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Biomedical subjects

W G Snow

Publications and source records attributed to W G Snow.

At least 19 recordsLinked to original sources
PubMed1994

Cardiopulmonary bypass, temperature, and central nervous system dysfunction.

BACKGROUND: Neurological injury is an important cause of morbidity and mortality after cardiac surgery. With the advent of warm heart surgery, the neuroprotective role of hypothermic cardiopulmonary bypass (CPB) has come under increasing scrutiny. Preliminary work by us in the area found no increased risk of neurological morbidity with normothermic CPB in a small group of patients and suggested a possible benefit. The purpose of the present study is to compare the incidence of neurological and neuropsychological dysfunction in a larger number of patients randomized to warm or cold aortocoronary bypass surgery. METHODS AND RESULTS: With the approval of the institutional research ethics committee, 201 aortocoronary bypass patients were randomized to normothermic or moderate hypothermic CPB and subjected to neurological and neuropsychological evaluation. These subjects were a subset of patients enrolled in a large multicenter trial comparing warm versus cold heart surgery. The examinations took place preoperatively, 5 days after operation, and a 3-month follow-up. The examination consisted of a clinical neurological examination and a brief neuropsychological test battery. The neuropsychological tests included the Buschke selective reminding procedure, the Wechsler memory scale-revised visual reproduction subtest, the trial making test (parts A and B), the Wechsler adult intelligence scale-revised digit symbol subtest, and the grooved pegboard test. The examiner and subjects were unaware of the CPB temperature allocation (warm, > 34 degrees C; cold, < or = 28 degrees C). Statistical analysis was performed using the SAS statistical software package. Two hundred one patients were enrolled in the study. Of these, 155 patients completed the entire protocol and were included in the final analysis (warm group, n = 78; cold group, n = 77). One patient in the warm group died perioperatively from a massive hemispheric stroke. Another warm group patient was unable to complete neuropsychological evaluation because of a perioperative stroke. Thus, 153 patients completed the entire series of neuropsychological tests. A total of 6 patients (warm group, n = 2; cold group, n = 4; P = NS) suffered from perioperative focal neurological deficits. There was a consistent deterioration in scores from tests of psychomotor speed/coordination (trial making, digit symbol, pegboard) in the early postoperative period, which resolved by the 3-month follow-up. Tests of memory (Buschke, Wechsler memory scale) showed no evidence of patient deterioration in the postoperative period. No difference was seen between the warm and cold groups. CONCLUSIONS: In this randomized trial of normothermic versus hypothermic CPB, we found deterioration in scores of tests of psychomotor speed but not of memory in the early postoperative period. We were unable to demonstrate any neuroprotective effect from moderate hypothermia in this patient population.

Blood↗
PubMed1992

Central-nervous-system dysfunction after warm or hypothermic cardiopulmonary bypass.

The increasing popularity of warm heart surgery led us to assess the effect of temperature during cardiopulmonary bypass (CPB) on neuropsychological function after coronary surgery. 34 patients enrolled in a randomised trial of normothermic versus hypothermic CPB were subjected to a battery of psychomotor and memory tests before and after their operations. The mean nasopharyngeal temperature for warm CPB was 34.7 (SD 0.5) degrees C and that for hypothermic CPB was 27.8 (2.0) degrees C. In all seven neuropsychological tests the postoperative scores were better in the warm CPB than in the hypothermic group, although only one difference achieved significance (trial-making test A; p less than 0.023). Thus, neurological function after normothermic CPB seems to be no worse than that after hypothermic procedures.

Body Temperature↗
PubMed1991

On the clinical value of the London Psychogeriatric Rating Scale.

The London Psychogeriatric Rating Scale (LPRS) was administered to 76 probable Alzheimer's patients, 59 patients with dementia unrelated to Alzheimer's, 102 neurologically normal subjects, and 27 patients with symptoms of both Alzheimer's and dementia of other etiologies. By examining the relationships among the four subscales of the LPRS and conducting factor analyses, it was demonstrated that the four subscales were not measuring different phenomena. The internal consistency of the full 36-item scale was high (Cronbach's Alpha = 0.96) indicating the total LPRS score provided a reliable global index of behavioral function. The total LPRS scores correlated with the independently administered Goldfarb Mental Status Examination scores (r = -0.79). The LPRS differentiated between the normals and the combined demented groups and between inpatients and outpatients. The LPRS continues to have clinical value for functional assessments in a non-intrusive manner. The LPRS may be particularly useful in situations where direct assessment of mental status is not practical.

