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Biomedical subjects

J Marshall

Publications and source records attributed to J Marshall.

At least 739 records · Page 41Linked to original sources
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Computed tomography in patients presenting with lacunar syndromes.

Of 312 stroke patients who had a CT scan, 37 had presented clinically with a lacunar syndrome. In 18 of the 37, lacunar sized infarcts were demonstrated on the scan, 13 had normal scans and in 6 large infarcts were found. Of these 6.5 and a pure motor hemiplegia and one a pure sensory stroke. Clinical evidence and angiography revealed a potential and treatable source of emboli in both the lacunar sized and the large infarcts. Two conclusions are drawn: a clinical lacunar syndrome may be associated with large infarct; demonstration of a lacunar infarct on CT scan does not exclude the need for angiography in appropriate cases to discover a possible source of emboli.

Ataxia↗
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Transient ischemic attacks and strokes with recovery prognosis and investigation.

This study analyzes 234 patients who recovered from an initial ischemic episode. The object was to see if the duration of the first episode influenced the chance of finding a treatable lesion or the chance of a further episode. The initial episodes varied from less than 5 minutes to longer than 3 weeks. There seemed to be no fundamental difference between transient ischemic attacks (TIAs) (less than 24 hours) and strokes which recover. However, 51% of those whose initial episode lasted less than 5 minutes had a subsequent stroke compared to 28% of those with an initial episode of more than 24 hours duration. Thirty percent of the former group who had angiograms had an operable lesion against 10% in the latter group. It seems that angiography has sufficiently high yield to be warranted in all patients where the initial attack lasted less than 30 minutes. In those with longer attacks the yield from angiography was much lower and noninvasive techniques should be considered in these patients, where available, prior to consideration for angiography. Investigation should be based on the degree of functional recovery and not on the arbitrary time division which normally divides TIAs and strokes. Bruits were the most reliable clinical indicators of stenosis. However the presence of intermittent claudication, hypertension and age over 50 were all more common in those with carotid stenosis.

Aged↗
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Prognostic significance of severity of carotid atheroma in early manifestations of cerebrovascular disease.

Two hundred and fifteen patients with transient ischaemic attacks, reversible ischaemic neurological deficit, or completed stroke were studied angiographically. The appearances of the carotid bifurcation were classified as normal, irregular, stenosed or occluded and the possible prognostic significance of the angiographic categories sought in a follow up study. Over a mean follow up period of 4.1 years 12% of patients were found to have died, and 10% had had a stroke. Fourteen percent had TIAs and 5.1% had sustained a myocardial infarction. Mortality and stroke risk were greatest with carotid occlusion which was least often followed by TIAs. Strokes, but not TIAs, were less frequent in the presence of normal angiograms.

Arterial Occlusive Diseases↗
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Prognosis in middle cerebral artery stenosis.

Among 21 patients with angiographically demonstrated stenosis of the middle cerebral artery (MCA) 14 presented with a stroke and 7 with transient ischaemic attacks (TIAs). Of the former 4 had further strokes (3 fatal); of the latter one had a fatal stroke. Only 2 of the 21 patients had TIAs during the follow-up period. The present study indicates that the prognosis for patients with MCA stenosis is less good than the literature suggests. There is appreciable risk of fatal stroke especially in those who present with a stroke. This perspective is important when deciding on the need for EC/IC bypass.

Adult↗
PubMedDate not supplied

Atrial fibrillation, TIAs and completed strokes.

A retrospective survey of 1076 patients with completed strokes and 789 with transient ischemic attacks (TIAs) revealed that 5.6% of those with completed strokes but only 1.6% of those with TIAs were in atrial fibrillation. TIAs in the presence of atrial fibrillation tended to last longer than 60 minutes except in individuals who had coexistent carotid disease that might have been the source of their attacks. It is suggested that emboli from the fibrillating atrium rarely cause brief TIAs, and more usually cause 'long' TIAs or completed strokes.

Adult↗
PubMedDate not supplied

Arteriographic comparison of amaurosis fugax and hemispheric transient ischaemic attacks.

The results of carotid angiography were compared in 53 patients with amaurosis fugax and 92 with hemispheric transient ischaemic attacks (TIAs). Evidence of extracranial disease was found in 71% of those with retinal ischaemia and these patients rarely had evidence of intracranial disease (11%) or normal angiograms (15%). By contrast patients with hemispheric symptoms less frequently showed disease of the cervical carotid artery (36%) and more often had intracranial disease (27%) or normal angiograms (35%). It is suggested that amaurosis fugax is usually due to emboli originating in the internal carotid artery but that the pathogenesis of cerebral TIAs in the carotid territory is more heterogeneous. These conclusions have implications for the design and interpretation of both medical and surgical trials.

