Fatal brain edema not related to metastatic disease in a patient with choriocarcinoma.
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Brain Edema↗
Biomedical subjects
M Lindqvist
Publications and source records attributed to M Lindqvist.
Attenuation of forearm vasodilator responses to mental stress by regional beta-blockade, but not by atropine.
Forearm blood flow during mental stress (Stroop's colour word conflict test) was studied in 18 healthy men before and during regional beta-adrenoceptor blockade (propranolol 0.5 mg), muscarinic receptor blockade (atropine 0.2 mg) and combined blockade, and compared with results obtained in untreated controls. Forearm blood flow was measured with venous occlusion plethysmography, and forearm vascular resistance was calculated. Arterial and venous blood sampling was performed for determination of adrenaline and noradrenaline in plasma. Mental stress increased heart rate, systolic and diastolic blood pressures and forearm blood flow, and lowered the forearm vascular resistance, to the same degree as in our previously studied controls. Neither of the intra-arterially administered drugs had any discernible systemic effects. Beta-blockade increased forearm vascular resistance by 32% and decreased forearm blood flow by 21% compared with unblocked levels during mental stress, whereas forearm vasodilation was maintained throughout the stress test in the control group (P < 0.05). Intra-arterial atropine had no certain effects. Arterial adrenaline levels during mental stress were similar in the receptor-blocked and control groups. In conclusion, the sustained forearm vasodilation during mental stress appears to be partly mediated via beta 2-adrenoceptor stimulation (i.e. by adrenaline), but we obtained no support for a cholinergic vasodilating mechanism.
Adrenergic beta-Antagonists↗
Plasma angiotensins and human forearm circulation: effects of sympatho-adrenal activation.
Complex interactions appear to exist between the renin-angiotensin system and sympathetic neurotransmission, and sympathetic activity may influence local angiotensin II formation. Arterial and forearm venous plasma levels of angiotensin I and II were therefore studied in 11 healthy males at rest during sympathetic activation elicited by mental stress, and during adrenaline induced vasodilation. Specific assays for angiotensin-(1-8) octapeptide and for angiotensin-(1-10) decapeptide (i.e. angiotensin II and I, respectively), were used. Special precautions to minimize ex vivo formation and/or degradation of angiotensins were employed. Mental stress increased regional noradrenaline overflow three-fold, with a concomitant three-fold increase in forearm blood flow, whereas intravenous adrenaline infusion increased forearm blood flow two-fold and noradrenaline overflow four-old. There was a constant positive veno-arterial concentration difference for angiotensin I under all conditions tested, compatible with local angiotensin I formation. We found no veno-arterial concentration difference for angiotensin II or regional net angiotensin II overflow under the conditions tested. These results in the forearm circulation support previous animal experimental evidence in skeletal muscle and provide no evidence in favour of a de novo formation of angiotensin II in skeletal muscle in vivo during basal conditions. Furthermore, sympathetic nerve stimulation does not seem to enhance angiotensin II generation importantly in this vascular bed.
Adrenal Glands↗
Evaluation of the post-operative lumbar spine with MR imaging. The role of contrast enhancement and thickening in nerve roots.
