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Biomedical subjects

S M Rao

Publications and source records attributed to S M Rao.

At least 73 records · Page 4Linked to original sources
PubMed1991

Multiple sclerosis: specificity of MR for diagnosis.

The specificity of magnetic resonance (MR) imaging in the diagnosis of multiple sclerosis (MS) has not been measured systematically. Conventional MR head images with sagittal localizer and axial multiple-echo sequences with long repetition times were obtained in 92 patients with clinically verified MS (Schumacher criteria), 100 healthy volunteers, 60 subjects with hypertension, and eight patients with dementia. Two readers, without the aid of any clinical or demographic information, classified each of the 260 studies as MS or not MS. The readers classified the studies again after being supplied with the subjects' ages and sex. True-negative and true-positive diagnoses of MS were tabulated. The specificity of the MR diagnosis of MS (true-negative results in proportion to all non-MS studies) was 95%-99% with all the control groups included. There is a small risk of misinterpreting incidental periventricular white matter foci as plaques of MS in MR studies.

Adult↗
PubMed1991

Cognitive dysfunction in multiple sclerosis. I. Frequency, patterns, and prediction.

Previous frequency estimates of cognitive dysfunction in multiple sclerosis have ranged from 54 to 65 percent. These studies may overestimate the frequency in the general MS population, since the patients in these studies were recruited from clinic populations. In the present study, we administered a comprehensive neuropsychological test battery to 100 community-based MS patients and 100 demographically matched healthy controls. Of 31 cognitive test indices examined, 48 MS patients and five controls were impaired on four or more test indices, yielding an overall frequency rate of 43% for the MS group. The pattern of cognitive decline was not uniform: MS patients were more frequently impaired on measures of recent memory, sustained attention, verbal fluency, conceptual reasoning, and visuospatial perception, and less frequently impaired on measures of language and immediate and remote memory. We developed a brief (20-minute) screening battery empirically by selecting the four most sensitive test indices from the comprehensive battery. The brief battery yielded a sensitivity value of 71% and a specificity value of 94% in discriminating cognitively intact from impaired MS patients, as defined by the comprehensive battery. Cognitive impairment was not significantly associated with illness duration, depression, disease course, or medication usage, but was significantly (albeit weakly) correlated with physical disability.

Adult↗
PubMed1991

Cognitive dysfunction in multiple sclerosis. II. Impact on employment and social functioning.

We designed a study to assess the specific contribution of cognitive dysfunction to multiple sclerosis patients' problems in daily living. Based on the results of a comprehensive neuropsychological test battery, we classified 100 MS patients as either cognitively intact (N = 52) or cognitively impaired (N = 48). In addition to a neurologic examination, MS patients completed questionnaires on mood and social functioning, underwent a comprehensive in-home occupational therapy evaluation, and were rated by a close relative or friend regarding specific personality characteristics. While there were no significant differences between the two groups on measures of physical disability and illness duration, patients in the cognitively impaired group were less likely to be working, engaged in fewer social and avocational activities, reported more sexual dysfunction, experienced greater difficulty in performing routine household tasks, and exhibited more psychopathology than cognitively intact patients. These findings suggest that cognitive dysfunction is a major factor in determining the quality of life of patients with MS.

Activities of Daily Living↗
PubMed1991

Situational factors associated with AIDS risk behavior lapses and coping strategies used by gay men who successfully avoid lapses.

While most gay men have reduced behavior practices at high risk for HIV infection, there is growing evidence that many also lapse to unsafe sex. This study examined situational factors related to risk behavior lapses as well as coping strategies used by men who successfully resist lapse urges. A convenience sample of 470 men patronizing gay bars or attending social organization meetings in four cities was surveyed. Forty-five percent of men were classified as "lapsers" (those who had had unprotected anal intercourse in the previous 6 months) and 24% were classified as "resisters" (those who successfully resisted urges to engage in this behavior). All provided information concerning the importance of factors related to the most recent occurrence of either unsafe sex or resisting unsafe urges. Most episodes of unsafe sex occurred outside monogamous relationships and with partners of unknown HIV serostatus, although simply inquiring about partner serostatus was relatively common. Lapsers rated affectionate feelings and wishing to please a partner as well as spontaneity of unsafe sex as the most important situational factors surrounding high-risk behavior. Resisters of unsafe sex urges reported active cognitive self-guidance, experience in safe sex, and recall of both AIDS fears and safety benefits as their most important coping strategies. Gay men who continue high-risk behavior may be overrelying on partner reports of negative serostatus. Lapse prevention approaches tailored to situations that create increased risk vulnerability must be developed. Teaching skills already used by men who successfully resist unsafe sex urges might be one approach.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Treatment of keloids by 90Sr-90Y beta-rays.

