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P Schmiedek

Publications and source records attributed to P Schmiedek.

At least 19 recordsLinked to original sources
PubMed2005

Power Doppler evaluation of revascularization in childhood moyamoya.

Moyamoya disease is generally recognized in young children. One potential treatment is direct extra-intracranial bypass combined with indirect revascularization using encephalo-myo-synangiosis. Standard follow-up to assess neoangiogenesis includes repeat cerebral angiography, which is invasive. The authors studied whether noninvasive power Doppler imaging could evaluate the patency of the bypass and the degree of indirect revascularization. They found that transcranial power Doppler imaging is a valid noninvasive alternative to cerebral angiography.

Cerebral Revascularization↗
PubMed2005

[Recommendations for the management of patients with aneurysmal subarachnoid hemorrhage].

After SAH, primary and secondary complications are frequent and often require neurosurgical interventions to avoid secondary brain damage. The authors of the present paper have summarized the available data about the treatment modalities often used for patients with SAH. The present recommendations have been developed as a neurosurgical and neuroanestesiological consensus. Evidence from prospective, randomized, double blind, placebo-controlled studies support grade A recommendations (standard) for the prophylaxis and treatment of cerebral vasospasm with oral Nimodipine in good grade patients. For intravenous Nimodipine or for oral nimodipine treatment in poor grade patients, available data only support grade C recommendations (options). Despite the lack of data supporting standards (grade A) or guidelines (grade B), avoidance and rigorous treatment of hypotension and hypovolemia remains the mainstay in the prophylaxis and treatment of a delayed ischemic neurological deficit (DIND). Prophylactic hypervolemia or prophylactic hypertension and hypervolemia was shown to be ineffective in reducing symptomatic vasospasm and improving outcome (grade B). Therapeutic hypertensive hypervolemic hemodilution is recommended as a treatment of symptomatic vasospasm but no prospective studies are available (grade C recommendation). Suggested target values for moderate triple-H-therapy are CPP 80- 120 mmHg (MAP 90-130), CVP > 7 mmHg and Hk 0.25-0.40. Balloon angioplasty should be considered for treatment of DIND cause by focal, proximal cerebral vasospasm. There is no evidence supporting the routine use of antifibrinolyticals, steroids or anticonvulsive prophylaxis. Clinical data indicate that current prophylaxis and treatment of cerebral vasospasm is still insufficient and aggressive triple-H-therapy is associated with an increased incidence of complications.

Angioplasty, Balloon↗
PubMed2004

Evaluation of extracranial-intracranial arterial bypass function with magnetic resonance angiography.

Extracranial-intracranial (EC/IC) arterial bypass surgery is a valuable therapeutic modality in the field of cerebrovascular surgery. The assessment of bypass patency and its functional parameters are of utmost importance in the postoperative course. The present study examined the potential role of quantitative MR-based volume flow measurement techniques for the investigation of bypass patency. Forty-one patients with steno-occlusive cerebrovascular disease treated with EC/IC bypass surgery underwent conventional angiographic (CA) and two-dimensional cine-phase MR-based angiographic assessment (MRA) of bypass function. CA bypass function was evaluated as poor (grade I), moderate (grade II), or extensive (grade III) and was compared with quantitative volume flow measurements (BVF) obtained in MRA studies. Bypass filling was classified as grade I in 15% of the cases, grade II and grade III in 36% and 49% of the studies, respectively. Mean BVF differed significantly in the different grades: 31.94 +/- 9.8 ml/min in grade I, 73.6 +/- 16.7 ml/min in grade II, and 97.2 +/- 26.6 ml/min in grade III. BVF values of 48 ml/min or lower (n = 6) were specific for grade I bypass function, while only BVF values higher than 111 ml/min (3/20, 15%) are specific for extensive angiographic bypass function. The assessment of EC/IC bypass patency with quantitative BVF measurements provides exact, investigator-independent information under physiological conditions. MRA is well correlated with the angiographic bypass grading system.

Aged↗
PubMed2004

Extracranial-intracranial arterial bypass surgery improves total brain blood supply in selected symptomatic patients with unilateral internal carotid artery occlusion and insufficient collateralization.

