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Biomedical subjects

R W Baumgartner

Publications and source records attributed to R W Baumgartner.

At least 19 recordsLinked to original sources
PubMed2003

[Secondary prevention after ischemic stroke].

This paper reviews secondary prevention of stroke by the therapy of vascular risk factors, anticoagulation, surgical and endovascular procedures. Two recently published studies, the PROtection aGainst REcurrent Stroke Study (PROGRESS) and the Heart Protection Study (HPS) demonstrated for the first time the efficacy of antihypertensive and lipid lowering by statins in stroke secondary prevention. PROGRESS has shown that the combination of perindoprile and indapamide reduced the occurrence of ischemic and hemorrhagic strokes in hyper- and normotensive patients by 40%, whereas HPS demonstrated a 20% reduction of ischemic strokes in cases with normal or elevated serum cholesterol. Symptomatic carotid stenoses with a distal degree of > or = 70% should undergo endarterectomy; in the presence of a distal degree of stenosis of 50-69% an individual treatment decision is performed; carotid surgery is not indicated in < 50% stenoses. Patients with a cardiac source of embolism (except those with cardiac myxoma or bacterial endocarditis) should be anticoagulated with a target INR of 2.5 (range 2-3). Patients who have no indication for vascular surgery or anticoagulation will be treated with platelet inhibitors. Aspirin 100 mg/d or the combination aspirin-dipyridamole are the treatment of choice. If cerebral ischemia reoccurs with aspirin or in case of aspirin intolerance clopidogrel will be administered. Patients with cerebral ischemia occurring while they are treated with clopidogrel may receive an oral anticoagulation with a target INR of 2.0 (range 1.5-2.5).

Administration, Oral↗
PubMed2003

Carotid dissection with permanent and transient occlusion or severe stenosis: Long-term outcome.

OBJECTIVE: To compare the rate of ischemic events and intracranial hemorrhage in the long-term follow-up of patients with persistent and transient severe stenosis or occlusion of the internal carotid artery (ICA) due to spontaneous dissection (ICAD). METHODS: One hundred and sixty-one consecutive patients with unilateral ICAD causing severe stenosis or occlusion were examined clinically and by ultrasound 1 year after symptom onset. Forty-six cases with persistent and 46 age- and latency-matched cases with transient (recanalization complete or less than 50% stenosis) severe stenosis or occlusion of the ICA were enrolled. Nine patients with surgical, endovascular, or fibrinolytic therapy for ICAD or associated stroke were excluded. Antithrombotic therapy was given at the discretion of the treating physician. Clinical follow-ups were done annually. RESULTS: Antithrombotic therapy and follow-up were similar in patients with permanent (6.2 +/- 3.4 years) and transient (7.2 +/- 4.3 years) severe stenosis or occlusion of the ICA. Cases with permanent carotid stenosis or occlusion showed annual rates of 0.7% for ipsilateral carotid territory stroke and of 1.4% for any stroke. Cases with transient carotid stenosis or occlusion showed annual rates of 0.3% for ipsilateral carotid territory stroke and of 0.6% for any stroke. CONCLUSIONS: This study suggests that ICAD has a benign long-term prognosis with low rates of ipsilateral carotid territory and any stroke and that the stroke rate in ICAD is not related to the persistence of severe carotid stenosis or occlusion. These results question the rationale of surgical or catheter-based revascularization in patients with ICAD.

Adult↗
PubMed2003

[Current controversies in the diagnosis and management of cerebral venous and dural sinus thrombosis].

