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Peter Schmiedek

Publications and source records attributed to Peter Schmiedek.

13 recordsLinked to original sources
PubMed2006

Effect of nicardipine prolonged-release implants on cerebral vasospasm and clinical outcome after severe aneurysmal subarachnoid hemorrhage: a prospective, randomized, double-blind phase IIa study.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate the effect of nicardipine prolonged-release implants (NPRIs) on cerebral vasospasm and clinical outcome after severe subarachnoid hemorrhage. METHODS: Thirty-two patients with severe subarachnoid hemorrhage and undergoing aneurysm clipping were included into this single center, randomized, double-blind trial. Sixteen patients received NPRIs implanted into the basal cisterns in direct contact to the exposed proximal blood vessels; in 16 control patients, the basal cisterns were opened and washed out only without leaving implants. Angiography was performed preoperatively and at day 8+/-1. Computed tomography imaging was analyzed for the incidence of territorial infarcts unrelated to surgery. Patient outcome was assessed using the modified Rankin and National Institute of Health Stroke scales. RESULTS: The incidence of angiographic vasospasm in proximal vessel segments was significantly reduced after implantation of NPRIs (73% control versus 7% NPRIs). Significant differences occurred also for the majority of distal vessel segments. Computed tomography scans revealed a lower incidence of delayed ischemic lesions (47% control versus 14% NPRIs). The NPRI group demonstrated more favorable modified Rankin and National Institute of Health Stroke scales as well as a significantly lower incidence of deaths (38% control versus 6% NPRIs). CONCLUSIONS: Implantation of NPRIs reduces the incidence of cerebral vasospasm and delayed ischemic deficits and improves clinical outcome after severe subarachnoid hemorrhage.

Adult↗
PubMed2006

Spontaneous recanalization of occluded standard extracranial-intracranial arterial bypass.

BACKGROUND: In the event of early failure of standard extracranial-intracranial arterial bypass, elective but prompt revision surgery is generally attempted under the assumption that early occlusion is permanent. However, little is known about the occurrence of spontaneous revascularization. OBJECTIVE: To estimate the frequency and time course of spontaneous recanalization in primary extracranial-intracranial arterial bypass occlusion and re-evaluate diagnostic and therapeutic options facing spontaneous development. METHODS AND RESULTS: In a retrospective analysis 176 patients with standard superficial temporal artery/middle cerebral artery bypass were included. Twenty-three patients had primary bypass occlusion. In 7 cases spontaneous recanalization was observed. Follow-up of these cases is presented. CONCLUSIONS: Early bypass occlusion has a high incidence of spontaneous recanalization within the first year. In stable patients the first choice may be noninvasive follow-up and postponing revision operation.

Adult↗
PubMed2006

2D cine phase-contrast MRI for volume flow evaluation of the brain-supplying circulation in moyamoya disease.

OBJECTIVE: The purpose of this study was to evaluate and quantify hemodynamic compromise in patients with moyamoya disease by measuring blood volume flow in the brain-supplying arteries. SUBJECTS AND METHODS: Thirty-five patients with angiographically proven moyamoya disease (31 women, 4 men; mean age, 39.4 +/- 12.2 years; range, 15-58 years; adult moyamoya disease) and 15 age-matched healthy controls were examined prospectively with 2D cine phase-contrast MRI. Blood volume flow was measured in both common carotid arteries (CCAs), both internal carotid arteries (ICAs), and the basilar artery. The diagnosis of moyamoya disease was based on results of selective intraarterial digital subtraction angiography. RESULTS: Blood volume flow of the brain-supplying arteries in age-matched controls was 435.6 +/- 47.9 mL/min for the CCA, 254.1 +/- 25.3 mL/min for the ICA, and 173.3 +/- 13.2 mL/min for the basilar artery. Patients with bilateral moyamoya disease had decreased mean blood flow in the CCA (309.4 +/- 89.9 mL/min) and ICA (117.9 +/- 64.0 mL/min) and increased blood volume flow in the basilar artery (433.7 +/- 165.9 mL/min). CONCLUSION: Moyamoya disease causes a significant decrease in carotid artery circulation, particularly ICA blood volume flow, with a compensatory increase in blood flow in the basilar artery to nearly 2.5 times normal basilar artery blood flow. 2D cine phase-contrast MRI with measurement of blood volume flow in the brain-supplying arteries is useful in the initial evaluation of moyamoya disease and in continuing assessment of hemodynamics in patients with this disease.

