Biomedical subjects
S M Davis
Publications and source records attributed to S M Davis.
Streptokinase in acute ischaemic stroke. Steering Committees of the ASK and MAST-E trials. Australian Streptokinase Trial.
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Trials of streptokinase in severe acute ischaemic stroke.
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Prediction of functional outcome and tissue loss in acute cortical infarction.
OBJECTIVE: To compare the acute Allen's Prognostic Score, Canadian Neurological Score, and subacute Barthel Index as predictors of outcome functional status and infarct size at 3 months in patients with acute cortical infarction. DESIGN: A prospective study of acute stroke predictors and outcome measurements in a cohort of sequential hospitalized patients. PATIENTS: Fifty-one patients with acute cortical infarction and without previous disability assessed 24 hours after onset with Allen's Prognostic Score and the Canadian Neurological Score and at 7 days with the Barthel Index. MAIN OUTCOME MEASURES: Mortality, Barthel Index, and volumetric measurement of infarct size on computed tomography 3 months after stroke. RESULTS: There were seven deaths. The outcome Barthel Index was measured in all 44 survivors, of whom 29 had computed tomography at the time outcome was determined. In a multivariate analysis, functional outcome was best predicted by Allen's Prognostic Score, a score of less than -15 having a sensitivity of 82% and specificity of 97% in predicting a poor outcome (Barthel Index, < or = 12 or death). Volumetric tissue loss was predicted only by Allen's Prognostic Score (r = .62, P < .001). CONCLUSIONS: Allen's Prognostic Score is a robust predictor of both functional outcome and tissue loss in acute cortical infarction and has a potentially important role in the analysis of the results of acute stroke intervention trials.
Tobacco use: baseline results from pathways to health, a school-based project for southwestern American Indian youth.
BACKGROUND: This paper describes a school-based cancer prevention project for fifth- and seventh-grade Navajo and Pueblo Indian children living in the Southwest. Baseline data are presented from 714 students who completed questionnaires on smoking and smokeless tobacco. METHODS: Questionnaires were administered in the fifth- and seventh-grade classrooms prior to students receiving the Pathways to Health cancer prevention curriculum. RESULTS: In our sample there were increases from fifth to seventh grade in self-reported current cigarette use and intention to use. Also, boys were more likely to use and intend to use cigarettes than girls. The use of smokeless tobacco also increased with increasing grade level, though this trend was less pronounced for girls. A significant gender difference was found in the use of smokeless tobacco with boys reporting higher use. However, reported use by girls was higher than is typically noted for non-Hispanic white girls. CONCLUSIONS: There is evidence of experimentation and regular use of tobacco products by both Navajo and Pueblo boys and girls. Even more students indicate intention to use tobacco products in the future. These data confirm the need for primary prevention programs designed for this population of American Indians.
Thrombolytic therapy for basilar artery thrombosis in the puerperium.
A case is presented of a woman in whom basilar artery thrombosis developed 14 days post partum. She was successfully treated with intraarterial urokinase. This case demonstrates that complete neurologic recovery can be achieved after recanalization of the basilar artery with thrombolytic therapy.
An investigation into nurses' understanding of health education and health promotion within a neuro-rehabilitation setting.
This qualitative study was undertaken at two neuro-rehabilitation centres in England, with the aim of exploring the nurses' understanding of health education and health promotion and their role within it, and their perception of illness and wellness related to disability. The principle of methodical triangulation was employed using questionnaires, group interviews and content analysis of client care plans. Although the nurses had difficulty distinguishing between health promotion and health education, differences did emerge which were supported by the literature. The nurses generally identified their role as being one of health promotion. However, they tended to equate wellness with physical independence. As a result of the study a health promotion model based on the principles of self-empowerment is suggested, which could be used as a framework for rehabilitation nurses and other professionals to enable them to focus on health and wellness rather than illness and disability.
The incidence of juvenile dermatomyositis: results from a nation-wide study.
