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Biomedical subjects

P A Good

Publications and source records attributed to P A Good.

At least 37 records · Page 2Linked to original sources
PubMed1991

The use of tinted glasses in childhood migraine.

20 children with clinically diagnosed migraine were asked to wear either a rose coloured tint or density matched blue tint for a period of 4 months. The frequency, duration and intensity of migraine attacks were recorded, together with the amount of visually provoked beta activity in the EEG. After one month's wear all the children in the study revealed an initial improvement in headache frequency. However, only those children wearing rose tints sustained this improvement up to 4 months, when the mean headache frequency had improved from 6.2 per month to 1.6 per month. The headache frequency of those children wearing blue tints revealed no overall improvement after 4 months. The improvements in headache frequency in children wearing rose tints correlated with a reduction in visually provoked beta activity.

Adolescent↗
PubMed1990

Visual evoked responses in children with migraine: a diagnostic test.

The visual evoked responses (VERs) to both flash and pattern stimulation were recorded in 44 children with migraine, with or without aura, and 8 with periodic syndrome. The controls were 50 age and sex matched children. VERs of 50 sex matched adults with migraine were also recorded. The fast wave amplitude in children with migraine was higher than that in controls. The amplitude was higher in younger children with migraine (under 13 years) than that in older children or adults with migraine. Children with periodic syndrome had VERs similar to those of children with migraine. The VER, especially in children, may prove to be a useful test in the diagnosis of migraine.

Adolescent↗
PubMed1990

The VEP in acephalgic migraine.

The diagnosis of acephalgic migraine is complicated by the fact that other neurological conditions such as transient ischaemic attacks, demyelinating disease, simple partial epilepsy, and even glaucoma, can present with similar symptoms. Using both flash and pattern stimulation, visual evoked potentials (VEPs) were examined as a means of differentiating between acephalgic migraine, migraine with aura, migraine without aura, demyelinating disease and a control group. This study demonstrated that by analysing the amplitude of the background fast activity in the flash and pattern VEP, acephalgic migraine can be differentiated from demyelinating disease, migraine with aura, migraine without aura and absolute controls.

Adult↗
PubMed1990

The VER as a diagnostic marker for childhood abdominal migraine.

Abdominal migraine is a common childhood migraine equivalent, for which diagnostic criteria have not been defined. As in other children with migraine equivalents this leads to difficulties in diagnosis and determination of prevalence. By recording the fast wave activity (beta rhythmn) in the visual evoked response (VER) to red and white flash, the pattern stimulation, 27 out of 28 children with clinically diagnosed abdominal migraine revealed significant differences compared with normal controls, outside the attack phase. Comparisons with children diagnosed as migraine with or without aura revealed, from the VER findings of higher amplitude fast wave activity and the presence of paroxysmal sharp wave activity, that abdominal migraine appears to be a specific form of childhood migraine. We found that both clinically and electrophysiologically, abdominal migraine changes with age; older children exhibiting a shorter duration of abdominal pain during attacks, and less evidence of sharp wave activity in the VER.

Abdominal Pain↗
PubMed1990

A model for desferrioxamine-induced retinopathy using the albino rat.

We describe a rat model of the ocular toxicity induced in patients by the iron chelator desferrioxamine (DFX). The functional integrity of the rat photoreceptor membrane is assessed by measurement of the electroretinogram b wave amplitude. Following single bolus doses of DFX (50, 100 and 150 mg), rats develop dose-related suppression of b wave amplitude within 48 h. Recovery takes place over the subsequent 14 days. This ocular damage is exacerbated by exposure to increased levels of white light and oxygen. Studies in this model also show that darkness and, in particular, red light protect the eye against DFX toxicity. This is of potential use in patient management during DFX therapy.

Animals↗
PubMed1989

The flash stimulated VEP in the diagnosis of glaucoma.

The Visual Evoked Potential using pattern stimulation has been used in recent years as an attempt to make an early diagnosis of glaucoma. However because of the macular dominance of responses obtained by this method, only diseases involving the papillomacular bundle reveal abnormality; such conditions do not occur in glaucoma. In this study we report the use of the early component (P1) of the flash stimulated visual evoked potential in the diagnosis of primary open angle glaucoma. It appears to provide an objective, accurate and repeatable screening technique. The size of P1 correlates well with the size of optic disc cupping, and field loss. The relationships between systemic vascular disease, P1 reductions, and glaucoma, lend support to the ischaemic origins of the disease.

Adult↗
PubMed1989

Ocular toxicity of desferrioxamine--an example of copper promoted auto-oxidative damage?

Three patients with rheumatoid disease were given the 'iron chelating' drug desferrioxamine (DFX), which also has an appreciable affinity for copper. The drug was injected cautiously, in lower doses than in patients with thalassaemia, and intramuscularly to evaluate its anti-inflammatory effects. Two of the three patients developed ocular abnormalities. One patient, who also received methyldopa, developed severe but reversible visual failure associated with an abnormal electro-oculogram (EOG); another showed reversible depression of the EOG. Analysis of the cerebrospinal fluid (CSF) of this patient showed an increase in phenanthroline detectable (non-caeruloplasmin-bound) copper. Analysis of the CSF of the third patient, who did not develop any clinical or electrophysiological ocular abnormalities, was normal. Haematological assessments indicated that all three patients probably had reduced iron stores. With in-vitro systems DFX was shown to mobilise copper from albumin and to facilitate copper movement across a cell membrane model, a property that was enhanced by methyldopa. Our observations are consistent with the concept that in rheumatoid patients low iron stores may result in binding of copper by DFX and that this may be of central importance in causing the ocular toxicity of DFX.

