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Biomedical subjects

K Schwerdtfeger

Publications and source records attributed to K Schwerdtfeger.

At least 19 recordsLinked to original sources
PubMed2003

Changes in linear dynamics of cerebrovascular system after severe traumatic brain injury.

BACKGROUND AND PURPOSE: We sought to describe the dynamic changes in the cerebrovascular system after traumatic brain injury by transfer function estimation and coherence. METHODS: In 42 healthy volunteers (mean+/-SD age, 37+/-17 years; range, 17 to 65 years), spontaneous fluctuations of middle cerebral artery blood flow velocity and of finger blood pressure (BP) were simultaneously recorded over a period of 10 minutes under normocapnic and hypocapnic conditions to generate normative spectra of coherence, phase shift, and gain over the frequency range of 0 to 0.25 Hz. Similar recordings were performed in 24 patients with severe traumatic brain injury (Glasgow Coma Scale score 70 mm Hg. Each blood flow velocity/BP recording was related to the presence or absence of middle cerebral artery territory brain parenchyma lesions on cranial CT performed within a close time frame. RESULTS: In controls, hypocapnia decreased coherence (0.0 to 0.20 Hz), increased phase shift (0.0 to 0.17 Hz), and decreased gain in the frequency range of 0.0 to 0.11 Hz but increased gain at frequencies of 0.20 to 0.25 Hz (P<0.01 for all frequency ranges reported). In patients with traumatic brain injury, 102 investigations were possible. Compared with controls, coherence was increased in the frequency range <0.03 Hz and between 0.13 and 0.25 Hz in both normocapnia and hypocapnia, irrespective of the CT findings. Gain was unchanged in normocapnia and in the absence of a CT lesion. Gain was decreased in hypocapnia at frequencies >0.12 Hz irrespective of the presence/absence of a CT lesion. Phase shift decreased rapidly between 0.06 and 0.13 Hz under hypocapnic conditions and under normocapnic conditions in the presence of a CT lesion (P< 0.01). CONCLUSIONS: Use of spontaneous fluctuations of blood flow velocity and BP to assess the cerebrovascular system dynamically requires consideration of the Paco2 level. In different conditions, including severe traumatic brain injury, the cerebrovascular system behaves linearly only in parts of the investigated frequency range.

Adolescent↗
PubMed2002

[Atypical symptoms in carpal tunnel syndrome - treatment and results].

PURPOSE: Additionally to the typical carpal tunnel symptoms, the patients of this study had atypical complaints. Other reasons for these symptoms than those caused by the compression of the median nerve could be excluded using medical examination or imaging techniques. Purpose of this study was to investigate whether decompression of the median nerve may reduce or even abolish the atypical complaints. METHOD: For this prospective study 378 patients with carpal tunnel syndrome were clinically and electroneurographically examined, which was performed before and after (3 months) they underwent surgical decompression of the median nerve. RESULTS: 70 patients (19 % of all patients) with carpal tunnel symptoms suffered from additional atypical symptoms such as cardiac pain, ipsilateral headache as well as neck and shoulder pain. The diagnosis of carpal tunnel syndrome was made using clinical and electroneurographical examination. Carpal tunnel symptoms of all patients disappeared completely after surgery. Respectively, 61 % of those patients with preoperative atypical complaints did also fully recover. CONCLUSION: This study shows that patients with carpal tunnel syndrome may also suffer from atypical complaints. These symptoms have been shown to be associated with the compression of the median nerve. They may be caused by spinal synaptic interaction between sensory and sympathetic/parasympathetic neuronal pathways by somatically-induced reflex responses.

Adult↗
PubMed2001

Guidelines for guidelines.