It remains controversial whether extracranial-intracranial (EC-IC) arterial bypass surgery leads to a significant increase in brain blood supply, allowing the reversal of regional cerebral hypoperfusion in symptomatic patients with occlusive cerebrovascular disease and hemodynamic impairment. The aim of the present study was to determine the effects of EC-IC bypass surgery on cerebral brain-supplying blood volume flow (BVF; ml/min) from a purely hemodynamic point of view, using 2D cine phase-contrast MR imaging. Twenty-five patients with symptomatic, unilateral internal carotid artery (ICA) occlusion and hemodynamic compromise received EC-IC arterial bypass surgery. All patients underwent quantitative BVF measurements of brain-supplying arteries preoperatively and postoperatively, including the direct BVF measurement in the established EC-IC bypass after surgery. Preoperatively, total brain BVF was reduced in comparison to normal controls (595 +/- 89 vs 663 +/- 49 ml/min; [mean +/- SEM]; p = 0.039). Mean BVF through the EC-IC bypass reached 84 +/- 32 ml/min (range: 14-177 ml/min), leading to a significant net increase in total BVF of 78 +/- 43 ml/min (range: 7-136 ml/min) when compared with BVF prior to surgery (p < 0.001), with resulting postoperative BVF reaching values obtained in normal controls. EC-IC arterial bypass surgery increases total brain blood supply, allowing restoration of local perfusion in hemodynamically compromised brain tissue in patients with symptomatic ICA occlusion.

Adult↗
PubMed2004

Concepts of neurosurgical management of chronic subdural haematoma: historical perspectives.

The history of chronic subdural haematoma (CSH), spanning from its possibly earliest beginnings throughout the centuries until the early 1980s, was investigated within the context of four different epochs. In the 'era of uncertainty', successful trephination, the modem method of choice for the treatment of CSH, was developed by neolithic men. Various historical sources indicate that patients with CSH might have undergone surgery at that time. CSH might have been one of the ailments that had spectacular courses of salvation after trephination. The entity of CSH was first described in the 'era of pioneers' in the seventeenth century by Johann Jacob Wepfer. The misconception of 'pachymeningitis hemorrhagica interna' was introduced by Rudolf Virchow in 1857. By the end of the nineteenth century it became more widely accepted that trauma was a possible cause of CSH. Successful neurosurgical treatment of CSH was first reported by Hulke in 1883. Putnam and Cushing, in 1925, focused on surgery as the treatment of choice for CSH. In the 'era of diagnostic refinement', the introduction of pneumencephalography and angiography allowed the diagnosis of CSH much earlier. Subsequently, the typical signs and symptoms of patients suffering from CSH changed from apathy and coma to headaches and discrete focal neurological symptoms. In the 'era of surgical routine', neurosurgical approaches became smaller and less invasive. Removal of the haematoma was identified as the primary goal of surgery. The use of closed system drainage markedly improved reexpansion of the brain after surgery. Burr hole craniostomy and twist drill craniostomy became the surgical treatment of first choice because of their low morbidity and mortality. There is growing evidence, however, that the neurosurgical learning curve has reached a plateau.

Cerebral Angiography↗
PubMed2003

Bilateral meningiomatous lesions of the spinal accessory nerves.

BACKGROUND: Meningiomas arising from cranial nerves with no dural attachment are exceedingly rare. The authors present a patient with bilateral meningiomatous lesions originating symmetrically from both spinal accessory nerves. CASE REPORT: A 61-year old woman presented with a one-year history of spinal ataxia and minimal left-sided motor impairment. Magnetic resonance imaging demonstrated two extrinsic lesions dorsolaterally of the medulla. Surgical exposure via a midline suboccipital approach with C1 laminectomy revealed the lesions arising from the spinal accessory nerves and in direct contact with the vertebral arteries. Histological investigation showed hypocellular fibrous lesions with proliferating meningothelial cells, psammoma bodies and immunoreactivity for vimentin, S-100 protein and epithelial membrane antigen. INTERPRETATION: To the authors' knowledge this is the first report of intradural tumours of the spinal accessory nerves not derived from Schwann cells and the first report of bilateral intracranial meningiomatous lesions without dural attachment.

Accessory Nerve Diseases↗
PubMed2003

German Society of Neurosurgery Section on Vascular Neurosurgery: Position Statement on the International Subarachnoid Hemorrhage Trial (ISAT).

