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A 27-year-old man presented to the casualty department with visual failure. Clinically he demonstrated the Foster-Kennedy syndrome. Computed tomography revealed a large space-occupying lesion which was subsequently shown to be a pituitary adenoma. The literature is reviewed and possible mechanisms of the Foster-Kennedy syndrome are discussed.
A 34-year-old woman who presented with hearing loss and tinnitus was found to have reduced vision bilaterally. Computed tomography scan revealed bilateral acoustic neuromas and bilateral optic nerve sheath meningiomas. The presence of bilateral acoustic neuromas fulfils the criteria for the diagnosis of central neurofibromatosis (neurofibromatosis type 2). Although this is the first report of bilateral optic nerve sheath meningioma in neurofibromatosis type 2, meningiomas are commoner in this dominantly inherited disorder, than in its absence and both forms of central nervous system tumour may be caused by loss of tumour suppressor genes on chromosome 22.
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AIMS: To develop and describe an objective classification system for the spatial patterns of visual field loss found in glaucoma. METHODS: The 560 Humphrey visual field analyser (program 24-2) records were used to train an artificial neural network (ANN). The type of network used, a Kohonen self organising feature map (SOM), was configured to organise the visual field defects into 25 classes of superior visual field loss and 25 classes of inferior visual field loss. Each group of 25 classes was arranged in a 5 by 5 map. RESULTS: The SOM successfully classified the defects on the basis of the patterns of loss. The maps show a continuum of change as one moves across them with early loss at one corner and advanced loss at the opposite corner. CONCLUSIONS: ANNs can classify visual field data on the basis of the pattern of loss. Once trained the ANN can be used to classify longitudinal visual field data which may prove valuable in monitoring visual field loss.
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BACKGROUND/AIMS: Progressive diaphyseal dysplasia (PDD) is a rare, autosomal dominant, osteosclerotic dysplasia affecting both endochondrally and intramembranously derived bones. Severely affected patients can develop progressive stenosis of the optic canals and compressive optic neuropathy. Although raised intracranial pressure (ICP) has been described in patients with PDD in whom visual loss has occurred, the elevation of ICP in those patients has been thought to be either non-contributory or only partially responsible for the accompanying visual loss. METHODS: Three cases were reviewed and the clinical and radiological characteristics are described here. RESULTS: All three patients had bilateral optic disc swelling with no radiological evidence of either compressive optic neuropathy or thrombosis of the intracranial venous sinuses. The aetiology of the disc swelling was proved to be papilloedema in the first two cases and was probably the dominant cause in the third case. CONCLUSION: The visual loss documented in at least two of the three patients reported appears to be solely attributable to raised ICP. Normalisation of the ICP has led to an improvement and stabilisation of the visual function in all three patients. Patients with PDD probably require periodic ophthalmic assessments.
One hundred and two patients with suspected or established multiple sclerosis (MS) were investigated by one or more of the following techniques: measurement of visual evoked potentials (VEP); measurement of cervical and cortical somatosensory evoked potentials (SEP); measurement of horizontal saccadic eye movement velocities (SV); and computerised axial tomography of the cranium and orbits (CT). Each of the techniques was valuable in detecting abnormalities, some of which were subclinical, in many patients. More abnormalities were found in patients studied by more than one technique, the most being detected in patients who were studied by all five techniques. We conclude that the techniques have a complementary role in investigating suspected MS.
OBJECTIVE: To present a large series of surgically treated tuberculum sellae meningiomas with particular regard to involvement of the optic canal and visual outcome. METHODS: A retrospective analysis was done on 53 patients (40 female) with meningiomas originating from the tuberculum sellae who underwent surgery between 1991 and 2002. The standard surgical approach consisted of pterional craniotomy. Sixteen meningiomas extended posteriorly onto the diaphragma sella, 29 anteriorly to the planum sphenoidale, and 19 to the anterior clinoid process. Thirty seven tumours involved the optic canal, three bilaterally. Follow up ranged from 6 to 108 months (mean 29.9 months). RESULTS: Total macroscopic resection was achieved in 48 patients. Median tumour size was 2.6 cm. Postoperatively, visual acuity improved in 20 patients and deteriorated in seven. Preoperative and postoperative visual acuity worsened with increasing duration of preoperative symptoms and with increasing age. Extension into the intraconal space was a negative predictor. However, tumour size did not influence visual acuity. Recurrence occurred in two cases (21 and 69 months postoperatively). Two patients died from causes unrelated to the tumour. CONCLUSIONS: In the majority of patients with tuberculum sellae meningiomas, total resection may be achieved through a pterional approach with minimal complications.