Clinical practice guidelines (CPGs) are suited tools for controlling and improving the effectiveness and efficiency of medical care. With the upcoming internet, the numbers of CPGs have increased rapidly, however, only few offer the attributes of good guidelines such as reliability/reproducibility, applicability, flexibility, clarity, multidisciplinary process, scheduled review and documentation of clinical and scientific evidence. Nearly identical criteria for appraisal of CPGs have been developed in many countries consisting of a checklist with questions concerning the quality of development, the content and format, and the applicability of the guideline. In the United States, guidelines which successfully passed the appraisal (or clearing) process, were stored in the National Guideline Clearinghouse, an internet-based database. A German counterpart is under construction, which will comprise clearing reports reviewing and appraising all existent guidelines covering a medical topic. Developing high-quality CPGs is a time consuming and expensive process. A widely accepted guideline for guideline development was published by the Scottish Intercollegiate Guideline Network. CPGs touching neurosurgical topics are rare and often developed without neurosurgical participation. Due to the potential medico-economic impact of CPGs in the future, national neurosurgical societies and their international associations should play a more active role in the development and implementation of CPGs.

Evidence-Based Medicine↗
PubMed2001

[Embolization of dural carotid cavernous sinus fistulas via the sylvian vein in 2 patients].

BACKGROUND: Dural carotid sinus cavernous fistulas account for about 12% of intracranial arteriovenous fistulas. These dynamic shunts are dilemmas not only for the clinical diagnosis but also for the management of ocular complications and in the application of diagnostic and therapeutic techniques. The traditional therapy is transarterial embolisation by an interventional neuroradiologist. We report on the management of two fistulas where the classical therapeutic methods were not possible or failed. PATIENTS AND METHODS: Two patients underwent an osteoplastic pterional craniotomy with cannulation of a vein of the sylvian fissure and controlled embolisation of the fistula with polyvinyl alcohol particles. RESULTS: Successful closure of both arteriovenous shunts was achieved on angiography with normalisation of clinical symptoms. As a severe complication one patient suffered from a stroke after the postoperative angiography. CONCLUSIONS: Arteriovenous fistulas not approachable by traditional therapeutic methods, can be embolised effectively via a superficial vein of the sylvian fissure. This surgical route should only be considered if other therapeutic ways fail or seem impossible.

Aged↗
PubMed2001

Alterations of norepinephrine levels in plasma and CSF of patients after traumatic brain injury in relation to disruption of the blood-brain barrier.

BACKGROUND: In injured brain tissue with a disrupted blood-brain barrier (BBB) catecholamines such as norepinephrine (NE) are known to enhance glucose consumption and cerebral blood flow but may lead to an energy depletion increasing the risk of ischemia. Therefore it is of great interest whether the exogenous administration of NE used mainly to maintain an adequate cerebral perfusion pressure influences CSF NE levels or not, and whether elevated plasma or CSF levels of NE can influence the actual clinical condition. We addressed this issue by measuring the levels of NE in CSF and plasma and correlating them with the actual clinical condition of the patients. METHODS: In 29 patients with severe TBI (< 8 points on the Glasgow Coma Scale, GCS) NE levels were analysed by high performance liquid chromatography (HPLC) in paired blood and CSF specimens which were collected from days 1 to 14 after severe TBI (total number of pairs = 121). The integrity of the BBB was evaluated by determining the CSF/serum albumin ratio. The clinical condition of the patients was assessed by GCS. RESULTS: Elevated plasma and CSF NE levels were observed in 50% of all samples, most consistently in patients treated with NE. NE elevation in CSF was independent of whether or not the BBB remained intact. There was no correlation between GCS and the levls of NE in CSF or plasma either in samples from the treated or the untreated group. INTERPRETATION: Exogenous administration of NE seems to increase NE levels in plasma and CSF. However, in this group of patients with severe TBI there was no clinical evidence that exogenous administration of NE was detrimental to the traumatized patients.

Adolescent↗
PubMed2001

Cerebral blood flow velocity and inflammatory response after severe traumatic brain injury.