Adolescent↗
PubMed2005

Hemodynamic reserve and high-intensity transient signals in moyamoya disease.

BACKGROUND: Moyamoya disease (MMD) as a rare obstructive cerebrovascular disease is assumed to present with ischemic symptoms due to hemodynamic compromise. However, alternative mechanisms, such as cerebral embolism in low-flow territories, may also contribute to clinical symptoms. The incidence of high-intensity transient signals (HITS) and the degree of hemodynamic compromise were studied in symptomatic patients with MMD. METHODS: Twenty-four patients (17 female, 7 male; mean age 33 +/- 13 years) with clinical symptoms attributable to cerebral ischemia and the angiographic features of MMD (21 definite form, 3 probable MMD; 22 patients 'late stage' MMD, 2 patients 'early stage' MMD) in 45 affected hemispheres were enrolled in the present study. Patients underwent parallel estimation of hemodynamic compromise by means of functional blood flow (rCBF) studies using SPECT, PET or xenon-CT and HITS detection by TCD. RESULTS: Hemodynamic compromise was observed in 37/40 (92%) hemispheres studied. During TCD monitoring, HITS were detected in 3 patients (12.5%), with a total frequency of 3 (6.6%) in the 45 hemispheres investigated. All patients with HITS showed hemodynamic compromise in functional rCBF studies. In these patients, HITS were recorded ipsilateral to the symptomatic hemisphere. HITS occurred in late stage MMD patients only once, while both cases with early stage MMD demonstrated multiple HITS. CONCLUSIONS: The incidence of HITS in patients with MMD appears to be lower compared to patients with atherosclerotic or atherothrombotic arterial obstructions. In addition, ischemia-related symptoms in 'late stage' MMD seem to be caused by hemodynamic compromise in the majority of these patients.

Adult↗
PubMed2005

Intraoperative control of extracranial-intracranial bypass patency by near-infrared indocyanine green videoangiography.

OBJECT: Recently, intraoperative fluorescence angiography in which indocyanine green (ICG) is used as a tracer has been introduced as a novel technique to confirm successful aneurysm clipping. The aim of the present study was to assess whether ICG videoangiography is also suitable for intraoperative confirmation of extracranial-intracranial bypass patency. METHODS: Forty patients undergoing cerebral revascularization for hemodynamic cerebral ischemia (11 patients), moya-moya disease (18 patients), or complex intracranial aneurysms (11 patients) were included. Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass surgery was performed 35 times in 30 patients (five patients with moyamoya underwent bilateral procedures), STA-posterior cerebral artery bypass surgery in two patients, and saphenous vein (SV) high-flow bypass surgery in eight patients. In each patient, following the completion of the anastomosis, ICG (0.3 mg/kg body weight) was given systemically via an intravenous bolus injection. A near-infrared light emitted by laser diodes was used to illuminate the operating field and the intravascular fluorescence was recorded using an optical filter-equipped video camera. The findings of ICG videoangiography were compared with those of postoperative digital subtraction (DS) or computerized tomography (CT) angiography. In all cases excellent visualization of cerebral arteries, the bypass graft, and brain perfusion was noted. Indocyanine green videoangiography was used to identify four nonfunctioning STA-MCA bypasses, which could be revised successfully in all cases. In two cases of SV high-flow bypasses, ICG videoangiography revealed stenosis at the proximal anastomotic site, which was also revised successfully. In all cases the final findings of ICG videoangiography could be positively validated during the postoperative course by performing DS or CT angiography. CONCLUSIONS: Indocyanine green videoangiography provides a reliable and rapid intraoperative assessment of bypass patency. Thus, ICG videoangiography may help reduce the incidence of early bypass graft failure.