The outcome after a specific treatment (clipping or coiling) of ruptured intracranial aneurysms is determined by both the periprocedural complication rate and the success of preventing re-bleeding from the treated aneurysm. The latter is associated with a cumulative risk over many years, particularly in incompletely treated aneurysms. Incomplete occlusion of the aneurysm is not infrequently seen after endovascular coiling, even in cases with a perfect anatomical configuration. Therefore, we believe that the 1-year outcome as reported in the ISAT is not an appropriate endpoint for the comparison of both methods. There has also been a tendency to apply the 1-year ISAT data to all patients harbouring intracranial aneurysms. It is inappropriate and dangerous to be less critical when selecting the endovascular approach as the method of choice for treating an aneurysm. This will ultimately result in a higher complication rate of coiling. Another striking finding is the poor surgical outcome in the ISAT. This good-grade patient population (94 % were WFNS grade 1-3 and 89 % were WFNS grade 1-2) had an almost 10 % higher rate of poor outcome compared to other good-grade patients in large prospective surgical studies or the same outcome as trials that included up to 20 % poor-grade patients.[nl]Neurosurgeons should acknowledge that endovascular coiling is a safe method associated with less complications than clipping in experienced hands (Fig. ). Endovascular radiologists should acknowledge that the success of complete obliteration is higher after surgery, that incompletely occluded aneurysms have a higher rate of re-rupture and that the definitive long-term re-rupture rate still remains unknown. Therefore, we await with interest the angiographic and clinical follow-up data that will provide evidence about the final patient outcome.

Germany↗
PubMed2003

Outcome of contemporary surgery for chronic subdural haematoma: evidence based review.

OBJECTIVE: To evaluate the results of surgical treatment options for chronic subdural haematoma in contemporary neurosurgery according to evidence based criteria. METHODS: A review based on a Medline search from 1981 to October 2001 using the phrases "subdural haematoma" and "subdural haematoma AND chronic". Articles selected for evaluation had at least 10 patients and less than 10% of patients were lost to follow up. The articles were classified by three classes of evidence according to criteria of the American Academy of Neurology. Strength of recommendation for different treatment options was derived from the resulting degrees of certainty. RESULTS: 48 publications were reviewed. There was no article that provided class I evidence. Six articles met criteria for class II evidence and the remainder provided class III evidence. Evaluation of the results showed that twist drill and burr hole craniostomy are safer than craniotomy; burr hole craniostomy and craniotomy are the most effective procedures; and burr hole craniostomy has the best cure to complication ratio (type C recommendation). Irrigation lowers the risk of recurrence in twist drill craniostomy and does not increase the risk of infection (type C recommendation). Drainage reduces the risk of recurrence in burr hole craniostomy, and a frontal position of the drain reduces the risk of recurrence (type B recommendation). Drainage reduces the risk of recurrence in twist drill craniostomy, and the use of a drain does not increase the risk of infection (type C recommendation). Burr hole craniostomy appears to be more effective in treating recurrent haematomas than twist drill craniostomy, and craniotomy should be considered the treatment of last choice for recurrences (type C recommendation). CONCLUSIONS: The three principal techniques-twist drill craniostomy, burr hole craniostomy, and craniotomy-used in contemporary neurosurgery for chronic subdural haematoma have different profiles for morbidity, mortality, recurrence rate, and cure rate. Twist drill and burr hole craniostomy can be considered first tier treatment, while craniotomy may be used as second tier treatment. A cumulative summary of data shows that, overall, the postoperative outcome of chronic subdural haematoma has not improved substantially over the past 20 years.

Chronic Disease↗
PubMed2002

[Recommendations for the management of unruptured intracranial aneurysms].

Optimal management of patients with unruptured intracranial aneurysms (UIAs) remains controversial. Recent studies have found conflicting data regarding the natural history and the treatment outcome of UIAs. Based on the recommendations published by the American Heart Association, the Section of Vascular Neurosurgery of the German Society of Neurosurgery has formed a task force to summarize the available data and to develop a practical framework for the management of UIAs. For UIAs, only evidence from nonrandomized historical cohort comparisons and case series without control subjects are available, supporting only grade C recommendations (options), but no standards (grade A) and no guidelines (grade B). The present recommendations have been developed as a neurosurgical, neuroradiological and neurological consensus. They are based on the existing data of both treatment risks and the risks of the natural history of UIAs.