Adult↗
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Clinical identification of TIAs due to carotid stenosis.

A retrospective case note survey of 139 cases of carotid territory TIAs was carried out. Angiographic evidence of carotid stenosis was more frequently encountered when the patient's attacks consisted of symptoms suggestive of ischemia of small cortical territories with involvement restricted to the arm or leg or to dysphasia. Attacks of hemiparesis affecting face, arm and leg, or arm and leg were less often associated with carotid stenosis. If patients described any attacks of a restricted nature the chance of finding carotid stenosis was 47%, if not 16%. It is argued that these findings are a reflection of the varied pathogenesis of TIAs, and the relevance of this heterogeneity to the interpretation of clinical trials is briefly mentioned.

Arterial Occlusive Diseases↗
PubMedDate not supplied

No evidence for transhemispheric diaschisis after human cerebral infarction.

Forty-four studies of regional cerebral blood flow (rCBF), fractional oxygen extraction (rOER) and oxygen consumption (rCMRO2) were made on twenty-five patients with recent internal carotid artery territory infarcts. The purpose was to study flow-metabolism relationships in the contralateral hemispheres, and to investigate whether contralateral rCMRO2 was depressed as a result of the recent infarcts. Two groups of controls were included for comparison--seventeen normal volunteers, and ten patients with proven extracranial cerebrovascular disease but without evidence of cerebral infarction. The results demonstrated that: contralateral hemispheric rCMRO2 was less variable than regional oxygen availability (the product of rCBF and arterial oxygen content). This was due, in part, to the effect of individual variations in PaCO2 on rCBF, but other uncontrolled factors, such as intracranial pressure, may have had influences. As a result, rCMRO2 did not correlate with rCBF; mean rCMRO2 in the contralateral hemispheres was 12% lower than normal (a significant difference), but was not different from the value found in patients with extracranial vascular disease in whom there was no evidence of infarction or ischemia; contralateral rCMRO2 did not correlate with the size of the infarct in the opposite hemisphere. It is concluded that rCMRO2 cannot be inferred from rCBF measurements in uncontrolled human studies (as frequently done in the past), and that depression of contralateral rCMRO2 may have preceded infarction in the opposite hemisphere, a consequence of the previous influences of diseases that predispose to stroke.

Adult↗
PubMedDate not supplied

Diurnal variation in occurrence of strokes.

The time of onset of a completed stroke was recorded in 707 patients. Of the 554 cerebral infarctions 40% occurred between midnight and 6 a.m. Onset at night was, if anything, less common among the 153 cases of cerebral hemorrhage.

Blood Pressure↗
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Variations in mean cerebral blood flow under anesthesia at rest and during cortical activation.

More than one cerebral blood flow (CBF) measurement was performed on the same occasion in three groups of patients using the intracarotid 133Xenon technique. In the anesthetized group there was a highly significant reduction in CBF (mean = 24.3%) from the first to the second measurement. In those at rest under local anesthesia there was also a significant fall (mean 9.8%). The third group, who were stimulated during the second estimation, showed no change. A second CBF determination some time after beginning a study is recommended, especially in pharmacological studies, to provide a more reliable resting control, rather than the first value which represents flow in an "activated" brain which has not yet adapted fully to its new environment.

Adolescent↗
PubMedDate not supplied

Ocular hypotensive effects of cholinergic and adrenergic drugs may be influenced by prostaglandins E2 in the human and rabbit eye.

PURPOSE: Increased PGE2 production by the iris and ciliary body regulate intraocular pressure (IOP) in vivo. Various cholinergic and adrenergic compounds are traditionally used as antiglaucoma drugs, and their effect on IOP reduction is antagonised by cyclooxygenase inhibitors, indicating a role for eicosanoids in their hypotensive activity. One of the most potent antiglaucoma drugs, PG2 alpha (Latanoprost), reduces IOP by increasing uveoscleral outflow and also increases PGE2 production by the iris and ciliary body in vivo. We investigated whether cholinergic and adrenergic antiglaucoma drugs induce the production of prostaglandin E2 (PGE2) in vitro by: 1) the iris-ciliary body (ICB) of rabbits and, 2) irises of glaucoma patients. METHODS: Pilocarpine 2%, epinephrine 1% and echothiophate iodide 0.125% were applied topically to both eyes of Albino rabbits. Control groups were treated with the corresponding vehicles, or untreated completely. Human iris specimens were obtained from nine untreated cataract eyes, and five eyes under antiglaucoma medication undergoing surgery. PGE2 were determined by a radioimmunoassay. RESULTS: PGE2 production by the ICB of treated rabbits in vitro was twice that of vehicle-treated or untreated rabbit eyes (p<0.001, for either group). In vitro PGE2 production by treated glaucoma patients' irises was three times higher (p<0.001) than in cataract control patients. CONCLUSIONS: The study found an increase in in vitro production of PGE2 by the irises of eyes treated with cholinergic and adrenergic antiglaucoma medications. This suggests a role for endogenous PG production in the hypotensive effect of both classes of drug.

