Biomedical subjects

Ulrich Sliwka

Publications and source records attributed to Ulrich Sliwka.

9 recordsLinked to original sources

PubMed2005

Conservative medical treatment and intravenous thrombolysis in acute stroke from carotid T occlusion.

BACKGROUND: We aimed to analyse the course of early recanalization and corresponding functional outcome in patients with an acute occlusion of the carotid T who were treated conservatively or underwent intravenous thrombolysis. METHODS: Forty-two patients with an acute occlusion of the carotid T within 6 h were recruited from consecutive admissions to a neurological department participating in the Duplex Sonography in Acute Stroke study. All patients underwent a standardized admission and follow-up procedure. Colour-coded duplex sonography was performed on admission, 30 min after thrombolysis, and at 6 and 24 h after onset of symptoms. Recanalization of the carotid T was classified as complete, partial and absent. Functional outcome was rated with the modified Rankin scale (mRS) at 3 months as favourable (mRS 0-2) or poor (mRS 3-6). RESULTS: Within 6 h, complete or partial recanalization occurred in 1 of 27 patients treated conservatively and in 6 of 15 thrombolysed patients. Intravenous thrombolysis predicted early recanalization also after adjustment for age, sex, cardioembolic stroke aetiology and time to treatment (adjusted odds ratio, OR, 39.7; 95% confidence interval, CI, 2.0-801.7; p = 0.016). An early recanalization was the only selected predictor of a favourable outcome (OR, 13.6; 95% CI, 1.0-179.0; p = 0.047) at regression analysis, and was achieved in 3 thrombolysed patients but in none with conservative medical treatment. CONCLUSIONS: In patients treated conservatively, functional outcome is poor and early recanalization rarely occurs. The latter can be achieved by intravenous thrombolysis with a rate comparable to that found at an intra-arterial approach without major intracranial bleeding complications. Early recanalization is associated with a better functional outcome.

Acute Disease↗

PubMed2005

Transcranial low-frequency ultrasound-mediated thrombolysis in brain ischemia: increased risk of hemorrhage with combined ultrasound and tissue plasminogen activator: results of a phase II clinical trial.

BACKGROUND: Clinical studies using ultrasound at diagnostic frequencies in transcranial Doppler devices provided encouraging results in enhancing thrombolysis with tissue plasminogen activator (tPA) in acute stroke. Low-frequency ultrasound does not require complex positioning procedures, penetrates through the skull better, and has been demonstrated to accelerate thrombolysis with tPA in animal experiments in wide cerebrovascular territories without hemorrhagic side effects. We therefore conducted the first multicenter clinical trial to investigate safety of tPA plus low-frequency ultrasound (300 kHz). METHODS: Acute stroke patients within a 6-hour time window were included (National Institutes of Health Stroke Scale scores >4). Magnetic resonance imaging (MRI) was used to document vascular occlusion and to rule out cerebral hemorrhage. Patients were allocated to combination therapy alternately; the first patient received tPA only, the second patient received tPA plus ultrasound, etc. Follow-up included serial MRI directly thereafter and 24 hours later to confirm recanalization and tissue imaging. Clinical recovery was measured after treatment and 3 months later. RESULTS: 26 patients (70.4+/-9.7 years) entered the trial (12 tPA, 14 tPA plus ultrasound). The study was prematurely stopped because 5 of 12 patients from the tPA only group but 13 of 14 patients treated with the tPA plus ultrasound showed signs of bleeding in MRI (P<0.01). Within 3 days of treatment, 5 symptomatic hemorrhages occurred within the tPA plus ultrasound group. At 3 months, neither morbidity nor treatment-related mortality or recanalization rates differed between both groups. CONCLUSIONS: This study demonstrated bioeffects from low-frequency ultrasound that caused an increased rate of cerebral hemorrhages in patients concomitantly treated with intravenous tPA.

Aged↗

PubMed2005

Decrease of carotid intima-media thickness in patients at risk to cerebral ischemia after supplementation with folic acid, Vitamins B6 and B12.

OBJECTIVE: Hyperhomocysteinemia is associated with atherosclerotic risk. Although vitamins can lower homocysteine (Hcy), information about effects on atherosclerosis is scarce. METHODS: We used carotid intima-media thickness (IMT) as an accepted marker of atherosclerotic changes. Fifty patients (60 +/- 8 years) with IMT> or =1 mm were included. In a double blind, randomized trial they received daily 2.5 mg folic acid, 25 mg Vitamin B6, and 0.5mg Vitamin B12 or placebo for 1 year. RESULTS: In the treatment group, Hcy decreased from 10.50 +/- 3.93 to 6.56 +/- 1.53 micromol/l (P < 0.0001), whereas it remained unchanged in the placebo group (10.76 +/- 2.36 versus 10.45+/-3.30 micromol/l). IMT decreased from 1.50 +/- 0.44 to 1.42 +/- 0.48 mm (P = 0.034) in the treatment group, whereas it increased from 1.47 +/- 0.57 to 1.54 +/- 0.71 mm in the placebo group. The mean individual changes of IMT between both groups differed significantly (-0.08 +/- 0.17 versus 0.07 +/- 0.25 mm, P = 0.019). Multiple regression analysis revealed that the observed effect on IMT depended only on medication. CONCLUSIONS: Vitamin supplementation significantly reduces IMT in patients at risk. This effect is independent of Hcy concentration.