There have been no previous attempts to estimate the incidence of juvenile dermatomyositis (JDM) in the UK and Ireland. Consultant paediatricians from these countries were asked to report all cases of JDM which were diagnosed in 1992 and 1993 to the British Paediatric Surveillance Unit. One-hundred-and-twenty-one reports were received, of which 48 were confirmed cases of JDM and three were confirmed cases of polymyositis. The estimated incidence of JDM was 1.9 per million children aged under 16 yr (95% confidence interval 1.4-2.6). The median age at onset was 6.8 yr and the median delay in diagnosis was 4 months. Girls were affected much more often than boys (ratio 5.0:1). In the cases with an onset in 1992 there appeared to be a cluster of cases with an onset in April and May.
Crossed cerebellar diaschisis and brain recovery after stroke.
BACKGROUND AND PURPOSE: Although crossed cerebellar diaschisis is well recognized after stroke, there is controversy concerning its clinical correlations and serial changes, and little is known about its prognostic value. METHODS: We studied crossed cerebellar diaschisis and cerebral hypoperfusion in 47 patients with acute middle cerebral cortical infarction using 99mTc-hexamethylpropyleneamine oxime and single-photon emission computed tomography within 72 hours of stroke onset. Thirty-one of these patients had outcome studies at 3 months; 15 of the 31 underwent an additional scan after acetazolamide injection. Tissue loss was determined with computed tomography, performed at outcome in 28 patients. Clinical stroke severity was assessed with the Canadian Neurological Scale and Barthel Index. Cerebellar blood flow asymmetry was studied in 22 healthy, age-matched control subjects. RESULTS: Cerebellar blood flow asymmetry was significant in patients (mean +/- SE, 9.76 +/- 0.78%; P < .001) but not in control subjects (-0.22 +/- 0.56%). Crossed cerebellar diaschisis was strongly associated with infarct hypoperfusion volume at both acute (regression coefficient +/- SEb, b = 6.76 +/- 0.65; P < .001) and outcome stages (b = 6.13 +/- 0.63; P < .001). Cross-sectionally over the first 72 hours, infarct hypoperfusion volume decreased by 2% for each hour from onset (P < .05), while crossed cerebellar diaschisis remained unchanged. Canadian Neurological Scale score at the acute stage was negatively associated with acute crossed cerebellar diaschisis (b = -0.10 +/- 0.05; P < .05) after allowing for infarct hypoperfusion volume. Crossed cerebellar diaschisis did not change between acute-stage, outcome, and postacetazolamide scans. Acute-stage crossed cerebellar diaschisis predicted outcome Barthel Index score (b = -0.28 +/- 0.14; P = .05) and tissue loss (b = 3.81 +/- 0.96; P < .001) but was no longer an independent prognostic factor after allowing for acute-stage infarct hypoperfusion volume. CONCLUSIONS: This study shows that crossed cerebellar diaschisis is a functional phenomenon that correlates with both stroke severity and infarct hypoperfusion volume and persists despite neurological recovery. Although acute-stage crossed cerebellar diaschisis has no prognostic value independent of acute-stage hypoperfusion volume, it might indicate the proportion of nutritional to nonnutritional perfusion at the infarct site and hence be useful in the evaluation of reperfusion therapies in the acute stage.
Risk factors for lacunar infarction syndromes.
BACKGROUND AND PURPOSE: Lacunar infarction is an important stroke subgroup with unique clinical and pathologic features, but its relative risks for associated risk factors have been rarely documented. To address this matter, we studied 203 consecutive patients with first-ever stroke due to lacunar infarction admitted to four general hospitals during the period 1985 to 1992. METHODS: We obtained information concerning risk factor exposure status among the patients by interview using a structured questionnaire and by comparison with age- and sex-matched neighborhood controls. Odds ratios were estimated with adjustment for confounding variables by using multivariate logistic regression. RESULTS: Significantly increasing the risk of lacunar stroke were hypertension (with an odds ratio of 8.9 [95% confidence intervals 4.2, 18.8]), current smoking (6.6 [2.9, 14.8]), and diabetes (2.3 [1.0, 5.5]), whereas frequent physical exercise was associated with a significantly decreased risk (0.3 [0.1, 0.7]). There was no risk of lacunar stroke associated with heart disease (odds ratio 1.0 [0.5, 1.9]). CONCLUSIONS: Patients with hypertension or diabetes, and those who currently smoke, are at a higher risk of lacunar stroke, whereas those who undertake regular physical exercise may be at lower risk. The high risk associated with hypertension but absent risk with heart disease supports the "lacunar hypothesis" of a unique pathophysiologic mechanism for lacunar stroke.