The use of radiations for the treatment of keloids was the topic of debate for years. Because of the benign nature of the keloids, surgery (keloidectomy) was treatment of choice. However, the use of surgery alone for arresting the keloids growth does not give satisfactory results due to the high frequency of recurrences. In this study 110 symptomatic cases were treated with 90Sr-90Y beta-radiation either alone for flat keloids or in combination with surgery for thick keloids. The results obtained with this method were found to be quite satisfactory. Patients were given four fractions of 5 Gy per fraction either as weekly or twice weekly schedules. Radiation dose of 2000 cGy given twice weekly in four fractions showed response in 86% of the cases as compared to 73% in those receiving four fractions of 5 Gy weekly. Further observations on different time dose fractionation schedules would open up newer dimensions in the radiotherapy of keloids.

Adolescent↗
PubMed1990

Rotation of the anatomic regions used for insulin injections and day-to-day variability of plasma glucose in type I diabetic subjects.

Treatment of type I diabetes mellitus is hindered by the often large fluctuations in blood glucose concentration experienced by affected individuals. To determine to what extent day-to-day variation in blood glucose levels can be reduced if insulin is injected in the same anatomic region rather than in different regions using a rotational scheme, as is commonly recommended, 12 type I diabetic subjects were studied. Insulin injections were given in the abdomen for 3 days and rotated among arms, abdomen, and thighs for 3 days using a crossover design with random assignment of treatment order. Blood samples for measurement of plasma glucose levels were obtained at nine scheduled times on each day. Insulin dose, diet, and physical activity were held constant for each subject. During the abdominal injection period, the mean SD of plasma glucose levels and the mean variance of plasma glucose levels were both less at all nine time points than during the rotating injection period. Overall values for the SD of plasma glucose levels were 2.7 +/- 0.2 mmol/L for the abdominal injection period and 3.7 +/- 0.3 mmol/L for the rotating injection period. Overall values for the variance of plasma glucose levels were 9.2 +/- 1.4 mmol2/L2 for the abdominal injection period and 17.4 +/- 2.2 mmol2/L2 for the rotating injection period. We conclude that the common clinical practice of rotating the anatomic regions used for insulin injections increases day-to-day variation in blood glucose concentration. Use of a single anatomic region, eg, the abdomen, for all insulin injections may reduce this variation and allow greater precision in the adjustment of insulin doses.

Abdomen↗
PubMed1990

Guidelines for neuropsychological research in multiple sclerosis.

Acquisition of scientific information regarding the neuropsychological aspects of multiple sclerosis has been hampered by studies using small, inadequately described patient and control samples and a wide array of cognitive test procedures that hinder multicenter data pooling. Based on a review of key issues of clinical need and experimental interest, research guidelines are proposed for investigations in this burgeoning research area. The guidelines include suggestions for sampling methods, population characterization, and control groups as well as a recommended core battery of neuropsychological tests for use in this population. It is hoped that these guidelines will advance knowledge about the neuropsychology of multiple sclerosis by helping to promote sound experimental design, facilitate cross-study comparison, and encourage multicenter collaborative efforts.

Cognition Disorders↗
PubMed1989

Neuropsychological test findings in subjects with leukoaraiosis.

Focal periventricular white-matter changes (leukoaraiosis) have been identified incidentally on brain imaging in normal healthy individuals and more commonly in the elderly and in hypertensive individuals. It has been suggested that leukoaraiosis represents the early stages of Binswanger's leukoencephalopathy, a dementing process thought to be related to hypertensive cerebrovascular disease. To test this hypothesis, extensive neuropsychological tests were administered to 50 consecutive normotensive, middle-aged, healthy volunteers. Ten subjects (20%) had white-matter changes on magnetic resonance scans; 40 subjects (80%) had normal scans. The differences observed on neuropsychological testing between subjects with and without leukoaraiosis were not significant. While this study argues against a link between leukoaraiosis and dementia, prospective longitudinal studies are needed to determine the value of leukoaraiosis in predicting future cognitive decline.

Adult↗
PubMed1989

Cerebral disconnection in multiple sclerosis. Relationship to atrophy of the corpus callosum.