Aged↗
PubMed1989

Value of the ERG in congenital nystagmus.

A group of 64 children with poor vision and early onset nystagmus were investigated retrospectively by the electroretinogram (ERG). Fifty-eight of these children also underwent analysis of the visual evoked potential (VEP), and 40 underwent colour vision analysis. Seventeen children were found to have complete congenital achromatopsia (rod monochromatism), being identified by their total colour blindness, reduced visual acuity, and reduced or absent photopic and flicker (30 Hz) ERGs. Two children with incomplete X-linked congenital achromatopsia were also found. This study identified the need to investigate children with nystagmus by means of the ERG and suggested that the ERG was useful where the diagnosis was uncertain, particularly at early school age. The incidence of congenital achromatopsia in a group of otherwise undiagnosed children with early onset nystagmus was high (29%), with 40% being classified as having congenital idiopathic nystagmus.

Adolescent↗
PubMed1986

Stimulus investigative range in the perimetry of retinitis pigmentosa: some preliminary findings.

The manipulation of perimetric stimulus parameters over a given dynamic range has been reported to provide diagnostic information additional to that of changes in differential sensitivity. Preliminary studies (Flanagan et al., 1984a) have indicated that the perimetric response in retinitis pigmentosa behaves atypically over a range of stimulus combinations and strategies. The current study investigated the perimetric response of 17 retinitis pigmentosa patients of various genetic types over a range of stimulus parameters (target size, presentation time and background luminance) and test strategies (kinetic and threshold static) using the Octopus automated perimeter, the Goldmann and Tubinger bowl perimeters and the Dicon Autoperimeter 3000. Statokinetic dissociation was found to be present with large target sizes at 10 asb and 31.5 asb bowl luminances. Some patients demonstrated enhanced sensitivity to shorter stimulus presentations.

Adult↗
PubMed1986

The interpretation of the differential threshold in the central visual field.

Computer assisted perimetry has revolutionised the investigation of the visual field. Experience of central field assessment with the Octopus Automated Perimeter shows that sensitivity recorded with target size 3 across all age groups can frequently be greater than the published normative values. Use of the latter values can therefore provide a serious underestimation of field loss. Inter-individual variation in sensitivity is found within and between age groups. The limitations associated with the use of the measurement error to define abnormality and the additional problems of hypernormal thresholds and resolution of the blind spot are discussed. It is suggested that methods should be developed to evaluate sensitivity on an intra-individual basis.

Adolescent↗
PubMed1985

Manipulation of sensitivity in visual field investigation.

Sophistication of computer software and flexibility of stimulus and background luminance parameters in static perimeter design offer the opportunity for increased information in the assessment of the visual field. Relationships between dynamic ranges and resulting sensitivity gradients in a group of 10 normal 21 year old subjects using the Octopus automated perimeter, the Dicon Autoperimeter 2000 and the Friedmann VFA II are assessed. Inadequacies in the use of normative data to assess the visual field are noted. Implications for the use of dynamic range/sensitivity gradient relationships in visual field assessment without reliance on normative data are discussed.

Adult↗
PubMed1985

Cerebral and ocular toxicity induced by desferrioxamine.

Seven patients with rheumatoid disease were given the iron-chelating drug desferrioxamine (DFX) to evaluate its possible anti-inflammatory effects. Two of these patients, who also received the anti-emetic prochlorperazine, lost consciousness for 48-72 h and then fully recovered. Electroencephalography showed abnormalities of the type associated with metabolic disturbance. One of these patients showed pyramidal features and subsequently developed an optic neuropathy and pigmentary retinopathy. Analysis of his cerebrospinal fluid showed a decrease in loosely-bound (catalytic) iron and increase in loosely-bound (catalytic) copper, total iron and products of lipid peroxidation, with values approaching normal as the symptoms resolved. Subsequent in vivo/vitro studies clearly demonstrated that the neurological effects were due to a synergistic action of desferrioxamine and prochlorperazine, probably resulting in exceptional fluxes of intra/extra cellular iron/copper disturbing noradrenergic and serotonergic systems. Two other patients who did not receive prochlorperazine, developed retinal problems which later improved, one after only 15 g of desferrioxamine. Our observations suggest a new model for metabolic encephalopathy studies and provide insight into the mechanisms of pigmentary retinopathy.

Adult↗
PubMed1984

The qualitative comparative analysis of the visual field using computer assisted, semi-automated and manual instrumentation: I. Scoring system.

Previous methods for the qualitative evaluation of visual field instruments are subject to certain limitations. A system is proposed to overcome these deficiencies. It has been developed from experiences of a clinical study involving 5 different visual field instruments. The method uses 4 levels of analysis and permits separate appraisals of diagnostic potential and detailed inter-instrument comparative evaluation.

Computers↗
PubMed1984

The qualitative comparative analysis of the visual field using computer assisted, semi-automated and manual instrumentation: II. Statistical analysis.

A comparative evaluation of the Octopus automated perimeter (Programmes 21 and 31), the Goldmann Bowl perimeter, the Bjerrum Screen and the Friedmann VFAs MkI and MkII was carried out on a heterogeneous sample of 75 patients. The results for the sample as a whole were analysed statistically in terms of the scoring system developed by Flanagan, Wild, Barnes, Gilmartin, Good and Crews (1984a). Statistically significant differences between the instruments were found at each of the 4 levels of analysis.

Adolescent↗