PURPOSE: Two new signs of lumbar nerve-root affection have been reported in recent years on the basis of MR examinations, namely: thickening in nerve roots; and contrast enhancement in nerve roots. The aim of this study was to assess contrast enhancement in nerve roots in a standardised way, and to evaluate the clinical significance of contrast enhancement and of nerve-root thickening in the symptomatic post-operative lumbar spine. MATERIAL AND METHODS: A total of 121 patients (who had previously been operated on for lumbar disc herniation) underwent 152 MR examinations, mainly on a 1.5 T system. Focal nerve-root enhancement was identified by visual assessment. Intradural enhancement was also quantified by pixel measurements that compared the affected nerve roots before and after contrast administration. Non-affected nerve roots were used as reference. RESULTS: Enhanced nerve roots in the dural sac increased at least 40-50% in signal intensity after contrast administration compared to pre-contrast images and also compared to non-affected nerve roots. Intradural nerve-root enhancement was seen in 10% of the patients and focal enhancement in the root sleeve was seen in a further 26%. Nerve-root thickening was seen in 30%. Good correlation with clinical symptoms was found in 59% of the patients with intradural enhancement, in 84% with focal enhancement, and in 86% with nerve-root thickening. The combination of thickening and enhancement in the nerve root correlated with symptoms in 86% of the patients. CONCLUSION: Nerve-root enhancement (whether focal or intradural) and thickening in the nerve root are significant MR findings in the post-operative lumbar spine. In combination with disc herniation or nerve-root displacement, these two signs may strengthen the indication for repeat surgery. However, root enhancement within 6 months of previous surgery may be a normal post-operative finding.
Adult↗
Blockade of endogenous nitric oxide production results in moderate hypertension, reducing sympathetic activity and shortening bleeding time in healthy volunteers.
BACKGROUND: Short-term infusion of NG-monomethyl-L-arginine (L-NMMA) reversibly inhibits endogenous nitric oxide (NO) production in humans. We studied responses to more long-lasting (60 min) infusions, at doses high enough to cause effective inhibition of endogenous NO. METHODS: Eight healthy volunteers had catheters (pulmonary, arterial and venous) placed. Measurements included hemodynamics, endogenous NO levels in nasal air, bleeding time, and cyclic guanosine monophosphate (cGMP) and catecholamines in plasma. L-NMMA was infused at 0.3 mg.kg-1.min-1 during 30 min, followed by 0.15 (n = 6) or 0.3 (n = 2) mg.kg-1.min-1 during 30 min. RESULTS: L-NMMA significantly elevated mean arterial pressure by 12 +/- 3%, due to an increase in systemic vascular resistance. Cardiac output decreased by 23 +/- 3%, due to a decrease in stroke volume. Pulmonary vascular resistance (P < 0.05) increased, but mean pulmonary arterial pressure was stable. Forearm vascular resistance (P < 0.05) decreased. Bleeding time was shortened by 31 +/- 4% (P < 0.01). L-NMMA infusion reduced NO concentrations in nasal air by 64 +/- 2% (P < 0.01). Arterial pressure remained elevated and nasal NO remained depressed 90 min after the infusion, whereas most other responses were reversed at that time. Plasma cGMP showed only minor changes. Plasma norepinephrine decreased, suggesting reflexogenic inhibition of sympathetic activity, whereas epinephrine levels were low and stable throughout the experiment. CONCLUSION: Dosage of (13.5 mg.kg-1 in 60 min) L-NMMA infusion in humans was well tolerated. Pronounced and long-lasting inhibition of endogenous NO production, as evidenced by measurements in nasal air, resulted in unevenly distributed vasoconstriction, a transient decrease in cardiac output, and reflexogenic sympathetic withdrawal. Furthermore, bleeding time was shortened, suggesting platelet activation.
Adolescent↗
Magnetic resonance imaging of obliterated arteriovenous malformations up to 23 years after radiosurgery.
The authors report outcomes in 18 patients with arteriovenous malformations (AVMs) who were treated with gamma knife radiosurgery and in whom magnetic resonance (MR) imaging was obtained a mean of 14 years (range 8-23 years) after treatment and 10 years (range 4-17 years) after confirmed obliteration of the AVM. All patients were asymptomatic after radiosurgery and during the time of the study. In five patients (28%), cyst formation was observed that corresponded to the site of the obliterated AVM. Cyst formation and contrast enhancement on MR imaging could not be statistically correlated to the radiation dose. In 11 (61%) of the 18 patients, contrast enhancement that was not related to a recanalization of the nidus was observed in the target area. In three patients (17%), an increased T2-weighted signal was detected at the site of previous AVM; this was interpreted as gliosis or demyelination, which appeared to be dose dependent. The study illustrates that cyst formation, contrast enhancement, and an increased T2-weighted signal can be observed in asymptomatic patients in the area that was targeted for AVM radiosurgery up to 23 years after the procedure. The report provides new and essential information about long-term effects on normal tissue after radiosurgery and provides a basis for the interpretation of MR studies in the follow up of small AVMs treated by radiosurgery.
