[Surgical procedures for treatment of spasticity]

BACKGROUND

The causes of spasticity are various and include cerebral palsy, spinal cord injury, stroke, multiple sclerosis or other congenital or acquired lesions of the central nervous system (CNS). While there is often a partial functional component, spasticity also results in varying degrees of impairment of the quality of life.

OBJECTIVE

A review of surgical treatment options for spasticity.

MATERIAL AND METHODS

A systematic PubMed review of the literature on epidemiology and treatment options with a focus on neurosurgical interventions for spasticity and developments in the last 20 years as well as inclusion of still valid older landmark papers was carried out. Illustration of indications, technique, follow-up, and possible pitfalls of the different methods for the surgical treatment of spasticity.

RESULTS

Depending on the affected region, the number of muscle groups, and the extent of spasticity, focal (selective peripheral neurotomy, nerve transfer), regional (selective dorsal rhizotomy), or generalized (baclofen pump) procedures can be performed. The indications are usually established by an interdisciplinary team. Conservative (physiotherapy, oral medications) and focally invasive (botulinum toxin injections) methods should be performed in advance. In cases of insufficient response to treatment or only short-term relief, surgical methods can be evaluated. These are usually preceded by test phases with, for example, trial injections.

CONCLUSION

Surgical methods are a useful adjunct in cases of insufficient response to conservative treatment in children and adults with spasticity.

Early biomarkers predicting outcome in a porcine model of acetaminophen intoxication: A pilot study

BACKGROUND

Acetaminophen intoxication has become the leading cause of acute liver failure (ALF) in Europe and the USA.

OBJECTIVES

To identify early biomarkers in order to predict the development of ALF in a porcine model of acetaminophen intoxication.

MATERIAL AND METHODS

Six German Landrace pigs received a single acetaminophen bolus of 1 g/kg body weight via a jejunal catheter. Cytokines and laboratory parameters were analyzed at 8-hour intervals for a total of 40 h.

RESULTS

Three of the 6 animals survived the intoxication. The nonsurviving animals had an increase in serum lactate and interleukin (IL)-6, with a simultaneous decrease in prothrombin time (PT) and albumin concentration 8 h after intoxication. In all nonsurviving animals, elevated levels of tumor necrosis factor alpha (TNF-α) at baseline before intoxication and during the course of ALF were observed. The acetaminophen serum concentrations and toxicokinetics did not differ between the nonsurviving and surviving animals. Methemoglobinemia was proportional to the administered doses and acetaminophen blood levels, but methemoglobinemia did not affect survival.

CONCLUSIONS

Tumor necrosis factor alpha, IL-6, lactate, prothrombin time, and albumin blood concentration were identified as early predictors of outcome after acetaminophen intoxication. An elevated TNF-α level before acetaminophen exposure was the earliest prognostic marker for a lethal outcome. Therefore, it could serve as a very early indicator of prognosis.

Pain inhibition through transplantation of fetal neuronal progenitors into the injured spinal cord in rats

Neuropathic pain after spinal cord injury (SCI) is a complex condition that responds poorly to usual treatments. Cell transplantation represents a promising therapy; nevertheless, the ideal cell type in terms of neurogenic potential and effectiveness against pain remains largely controversial. Here, we evaluated the ability of fetal neural stem cells (fNSC) to relieve chronic pain and, secondarily, their effects on motor recovery. Adult Wistar rats with traumatic SCI were treated, 10 days after injury, with intra-spinal injections of culture medium (sham) or fNSCs extracted from telencephalic vesicles (TV group) or the ventral medulla (VM group) of E/14 embryos. Sensory (von Frey filaments and hot plate) and motor (the Basso, Beattie, Bresnahan locomotor rating scale and inclined plane test) assessments were performed during 8 weeks. Thereafter, spinal cords were processed for immunofluorescence and transplanted cells were quantified by stereology. The results showed improvement of thermal hyperalgesia in the TV and VM groups at 4 and 5 weeks after transplantation, respectively. Moreover, mechanical allodynia improved in both the TV and VM groups at 8 weeks. No significant motor recovery was observed in the TV or VM groups compared with sham. Stereological analyses showed that ~70% of TV and VM cells differentiated into NeuN⁺ neurons, with a high proportion of enkephalinergic and GABAergic cells in the TV group and enkephalinergic and serotoninergic cells in the VM group. Our study suggests that neuronal precursors from TV and VM, once implanted into the injured spinal cord, maturate into different neuronal subtypes, mainly GABAergic, serotoninergic, and enkephalinergic, and all subtypes alleviate pain, despite no significant motor recovery. The study was approved by the Animal Ethics Committee of the Medical School of the University of São Paulo (protocol number 033/14) on March 4, 2016.