Reperfusion after thrombolytic therapy in ischemic stroke measured by single-photon emission computed tomography.
BACKGROUND AND PURPOSE: We used 99mTc-hexamethylpropyleneamine oxime single-photon emission computed tomography (SPECT) to study cerebral perfusion in patients treated with streptokinase for acute ischemic stroke in an open and prospective study. Our primary aims were (1) to compare the extent of reperfusion between patients who had received thrombolytic therapy and a control group studied during the same period who were ineligible to receive such therapy and (2) to determine if, among all patients, reperfusion led to improved outcome. METHODS: Fifty-seven patients (22 treated with streptokinase) had two SPECT studies performed, the first before streptokinase administration and the second 24 hours later. RESULTS: On the first SPECT study hyperfusion was present in the middle cerebral artery or anterior cerebral artery territories in 40 patients (17 treated with streptokinase). Patients in the treatment and control groups with initial hypoperfusion on SPECT were well matched for the volume of the perfusion defect and the severity of neurological deficit. A greater number of patients who received streptokinase developed at least partial reperfusion (streptokinase, 65%; control, 52%) on the second study but not significantly so (P = .43). Similarly, the proportion of each hypoperfused region that reperfused (P = .74) and the reduction in the size of the perfusion defect (P = .06) were higher in the streptokinase group but did not reach statistical significance. When all patients were considered, those who did not reperfuse had higher mortality rates (P = .008), less neurological improvement (P = .016), and more functional disability (P < .001) than patients who had reperfusion or normal perfusion initially. CONCLUSIONS: These findings suggest that at least some reperfusion during the first 48 hours of ischemic stroke is a common natural occurrence and is of prognostic significance. The observed trend toward better reperfusion indexes among patients treated with streptokinase is encouraging, but larger controlled trials are required to answer this definitively.
The potential for elderly donors to increase renal transplantation rates in Australia.
OBJECTIVE: To estimate the potential increase in renal donation rates if elderly donors (those over 60 years of age) were considered. DESIGN: Patients dying from acute brain damage resulting from stroke were identified using the Royal Melbourne Hospital (RMH) Stroke Service Register. Their records were retrospectively analysed to assess their eligibility as potential renal donors. SETTING: One hundred and ninety-eight patients dying from acute brain damage caused by stroke at a large metropolitan teaching hospital (RMH), from May 1987 to December 1990 inclusive. PATIENT ASSESSMENT: Patients were considered "eligible", "ineligible" or "possibly eligible" (requiring further assessment) as donors according to existing strict criteria (see methods) but irrespective of age. RESULTS: Of 198 stroke patients dying of brain damage, 92 satisfied the criteria of eligibility for renal donation; 51 of these were over 60 years old, yet only one became a renal donor. CONCLUSION: There is good evidence that elderly donors are acceptable for renal transplantation, yet they are not being referred. The consideration of elderly stroke victims as renal donors could have a dramatic effect on decreasing transplant waiting lists, increasing recipient patient well-being, and reducing hospital costs.
Cerebral hypoperfusion in stroke prognosis and brain recovery.
BACKGROUND AND PURPOSE: The value of acute cerebral blood flow measurements in stroke prognosis is controversial. No previous study has determined whether acute perfusion deficits independently add to a validated clinical prognostic score. We aimed to compare the value of acute hypoperfusion deficits with a quantitative clinical score in stroke prognosis and to correlate the changes in perfusion with brain recovery. METHODS: Volumetric analysis of regional hypoperfusion was performed in 38 patients with middle cerebral infarction within 72 hours of onset by use of single photon emission computed tomography and 99mTc hexamethylpropylene amine oxime. Stroke severity was assessed by the Canadian Neurological Score and Barthel Index. Allen's prognostic score was determined acutely in all patients. Clinical outcome was evaluated in 36 of 38 patients, of whom 18 had repeat blood flow studies. RESULTS: Acute hypoperfusion correlated with both the outcome Barthel Index (P < .001, r = -.61) and Canadian Neurological Score (P < .001, r = -.64). Allen's score correlated better with both the outcome Barthel Index (P < .001, r = .80) and Canadian Neurological Score (P < .001, r = .81). Acute hypoperfusion deficits, after allowing for Allen's score, independently predicted neurological but not functional outcome. Despite overall neurological improvement, mean hypoperfusion increased on the repeat blood flow studies (P < .05). CONCLUSIONS: Volumetric analysis of acute regional hypoperfusion within 72 hours of onset predicts stroke outcome after 3 months, but Allen's score is a better prognostic method. Neurological recovery is not associated with chronic infarct reperfusion.