Over the last few years, the results from clinical studies and innovative radiological approaches have significantly altered the management of patients with cerebral venous thrombosis. In contrast to previously held beliefs, cerebral venous thrombosis is considered to be a relatively benign disease with an overall favourable prognosis. Mortality is <10%, and the vast majority of patients recover completely. Although the efficacy of heparin has not been unequivocally proven, it is employed in most centres as the standard therapy. There are not sufficient data supporting long-term anticoagulation. In patients with a proven hypercoagulability syndrome, anticoagulation therapy is generally recommended for a period of 6 months. Whether patients with idiopathic thrombosis should also be treated remains controversial. Non-invasive MR and CT angiography techniques have largely replaced conventional angiography for initial evaluation and follow-up examinations. Both methods have a high sensitivity for cerebral venous thrombosis. Local fibrinolytic therapy or other aggressive recanalizing methods can not be generally recommended.

Anticoagulants↗
PubMed2003

Ischemic infarct involving all arterial territories of the thalamus.

Ischemic infarcts of the thalamus involve one or two of its four arterial territories that are usually supplied by the posterior cerebral (PCA) and the posterior communicating (PCoA) arteries. We report a patient who suffered ischemic infarcts in all arterial territories of the right thalamus. Magnetic resonance (MR) angiography showed an occlusion of the right PCA and failed to visualize a PCoA. We assume that the absence of a relevant thalamic blood supply deriving from the PCoA enabled PCA occlusion to cause infarcts in all thalamic territories.

Arteries↗
PubMed2003

Recanalisation of cerebral venous thrombosis.

OBJECTIVE: To investigate recanalisation in the first 12 months after cerebral venous thrombosis. METHODS: 33 consecutive patients presenting with cerebral venous thrombosis were enrolled in the study. Diagnosis was made by magnetic resonance imaging (MRI) and magnetic resonance venography (MRV) or catheter angiography. Patients were initially treated with intravenous heparin. Warfarin was given for at least four months. Cerebral MRI and MRV were done at four months and repeated after 12 months if venous thrombosis persisted. Outcome was evaluated by the Rankin scale at 12 months. RESULTS: Outcome at 12 months was good, with a median modified Rankin scale score of 0 (range 0 to 2); 27 patients (82%) had no residual deficits. No patient suffered recurrent cerebral venous thrombosis, deep vein thrombosis, or pulmonary embolism during follow up. After four months, all deep cerebral veins and cavernous sinuses, 94% of superior sagittal sinuses, 80% of straight sinuses, 73% of jugular veins, 58% of transverse sinuses, and 41% of sigmoid sinuses had recanalised. No further recanalisation was observed thereafter. CONCLUSIONS: The results suggest that recanalisation only occurs within the first four months following cerebral venous thrombosis and not thereafter, irrespective of oral anticoagulation.

Adult↗
PubMed2002

[Clinical relevance of detection of microembolism signals with transcranial Doppler ultrasound diagnosis].

Detection of microembolic signals (MES) has been described in several patients groups. A potential clinical relevance of this technique has been established (1) during the first hours following carotid endarterectomy and (2) for patients with asymptomatic ICA stenosis or various autoimmune disorders. Intraoperative monitoring in patients undergoing cardiac or carotid surgery can be used to improve the surgical technique but provides no prognostic information for individual patients. Microembolic signals in patients with prosthetic heart valves cannot be used as markers for stroke risk; their potential significance as markers for neuropsychological deficits remains unclear. Recent reports suggest that MES can be used as surrogate markers for assessing the efficacy of antiplatelet agents. The fact that automated MES detection is not feasible greatly reduces the technique's applicability. On the whole, MES detection--with the exception of the patient groups listed above--provides pathophysiological rather than clinically relevant information.

Feasibility Studies↗
PubMed2002

Cerebral autoregulation under moderate hypothermia in patients with acute stroke.