Aged↗

PubMed2004

Cerebral venous flow velocity predicts poor outcome in subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Predictors of clinical outcome in aneurysmal subarachnoid hemorrhage (SAH) vary in reliability. Measurement of cerebral venous hemodynamics by transcranial color-coded duplexsonography (TCCS) has become of increasing interest lately, and correlation with intracranial pressure (ICP) seems to be high. The aim of the presented study was to assess changes of cerebral venous hemodynamics in SAH and evaluate its relationship with clinical outcome. METHODS: We performed sequential TCCS of venous peak flow velocities (vp-FVs) in the transversal sinus in 28 consecutive patients with aneurysmal SAH (Hunt and Hess scale 1 to 5). Measurement was initiated at onset of arterial vasospasm up to 5 days after SAH. All patients had a continuous ICP monitoring. Clinical outcome was evaluated with the modified ranking scale (MRS) 30 days after SAH. Patients were divided according to outcome: group I good recovery (MRS 0-III) and group II poor outcome (death or MRS IV-V). Maximum vp-FV, time-averaged vp-FV (mv-FV), and ICP were compared between groups. RESULTS: Vp-FV and mv-FV as well as ICP of group II exceeded values of group I (P<0.001 for all 3 parameters). Vp-FV showed a positive correlation with ICP (r=0.63; P<0.001). A vp-FV exceeding 35.4 cm/s (sensitivity 100%; specificity 90.9%), an mv-FV exceeding 27.3 cm/s (sensitivity 94.1%; specificity 81.8%), and an ICP exceeding 24 mm Hg (sensitivity 87.5%; specificity 81.8%) predicted poor outcome (receiver operating characteristic analysis). CONCLUSIONS: Increased ICP values correlate with increased venous flow velocities. In SAH, increased ICP and increased venous flow velocities are associated with poor outcome. Flow velocity of the transversal sinus is a highly sensitive, reliable, and early predictor of outcome in SAH.

Adult↗

PubMed2004

Treatment with anticoagulants in cerebral events (TRACE).

90 patients with acute stroke and a concomitant cardiac embolism source or a symptomatic high-grade stenosis of an extra-or intracranial vessel received in a mulitcenter, randomized, controlled study either Enoxaparin 1 mg/kg BW s.c. b.i.d. or i.v. heparin aPTT-adjusted daily for 8 +/- 2 days as secondary prophylaxis. There were no significant differences between the two groups regarding cerebral and systemic embolic events, bleeding complications, length of hospital stay, number of diagnostic and therapeutic measures and outcome after three months. This suggests that Enoxaparin, which is easier to administer and monitor, is a safe drug in patients with acute cerebral events.

Aged↗

PubMed2004

Unstable cerebral hemodynamics in carotid artery occlusion and large hemispheric stroke: a cerebral blood flow volume study.

PURPOSE: In chronic internal carotid artery (ICA) occlusion, cerebral hemodynamics are likely to be stable due to collateral flow. The authors evaluated cerebral hemodynamics in ICA occlusion using the sonographic method of cerebral blood flow volume (CBVF) measurement to find differences that might identify patients with large hemispheric stroke in ICA occlusion. METHOD AND RESULTS: The ultrasound method of CBVF measurement was used, which represents the sum of flow volumes of both internal carotid and both vertebal arteries. CBVF was measured in 29 patients with ICA occlusion including patients with (1) chronic ICA occlusion without acute minor stroke, (2) chronic ICA occlusion with acute minor stroke, (3) acute minor stroke due to acute ICA occlusion, and (4) ICA occlusion and large hemispheric stroke. In ICA occlusion, overall CBVF is lower compared to healthy volunteers, due to a significant reduction of CBVF in groups 3 and 4. Comparing groups, there were no differences in CBVF between groups 1, 2, and 3. CBVF in group 4 is reduced compared to all other groups. By receiver-operating characteristic analysis, a CBVF cutoff value for large hemispheric stroke was computed with a sensitivity of 100% and a specificity of 95.8%. CONCLUSION: Stroke due to acute ICA occlusion is associated with decreased CBVF compared to chronic ICA occlusion. Moreover, ICA occlusion and large hemispheric stroke are associated with decreased CBVF compared to all other groups, indicating instability of cerebral hemodynamics. CBVF measurement thus may be a useful tool in predicting large middle cerebral artery stroke early in ICA occlusion.