Two patients with sectorial optic atrophy and homonymous, horizontal sectoranopia are described. Neuroradiological investigations localised the visual pathway lesion to the lateral geniculate body. The peculiar nature of the field defect and the optic atrophy appeared explicable in terms of ischaemia in the territory of the lateral choroidal artery.
A 76-year-old man with bilateral temporal lobe agenesis producing clinical features resembling the Robinson syndrome is described. The malformation was discovered during a routine CT examination after the appearance of a homonymous visual field defect. The patient was examined by (neuro) psychological testing. The findings are compared with other reported cases and discussed with regard to cerebral localisation.
A unique disorder is described in seven members of two families in whom dystonia was variably associated with subacute visual loss or asymptomatic optic atrophy, and striking bilateral symmetrical lucencies on CT scan, especially involving the putamen. It is possible that this is a variant of Leigh's disease. However, there were considerable differences between these patients and those with pathologically proven Leigh's disease. This condition must be excluded in all patients thought to have idiopathic dystonia, subacute visual failure similar to Leber's optic neuropathy, or a combination of these disorders.
A 68 year old Japanese female with unilateral metamorphopsia of the face that developed after a small haemorrhage in the contralateral retrosplenial region, is described. The patient claimed that the right side of a face, that is, the left side when looked at by the patient, appeared smaller than the left. In addition, her drawings of the face showed some distortions. Objects other than the face were perceived normally. Cranial CT scan revealed a small high density area in the right retrosplenial region. The face appears to have a special representation in the posterior hemisphere.
BACKGROUND: The term "posterior cortical atrophy" (PCA) refers to a clinical syndrome in which higher order visual processing is disrupted owing to a neurodegenerative disorder, the most commonly associated pathology being Alzheimer's disease. OBJECTIVE: To map the topography of hypometabolic brain regions in a group of subjects with PCA who had undergone detailed neuropsychological characterisation. METHODS: Resting cerebral metabolism was measured with ((18)F)fluorodeoxyglucose-positron emission tomography (FDG-PET) in patients with PCA (n = 6), typical Alzheimer's disease (n = 10), and healthy controls (n = 10). The data were analysed using statistical parametric mapping (SPM99) and region of interest techniques. RESULTS: Clinically, the PCA subjects showed predominant visuospatial deficits (including features of Balint's syndrome) consistent with damage to the dorsal stream of visual processing. Compared with the controls, the PCA group showed marked glucose hypometabolism primarily affecting the posterior cerebral hemispheres (right worse than left). In addition, the PCA group showed two symmetrical areas of hypometabolism in the region of the frontal eye fields. Compared with typical Alzheimer's disease, the PCA group had selective hypometabolism in the occipito-parietal region (right much worse than left). CONCLUSIONS: The neuropsychological and PET findings are consistent with damage predominantly to the dorsal stream of visual processing. Frontal eye field hypometabolism secondary to loss of input from the occipito-parietal region may be the mechanism for the ocular apraxia seen in Balint's syndrome.
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The case of a 21 year old woman who presented with recurrent sterile meningitis and bitemporal hemianopia is described. Computed tomographic scan showed a large low density ring enhancing lesion above and within the pituitary fossa which at operation and on histological examination was found to be compatible with an abscess. The visual field defect recovered completely and the scan appearances returned to normal postoperatively.
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In this review, routine radiographs with computed tomographic (CT) correlation are used to demonstrate practical applications of Mach band theory in thoracic analysis. Mach bands represent optical psychophysiologic edge-enhancement phenomena produced by means of lateral inhibition in the retina of the eye. Visualization of Mach bands depends on a set of variables that involve primarily the contour and optical density of a structure at an interface relative to that of its surround. On the basis of their appearance, the bands are defined as positive (white) or negative (black). The concept of Mach bands contributes to a greater understanding of three-dimensional structures projected onto two-dimensional routine radiographic images of the thorax. Mach bands can help differentiate normal from abnormal anatomy and thus increase the diagnostic yield from such images. Mach bands can be seen on images that use transmitted or reflective light, including CT scout images (topograms) of the thorax.