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K F Mortel

Publications and source records attributed to K F Mortel.

52 records · Page 3Linked to original sources
PubMed1983

Cerebral vasomotor responsiveness during 100% oxygen inhalation in cerebral ischemia.

Cerebral vasoconstrictor responsiveness to 100% oxygen inhalation was measured in 149 subjects, including normal healthy volunteers and those with risk factors for cerebral arteriosclerosis (N = 87). Test results were compared among patients with hemispheric stroke and vertebrobasilar insufficiency (N = 62) with the 133Xe inhalation method. Normal volunteers without risk factors (N = 49), aged 25 to 86 years, showed symmetrical vasoconstriction. Asymptomatic subjects with risk factors (N = 38) and those with vertebrobasilar insufficiency (N = 25) had decreased hemispheric gray matter flow (Fg) values during rest, but vasoconstrictor responsiveness to 100% oxygen inhalation was not significantly reduced. In patients with acute hemispheric infarction, regional vasoconstrictor responsiveness to 100% oxygen inhalation was lost and/or paradoxically reversed; in patients with chronic hemispheric infarction, it was decreased. Testing vasomotor responses during hyperoxia is safe, clinically helpful, and demonstrates impaired vasomotor reactivity in infarcted regions.

Adult↗
PubMed1983

Cerebral vasomotor responses during oxygen inhalation. Results in normal aging and dementia.

Resting-state regional gray matter flow (Fg) values and cerebral vasoconstrictor responses induced by 100% oxygen inhalation were measured with the 133 Xe inhalation method in normal healthy volunteers aged between 15 and 86 years and in patients with senile dementia of Alzheimer's type (SDAT) or multi-infarct dementia (MID). Cross-sectional analysis revealed that there were linear decreases of oxygen responses with advancing age in 84 normal volunteers between the second to ninth decades. Eleven patients with SDAT showed bilateral and symmetrical reductions of resting-state Fg values compared with 22 age-matched normal healthy volunteers. Eight patients with MID showed no significant reduction of mean Fg values compared with normal controls and patients with SDAT. Oxygen vasoconstrictive responses in SDAT were symmetrical and similar to those seen in age-matched controls. Compared with patients with SDAT, patients with MID showed reduced oxygen vasoconstrictive responses that were asymmetrical between hemispheres as well as heterogeneous within hemispheres. Testing cerebral vasoconstrictor responses by 100% oxygen inhalation is helpful for differentiating SDAT from MID.

Aged↗
PubMed1983

Reductions in regional cerebral blood flow associated with chronic consumption of alcohol.

Neurotoxic effects of habitual alcohol consumption were investigated by correlating the subjects' estimates of abstinence or frequency and amount of alcohol consumed with measurements of gray matter blood flow utilizing the 133Xe inhalation method. Two hundred and twenty-two subjects were studied, including 136 healthy subjects, 82 subjects with well-established risk factors for stroke (hypertension, hyperlipidemia, heart disease, and diabetes mellitus), and four subjects with chronic alcoholic dementia of the Wernicke-Korsakoff type. Subjects were classified according to average quantitative amounts of alcohol consumed per day, week, or month for the past five years. Comparisons of mean values for hemispheric gray matter blood flow indicated significant inverse relationships with the average amounts of alcohol consumed. This linear relationship occurred regardless of whether or not other risk factors were present and indicated that alcohol itself was a risk factor reducing gray matter blood flow and had additive effects of reducing cerebral blood flow further when combined with other risk factors. Patients who had chronic Wernicke-Korsakoff syndrome had the most severely reduced blood flow levels, as might be predicted from extrapolation of the regression line comparing cerebral blood flow values with the degree of chronic alcohol consumption.

Aged↗
PubMed1982

Stable xenon CT cerebral blood flow measurements computed by a single compartment--double integration model in normal aging and dementia.

Programs have been developed, using a single compartmental analysis model, that provide rapid computer derivation for values of both local cerebral blood flows (LCBF) and local tissue: blood partition coefficients (L lambda) using inhaled stable xenon gas (Xes) as the indicator. These programs are planned for utilization of raw data points derived from serial computed tomography scans made between the 3rd and 9th min after 35% Xes inhalation, while concentrations of end-tidal Xes (PEXes) are concurrently monitored. Double integration and least squares fitting permitted estimation of corresponding arterial (assumed from PEXes) and tissue Xes concentrations at each scanning interval during Xes saturation. Derived estimates for L lambda and LCBF values for each region of interest mathematically approximate values saturated to infinity. The method described can be utilized for any freely diffusible indicator. Cross-sectional analysis of results obtained in 13 normal healthy volunteers between 20 and 80 years of age showed no age-related changes in L lambda values but progressive decreases in blood flow of cortex, basal ganglia, and white matter with advancing age. In senile dementia of Alzheimer's type (SDAT, n = 8) L lambda values were likewise found to be unchanged, but cortical and thalamic gray matter LCBF values were significantly reduced compared to age-matched normal volunteers.