OBJECTIVES: The cerebral blood flow velocity (CBVF) was measured by transcranial Doppler sonography in patients with severe traumatic brain injury (TBI) in order to determine, whether it depends on the posttraumatic inflammatory response. MATERIAL AND METHODS: CBVF in both middle cerebral arteries (MCA) was recorded in 25 comatous TBI patients (male 20; female five; mean age +/- standard deviation (S.D.), 41 +/- 20 years) and correlated to the levels of interleukine-(IL) 6, IL-8 and IL-10 in corresponding CSF/plasma samples, to PaCO2 and to intracranial (ICP), mean arterial (MAP) and cranial perfusion pressure (CPP). RESULTS: CSF IL-6 and IL-8 were clearly higher than the corresponding plasma levels (mean CSF/plasma quotient for IL-6: 159 +/- 582; for IL-8: 143 +/- 311). CBVF did not show large side-to-side differences at each examination indicating that CBFV in both MCAs was determined mostly by systemic conditions and not by severe regional abnormalities. Since all other evaluated variables including interleukines represent also systemic conditions we used the mean value (MCBFV) of both CBFVs for analysis. By stepwise regression analysis between MCBVF (mean +/- S.D., 80 +/- 26 cm/s) and the variables PaCO2 (33 +/- 4 mmHg), MAP (86 +/- 12 mmHg), ICP (20 +/- 11 mmHg), CPP (70 +/- 14 mmHg) and CSF or plasma IL-6, IL-8 and IL-10, it turned out that MCBFV correlated significantly with PaCO2 (r = 0.478; P < 0.01) and CSF IL-8 (r = -0.361; P < 0.05). CONCLUSIONS: When CPP is adequate for brain perfusion, CBFV in large brain supplying arteries depends predominantly on PaCO2 and shows only a slight association to intrathecal IL-8 levels. For clinical interpretation of CBFV data, the inflammatory response seems to be of minor relevance.

Adult↗
PubMed2001

Ultrasound-guided aspiration of brain abscesses through a single burr hole.

Surgical aspiration and/or drainage of brain abscesses is considered to be the first-line treatment for abscesses larger than 25 mm. This is ususally performed with the aid of CT-guided stereotaxy. A method of ultrasound guidance is presented that allows a single burr hole approach with real-time imaging of the whole procedure. A bayonet-like shaped ultrasound probe with tip dimension of 8 x 8 mm only (EUP-NS 32, Hitachi/Ecoscan) with frequencies of 3.5 and 5 MHz is used. After placement of a burr hole the target is identified by transdural insonation, a guideline is adjusted and a mounted puncture-adapter guides the cannula towards the lesion under real-time imaging control. Up to now 12 abscesses in 10 patients were treated. Visualization was always excellent. A second aspiration had to be performed twice. One abscess did not contain enough pus to be cured by aspiration and was removed by open surgery, another could not be tapped by the blunt cannula and was aspirated under stereotactic control using a sharp trocar. Outcome was excellent in 6 patients and fair in 2 patients but this was due to the pre-existing disease. Two patients admitted in deep coma died despite an emergency operation. The presented method has proven to be a very powerful guiding tool in the surgical treatment of brain abscesses through a single burr hole approach.

Adolescent↗
PubMed2001

Differential release of interleukines 6, 8, and 10 in cerebrospinal fluid and plasma after traumatic brain injury.

Traumatic brain injury (TBI) is characterized by a high mortality which is largely determined by the initial cerebral trauma, secondary brain injury or indirectly during a Multiple Organ Dysfunction Syndrome (MODS). Therefore, we analyzed IL-6, IL-8, and IL-10 in cerebrospinal fluid (CSF) and in plasma with respect to blood-brain barrier (BBB) integrity in 29 patients suffering from isolated TBI. IL-6 and IL-8 were significantly increased compared to baseline levels early after trauma in CSF and plasma. In all patients CSF IL-6 and IL-8 were found to be higher than corresponding plasma levels. IL-10 in plasma was significantly increased above control plasma values, however, without a significant difference to the corresponding CSF values. BBB dysfunction was temporary present in 23 patients. Significant correlations between BBB dysfunction and cytokines were not found. Thus, alterations of the BBB seems not to influence the distribution pattern of interleukines in CSF and plasma after trauma.

Adolescent↗
PubMed2001

Therapy of invasive mucoceles of the frontal sinus.