Administration, Topical↗
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Corneal haze after excimer laser refractive surgery: objective measurements and functional implications.

Postoperative changes in corneal transparency is a major concern after PRK. Data were obtained from 69 human eyes treated with excimer laser photorefractive keratectomy in order to evaluate a relationship between objective measurements of corneal transparency and visual performance. A CCD-camera device was employed and by using polarizing filters the system could discriminate between reflected and scattered light. We observed two groups of postoperative behaviour in corneal transparency. Each group showed an increase in both scattered and reflected light signals with a maximum at around two months postoperatively. In the majority group (70%) this was followed by a subsequent decline of the scattered light signal, whereas the combined signal generated by reflected and scattered light showed a biphasic curve with a second peak at around 4 to 5 months postoperatively. In the minority patient group (30%) the timebase variations in pattern of both signals were indistinguishable throughout the period of observation. In all patients we observed a good correlation between the signal generated by scattered light alone and the reduction in the 5% contrast visual acuity performance, whereas correlation was poor when the combined signal of reflected and scattered light was considered. These disturbances in low contrast visual performance were only significant during the first three to four months postoperatively and thereafter most patients returned to their preoperative value. Eighteen percent of our patients discontinued topical steroids postoperatively. No differences in either corneal transparency or final refraction was observed. We consider that PRK is an effective form of refractive surgery and the marginal loss of corneal transparency should only be a problem during the first three or four months postoperatively.

Adult↗
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Night vision after excimer laser photorefractive keratectomy: haze and halos.

A series of 85 patients with myopia, up to -6.00D, was treated by photorefractive keratectomy (PRK), using a 5 mm diameter ablation zone. At six months, 38 patients (45%) reported slight disturbances of night vision, nine (11%) of whom had significant problems. Perturbations of night vision after PRK are seen as starbursts and halos around lights. Corneal haze produces the starbursts, which are usually transient. In contrast, halos are myopic blur circles and may be persistent. Using a computer program, halos after PRK were found to be significantly larger than those in emmetropes and myopes corrected with spectacles (p < 0.01). The halos were diminished by using either artificial pupils or negative lens over-correction. In patients with identical bilateral PRK corrections, except for the ablation zone size, the magnitude of the halo was less with 5 mm than 4 mm zones (p < 0.01). Patients treated with 5 mm reported fewer problems attributable to halo than with the 4 mm ablation diameters (p < 0.01). Halos and pupil diameters were measured in nine patients with significant impairment of night vision haze. Those with starbursts had small hyperopic shifts, minimal halos and high haze and light scatter measurements, whilst patients with halos had large hyperopic shifts, little haze and large pupil diameters. Patients with persistent halo problems benefited from either negative lens over-correction or miotics at night.

Adult↗
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Regression and wound healing after excimer laser PRK: a histopathological study on human corneas.

BACKGROUND: The results of excimer laser PRK are promising as more than 80% of eyes with up to -6.0 diopters of attempted correction have refractive results within 1.0 diopter of emmetropia. However, throughout the dioptric range some unexpected results have been observed with individual patients showing an aggressive wound healing response with excessive myopic regression and severe corneal haze. Unfortunately, only limited data are available about the cellular and extracellular responses in human corneas after PRK and this information is important to establish adequate postoperative pharmaceutical treatment. METHODS: We made a histopathological and immunohistochemical study on 20 human corneal samples from patients with severe corneal haze and myopic regression. The indirect immunofluorescence method was used for demonstration of collagen types I, III, IV laminin, chondroitin sulphate, dermatan sulphate, and keratin. RESULTS: All corneal specimens showed a hyperplastic epithelium. Histologically, most samples (16/20) showed mainly a loose lamination of extracellular material which could be identified as collagen type IV. The remaining four samples had newly synthesised collagen type III. CONCLUSIONS: Our histopathological results indicate that corneal wound healing after excimer laser PRK varies among individuals. In some people epithelial basement proteins, such as collagen type IV, are the main wound healing products, whereas in others mainly collagen type III is found postoperatively, which does not effect the synthesis of collagen type IV. This suggests the need for individually-tailored postoperative pharmaceutical treatment regimens.

Chondroitin Sulfates↗