Adolescent↗
Sustained forearm vasodilation in humans during mental stress is not neurogenically mediated.
To evaluate the possible neurogenic influence on forearm vasodilation during mental stress (Stroop's colour word conflict test), haemodynamic and catecholamine responses were registered in 12 healthy men after axillary blockade. Forearm blood flow was measured with venous occlusion plethysmography and forearm vascular resistance was calculated, with intraarterial blood pressure data. Blood samples for arterial and venous adrenaline and noradrenaline determinations were collected. Basal forearm blood flow increased markedly after axillary blockade, but the relative responses of forearm blood flow and forearm vascular resistance to mental stress were the same as in previously studied unblocked individuals (about +125% and about -40%, respectively). There was no increase in noradrenaline overflow from the forearm during mental stress in the nerve blocked arm. Heart rate and arterial systolic pressure responses as well as catecholamine responses to mental stress were augmented in the nerve blocked group, presumably due to a certain arousal caused by the experimental procedure. Increases in forearm blood flow and decreases in forearm vascular resistance during infusion of adrenaline were similar in the nerve blocked and in the control arm. In conclusion, vasodilation in the forearm during mental stress occurs in the absence of nervous control of the vascular bed. The reactivity of the vascular bed to an exogenous vasodilator (adrenaline) remains unchanged after axillary blockade.
Adrenergic Agonists↗
Forearm vasodilator mechanisms during mental stress: possible roles for epinephrine and ANP.
The contribution of epinephrine (Epi) to forearm vasodilator responses to mental stress was evaluated in 12 healthy men by comparing hemodynamic and plasma catecholamine responses to mental stress and to intravenous and intra-arterial infusions of epinephrine. Mental stress decreased forearm vascular resistance (FVR) by 45%, increased arterial Epi from 0.23 to 0.44 nmol/l in arterial plasma, and increased forearm norepinephrine overflow. Intra-arterial Epi infusion decreased FVR concentration dependently by up to 43%. Intravenous Epi infusion decreased diastolic arterial pressure and increased heart rate and systolic blood pressure dose dependently. FVR decreased by up to 39% at 4.60 nmol/l Epi in arterial plasma. The average Epi contribution to forearm vasodilation during mental stress was calculated to be between 9 and 30%, depending on if responses to stress were compared with intravenous or intra-arterial Epi infusion. Arterial atrial natriuretic peptide immunoreactivity increased by 23% during stress, supporting a vasodilator influence, whereas vasopressin immunoreactivity was unaffected. Thus secretion of Epi explains only part of the stress-induced forearm vasodilation. Intravenous infusion of Epi appears to activate sympathetic counterregulation.
Adult↗
Intracranial traumatic and non-traumatic haemorrhagic complications of warfarin treatment.
An increased referral of patients with anticoagulation related haemorrhages necessitated an analysis of causes and outcome of these complications in a patient group that reflected Swedish therapeutic traditions of anticoagulation treatment. Prospectively, all patients from Stockholm evaluated for warfarin related intracranial haemorrhage occurring during 1987 were analysed and their 6 month outcome recorded. Sixty-eight patients were included. The results of intracranial haemorrhagic complications were catastrophic with a 77% mortality rate. Their incidence was much higher than expected. Forty-one patients had non-traumatic intracerebral haematomas, 1 had a non-traumatic subarachnoid haemorrhage and 26 had traumatic injuries. In the 42 patients with non-traumatic haemorrhages, the indications for anticoagulation were cerebral ischaemic events in a majority (27/42). The remaining 15 patients had different indications for anticoagulation. They also had an increased frequency of hypertension (p < 0.05). In the 26 patients with traumatic haematomas, only 6/26 patients had previous cerebral ischaemic injuries (p < 0.01). Valvular heart prosthesis was their most common indication (11/26) for anticoagulation. Caution in instituting anticoagulation therapy in patients with hypertension or cerebrovascular disease, which is an important indication for anticoagulation in Sweden, is mandatory. Adherence to strict treatment regimens and their continuous reevaluation may help to avoid complications. The finding of more patients than expected with haemorrhagic complications is not compatible with the risk evaluations used to justify anticoagulation therapy in the patient groups studied. Clinical practice must have changed with time, showing that risk evaluations from controlled trials or retrospectively collected clinical data from selected patients are not necessarily applicable for long-term clinical practice.