Left ear suppression to dichotically presented verbal stimuli has been observed in patients with multiple sclerosis (MS). Rubens and coworkers have suggested that a disconnection of the auditory callosal pathways may account for this finding. To examine this proposal, we compared the performance of 28 MS patients with significant corpus callosum atrophy (CCA) on midsagittal magnetic resonance scans, 16 MS patients without significant CCA, and 64 demographically matched normal control subjects on two laterality tasks: verbal dichotic listening (consonant-vowel syllables) and tachistiscopic object-naming latency. Results indicated that left ear suppression was found only in the MS patients with CCA. Likewise, patients in the MS group with CCA were slow in responding to stimuli presented in the left visual field; this effect was not observed in patients without CCA. These findings support the hypothesis that efficiency of cross-callosal information flow is reduced in MS patients with CCA.

Adult↗
PubMed1989

Information processing speed in patients with multiple sclerosis.

We have recently proposed that the cognitive deficits of patients with multiple sclerosis (MS) share numerous characteristics associated with the syndrome of subcortical dementia. One such characteristic, slowness of mental processing, was evaluated in the present study. Thirty-six MS patients were compared to 26 normal controls of equivalent age, education, and verbal intelligence on the Sternberg memory scanning test. As anticipated, the motor-involved MS patients had an overall slower reaction time than did controls. Their scanning rate, a measure of pure cognitive speed, was also significantly slower than controls. These results suggest that MS patients exhibit a slowing of mental processing independent of motor involvement.

Adult↗
PubMed1989

On the nature of memory disturbance in multiple sclerosis.

Thirty-seven patients with multiple sclerosis (MS) were compared to 26 normal controls of equivalent age, education, and verbal intelligence on measures of verbal learning and memory (Digit Span and Supraspan, Brown-Peterson Distractor Task, Selective Reminding Test, Story Recall, and Free Verbal Recall) and verbal fluency (Letter and Animal Fluency). The MS patients exhibited deficits on measures of secondary (long-term) memory and verbal fluency, but performed normally on measures of primary (short-term) memory, recognition memory, and rate of forgetting from secondary memory. These results suggest that the memory disturbance in MS results primarily from an imparied ability to access information from secondary memory, while encoding and storage capacity is intact. Degree of memory impairment was unrelated to length of illness, severity of disability, or self-reported depression.

Adult↗
PubMed1989

Correlation of magnetic resonance imaging with neuropsychological testing in multiple sclerosis.

Previous research has suggested that cerebral lesions observed on magnetic resonance imaging (MRI) of MS patients are clinically "silent." We examined the validity of this assertion by correlating neuropsychological test performance with MRI findings in 53 MS patients. We used a semiautomated quantitation system to measure three MRI variables: total lesion area (TLA), ventricular-brain ratio (VBR), and size of the corpus callosum (SCC). Stepwise multiple regression analyses indicated that TLA was a robust predictor of cognitive dysfunction, particularly for measures of recent memory, abstract/conceptual reasoning, language, and visuospatial problem solving. SCC predicted test performance on measures on mental processing speed and rapid problem solving, while VBR did not independently predict cognitive test findings. These findings suggest that cerebral lesions in MS produce cognitive dysfunction and that MRI may be a useful predictor of cognitive dysfunction.

Brain↗
PubMed1986

Neuropsychology of multiple sclerosis: a critical review.

Multiple sclerosis (MS) is a relatively common, chronic progressive neurological illness affecting individuals primarily in the third and fourth decades of life. Autopsy studies indicate that the disease preferentially attacks white matter throughout the CNS, including the cerebral hemispheres. This article reviews the current state of knowledge regarding cognitive dysfunction in MS and relates these findings to neuropathological changes. The view that affective disturbance may also result from cerebral demyelination is presented, along with a brief discussion of MS as a prototype "subcortical" dementia. Finally, methodological problems intrinsic to the study of MS are presented, and suggestions for future research are made.

Cognition Disorders↗
PubMed1985

Chronic progressive multiple sclerosis. Relationship between cerebral ventricular size and neuropsychological impairment.

Forty-seven patients with chronic progressive multiple sclerosis were examined to assess the possible relationship between cerebral atrophy (by computed tomography [CT] ) and performance on neuropsychological tests of memory and verbal intelligence. Nineteen patients were found to have mildly dilated ventricles and another nine patients had moderate to severe ventricular enlargement. Performance on memory and intelligence testing was related to the degree of ventriculomegaly. Three linear CT measurements were also recorded. Using this method, the width of the third ventricle proved to be the best indicator of intellectual and memory dysfunction. Measures of cognition and ventricular size did not correlate with length of illness or overall disability as rated by the Kurtzke Disability Status Score.

Adult↗