Adolescent↗
PubMed2005

Clazosentan (AXV-034343), a selective endothelin A receptor antagonist, in the prevention of cerebral vasospasm following severe aneurysmal subarachnoid hemorrhage: results of a randomized, double-blind, placebo-controlled, multicenter phase IIa study.

OBJECTIVE: The goal of this study was to investigate the safety and tolerability of the novel endothelin A (ETA) receptor antagonist clazosentan in patients with subarachnoid hemorrhage (SAH) and its potential to reduce the incidence and severity of cerebral vasospasm following surgical clipping of the aneurysm. METHODS: This Phase IIa multicenter study had two parts: a double-blind, randomized Part A (some patients given clazosentan [0.2 mg/kg/hr] and others given placebo), in which statistical inference was performed, and an open-label Part B (patients with established vasospasm given clazosentan [0.4 mg/kg/hr for 12 hours followed by 0.2 mg/kg/hr]) for exploratory purposes only. Primary end points were the incidence and severity of angiographic vasospasm on Day 8 after SAH and the safety and tolerability of the drug. Thirty-four patients (Hunt and Hess Grades III and IV and Fisher Grade > or = 3) were recruited and 32 (15 in the clazosentan group and 17 in the placebo group) were retained in the intent-to-treat population; 19 patients entered Part B. In Part A, treatment with clazosentan resulted in a reduced incidence of angiographically evident cerebral vasospasm (40% compared with 88% of patients, p = 0.008). In addition, the severity of vasospasm was reduced in the clazosentan group (p = 0.012). In Part B of the study, in 50% of assessable patients who were initially treated with placebo reversal of vasospasm was observed following the initiation of clazosentan therapy. The incidence of new infarctions was 15% in the clazosentan group and 44% in the placebo group (p = 0.130). There was no adverse event pattern indicating a specific organ toxicity of clazosentan. CONCLUSIONS: This study indicates that clazosentan reduces the frequency and severity of cerebral vasospasm following severe aneurysmal SAH with the incidence and severity of adverse events comparable to that of placebo.

Adult↗
PubMed2005

Power Doppler imaging in detection of surgically induced indirect neoangiogenesis in adult moyamoya disease.

OBJECT: Moyamoya is a rare, chronic disease that leads to the progressive narrowing and/or occlusion of the distal internal carotid and proximal cerebral arteries. Chronic cerebral ischemia ensues due to insufficient collateral blood supply. One potential treatment consists of the restoration of regional cerebral blood flow by direct or indirect revascularization surgery. The extent of neovascularization, especially in indirect procedures such as encephalomyosynangiosis (EMS), is currently evaluated with conventional angiography. Because this method is invasive and carries some risks, the authors investigated power Doppler imaging as an alternative noninvasive bedside procedure that can be used to assess surgically induced indirect revascularization in adult patients with moyamoya disease. METHODS: Twelve symptomatic patients with adult moyamoya disease (seven women and five men, mean age 38 +/- 17 years) underwent combined (direct and indirect) revascularization. They were then examined using conventional angiography and power Doppler imaging to assess the extent of revascularization within 120 days postsurgery. According to the number of intracranial vessels demonstrating opacification on conventional angiography and power Doppler imaging studies, EMS was graded as follows: 1, absent (0 vessels); 2, moderate (one-four vessels); and 3, extensive (> four vessels) for both methods. Examiners were blinded to the classification results for the procedure that they did not grade. All 24 hemispheres were examined. The visual grading of EMS revealed a highly significant agreement between conventional angiography and power Doppler imaging (Spearman rank coefficient, r = 0.92; p < 0.001) and there was 100% agreement of patency of the bypass between the direct and indirect methods. CONCLUSIONS: The authors found excellent agreement between the two methods. Therefore, power Doppler imaging is a valid noninvasive alternative to carotid artery angiography in evaluating direct and indirect revascularization.