Autoradiography↗
PubMed2001

[Spontaneous occlusion of the circle of Willis (moyamoya disease). Diagnosis and therapy].

Spontaneous occlusion of the circle of Willis (moyamoya disease), a rare cerebrovascular disease, may lead to repeated hemodynamic stroke due to unremitting changes of the basal cranial vessels. Moyamoya can be diagnosed on its specific epidemiological, clinical, and radiological features. In patients with distinctive Moyamoya disease, improvement of cerebral blood supply by means of neurosurgical revascularization enables definitive treatment. This review summarizes current knowledge of the clinical and diagnostic features of this disease and illustrates its pathological and pathophysiological characteristics. Additionally, indications and techniques of current neurosurgical revascularization procedures are illustrated.

Cerebral Infarction↗
PubMed2001

Specific pattern of growth factor distribution in chronic subdural hematoma (CSH): evidence for an angiogenic disease.

BACKGROUND: The aim of this prospective study was to evaluate the significance of growth factors as determinants of the pathological degree of neovascularisation found in the parietal neomembrane of chronic subdural hematoma (CSH). Thus far the pathogenesis of the vascularisation has not been elucidated. METHOD: The concentrations of growth factors, i.e. vascular endothelial derived growth factor (VEGF), basic fibroblast growth factor (bFGF) and platelet derived growth factor (PDGF) were determined using ELISA technique in hematoma fluid and serum of 20 patients with uni- or bilateral CSH. For comparison, growth factor concentrations were determined in cerebrospinal fluid (CSF) of patients undergoing diagnostic myelography. FINDINGS: Concentrations of VEGF and bFGF were significantly (p < 0.001) increased in the hematoma fluid as compared with serum (VEGFh = 8.142 pg/ml, bFGFh = 8.7 pg/ml versus VEGFS = 368 pg/ml, bFGF, = 1.8 pg/ml). In contrast, PDGF concentration was significantly (p < 0.001) lower in the hematoma (PDGFh = 3,456 pg/ml versus PDGF, = 31,937 pg/ml). The serum levels for VEGF, bFGF and PDGF in CSH patients lay within the range of normal volunteers. No growth factors were found in normal CSF. INTERPRETATION: These results reveal a specific distribution pattern of growth factors in CSH patients. This pattern suggests that CSH may be considered a member of the angiogenic disease family.

Aged↗
PubMed2001

Bedside monitoring of cerebral blood flow by transcranial thermo-dye-dilution technique in patients suffering from severe traumatic brain injury or subarachnoid hemorrhage.

Bedside measurement of cerebral blood flow (CBF) represents an important feature in monitoring of neurointensive care patients which is hard to establish. Therefore, we adopted a recently described thermo-dye-dilution-based approach for monitoring CBF in patients suffering from severe cerebral insults, that is, traumatic brain injury (TBI) or subarachnoid hemorrhage (SAH). Combined fiberoptic-thermistor catheters were placed in one jugular venous bulb and in the abdominal aorta of 16 patients. Following central venous injection of a 50-mL bolus of precooled indocyanine green (ICG) solution, CBF was determined as a function of the mean transit times of coldness and dye. In addition, measurements of CBF using stable xenon-enhanced computerized tomography (sXe-CT) were simultaneously performed in 10 patients. A total of 272 thermo-dye-dilution measurements yielded 196 valid results, with CBF ranging from 26.2 to 144.8 mL 100 g(-1) min(-1). Reproducibility was fairly good, with the standard deviation within sets of repeated measurements being 6.3 mL 100 g(-1) min(-1) and 9.4 as the mean coefficient of variation. Simultaneously obtained values with sXe-CT displayed a good correlation (r = 0.843, p < 0.01); however, the thermo-dye-dilution method consistently overestimated CBF. Data analysis using the Bland and Altman methodology revealed a large bias of 45.7 mL 100 g(-1) min(-1) with a +/- 2 SD range of 37 mL 100 g(-1) min(-1), indicating a rather poor agreement. The thermo-dye-dilution method proved a reasonably reproducible technique, enabling repeated long-term bedside measurements of CBF in neurointensive care patients with a minimum of time effort. However, a high failure rate was also noted, and consistent overestimation of perfusion was observed in comparison to sXe-CT measurements. Although the thermo-dye-dilution technique has been successfully validated in patients with normal neurovascular function, its applicability for bedside monitoring of CBF appears uncertain in patients suffering from severe TBI or SAH.