Adult↗
Determination of cause of death among breast cancer cases in the Swedish randomized mammography screening trials. A comparison between official statistics and validation by an endpoint committee.
Between 1976 and 1982, four randomized mammography screening trials started in five screening centres in Sweden, involving 282,777 women (156,911 invited and 125,866 controls) with the aim to study if invitation to screening reduced the breast cancer mortality. An overview of the trials was performed to reduce the confidence intervals for the relative risk estimates. All 1,296 deaths occurring in women with breast cancer detected after randomization were evaluated by an independent endpoint committee (EPC), consisting of four physicians who reviewed collected medical information that was blinded regarding mammography screening. If there was disagreement between the EPC members at the initial individual evaluation the final classification was made at consensus meetings. In only 6.9% (n = 89) of the cases was there disagreement as to whether breast cancer was or was not the underlying cause of death. It was also found that 'breast cancer as underlying cause of death' and 'breast cancer as underlying or contributory cause of death' according to Statistics Sweden resulted in relative risk estimates very similar to those based on the classification by the EPC. The study thus supports the use of official health statistics in the evaluation of randomized breast screening trials in Sweden.
Adult↗
[Patients' right and physicians' power].
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Confidentiality↗
Optic neuritis: findings on MRI, CSF examination and HLA class II typing in 60 patients and results of a short-term follow-up.
Optic neuritis (ON) is a common first manifestation of multiple sclerosis (MS), and examination of patients with ON provides opportunities to study the early clinical stages of MS. This prospective study compares results of brain magnetic resonance imaging (MRI), cerebrospinal fluid (CSF) examinations and HLA-Dw2 phenotyping in 60 consecutive patients with ON. At a median of 17 days after the onset of ON, 69% had oligoclonal IgG bands, and at a median on 79 days after onset, 53% had multiple (> or = 3) white matter lesions on MRI. Subgroup analyses revealed that MRI abnormalities and oligoclonal IgG bands were equally common in patients examined early or late after the onset of ON. Strong correlations were found between the presence of MRI abnormalities and oligoclonal IgG bands. The HLA-Dw2 phenotype was significantly increased in ON patients compared with controls, but also significantly different from a group of MS patients from the same geographical area. A significant relation was found between Dw2 phenotype and oligoclonal IgG bands. During a mean follow-up time of about 2 years, the diagnosis in 17 of the patients changed to clinically definite MS. Initially, 16 of them had oligoclonal IgG bands and 12 had three or more MRI lesions. Both MRI and CSF studies are important diagnostic tools in the workup of ON patients.
Adolescent↗
Acute and chronic calcium antagonist treatment elevates sympathetic activity in primary hypertension.