Aged↗

PubMed2004

Hemodynamic changes of the cerebral circulation after stent-protected carotid angioplasty.

BACKGROUND AND PURPOSE: Stent-protected carotid angioplasty (SPAC) is an option for treating cervical symptomatic high-grade internal carotid artery (ICA) stenosis. So far, knowledge about hemodynamic changes in the early postinterventional phase is limited. The purpose of this study was to evaluate these changes. METHODS: Thirty-four consecutive patients with a high-grade ICA stenosis (according to European Carotid Surgery Trial criteria) and 10 healthy volunteers were enrolled. Hemodynamics of the cerebral circulation were assessed before and within 6 hours after SPAC. ICA flow volume, cerebral blood volume flow (CBVF), and collateral flow volume were sonographically assessed. The ratio of flow velocities in the middle cerebral artery (MCA) ipsilateral to the ICA stenosis was calculated and compared with that in the contralateral MCA. This ratio was designated rMCA. RESULTS: Preinterventional CBVF, ICA flow volume, and rMCA were significantly reduced compared with results in healthy volunteers. After SPAC, CBVF, ICA flow volume, and rMCA increased significantly. The rMCA did not exceed 1.0. Collateral flow volume decreased in patients with posterior collateral flow only. Postinterventional CBVF and ICA flow volume in patients did not differ from values in healthy volunteers. CONCLUSION: Cerebral hemodynamics appear to be impaired in patients with symptomatic high-grade ICA stenosis. After SPAC, hemodynamic parameters normalize within 6 hours. We did not detect hyperperfusion. However, flow volume in the contralateral ICA remains increased in patients with former anterior cross-filling.

Adult↗

PubMed2003

Horner syndrome related to ipsilateral carotid wall hematoma after stent placement for the treatment of carotid stenoses.

BACKGROUND AND PURPOSE: We prospectively studied the incidence and natural history of Horner syndrome following stent-supported percutaneous angioplasty of the carotid artery (SPAC). We assessed the hypothesis that postinterventional Horner syndrome is related to ipsilateral carotid wall hematoma. METHODS: We performed duplex sonography of the carotid arteries and clinical examination in 28 consecutive patients before and 4 hours +/- 2, 24 hours +/- 2, and 7 days +/- 1 after SPAC. RESULTS: Within 24 hours +/- 2 after SPAC, 11 of the 28 patients developed ipsilateral Horner syndrome. Ten of these 11 patients had a postinterventional sonographic appearance of a carotid wall hematoma, whereas only two of the 17 patients without Horner syndrome had this finding (P <.001). In all patients, both Horner syndrome and carotid wall hematoma had resolved 7 days +/- 1 after SPAC. CONCLUSION: Horner syndrome appears to be a common yet transient event after SPAC. Although postinterventional Horner syndrome is significantly related to ipsilateral carotid wall hematoma, causality of the procedure-related formation of a carotid wall hematoma and oculosympathetic disturbance remains unproven.

Adult↗

PubMed2002

Developmental changes in cerebral autoregulatory capacity in the fetal sheep parietal cortex.

We validated laser Doppler flowmetry (LDF) for long-term monitoring and detection of acute changes of local cerebral blood flow (lCBF) in chronically instrumented fetal sheep. Using LDF, we estimated developmental changes of cerebral autoregulation. Single fibre laser probes (0.4 mm in diameter) were implanted in and surface probes were placed on the parietal cerebral cortex at 105 +/- 2 (n = 7) and 120 +/- 2 days gestational age (dGA, n = 7). Basal lCBF was monitored over 5 days followed by a hypercapnic challenge (fetal arterial partial pressure of CO(2), P(a,CO2): 83 +/- 3 mmHg) during which lCBF changes obtained by LDF were compared to those obtained with coloured microspheres (CMSs). Mean arterial blood pressure (MABP) was increased and decreased using phenylephrine and sodium nitroprusside at 110 +/- 2 and 128 +/- 2 dGA. Intracortical and cortical surface laser probes gave stable measurements over 5 days. The lCBF increase during hypercapnia obtained by LDF correlated well with flows obtained using CMS (r = 0.89, P < 0.01). The signals of intracortical and surface laser probes also correlated well (r = 0.91, P < 0.01). Gliosis of 0.35 +/- 0.06 mm around the tip of intracortical probes did not affect the measurements. The range of MABP over which cerebral autoregulation was observed increased from 20-48 mmHg at 110 dGA to 35 to > 95 mmHg at 128 dGA (P < 0.05). Since MABP increased from 33 to 54 mmHg over this period (P < 0.01), the range between the lower limit of cerebral autoregulation and the MABP increased from 13 mmHg at 110 dGA to 19 mmHg at 128 dGA (P < 0.01). LDF is a reliable tool to assess dynamic changes in cerebral perfusion continuously in fetal sheep.

Animals↗