Hematologic abnormalities occur in both cortical and lacunar infarction.
BACKGROUND AND PURPOSE: Primary hematologic abnormalities are a rare but established cause of ischemic stroke. In addition, activation of hemostatic parameters is often present during the acute phase of stroke. However, it is uncertain whether these abnormalities occur in both cortical and lacunar infarction; this study aimed to further assess this issue. METHODS: Hematologic parameters (prothrombin, activated partial thromboplastin, thrombin clotting, and euglobulin lysis times; and fibrinogen, fibrinopeptide A, antithrombin III, protein C, protein S, and plasminogen levels) were measured in 19 patients within 48 hours of the onset of acute cerebral infarction. These patients included 10 with cortical infarcts and 9 with lacunar infarcts, as determined by standard clinical and radiological criteria. RESULTS: Five patients with lacunar infarction and 7 patients with cortical infarction demonstrated raised fibrinopeptide A levels, indicating enhanced thrombin activity. Fibrinolysis, assessed by the euglobulin lysis time, was impaired in 6 of 9 patients with lacunar infarction and in 2 of 10 patients with cortical infarction. Lupus anticoagulants were detected in 3 patients with lacunar infarction and in 1 patient with cortical infarction. Three patients in each group displayed decreased antithrombin III function, and 1 patient with a lacunar infarction had a low protein C level. CONCLUSIONS: Primary hematologic disorders and secondary hemostatic derangements may occur in patients with either cortical or lacunar infarction.
Early seizures after acute stroke. Risk of late seizures.
The prognosis of early seizures after stroke is controversial. We assessed the incidence of late seizures in 31 patients with early seizures complicating acute stroke and compared this with the incidence of late seizures in 31 matched patients with stroke without early seizures. Ten (32%) of 31 patients with early seizures had late seizures during a mean follow-up period of 26 months. Only three (10%) of 31 patients without early seizures had late seizures during the follow-up period of 28 months, a significantly lower incidence than in patients with early seizures. The risk of seizure recurrence in patients with early seizures did not correlate with stroke type or lesion size as imaged on the computed tomographic scan. We conclude that early seizures are not benign and are associated with a significant risk of seizure recurrence.
Acute stroke outcome: effects of stroke type and risk factors.
We studied 925 consecutive patients hospitalised with acute stroke to determine how stroke type, age, gender and risk factors influence acute, in-hospital outcome. Stroke types included carotid territory cortical or large subcortical infarction (52%), vertebrobasilar infarction (12%), lacunar infarction (11%), intracerebral haemorrhage (16%), and subarachnoid haemorrhage (9%). Mean age (mean +/- 1 SD) was 66 +/- 15 years, but patients with cerebral infarction were older than those with cerebral haemorrhage. The prevalence of hypertension, diabetes mellitus and cardiac disease increased with age across all stroke types, while the prevalence of smoking decreased with age. Mortality was 19% overall, but varied significantly between stroke types, highest in intracerebral haemorrhage (34%), and lowest in lacunar infarction (1%). Age had a marked adverse effect on mortality, independent of stroke type, the probability of death increasing by 3 +/- 0.5% per year from 20-92 years, whereas gender had no effect. Cardiac disease and diabetes were independent adverse prognostic factors (Odds Ratios 1.6 and 1.5 respectively). Cerebral haemorrhage, age, cardiac disease and diabetes all independently worsen acute stroke outcome.