BACKGROUND AND PURPOSE: We undertook this study to examine the integrity of cerebral autoregulation in patients with acute ischemic stroke treated with moderate hypothermia (33 degrees C). METHODS: Fourteen patients, aged 58+/-11 years, with an acute anterior circulation infarction and National Institutes of Health Stroke Scale score >15 were evaluated. Patients received catecholamines (norepinephrine) via continuous intravenous infusion and were mechanically ventilated. Alpha-stat was used for pH maintenance. Arterial pressure (AP) and intracranial pressure (ICP) were invasively monitored. Flow velocity in the middle cerebral artery (MCA) supplying the unaffected hemisphere was continuously monitored. Instantaneous maximum flow velocity (V(max) MCA), ICP, and AP were simultaneously recorded in real time. Mean values of V(max) MCA (V(mean) MCA) and AP (MAP) were calculated over 1 minute. Static cerebral autoregulation (sCA) was calculated as sCA=(%DeltaCVR/%DeltaMAP)x100% (where %DeltaCVR is an estimate of percent change in cerebrovascular resistance). An sCA value of 0% indicates absent autoregulation, and a value of 100% indicates perfect autoregulation. Autoregulation is considered impaired when sCA values are <40%. MAP changes were produced by increasing the rate of the norepinephrine infusion. Six patients were examined under both normothermic and hypothermic conditions, while 8 were examined only under hypothermia. RESULTS: The induced MAP increase was 22+/-7 mm Hg (minimum 13, maximum 40 mm Hg). Mean sCA was 64+/-16% (minimum 40%, maximum 100%). No effect of moderate hypothermia on sCA or V(mean) MCA was evident in any of the 6 serially examined patients. Normocapnia was observed in all cases. CONCLUSIONS: sCA appears intact under moderate hypothermia with the use of alpha-stat for pH maintenance.

Acute Disease↗
PubMed2001

Carotid dissection with and without ischemic events: local symptoms and cerebral artery findings.

OBJECTIVE: To study whether spontaneous dissections of the cervical internal carotid artery dissection (ICAD) with and without ischemia of the brain or retina differ in the prevalence of vascular risk factors, local neurologic signs and symptoms, and stenoses and occlusions of the cerebral arteries. METHODS: The authors prospectively studied 181 consecutive patients with 200 ICAD. Diagnosis was based on ultrasonography and MRI or catheter angiography. Vascular risk factors, presenting local (headache, neck pain, Horner syndrome, pulsatile tinnitus, cranial nerve palsy on the side of the ICAD) and ischemic signs and symptoms, and ultrasonographic findings in the carotid and basal cerebral arteries were evaluated. RESULTS: ICAD with ischemic events (n = 145) had a higher prevalence of hypercholesterolemia (p < 0.05), >80% stenoses and occlusions of the ICA (p < 0.0001), and intracranial obstructions (p < 0.001). ICAD without ischemic events (n = 55) had a higher prevalence of Horner syndrome (p < 0.001), cranial nerve palsy (p < 0.01), and normal ICA findings (p < 0.0001). CONCLUSIONS: These data suggest that ICAD causing high-grade stenosis and occlusion are more likely to lead to intracranial obstructions and cerebral or retinal ischemic events. Conversely, ICAD without luminal narrowing cause more local signs and symptoms.

Adolescent↗
PubMed2001

Stroke in hemoglobin (SD) sickle cell disease with moyamoya: successful hydroxyurea treatment after cerebrovascular bypass surgery.

An 11-year-old boy with hemoglobin sickle disease (HbSD), bilateral stenosis of the intracranial carotid arteries, and moyamoya syndrome had recurrent ischemic strokes with aphasia and right hemiparesis. His parents (Jehovah's Witnesses) refused blood transfusions. After bilateral extracranial-intracranial (EC-IC) bypass surgery, hydroxyurea treatment increased hemoglobin F (HbF) levels to more than 30%. During a follow-up of 28 months, flow velocities in the basal cerebral arteries remained stable, neurologic sequelae regressed, and ischemic events did not recur. This is the first report of successful hydroxyurea treatment after bypass surgery for intracranial cerebral artery obstruction with moyamoya syndrome in sickle cell disease. The patient's religious background contributed to an ethically challenging therapeutic task. (Blood. 2001;97:2165-2167)

Anemia, Sickle Cell↗
PubMed2001

A survey of neuroimaging research in European neurological departments.