Eleven men with mild to moderate primary hypertension were studied at rest and during mental stress before and during intravenous infusion of the calcium antagonist felodipine. Eight of them were restudied during long-term treatment (extended-release felodipine, 10 mg daily). For comparison, 10 normotensive control subjects were studied with the short-term protocol. Heart rate, cardiac output, central cardiovascular pressures, and forearm blood flow were registered. Arterial and venous sampling was performed. Norepinephrine spillovers to arterial plasma and from the forearm were assessed with the use of radiotracer methodology. In the hypertensive patients, felodipine lowered mean arterial blood pressure acutely by 8% (P < .01). Systemic vascular resistance decreased by 22% (P < .001), cardiac output increased by 20% (P < .01), and norepinephrine spillover to arterial plasma increased by 61% (P < .001). Forearm vascular resistance fell by 30% (P < .001), but norepinephrine overflow from the forearm increased by 115% (P < .001). These forearm responses were not seen in normotensive subjects despite similar systemic responses to felodipine infusion. After 8 weeks of treatment, mean arterial pressure decreased to 15% below baseline (P < .001), cardiac output returned toward pretreatment levels, and systemic vascular resistance remained low. Forearm blood flow returned toward basal levels, but forearm vascular resistance remained lowered. Total body and forearm norepinephrine spillover values were as elevated as in the acute situation. The hemodynamic "defense reaction" and the sympathoadrenal response to mental stress were essentially unaffected by felodipine. Stress-induced small elevations of neuropeptide Y-like immunoreactivity persisted during felodipine. Thus, the vasodilatation induced by felodipine elicits sympathetic counterregulation, which persists in the long term with respect to peripheral and total sympathetic activities, despite resetting of the baroreflex control of heart rate.
Calcium Channel Blockers↗
Breast cancer screening with mammography: overview of Swedish randomised trials.
Despite encouraging results from screening trials the efficacy of mammography in reducing mortality remains somewhat controversial. Five studies have been done in Sweden. This overview, based on 282,777 women followed for 5-13 years in randomised trials in Malmö, Kopparberg, Ostergötland, Stockholm, and Gothenburg, reveals a 24% (95% confidence interval 13-34%) significant reduction of breast cancer mortality among those invited to mammography screening compared with those not invited. To avoid the potential risk of differential misclassification causes of death were assessed by an independent end-point committee after a blinded review of all fatal breast cancer cases. The mortality reduction was similar, irrespective of the end-point used for evaluation ("breast cancer as underlying cause of death" or "breast cancer present at death"). There was a consistent risk reduction associated with screening in all studies, although the point estimate of the relative risk for all ages varied non-significantly between 0.68 and 0.84. The cumulative breast cancer mortality by time since randomisation was estimated at 1.3 per 1000 within 6 years in the invited group compared with 1.6 in the control group. The corresponding figures after 9 years are 2.6 and 3.3 and after 12 years 3.9 and 5.1. The largest reduction of breast cancer mortality (29%) was observed among women aged 50-69 at randomisation. Among women 40-49 there was a non-significant 13% reduction. In this younger age group cumulative breast cancer mortality was similar in the invited and control group during the first 8 years of follow-up. After 8 years there was a difference in favour of the invited women. There was no evidence of any detrimental effect of screening in terms of breast cancer mortality in any age group. Among women aged 70-74 years screening seems to have had only a marginal impact.
Adult↗
Even the smallest remnant of an AVM constitutes a risk of further bleeding. Case report.
A case with an ill-defined arteriovenous malformation in the parieto-occipital region is presented. Open surgery was unsuccessful in removing the AVM totally, and treatment with gamma knife radiosurgery was then attempted. At 14 months after this treatment the AVM was believed to be obliterated. The patient had a new intracranial haemorrhage 59 months after radiosurgery. Renewed angiography showed an obvious AVM outside the previously irradiated area. Retrospective analysis of the angiogram at 14 months after radiosurgery revealed early filling of a draining vein as a sign of residual AVM at this time. Renewed radiosurgical treatment was performed. It is believed that an ill-defined margin, laminar flow, and effects of previous surgery might add to difficulties in a proper visualisation and delineation of an AVM. Further, a small remaining shunt may be overlooked if the angiogram is not carefully analysed or if the angiogram is of inferior quality. It should be stressed that partial or almost total obliteration of an AVM is no protection against rebleeding.