Adult↗
PubMedDate not supplied

Cerebral blood flow and brain atrophy correlated by xenon contrast CT scanning.

Correlations between cerebral blood flow (CBF) measured during stable xenon contrast CT scanning and standard CT indices of brain atrophy were investigated in the patients with senile dementia of Alzheimer type, multi-infarct dementia and idiopathic Parkinson's disease. Compared to age-matched normal volunteers, significant correlations were found in patients with idiopathic Parkinson's disease between cortical and subcortical gray matter blood flow and brain atrophy estimated by the ventricular body ratio, and mild to moderate brain atrophy were correlated with stepwise CBF reductions. However, in patients with senile dementia of Alzheimer type and multi-infarct dementia, brain atrophy was not associated with stepwise CBF reductions. Overall correlations between brain atrophy and reduced CBF were weak. Mild degrees of brain atrophy are not always associated with reduced CBF.

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PubMedDate not supplied

Acetazolamide testing of cerebral vasodilator capacity provokes "vascular" but not tension headaches.

Cerebrovascular capacitance was tested by measuring local cerebral blood flow (LCBF) by xenon-contrasted CT scanning before and after the oral administration of 14.3 mg/kg of acetazolamide among 45 subjects including 15 age-matched controls without history of headache, 20 migraineurs with and without aura, 3 patients with cluster headache, and 7 patients with tension-type headache. Percentage increases of LCBF were measured in 10 regions located throughout both hemispheres. Laterality indices for asymmetric LCBF increases were calculated. Local cerebral blood flow in cortical gray matter increased 5.9% in controls, 9.9% in patients with tension headaches, but 18.6% in both migraine and cluster headache patients; significantly greater LCBF increases than among controls or among patients with tension headaches (P < 0.05). Increases in LCBF were significantly asymmetric among migraine and cluster patients and provoked typical unilateral vascular headaches which responded to sumatriptan. Maximal asymmetric LCBF increases also corresponded to the reported side of the induced headaches confirming their vascular pathogenesis. Patients with tension headaches and controls without history of headache did not develop head pain after acetazolamide.

Acetazolamide↗
PubMedDate not supplied

Leuko-araiosis and cerebral perfusion in normal aging.

To clarify the incidence, age relationships and pathogenesis of white matter lesions of unknown origin (leuko-araiosis) detected by neuroimaging among normal elderly volunteers, we measured the severity of leuko-araiosis using computerized tomographic (CT) densitometry among 42 healthy self-supporting men and women of different ages, all with normal neurological and cognitive test performance. Results were correlated with local cerebral perfusion using xenon-contrasted CT. The 42 volunteers, who are followed in this laboratory for studies of normal aging, were divided into two groups in order to determine aging effects by an extremes design. One group consisted of 19 adults below age 60 (M = 53.3, SD = 6.0). The index group comprised 23 individuals all over the age of 60 (M = 71.6, SD = 8.7). Leuko-araiosis around the anterior horns of the lateral ventricles (frontal leuko-araiosis) was more severe (p < .01) among the older group, however, occipital leuko-araiosis did not significantly differ between older and younger groups. Cerebral perfusion in frontal, temporal, and parietal cortex was decreased among older compared with younger volunteers (ps < .001, .01, and .05, respectively). Multiple regression analyses disclosed significant and direct relationships between severity of frontal leuko-araiosis and (a) frontal cortical atrophy and (b) reductions of cerebral perfusion within frontal white matter and caudate nucleus. We conclude that cortical atrophy with hypoperfusion and ischemia of frontal white matter play a part in the pathogenesis of frontal leuko-araiosis associated with normal aging and this may be a predictor for later cognitive declines.

Adult↗
PubMedDate not supplied

Education and occupation as risk factors for dementias of the Alzheimer and ischemic vascular types.