In the international neurological literature, neuroimaging research plays an important role. Neuroimaging techniques are also of steadily increasing importance for clinical diagnosis and treatment monitoring. Therefore, neuroimaging research activities were surveyed by a questionnaire, which was completed by 100 neurological centres across Europe. It showed that most groups use magnetic resonance imaging (MRI), fMRI, computerized tomography (CT) and single photon emission computerized tomography (SPECT). Positron emission tomography (PET) and ultrasound are also employed by nearly half of the centres. Neuroimaging research involves co-operation amongst typically five to 10 disciplines. Cerebrovascular disease, dementia, cognitive disorders, epilepsy, movement disorders, brain tumours and multiple sclerosis are frequently being studied. Many groups rely on small budgets, have few full-time scientists and limited access to expensive resources. There is little exchange of scientists amongst laboratories. It was felt that funding and co-operation needed improvement in order to maintain a high standard in neuroimaging research.

Data Collection↗
PubMed2001

Microembolic signal counts increase during hyperbaric exposure in patients with prosthetic heart valves.

BACKGROUND: Patients with prosthetic heart valves have an increased risk of thromboembolic events, and transcranial Doppler sonography reveals microembolic signals. Whereas microembolic signals were initially assumed to be of particulate matter, recent studies suggest that they are partially gaseous in origin. If this is true, alteration of environmental pressure should change microembolic signal counts. We undertook this study to evaluate the influence of hyperbaric exposure on microembolic signal counts in persons with prosthetic heart valves. METHODS AND RESULTS: Microembolic signal counts were monitored by transcranial Doppler sonography of both middle cerebral arteries under normobaria (normobaria 1), 2 subsequent periods of hyperbaria (2.5 and 1.75 bar), and a second period of normobaria (normobaria 2) in 15 patients with prosthetic heart valves. Each monitoring period lasted 30 minutes. Compression and decompression rates were 0.1 bar/min. Microembolic signal counts increased from 20 (12-78) at normobaria 1 to 79 (30-165) at 2.5 bar (P <.01 vs normobaria 1 and 2), decreased to 44 (18-128) at 1.75 bar (P <.01 vs normobaria 1 and 2.5 bar; P <.001 vs normobaria 2), and returned to 20 (8-96) at normobaria 2 (values are medians and 95% confidence intervals). CONCLUSIONS: Our results strongly suggest that gaseous bubbles are underlying material for part of the microembolic signals detected in patients with prosthetic heart valves.

Aortic Valve↗
PubMed2001

Influence of positive end-expiratory pressure on intracranial pressure and cerebral perfusion pressure in patients with acute stroke.

BACKGROUND AND PURPOSE: We undertook this study to evaluate the influence of positive end-expiratory pressure (PEEP) on intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in patients with acute stroke. METHODS: A total of 20 ventilated patients of a neurological intensive care unit were examined under a protocol entailing variation of PEEP to 4, 8, 12, and 4 mm Hg; mean arterial blood pressure (MAP), ICP, heart rate, and mean velocity of the middle cerebral arteries (V(m) MCA) were recorded. RESULTS: CPP significantly changed depending on the various PEEP levels. No significant differences in remaining parameters were evident. Three distinct reaction patterns of the parameters monitored were observed: (1) All parameters remained stable through the various PEEP levels (15 patients, 40 examinations). (2) Increase in PEEP resulted in a significant decrease of MAP, while V(m) MCA remained unchanged, indicating an intact cerebral autoregulation. A slight (statistically insignificant) increase in ICP, which was significantly related to the MAP changes, was evident (7 patients, 16 examinations). (3) Increase in PEEP resulted in a decrease of MAP and V(m) MCA; ICP remained unchanged or demonstrated a slight decline (3 patients, 6 examinations). CONCLUSIONS: PEEP increase up to 12 mm Hg does not significantly influence ICP. The observed marked changes in CPP are mediated through the MAP. Thus, PEEP application should be safe, provided that MAP is maintained.