Cerebral Angiography↗
Cardiovascular and sympatho-adrenal responses to mental stress in primary hypertension.
1. Eleven untreated men with mild to moderate primary hypertension and 10 normotensive control subjects were studied at rest and during a mental stress test (Stroop colour word conflict test), which has previously been used in studies of hypertensive patients with regard to non-invasive cardiovascular variables and venous plasma catecholamine concentrations. 2. Heart rate, central cardiovascular pressures, cardiac output (thermodilution) and forearm blood flow (strain gauge plethysmography) were determined. Systemic and forearm vascular resistances were calculated. Arterial and venous plasma adrenaline and noradrenaline concentrations were measured by h.p.l.c., and arterial noradrenaline spillover and noradrenaline overflow from the forearm were assessed by isotope methodology ([3H]noradrenaline). Neuropeptide Y-like immunoreactivity was measured by radioimmunoassay. 3. In hypertensive patients heart rate, arterial blood pressure, cardiac output and forearm blood flow increased by 28%, 13%, 37% and 115%, respectively, and forearm and systemic vascular resistances decreased by 48% and 21%, respectively (P < 0.001 for all responses), during stress. These responses were not different from those of the control group. 4. Arterial noradrenaline spillover rose by 63% and noradrenaline overflow from the forearm rose by 150% in the hypertensive patients in response to mental stress (P < 0.001); no significant group differences could be demonstrated. However, the forearm noradrenaline overflow response to stress tended to be greater in the hypertensive group (P = 0.11). Arterial adrenaline concentrations doubled in both groups (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Adrenal Glands↗
Minimally invasive and non-invasive diagnosis of carotid artery obstructive disease: an evaluation of supraorbital fluorescein angiography and ultrasonic duplex technique.
The carotid arteries of twenty-five patients with transient ischaemic attacks, minor stroke or amaurosis fugax were examined by conventional angiography, the ultrasonic duplex technique and supraorbital fluorescein angiography (SOFA). The results of the last two techniques (non-invasive and minimally invasive, respectively) were compared with the results of angiography. We found that the ultrasonic duplex technique is highly sensitive and specific for both high and low-grade carotid stenoses while the less costly SOFA can only identify stenoses equal to or more than 75%. However, since tight stenosis has proved to be an indication for surgical reconstruction, SOFA - or possibly the still simpler procedure with direct ocular inspection of the supraorbital fluorescence pattern without any recording - would be useful for initial screening in smaller units without access to ultrasonic duplex examination. In this way potential candidates for surgery can be identified without delay and forwarded to larger units for further supplementary examinations.
Adult↗
Target delineation in radiosurgery for cerebral arteriovenous malformations. Assessment of the value of stereotaxic MR imaging and MR angiography.
A study of 6 selected arteriovenous malformation (AVM) patients was performed to investigate the feasibility of delineating an AVM on MR images and to compare the AVM volume outlined on different images. Conventional stereotaxic angiograms, stereotaxic MR images and MR angiograms using several different pulse sequences were obtained prior to radiosurgery. Treatment plans were made from the conventional stereotaxic angiograms. These plans were then transferred to a separate dose planning computer which displayed the MR images with the superimposed isodose lines. The radiated volumes of AVM and brain tissue were measured from these MR images. Last, an assessment was made of the radiation volume needed for an appropriate treatment of the AVM if the treatment plan was made from the MR images rather than from the conventional stereotaxic angiogram. It was possible to delineate medium and large size AVM nidi on stereotaxic MR images based on an integration of information obtained from various pulse sequences. The estimated volumes of the AVM nidi were found to be larger on the conventional stereotaxic angiograms than on the stereotaxic MR images. Consequently, a dose plan based on a conventional stereotaxic angiogram would result in a higher integral dose to the brain with the same target dose. By using reliable MR information it is expected that the volume of brain exposed to radiation could be decreased and the adverse effects of stereotactic radiosurgery for AVM thereby minimized.
Adult↗