Aged↗
PubMed1990

Sex differences among non-brain-damaged adults on the Wechsler Adult Intelligence Scales: a review of the literature.

We reviewed studies of the performance of non-brain-damaged men and women on the Wechsler Adult Intelligence Scales (i.e., the Wechsler-Bellevue, Wechsler Adult Intelligence Scale, and Wechsler Adult Intelligence Scale-Revised) to determine if there were sex differences on specific test items, on specific subtests, or on Verbal IQ, Performance IQ, or the Verbal-Performance Discrepancy score. There were sex differences on some items of each of the three measures, but the number of such differences was small. A number of studies suggested differences on subtests of these scales. A meta-analysis indicated that females tended to outperform males by about a third of a standard deviation on the Digit Symbol subtest, while males tended to outperform females to the same extent or greater on the Arithmetic and Information subtests. Finally, in the few studies on IQ or discrepancy-score differences, there was no evidence of any consistent differences between the sexes in the Verbal-Performance Discrepancy, although there was some tendency for males to obtain higher Verbal IQs. This review, therefore, does not suggest that there are any major differences between non-brain-damaged males and females on the Wechsler adult intelligence scales.

Brain Damage, Chronic↗
PubMed1989

Psychological, topographic EEG, and CT scan correlates of frontal lobe function in schizophrenia.

This study examined frontal lobe function in a group of 20 patients with schizophrenia, on and off medication, compared to 20 normals matched for age, sex, handedness, intelligence, and educational level. Schizophrenic patients generally did not perform as well as normals on the Wisconsin Card Sorting Test (WCST). Patients off medication performed less well on this test than those on medication. Those on medication did not perform as well as those off medication on the design and word fluency tests, which suggested that medications may affect various aspects of frontal lobe function differently. During the WCST, normal subjects demonstrated an increase in beta mean frequency of the electroencephalogram in frontal and centrotemporal regions which was not statistically significant in either schizophrenic group. This shift in beta mean frequency was found to correlate positively with performance on the WCST in normals, but not in patients. Patients with more negative symptoms tended to show a smaller increase in beta mean frequency during the WCST. Performance on the WCST was correlated negatively with ventricle-brain ratio in all subjects, suggesting that frontal lobe function might be related to computed tomographic measures in the normal population as well as in schizophrenic patients. There was no correlation with performance on the WCST and length of illness.

Adult↗
PubMed1989

WAIS-R test-retest reliability in a normal elderly sample.

We examined the 1-year test-retest reliability of WAIS-R Verbal, Performance, and Full-Scale IQs in a sample of 101 older normal individuals (mean age = 67.1). The respective Pearson rs were .86, .85, and .90. The median retest reliability coefficient for the WAIS-R subtests was .71. The test-retest reliability for the Verbal-Performance Discrepancy was .69. These data indicate that IQ scores are reliable in older normal individuals for this retest interval, but less confidence can be placed in the reliability of subtest scores and the Verbal-Performance Discrepancy.

Aged↗
PubMed1989

Dementia diagnosis.

Explore the source record for details and available documents.

Alzheimer Disease↗
PubMed1988

The NINCDS-ADRDA Work Group criteria for the clinical diagnosis of probable Alzheimer's disease: a clinicopathologic study of 57 cases.

Neuropathologic confirmation is required to validate the NINCDS-ADRDA Work Group criteria for the clinical diagnosis of Alzheimer's disease (AD). Neuropathologic inclusion and exclusion criteria for AD, however, are not uniform. The purpose of this investigation was to examine the confirmation rate for the Work Group criteria against differing neuropathologic criteria for AD. The sample consisted of 57 cases, 22 of which had received a clinical diagnosis of AD. Nine neuropathologic criteria for AD were applied in a blind fashion to each of the 57 cases. Our results indicated that, depending on the neuropathologic criteria applied, the clinicopathologic agreement ranged from 64% to 86%. These findings demonstrate the need for universally accepted neuropathologic and clinical criteria for AD.

Aged↗
PubMed1988

Demographic and medical characteristics of adult head injuries in a Canadian setting.

This study provides demographic and medical information about patients admitted with head injuries to Sunnybrook Medical Centre, Toronto, Ont., in 1978 and in 1982. Data are presented about patient age and sex, type and cause of accident, length of stay, extracranial complications, severity of head injury, frequency of use of various neurodiagnostic techniques and type of discharge placement. The costs of hospitalization for such patients, both in the Sunnybrook Medical Centre and for Canada as a whole, are estimated.

Adolescent↗
PubMed1987

Psychometric differentiation of dementia. Replication and extension of the findings of Storandt and coworkers.