Mucoceles of the frontal sinus that extend into the orbits and the anterior cranial fossa can, in certain cases, be difficult to manage therapeutically and may lead to lethal complications. The surgeon will have to make a decision between an endonasal and an extranasal, transfacial procedure to provide an adequate access. Between 1995 and 1998 we treated 12 patients suffering from invasive mucoceles of the frontal sinus. The mucocele was localized medially in 7 cases and in the lateral part of the frontal sinus in 5 cases. Five of the patients exhibited destruction of the orbital roof and in 7 cases combined destruction of the orbital roof and the floor of the frontal sinus were noted. The posterior wall of the frontal sinus was destructed in 6 patients, with one patient additionally showing partial destruction of the anterior frontal sinus wall. The causes of mucocele formation were previous frontal sinus operations (n = 8) and frontal sinus fractures (n = 3). In one case the cause remained unknown. In 7 cases with a medially localized mucocele the mucocele was marsupialized using an endonasal access. The mucoceles with a lateral localization were osteoplastically operated via an external access. Here we performed median drainage in 3 cases and, in one case each, obliteration and cranialization of the frontal sinus. The follow-up period was 2.8 years on average. All patients were free of complaints immediately after the operation. Mucocele recurrence or other complications did not arise. The cosmetic results were satisfactory in all cases.

Adult↗
PubMed2000

Assessment of middle cerebral artery diameter after aneurysmal subarachnoid hemorrhage by transcranial color-coded duplex sonography.

This study examined if vasospasm after aneurysmal subarachnoid hemorrhage could be visualized by middle cerebral artery (MCA) diameter changes in transcranial color-coded duplex sonography (TCCS). Comparative measurements between mean blood velocity (MBV) and MCA diameter were carried out in 17 patients in 76 instances. At two depth ranges (proximal, 60 55 mm: distal, 50-45 mm) two observers assessed the MCA diameter as indicated by the visualized blood flow column. At both points of measurement, the diameter differences between the two observers were within the ¿ 2 S.D. range of the mean difference indicating interobserver agreement. In 17 instances, MBV was > 120 cm/s indicating vasospasm but MBV did not correlate with absolute or relative diameter changes. MCA diameter assessment in TCCS seems reproducible. Because TCCS imaging is influenced by several factors comparative angiographic studies are necessary to clarify the TCCS findings.

Female↗
PubMed1999

Identification of somatosensory pathways by focal-cooling-induced changes of somatosensory evoked potentials and EEG-activity--an experimental study.

OBJECT: Function-preserving neurosurgery requires methods to identify functionally important CNS-areas intraoperatively. We investigated whether a combination of focal cerebro-cortical cooling and monitoring of somatosensory evoked potentials (SEP) is suited for this task, i.e. whether it is able to outline structures belonging to the somatosensory pathway. METHODS: In 17 Wistar rats the somatosensory cortex was focally cooled by 20 degrees C below the initial tissue temperature for periods of five minutes. A cryoprobe with a tip diameter of 3 mm was used and tissue temperatures were measured below and at different distances to the cryoprobe. Tibial nerve evoked SEPs and EEG-spectra were recorded continuously. RESULTS: During cortical cooling the SEP-responses showed a marked delay and amplitude increase of the cortically generated components P13 and N18 and a small latency increase of the subcortically generated wave III. EEG-spectra were depressed mainly in the low frequency range. All cooling effects were reversible and in light- as well as electron-microscopic examinations no tissue damage was found. CONCLUSIONS: Focal cooling of the cortex induces easily recognizable and reversible changes of the bio-electrical activity without causing any histological damage. Therefore the method seems suitable for identifying eloquent areas. It can be expected that clinical application of the cooling technique in combination with intraoperative electrophysiological monitoring will be helpful to further lower the risk of neurosurgical operations. We propose that cooling mainly interferes with the synaptic transmission within the somatosensory cortex, because the observed amplitude increase can be explained by cold-induced depression of inhibitory cortical activity (disinhibition).

Animals↗
PubMed1999

[Value of German Hospital Diagnosis Statistics in epidemiology-- an analysis with subarachnoid hemorrhage as an example].