Education and occupation as sociodemographic risk factors for dementias of the Alzheimer (DAT) and ischemic vascular types (IVD) were evaluated by two case series studies. Cases were compared to well-evaluated individuals identified as healthy normals acting as controls. There were 150 patients with probable DAT, 102 patients with probable IVD, and 188 neurologically and cognitively normal subjects. Logistic regression indicated that for DAT, education with occupation was the best predictor (OR, 1.51; 95% CI, 1.23-1.87). For IVD, the two predictors were: education with occupation (OR, 1.84; 95% CI 1.38-4.50) and education with gender (OR, 3.40; 95% CI, 1.29-8.92). We conclude that risk of dementia is increased in those with limited educational background and occupational achievement.

Achievement↗
PubMedDate not supplied

Cognitive performance after small strokes correlates with ischemia, not atrophy of the brain.

Computerized tomographic measures of recurrent cerebral infarctions, atrophy and local perfusion were all prospectively correlated with cognitive testing during treatment of risk factors plus antiplatelet therapy among vascular dementia patients. Neurological and cognitive status were quantified among 22 demented patients with small strokes and compared with 22 age-matched normal volunteers. In vascular dementia, risk factor control plus antiplatelet therapy reduced cerebral infarctions, increased perfusion, and stabilized or improved cognitive test performance, despite age-related, progressive cerebral atrophy.

Aged↗
PubMedDate not supplied

CT-CBF correlations of cognitive deficits in multi-infarct dementia.

Fifteen right-handed patients with Multi-Infarct Dementia underwent cognitive testing by the Jacobs Mini-Mental Scale (MMQ), and xenon contrast CT scanning. Local cerebral blood flow (LCBF) and local partition coefficient (L lambda) values were measured by stable xenon contrast CT scanning and potential methodological errors were discussed. Reduced values were graded: 0 = normal, 1 = mild, 2 = moderate, 3 = severe. Graded values were pooled and plotted on composite brain maps to display locations of abnormal L lambda and LCBF values. Topographic brain maps, showing most frequent locations of reduced L lambda values, confirmed the common anatomical locations of multiple cerebral infarcts to be distributed in both thalami, temporal lobes, basal ganglia, left internal capsule and right cingulate cortex. Gray matter flow values were reduced in similar cortical and subcortical regions. There were no correlations between MMQ scores and reduced LCBF values for caudate and lenticular nuclei. Direct and statistically significant correlations were found between reduced MMQ scores and mean LCBF values for left or right frontal cortex, left or right temporal cortex and left or right thalamus. Subgrouping MMQ tests according to functions assessed, indicated that left mid-temporal ischemia correlated with dyscalculia and memory disturbances while ischemia of both frontal lobes correlated with disorientation to time and place.

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PubMedDate not supplied

Long-term assessment of cerebral perfusion following STA-MCA by-pass in patients.

A prospective study of mean hemispheric cerebral blood flow (CBF) correlated with clinical status has now been completed for the past 54 months. Thirty-eight patients underwent superficial temporal to middle cerebral artery (STA-MCA) by-pass. They were compared with 22 patients with similar arteriographic lesions and clinical symptoms, treated medically throughout the same interval of time. Assignment to either treatment group was not randomized but depended solely on choice of patient or treating physician. Both groups were matched for age, clinical symptoms, angiographic abnormalities, and CBF values. All patients had proximal occlusion of one internal carotid artery or intracranial occlusive disease of the internal carotid or middle cerebral arteries. CBF measurements and clinical evaluations were repeated at regular intervals up to 54 months following surgery or institution of medical treatment. Mean follow up interval after STA-MCA by-pass was 28.7 months and for medical treatment was 29.7 months. Mean hemispheric CBF values for STA-MCA patients became significantly increased 2 weeks after operation. After that, CBF flow values decreased. At 24 months after surgery, flow values for surgically treated patients were significantly higher than among those treated medically, although there were no differences in flow values between the two groups at 3, 6, 12, 36 and 48 months. Prospective clinical evaluations after STA-MCA by-pass were as follows: 12 (32%) improved with cessation of TIAs and/or neurological improvement, 16 (42%) remained unchanged, 7 (18%) deteriorated (due to new or recurrent strokes) and 3 (8%) expired. Clinical results were the same for medical treatment: 6 (27%) improved, 10 (46%) unchanged, 4 (18%) deteriorated due to new or recurrent stroke, and 2 (9%) expired.

Adult↗
PubMedDate not supplied

Prospective analysis of long term control of mild hypertension on cerebral blood flow.