In a previous investigation by Storandt and coworkers, a brief battery of four neuropsychological tests was found to accurately distinguish a sample of patients with senile dementia of the Alzheimer type (SDAT) from normal elderly persons. The present study examined the value of these tests in the distinction between SDAT and dementias of other etiologies. Our results replicated those of Storandt and coworkers in that these tests did distinguish normal persons from patients with both SDAT and other dementias. These tests, however, did not accurately differentiate among the dementias. These results indicate that assessment batteries utilizing additional procedures to supplement cognitive testing are indicated to more accurately discriminate among the dementias.

Aged↗
PubMed1987

Aphasia Screening Test performance in patients with lateralized brain damage.

Patients with lateralized stroke (N = 36) or tumor (N = 14) were compared in the frequency of errors on specific test items of the Aphasia Screening Test (Reitan, 1984). Right- and left-hemisphere damaged patients showed a statistically significant difference on only 1 of the 33 items of this measure. When items were categorized according to task type (e.g., spelling, reading, calculation, etc.) only 1 of 9 comparisons was significant. Several possible explanations for the lack of differences are discussed and suggestions offered for potential modifications to this measure.

Adult↗
PubMed1986

The differential diagnosis of Alzheimer's disease: conceptual and methodological issues.

The study of Alzheimer's disease is hampered by insufficient knowledge of its cause. It can best be described as a syndrome whose clinical and pathological features, and their associations over time, need to be more carefully examined. Issues which impede our understanding of this syndrome include the lack of: a singular "gold standard" for its identification; longitudinal studies with appropriate comparison groups and neuropathological follow-up; and standardized multifaceted clinical assessment procedures. Our awareness of the significance of these issues has led us to undertake a large-scale prospective, longitudinal investigation of 399 dementing and normal individuals at Sunnybrook Medical Centre. As a result of problems identified, it is proposed that research efforts across various Canadian centres be coordinated to best utilize available resources and expertise.

Alzheimer Disease↗
PubMed1986

Lateralized brain damage, sex differences, and the Wechsler Intelligence Scales: a reexamination of the literature.

Recent reviews have suggested that males and females show different patterns of intellectual impairment following lateralized brain injury. As the percentage of males in such studies increases, the magnitude of the difference between Verbal and Performance IQs increases. The present review reexamines this literature. Although the association between patient sex, pattern of intellectual deficit, and lateralized brain injury is reconfirmed for studies which used the Wechsler-Bellevue Intelligence Scale, there was no such relationship in those which used the more recent Wechsler Adult Intelligence Scale. In addition, it is shown that, in studies which used the former measure, the percentage of males may be highly correlated with other variables, a relationship which could have an effect on the pattern of intellectual loss following brain injury.

Adult↗
PubMed1986

Predictors and indicators of quality of life in patients with closed-head injury.

This study examined predictors and indicators of quality of life in 71 patients with closed-head injury (CHI), 2-4 years postinjury. Predictors included premorbid characteristics and acute injury-related data. Indicators included follow-up data, e.g., neuropsychological functioning. Exploratory canonical correlation analyses demonstrated that the combination of the predictor variable, initial Glasgow Coma Scale score, and indicator variables of neuropsychological data in the areas of motor functioning, memory, and constructional ability were related most strongly to quality of life as reported by the patients. Severity of head injury and motor disability also related strongly to quality of life, based on reports by relatives (n = 68) on the Katz Adjustment Scale (Relatives' Form). These findings suggest that quality of life is adversely affected by increased severity of head injury and greater residual motor deficits. Implications of these findings for treatment and recovery are discussed.

Adolescent↗
PubMed1986

Quality of life in patients 2 to 4 years after closed head injury.

This study evaluated quality of life in 78 patients with closed head injury (CHI) 2 to 4 years postinjury. Using both interview data and mean data from the Sickness Impact Profile questionnaire, impaired quality of life was observed in the areas of psychosocial functioning, social role functioning, leisure activities, and, to a lesser extent, physical functioning, during chronic phases of recovery. Relatives and close friends reported by means of the Katz Adjustment Scale that the CHI patients showed a series of negative behavioral symptoms 2 to 4 years postinjury. These data suggest that CHI patients may experience impaired quality of life in a number of domains well beyond the acute postinjury phases. An attempt was also made to compare patients' and relatives' reports of patient quality of life. Preliminary analyses indicated modest correspondence between relatives' and patients' ratings of some areas of postinjury dysfunction, including cognitive and behavioral slowing and social withdrawal.

Activities of Daily Living↗