congenital communicating hydrocephalus. We found five cases of defects in visual field typical of a chiasmal or optic nerve lesion: (1) inferior altitudinal hemianopia with inferior nasal quadrantanopia in the opposite eye; (2) inferior binasal quadrantanopia; (3) unilateral inferior nasal depression; (4) unilateral temporal defect; (5) bilateral central scotoma. In these cases CT demonstrated moderate or marked symmetrical dilatation of the third and lateral ventricles. Four out of five cases showed bulging of the third ventricle anteriorly into the sella turcica on CT or ventriculography. Other three patients had incongruous homonymous hemianopia. Characteristic asymmetrical dilatation of the lateral ventricles was noted in all three cases. The more enlarged lateral ventricles were ipsilateral with the affected visual pathways. The sites of lesion responsible for these field defects seemed to be optic tract in one case and optic radiation in two cases. Ventriculoperitoneal shunt was placed in five out of seven cases. Impaired visual field improved in three patients after shunt insertion. A 28-year-old female who had history of blurred vision fos 14 days showed improvement in visual acuity and field when the enlarged ventricles became slit-like by shunting. In the other two patients defects in visual fields improved in spite of consistent ventriculomegaly. These facts suggested that not only the mechanical forces with distended third ventricle but also increased intracranial pressure played an important role in producing visual field defects in hydrocephalic patients.

Adolescent↗
PubMed1988

Pseudo-pseudo-Foster Kennedy syndrome.

An 80-year-old woman presented with a classic story and findings of an anterior ischemic optic neuropathy in her left eye. Her right eye had slow and progressive decreased vision, ostensibly secondary to a cataract. However, the right eye showed slight temporal pallor of the optic disc and a superior temporal field defect was found. Her radiologic exam showed a tuberculum sella meningioma extending into the right optic canal compressing the right optic nerve. Two diseases, ischemic optic neuropathy and meningioma, in one patient may be termed a pseudo-pseudo-Foster Kennedy syndrome.

Aged↗
PubMedDate not supplied

Fractures of the sphenoid bone.

Fractures of the sphenoid bone occur following injury to the orbit and base of the skull. Such fractures are important since they can cause loss of vision and damage to various neural and muscular tissues. Ocular injury is also commonly associated. This paper reviews the hospital records of 112 consecutive patients with fractures of the base of the skull for the cause, frequency of signs and symptoms, and treatment of the sphenoid bone injury. Various deformities and dysfunctions are correlated with imaging data and classified to describe specific clinical syndromes. Several cases of sphenoid bone fracture serve as examples of diagnostic and treatment techniques.

Eye Injuries↗
PubMed1990

Extrageniculate vision in hemianopic humans: saccade inhibition by signals in the blind field.

The functional competence of extrageniculate visual pathways in hemianopic humans was demonstrated by showing that distractor signals in the blind half of the visual field could inhibit saccades toward targets in the intact visual field. This inhibitory effect of unseen distractors in patients occurred only when distractors were presented in the temporal half of the visual field, was specific to oculomotor responses, and did not occur in normal subjects. These results show that a peripheral visual signal activates retinotectal pathways to prime the oculomotor system and that these pathways can mediate orienting behavior in hemianopic humans.

Analysis of Variance↗
PubMed1992

Visual evoked potentials during the early phase of optic nerve compression in the orbital cavity.

We obtained case histories and electrophysiologic recordings from four patients with transient vision impairment due to acute orbital compression. The visual evoked potentials (VEPs) displayed alterations that depended on the size and consistency of the compressing pathology and also on the duration of the compression. This study provides evidence of the utility of the VEP in the assessment of the severity and reversibility of optic nerve lesions. The case histories also emphasized the necessity to elucidate the pathologic process of compressive lesions of the optic nerve.

Acute Disease↗
PubMed1987

Recovery of vision after presumed direct optic nerve injury.

Immediate loss of light perception after direct optic nerve injury is usually irreversible. Our patient sustained presumed direct optic nerve injury because of a shotgun injury with loss of light perception, absent pupillary response, and absent visual-evoked potential. A small pupillary response was noted 12 days after injury, light perception returned by 15 days, and visual acuity was 20/100 at 4 months. A variety of pathophysiologic mechanisms may lead to visual loss after direct optic nerve injury. It is important to recognize that blindness is not always permanent in these cases despite the results of initial clinical and electrophysiologic testing.

Adolescent↗
PubMed1978

[Impaired visual perception in progressive multifocal leukoencephalopathy; a clinical diagnosis based on sequential computerized axial tomography (author's transl)].