Adolescent↗
PubMed2001

Therapy of malignant intracranial hypertension by controlled lumbar cerebrospinal fluid drainage.

OBJECTIVES: To evaluate the effect of controlled lumbar cerebrospinal fluid drainage in adult patients with refractory intracranial hypertension. DESIGN: Prospective, pre- vs. postintervention study. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: Twenty-three patients with severe traumatic brain injury or delayed ischemia after subarachnoid hemorrhage with intracranial hypertension refractory to aggressive treatment, including repeated applications of tromethamine, hypertonic saline solution, barbiturate coma, and decompressive craniectomy. Patients were considered for controlled lumbar cerebrospinal fluid drainage if basal cisterns on computerized tomography scan were discernible. INTERVENTIONS: After institution of a lumbar drain, cerebrospinal fluid was gradually aspirated, and then, continuous cerebrospinal fluid drainage was maintained under control of intracranial pressure (ICP) and pupillary status. MEASUREMENTS AND MAIN RESULTS: ICP and cerebral perfusion pressure before and after initiation of lumbar cerebrospinal fluid drainage and related complications were documented. The neurologic outcome of the patients was assessed according to the Glasgow Outcome Scale 6 months after injury. As a result of lumbar cerebrospinal fluid drainage, all patients demonstrated an immediate and lasting decrease of ICP and a concomitant increase of cerebral perfusion pressure. Two patients temporarily showed a unilateral fixed and dilated pupil 6 and 8 hrs after onset of lumbar cerebrospinal fluid drainage, respectively. Ten patients showed a favorable outcome, four patients survived with a severe permanent neurologic deficit, one patient remained in a persistent vegetative state, and eight patients died. CONCLUSIONS: Controlled lumbar cerebrospinal fluid drainage significantly reduces refractory intracranial hypertension. The danger of transtentorial or tonsillar herniation is minimized by considering lumbar drainage in the presence of discernible basilar cisterns only.

Adolescent↗
PubMed2001

Effect of moderate hypothermia on experimental severe subarachnoid hemorrhage, as evaluated by apparent diffusion coefficient changes.

OBJECTIVE: The aims of this study were to investigate the early changes in the mean apparent diffusion coefficient (ADC) after severe subarachnoid hemorrhage (SAH), as a marker of ischemic damage, and to examine the effects of moderate hypothermia, induced at various time points, on ADC changes. METHODS: ADC maps were calculated from diffusion-weighted, blipped-epi, spin echo, magnetic resonance imaging sequences (2.35-T BIOSPEC 24/40 scanner; Bruker Medizin Technik GmbH, Karlsruhe, Germany) for 21 anesthetized (0.45-1% halothane, temperature-adjusted/30% oxygen/69% nitrogen) and ventilated Wistar rats. After baseline scanning, bolus injection of 0.5 ml of autologous arterial blood or artificial cerebrospinal fluid (control group), into the cisterna magna, was performed. Serial scanning was performed for 3 hours after injection, using normothermic or hypothermic (32 degrees C) rats. In an additional series of experiments, hypothermia was initiated either immediately or 60 minutes after normothermic SAH. The water contents of the removed brains were calculated using the wet/dry weight method. RESULTS: The ADC values did not change in the control group but decreased to 88.6+/-5.2% (P < 0.05 versus baseline) after SAH and remained significantly decreased throughout the experiment in normothermia. An injection of blood during hypothermia caused an initial decrease in ADC to 96.1+/-5.6% (P < 0.05 versus baseline); values continuously increased and reached normal levels within 60 minutes. Delayed hypothermia also normalized ADC values within the observation period. The brain water content in the control group was 80.3+/-0.1%, that after SAH in normothermia was 81.1+/-0.7%, and that after SAH in hypothermia was 79.3+/-0.5%. CONCLUSION: This model of severe SAH in rats causes significant ADC changes, which are reversible by application of moderate hypothermia even when it is induced after a 60-minute delay. These findings support the concept of moderate hypothermia exerting a neuroprotective effect in severe SAH.