A group of 12 otherwise normal elderly volunteers (mean age = 69.8 years), were detected to have mild hypertension. Cerebral blood flow (CBF) values were measured using 133Xe inhalation method prior to initiating medical treatment and repeated at 6, 12, 24 and 36 months after BP was adequately controlled and restored to normal (below 150/90). Results indicate that CBF values increased markedly during follow-up intervals at 6, 12 and 24 months but not at 36 months. Hypertension is known to be a risk factor for stroke and 4 of the 12 subjects subsequently developed symptoms of cerebrovascular disease (stroke, multi-infarct dementia or transient ischemic attacks) despite control of hypertension. Analyses separating asymptomatic and symptomatic groups indicated that the eight asymptomatic patients continued to maintain increased CBF levels throughout the entire three year interval, whereas the 4 symptomatic patients developed declines in CBF which began, and progressively decreased below the initial pretreatment values, during the second and third years.

Aged↗
PubMedDate not supplied

Additional predisposing risk factors for atherothrombotic cerebrovascular disease among treated hypertensive volunteers.

A 7-year prospective study of a cohort of 107 neurologically normal elderly hypertensive volunteers (mean age, 65.8 +/- 8.3 years) was undertaken to investigate the predictive validities of additional risk factors for atherothrombotic cerebrovascular disease including stroke, transient ischemic attacks, reversible ischemic neurological deficits, and multi-infarct dementia. This longitudinal study has been in progress now for 7 years with a mean follow-up interval of 50.12 +/- 5.76 months. Among 107 formerly symptom-free, normal hypertensive volunteers, 25 (23%) have developed cerebrovascular disease, 7 (6.5%) sustained a stroke, 10 (9.3%) developed multi-infarct dementia, and 18 (16.8%) have transient ischemic attacks. None have suffered intracranial hemorrhage. Mean gray matter cerebral blood flow (CBF) values measured at the initial visit were sensitive predictors of cerebrovascular disease. Eight of 16 hypertensives (50%) with initial CBF values below 60.0 ml/100 g/min now exhibit signs and symptoms of cerebrovascular disease, while 11 of 43 hypertensives (25.6%) with initial CBF values between 60.1 and 69.9 ml/100 g/min and only 6 of 48 (12.5%) with initial CBF levels above 70.0 developed cerebrovascular disease. Incidence of cerebrovascular disease among cigarette smoking hypertensive volunteers (32.5%) was significantly greater than among nonsmokers (17.2%).

Age Factors↗
PubMedDate not supplied

Improved cognition after control of risk factors for multi-infarct dementia.

A cohort of 52 patients (30 men and 22 women) with multi-infarct dementia (MID) has been followed up prospectively for a mean interval of 22.2 months. Clinical course has been documented by serial history taking and interviews and neurological, medical, and psychological examinations, and correlated with measurements of cerebral blood flow. The clinical course and cognitive performance have been compared with those of age-matched normal volunteers and patients with Alzheimer's disease. Patients with MID were subdivided into hypertensive and normotensive groups, and also into those displaying stabilized or improved cognition and those whose condition deteriorated. Among hypertensive patients with MID, improved cognition and clinical course correlated with control of systolic blood pressure within upper limits of normal (135 to 150 mm Hg), but if systolic blood pressure was reduced below this level, patients with MID deteriorated. Among normotensive patients with MID, improved cognition was associated with cessation of smoking cigarettes.

Adult↗
PubMedDate not supplied

Abstention from cigarette smoking improves cerebral perfusion among elderly chronic smokers.

A cross-sectional study of cerebral blood flow (CBF) levels in 268 neurologically normal volunteers contrasting nonsmokers, smokers who quit, and current cigarette smokers indicated that subjects who quit smoking had significantly higher cerebral perfusion levels than subjects who had continued to smoke but remained lower than subjects without a history of cigarette smoking. All subjects were matched for age and sex, and smoking groups were matched for duration and amount of smoking. A prospective study of 11 subjects who were able to stop smoking in which CBF levels were available both antecedent to and following cessation of the habit indicated that significant gains occurred in cerebral perfusion levels within one year following cessation of smoking. A control group of 22 subjects who continued to smoke (matched for age, sex, duration of smoking, and duration of time between baseline and follow-up) showed no change in CBF values. A correlation between magnitude of CBF change and duration of cessation of cigarette smoking demonstrated a significant linear increase in CBF during the one-year period. These results suggest that elderly individuals who have smoked for three to four decades can benefit substantially by abstaining from cigarette smoking and that significant improvement in cerebral circulation occurs within a relatively short period.

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