Progressive multifocal leukoencephalopathy (PML) is a viral illness affecting principally cerebral white matter of patients, who have diminished immunologic resistance. A patient is presented, whose initial complaint was blurred vision. Relentless progression over a period of seven months to left hemianopsia, prosopagnosia, alexia with agraphia and eventually cortical blindness was observed. Accompanying the visual impairment was a steady deterioration of mental function. Sequential computerized axial tomography defined low density lesions in the occipital white matter with sparing of the cortical ribbon. As hemianopsia progressed to cortical blindness, the scans confirmed the evolution of bilaterial occipital lesions. The diagnosis was made clinically and established on histological and cultural grounds. Computerized tomography seems to be valuable in diagnosis and monitoring progress of PML.

Aged↗
PubMed1985

Rapid fading of visual sensations in a subject with a parietal-occipital tumour.

We present psychophysical data measured for a single subject, who had a tumour in the left parieto-occipital region, located by CT scan and post-mortem study. Her vision was characterised by rapid fading during voluntary fixation of images located in the right hemifield. We describe a number of simple tests which we developed in order to study this phenomenon. The results of these tests established that significant loss of function occurs within 1 s of fixation and that the effects associated with fixation are spatially localised. We compare our subject's response characteristics with those observed in other cases of visual disturbance and we examine the possible underlying mechanisms which give rise to the rapid fading of her visual images.

Adult↗
PubMed1989

Surgical treatment of progressive visual loss in traumatic optic neuropathy. Report of two cases.

In two patients with traumatic optic neuropathy progressive visual loss was reversed by surgical decompression of the optic nerve sheath. The first patient with hemorrhage beneath the optic nerve sheath had progressive loss of vision from counting fingers to no light perception within 24 hours after the injury. Surgical evacuation of the hematoma improved visual acuity to 8/30. The second patient had progressive visual loss from 20/20 to 20/400 within the 1st week after injury. Drainage of an arachnoid cyst of the optic nerve sheath improved visual acuity to 20/25. Computerized axial tomography disclosed the hemorrhage in the first case and enlargement of the optic nerve sheath in the second. While the management of traumatic optic neuropathy is controversial, surgical intervention for an arachnoid cyst and hematoma involving the optic nerve is clearly beneficial.

Adult↗
PubMed1986

Circulatory parameters of the retina in patients with lacunar stroke.

Ophthalmological data were obtained in 40 patients presenting with lacunar stroke. The stroke was verified clinically as well as by computed tomography. Vision was tested and the visual field, intraocular pressure, retinal arteriovenous passage time, arm-retina time, and erythrocyte flow velocity in the conjunctival capillaries were all determined; ophthalmoscopy was also carried out. Microcirculatory parameters were obtained from 21 patients. Significant disturbances of the retinal arteriovenous passage time were observed, but there were no significant disturbances of the conjunctival erythrocyte flow velocity. The concurrently measured haemorheological parameters were all pathological with the exception of the haematocrit. Ophthalmoscopic examination revealed arteriosclerotic alterations in 38 of 40 patients. These angiological and rheological findings confirm the importance of disturbed microcirculation in lacunar stroke.

Aged↗
PubMed1988

Sneddon's disease presenting with visual loss and dementia.

A 51-year-old woman with Sneddon's disease presented with transient right hemifield loss of vision and transient right-sided weakness. Over the preceding decade she had experienced a slow decline in mental function. She also had hypertension, migraine, and a mixed seizure disorder. She had skin changes typical for generalized livedo reticularis but she did not have Raynaud's phenomenon or winter ulcerations. Her disease was not understood until the stroke-related symptoms were associated with the skin abnormalities. We review the neuro-ophthalmic manifestations of Sneddon's disease and add data from our case to the growing body of fact that suggests that Sneddon's disease may be an immunologically mediated vasculopathy.

Cerebrovascular Disorders↗
PubMed1995

Live cell image segmentation.

A major requirement of an automated, real-time, computer vision-based cell tracking system is an efficient method for segmenting cell images. The usual segmentation algorithms proposed in the literature exhibit weak performance on live unstained cell images, which can be characterized as being of low contrast, intensity-variant, and unevenly illuminated. We propose a two-stage segmentation strategy which involves: 1) extracting an approximate region containing the cell and part of the background near the cell, and 2) segmenting the cell from the background within this region. The approach effectively reduces the influence of peripheral background intensities and texture on the extraction of a cell region. The experimental results show that this approach for segmenting cell images is both fast and robust.

Algorithms↗