Animals↗
PubMed2001

Inflammatory cytokines in subarachnoid haemorrhage: association with abnormal blood flow velocities in basal cerebral arteries.

Subarachnoidal release of inflammatory cytokines (interleukin (IL)-1beta, IL-6, and tumour necrosis factor (TNF)-alpha) was characterised in 35 patients with subarachnoid haemorrhage (SAH) and control subjects and compared with development of complicating haemodynamic abnormalities in basal cerebral arteries and clinical outcome. Serial analysis allowed the observation of a subacute response profile of these key mediators of inflammation in the subarachnoidal space. This compartmentalised inflammatory host response was closely associated in time and extent with development of increased blood flow velocities in the basal cerebral vessels as recorded by transcranial Doppler sonography. Moreover, intrathecal secretion of inflammatory cytokines was significantly increased in patients with poor clinical outcome. Together, these findings suggest a role of excessive compartmentalised inflammatory host response in pathogenesis of cerebrovascular complications after SAH.

Adult↗
PubMed2001

Quantitative regional cerebral blood flow measurement techniques improve noninvasive detection of cerebrovascular vasospasm after aneurysmal subarachnoid hemorrhage.

Adequate therapy of vasospasm (VS) in patients suffering from aneurysmal subarachnoid hemorrhage critically depends upon early and reliable diagnosis of cerebral hypoperfusion. The objective of the present study was to evaluate the usefulness of quantitative regional blood flow (rCBF) analysis as an adjunct in noninvasive prediction of VS. Therefore, 33 transcranial Doppler sonography (TCD) studies assuming cerebrovascular VS (TCD flow velocity >120 cm/s) were followed by (s)Xe/CT and cerebral panangiography (PA). TCD plus (s)Xe/CT significantly increased the predictability of VS from 34 to 91%, proving that a combination of TCD and rCBF studies improves the noninvasive detection of VS and might help to prevent unnecessary angiographic examinations.

Adult↗
PubMed2001

Effect of intra-arterial papaverine on regional cerebral blood flow in hemodynamically relevant cerebral vasospasm.

BACKGROUND AND PURPOSE: It remains controversial whether the intra-arterial administration of papaverine (IAP) is effective in reversing vasospasm-associated cerebral hypoperfusion after aneurysmal subarachnoid hemorrhage. The aim of the present study was to continuously assess regional cerebral blood flow (rCBF) during and after IAP with the use of quantitative, bedside thermal diffusion flowmetry. METHODS: Eight patients with cerebral vasospasm after subarachnoid hemorrhage (mean flow velocity >120 cm/s; angiographic vessel constriction >33%; hemispheric cerebral blood flow [CBF] <32 mL/100 g per minute) were prospectively entered into the study. Before IAP, thermal diffusion microprobes were implanted into the white matter of each affected vascular territory (n=10) for rCBF monitoring. During and after IAP (300 mg papaverine/50 mL saline over 1 hour), mean arterial blood pressure, intracranial pressure, cerebral perfusion pressure, thermal diffusion rCBF (TD-rCBF), and cerebrovascular resistance (CVR) were recorded continuously. RESULTS: IAP significantly increased TD-rCBF from 7.3+/-1.6 to 37.9+/-6.6 mL/100 g per minute (mean+/-SEM), indicating reversal of cerebral hypoperfusion. This TD-rCBF response was dependent on the degree of cerebral vasospasm and reduced perfusion within the vascular territory. Long-term analysis of TD-rCBF, however, demonstrated that this beneficial effect of IAP on cerebral hypoperfusion was only transient: within 3 hours after treatment, TD-rCBF and CVR returned to baseline values. Furthermore, a lack of correlation between transcranial Doppler sonography and thermal diffusion flowmetry suggested that transcranial Doppler sonography is not suited for CBF-based neuromonitoring after IAP. CONCLUSIONS: IAP is not effective in permanently reversing cerebral hypoperfusion in patients with cerebral vasospasm. The need to validate alternative therapeutic strategies that seek to improve cerebral perfusion in vasospasm warrants continued development of CBF-based neuromonitoring strategies.

Adult↗