Adult↗
PubMed2000

[Carotid stenosis: epidemiology and symptomatology (see comment)].

Risk factors for atherosclerotic carotid stenoses are smoking, arterial hypertension, diabetes mellitus and hypercholesterolaemia. Atherosclerotic carotid artery disease is a risk factor for the development of coronary artery disease (CAD), and in older men the risk of CAD-related death is five times higher than the risk of death related to ischaemic stroke. The prevalence of > 50% carotid stenoses in population-based studies in 6-11% for older men and 5-7% in older women. Diagnosis and differential diagnosis of ischaemia-related ophthalmologic and neurological deficits in the territory of the carotid artery are discussed.

Aged↗
PubMed2000

[Transient ischemic attacks and prolonged reversible ischemic neurologic deficit. Diagnosis, differential diagnosis and treatment].

Cerebral and ocular ischemic events are classified according to their duration and localisation in transient (< 24 hours) or permanent (> or = 24 hours) cerebral (transient ischemic attack (TIA), cerebral infarct) and ocular (amaurosis fugax, retinal infarct) deficits. The terms "Prolonged Reversible Ischemic Neurological Deficit" (PRIND, > or = 24 hours to < or = 7 days) and "Reversible Ischemic Neurological Deficit" (RIND, > or = 24 hours to < or = 3 days) are no longer used. The differential diagnosis of TIAs and ischemic strokes is discussed. Ischemic strokes are an emergency and should be referred within five hours at the latest to a centre, which offers around the clock acute therapies such as fibrinolysis and an organised stroke management. Secondary stroke prevention after TIA or stroke encompasses the treatment of vascular risk factors, carotid endarterectomy, anticoagulation in the presence of cardiac embolism (target international normalised ratio, 2.5; range 2.0-3.0) and the administration of platelet inhibitors. Carotid endarterectomy is indicated, when luminal narrowing is at least 70%, and not indicated when it is less than 50%. The benefit of endarterectomy in 50-69% stenoses decreases, and individual predictors of the operation risk are useful for choosing the appropriate treatment. Patients without indication for carotid endarterectomy or oral anticoagulation are treated with platelet inhibitors. We use the combination dipyridamole-aspirin as first choice drug, because it has been shown to be superior to aspirin and dipyridamole alone. In the presence of adverse effects or contraindications for dipyridamole we prescribe aspirin (100-300 mg daily). We administer clopidogrel (75 mg daily) if dipyridamole and aspirin are not indicated, have caused adverse effects, or did not prevent ocular or cerebral ischemic events.

Aspirin↗
PubMed2000

Comparison of the ECST, CC, and NASCET grading methods and ultrasound for assessing carotid stenosis. European Carotid Surgery Trial. North American Symptomatic Carotid Endarterectomy Trial.

We compared three angiographic methods for grading of carotid stenosis and examined the correlation between angiographic and ultrasound findings. Two observers independently measured 111 carotid stenoses on arteriographic films of 84 patients. The stenoses were graded according to the European Carotid Surgery Trial (ECST), North American Symptomatic Carotid Endarterectomy Trial (NASCET), and Common Carotid (CC) methods. The results obtained by these methods were compared, and the interobserver reproducibility of the measurements was calculated. In addition, all angiographic results were compared to ultrasound findings obtained before angiography. Measurements using the CC method were the most reproducible and those using the NASCET method the least. The NASCET method underestimated the degree of stenosis compared to the other methods. The ECST and CC methods yielded almost identical results (97% agreement). Ultrasound provided an accuracy of 94% compared to ECST and CC methods and 84% compared to the NASCET method. Interobserver reproducibility of angiographic quantification of carotid stenoses was best for the CC and ECST methods and least for the NASCET method. Ultrasound demonstrated better accuracy than the ECST and CC methods.

Adult↗