Due to the Hospital Statistics Regulations of the 10th April 1990, the German Hospital Diagnosis Statistics were introduced in 1993 with the intention to serve as a database of health care decisions. This purpose requires a high-quality collection of epidemiologically relevant data. From 1993 to 1996 we analysed the datasets obtainable for subarachnoid haemorrhage which is coded with ICD 430. A subset concerning the data of 1996 and the Saarland region was compared to the data of the Saarland medical school at Homburg/Saar. Cases treated in the neurosurgical department were critically reviewed. About 20% of the cases coded with ICD 430 showed no subarachnoid haemorrhage. On the other hand, again about 20% of subarachnoid haemorrhage cases were not coded with ICD 430. The statistics comprise duplicates due to transfers between hospitals. The calculation of incidence is not possible because new bleeding cases cannot be outlined. In the present form the German Hospital Diagnosis Statistics are not suitable as a reliable base of health care decisions. This is partly caused by the inadequacy of the ICD-classification but, also, by the criteria for collecting data. We propose several modifications which can improve data quality in order to meet the intended requirements.

Databases, Factual↗
PubMed1998

Patterns of relapse and late toxicity after resection and whole-brain radiotherapy for solitary brain metastases.

BACKGROUND: This retrospective analysis was performed in order to evaluate the pattern of relapse and the risk of late toxicity for solitary brain metastases treated with surgery and whole-brain radiotherapy and to correlate the results with those from radiosurgical trials. PATIENTS AND METHODS: From a total of 66 patients, 52 received 10 x 3 Gy and 10 were treated with 20 x 2 Gy whole-brain radiotherapy after resection of their brain metastases. RESULTS: The actuarial probability of relapse was 27% and 55% after 1 and 2 year(s), respectively. The local relapse rate (at the original site of resected brain metastases) was rather high for melanoma, non-breast adenocarcinoma, and squamous-cell carcinoma. No local relapse occurred in breast cancer and small-cell carcinoma. Failure elsewhere in the brain seemed to be influenced by extracranial disease activity. Size of brain metastases and total dose showed no correlation with relapse rate. Occurrence of brain relapse was not associated with a reduced survival time, because 10/15 patients who developed a relapse received salvage therapy. Of the patients, 11 had symptoms of late radiation toxicity (the actuarial probability was 42% after 2 years). CONCLUSIONS: Most results of surgical and radiosurgical studies are comparable to ours. Several randomized trials investigate surgical resection versus radiosurgery, as well as the effects of additional whole-brain radiotherapy in order to define the treatment of choice. Some data support the adjuvant application of 10 x 3 Gy over 2 weeks as a reasonable compromise when local control, toxicity, and treatment time have to be considered.

Actuarial Analysis↗
PubMed1990

[Intra- and postoperative effect of different hydroxyethyl starch solutions on the flow properties of the blood and on the oxygen partial pressure of the conjunctiva].

During lumbar disc operation in the flexed prone position, a decrease in conjunctival pO2 can be observed although there is an increase in systemic blood flow after infusion of colloidal volume expanders. The regions of the body situated below the heart do not profit from the increase in systemic blood flow due to compression. The pO2 decreases more significantly after the infusion of a medium-molecular-weight solution with a more marked hemodynamic effect than after the infusion of low-molecular-weight hydroxyethyl starch. As the decrease in conjunctival pO2 is considerably less after low-molecular-weight hydroxyethyl starch, improved blood fluidity may be responsible for the increased tissue perfusion in the compressed area.

Adult↗
PubMed1990

[Economic aspects of alveolitis].

In 1680 cases of alveolitis ("dry socket") the national economic-loss is more than 339,693.-marks. Nearly 3 million teeth will be extracted in one year in the DDR. By a valuation of nearly 3% of the alveolitis 90,000 patients have this complication. That will be a economic-loss of 18.1 million marks in one year. The prophylaxis of this complication is therefore a most important problem.

Costs and Cost Analysis↗
PubMed1990

Acute spinal intradural extramedullary hematoma: a nonsurgical approach for spinal cord decompression.

The authors present the case of a 60-year old man with a spontaneous spinal intradural hematoma in the thoracic and lumbar region, which was caused by anticoagulant therapy and led to a severe progressive transverse lesion. After substitution of coagulation factors, a small catheter was inserted into the subarachnoid space via a lumbar puncture. By alternating irrigation and suction removal of the blood clot, restoration of the cerebrospinal fluid passage was possible along with a marked improvement in the neurological deficits. At 8 months' follow-up, the patient had completely recovered from the severe paraparesis and bladder dysfunction.

Catheterization↗