Adult↗
PubMed2005

Outcome after lumbar sequestrectomy compared with microdiscectomy: a prospective randomized study.

OBJECT: Microdiscectomy currently constitutes the standard treatment for herniated lumbar discs. Although limiting surgery to excision of fragments has occasionally been suggested, prospective data are lacking. Therefore, the objective of this study was to compare early outcome and recurrence rates after sequestrectomy and microdiscectomy. METHODS: Eighty-four consecutive patients 60 years of age or younger who harbored free, subligamentary, or transanular herniated lumbar discs refractory to conservative treatment were randomized to one of two treatment groups. Intraoperative parameters and findings were documented as well as pre- and postoperative symptoms such as pain, Patient Satisfaction Index (PSI), Prolo Scale score, and Short Form (SF)-36 subscale results. Follow up of at least 12 months was available in 73 patients (87%). Preoperative intergroup symptoms did not differ significantly. Surgery was significantly shorter in the sequestrectomy-treated group. Overall, low-back pain and sciatica were drastically reduced in both groups and most sensorimotor deficits improved. At 4 to 6 months, SF-36 subscales and PSI scores showed a trend in favor of sequestrectomy, leaving 3% of patients unsatisfied compared with 18% of those treated with discectomy. Outcome according to the Prolo Scale was good or excellent in 76% of discectomy-treated patients and 92% of sequestrectomy-treated patients. Reherniation occurred in four patients after discectomy (10%) and two patients after sequestrectomy (5%) within 18 months. CONCLUSIONS: Sequestrectomy does not seem to entail a higher rate of early recurrences compared with microdiscectomy. Analysis of early outcome demonstrated a trend toward superior results when sequestrectomy is performed. Although long-term follow-up data are mandatory, sequestrectomy may be an advantageous alternative to standard microdiscectomy.

Adult↗
PubMed2005

Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy.

OBJECT: Recently, limited decompression procedures have been proposed in the treatment of lumbar stenosis. The authors undertook a prospective study to compare the safety and outcome of unilateral and bilateral laminotomy with laminectomy. METHODS: One hundred twenty consecutive patients with 207 levels of lumbar stenosis without herniated discs or instability were randomized to three treatment groups (bilateral laminotomy [Group 1], unilateral laminotomy [Group 2], and laminectomy [Group 3]). Perioperative parameters and complications were documented. Symptoms and scores, such as visual analog scale (VAS), Roland-Morris Scale, Short Form-36 (SF-36), and patient satisfaction were assessed preoperatively and at 3, 6, and 12 months after surgery. Adequate decompression was achieved in all patients. The overall complication rate was lowest in patients who had undergone bilateral laminotomy (Group 1). The minimum follow up of 12 months was obtained in 94% of patients. Residual pain was lowest in Group 1 (VAS score 2.3 +/- 2.4 and 4 +/- 1 in Group 3; p < 0.05 and 3.6 +/- 2.7 in Group 2; p < 0.05). The Roland-Morris Scale score improved from 17 +/- 4.3 before surgery to 8.1 +/- 7, 8.5 +/- 7.3, and 10.9 +/- 7.5 (Groups 1-3, respectively; p < 0.001 compared with preoperative) corresponding to a dramatic increase in walking distance. Examination of SF-36 scores demonstrated marked improvement, most pronounced in Group 1. The number of repeated operations did not differ among groups. Patient satisfaction was significantly superior in Group 1, with 3, 27, and 26% of patients unsatisfied (in Groups 1, 2, and 3, respectively; p < 0.01). CONCLUSIONS: Bilateral and unilateral laminotomy allowed adequate and safe decompression of lumbar stenosis, resulted in a highly significant reduction of symptoms and disability, and improved health-related quality of life. Outcome after unilateral laminotomy was comparable with that after laminectomy. In most outcome parameters, bilateral laminotomy was associated with a significant benefit and thus constitutes a promising treatment alternative.

Aged↗
PubMed2004

Arterio-embolic ischemic stroke in children with moyamoya disease.

INTRODUCTION: Moyamoya (MM) disease is a rare steno-occlusive cerebrovascular disease known to occur in children and adults. The most serious complications in children are developmental delay and mental retardation due to recurrent hemodynamic stroke. CASES: We report two pediatric patients without coagulopathy who suffered from severe arterio-embolic ischemic complications despite antiplatelet medication. DISCUSSION: These observations underline the potential impact of cerebral thromboembolism on the pathophysiology of the stroke and thus on the treatment of children with MM disease.

Anterior Cerebral Artery↗
PubMed2004

Moyamoya-like vasculopathy (moyamoya syndrome) in children.

INTRODUCTION: A large variety of inherited or acquired childhood disorders and conditions may present in conjunction with progressive bilateral stenosis and/or occlusion of the terminal segments of the internal carotid artery. In addition, the development of pathological collateral vessels can be observed in the vicinity of the steno-occlusive changes in these patients. This condition is known as moyamoya-like (MML) vasculopathy. The natural history, the angiographic appearance, and the pathology of MML vasculopathy probably differ from those of definite moyamoya disease. Adequate cerebral vascular imaging should be considered in all pediatric patients with inherited or acquired systemic disorders and symptoms attributable to cerebral ischemia. CASES AND DISCUSSION: We present four pediatric cases of MML vasculopathy, and outline the etiology, the current classification, and the therapeutic approaches for this heterogeneous disease entity.

Brain Neoplasms↗
PubMed2003

Regional cerebral blood flow monitoring in the diagnosis of delayed ischemia following aneurysmal subarachnoid hemorrhage.

OBJECT: The goal of this study was to evaluate regional cerebral blood flow (rCBF) monitoring, performed using thermal-diffusion (TD) flowmetry, as a novel means for the bedside diagnosis of symptomatic vasospasm. METHODS: Fourteen patients with high-grade subarachnoid hemorrhage (SAH) who underwent early clip placement for anterior circulation aneurysms were prospectively entered into the study. Thermal-diffusion microprobes were implanted into the white matter of vascular territories that were deemed at risk for developing symptomatic vasospasm. Data on arterial blood pressure, intracranial pressure, cerebral perfusion pressure, rCBF measurement obtained using a TD probe (TD-rCBF), cerebrovascular resistance (CVR), and blood flow velocities were collected at the patient's bedside. The diagnosis of symptomatic vasospasm was based on the manifestation of a delayed ischemic neurological deficit and/or a reduced territorial level of CBF as assessed using stable Xe-enhanced computerized tomography (CT) scanning in combination with vasospasm demonstrated by angiography. Bedside monitoring of TD-rCBF and CVR allowed the detection of symptomatic vasospasm. In the 10 patients with vasospasm the TD-rCBF decreased from 21 +/- 4 to 9 +/- 1 ml/100 g/min (mean +/- standard error of the mean), whereas in the four other patients the TD-rCBF value remained unchanged (mean TD-rCBF = 25 +/- 4 compared with 21 +/- 4 m/100 g/min). A comparison of the results of TD-rCBF and Xe-enhanced CT studies, as well as the calculation of sensitivities, specificities, predictive values, and likelihood ratios, identified a TD-rCBF value of 15 ml/100 g/min as a reliable cutoff for the diagnosis of symptomatic vasospasm. In addition, TD flowmetry was characterized by a more favorable diagnostic reliability than transcranial Doppler ultrasonography. CONCLUSIONS: Thermal-diffusion flowmetry represents a promising method for the bedside monitoring of patients with SAH to detect symptomatic vasospasm. This is of major clinical interest for patients with high-grade SAH, who often cannot be assessed neurologically.

Adolescent↗