Diagnosis of Lumbar Spinal Stenosis with Functional Myelography

BACKGROUND AND STUDY AIMS

 The diagnosis of a lumbar spinal stenosis demands advanced diagnostic radiologic techniques. In recent decades magnetic resonance imaging (MRI) has replaced myelography, now considered an old-fashioned technique. It was our hypothesis that functional myelography still plays an important role in selected cases. We investigated how our surgical strategy was influenced by the results of MRI, functional myelography, and postmyelography computed tomography (CT) in patients with a lumbar spinal stenosis.

METHODS

 The sagittal diameters of the lumbar spinal canal were measured from L1 to S1 on patients with lumbar spinal stenosis. MRI, functional myelography, and postmyelography CT were compared in each of the patients. Sensitivity and specificity were calculated in each method. We examined how the surgical strategy was influenced by the results of these different methods.

RESULTS

 Fifty consecutive patients (21 women and 29 men; mean age: 70 years, [range: 49-86 years]) fulfilled the inclusion criteria. Functional myelography revealed a sensitivity of 0.99, a specificity of 0.79, and a positive predictive value of 0.45. The MRI exhibited a sensitivity of 0.93, a specificity of 0.74, and a positive predictive value of 0.39. Postmyelography CT showed a sensitivity of 0.96, a specificity of 0.75, and a positive predictive value of 0.41. A functional myelography revealed more information than the MRI and resulted in a change in the surgical strategy in 11 of 50 patients (22%) in comparison with the sole results of MRI or a postmyelography CT.

CONCLUSIONS

 In selected cases with multilevel lumbar spinal stenosis, functional myelography revealed the highest precision in reaching a correct diagnosis. It resulted in a change in the surgical approach in every fifth patient in comparison with the MRI and proved most helpful, especially in elderly patients.

High-Resolution Three-Dimensional Computed Tomography for Assessing Complications Related to Intrathecal Drug Delivery

Background: The assessment of the functionality of intrathecal drug delivery (IDD) systems remains difficult and time-consuming. Catheter-related problems are still very common, and sometimes difficult to diagnose. Objectives: The aim of the present study is to investigate the accuracy of high-resolution three-dimensional computed tomography (CT) in order to detect catheter-related pump dysfunction. Study Design: An observational, retrospective investigation. Setting: Academic medical center in Germany. Methods: We used high-resolution three dimensional (3D) computed tomography with volume rendering technique (VRT) or fluoroscopy and conventional axial-CT to assess IDDrelated complications in 51 patients from our institution who had IDD systems implanted for the treatment of chronic pain or spasticity. Results: Twelve patients (23.5%) presented a total of 22 complications. The main type of complication in our series was catheter-related (50%), followed by pump failure, infection, and inappropriate refilling. Fluoroscopy and conventional CT were used in 12 cases. High-resolution 3D CT VRT scan was used in 35 instances with suspected yet unclear complications. Using 3D-CT (VRT) the sensitivity was 58.93% – 100% (CI 95%) and the specificity 87.54% – 100% (CI 95%).The positive predictive value was 58.93% – 100% (CI 95%) and the negative predictive value: 87.54% – 100% (CI 95%). Fluoroscopy and axial CT as a combined diagnostic tool had a sensitivity of 8.3% – 91.7% (CI 95%) and a specificity of 62.9% – 100% (CI 95%). The positive predictive value was 19.29% – 100% (CI 95%) and the negative predictive value: 44.43% – 96.89% (CI 95%). Limitations: This study is limited by its observational design and the small number of cases. Conclusion: High-resolution 3D CT VRT is a non- invasive method that can identify IDDrelated complications with more precision than axial CT and fluoroscopy. Key words: Volume rendering technique (VRT), intrathecal drug delivery systems, highresolution 3D computed tomography, complications, spasticity, chronic pain, cost effectiveness, fluoroscopy

High-Resolution Three-Dimensional Computed Tomography for Assessing Complications Related to Intrathecal Drug Delivery

BACKGROUND

The assessment of the functionality of intrathecal drug delivery (IDD) systems remains difficult and time-consuming. Catheter-related problems are still very common, and sometimes difficult to diagnose.

OBJECTIVES

The aim of the present study is to investigate the accuracy of high-resolution three-dimensional computed tomography (CT) in order to detect catheter-related pump dysfunction.

STUDY DESIGN

An observational, retrospective investigation.

SETTING

Academic medical center in Germany.

METHODS

We used high-resolution three dimensional (3D) computed tomography with volume rendering technique (VRT) or fluoroscopy and conventional axial-CT to assess IDD-related complications in 51 patients from our institution who had IDD systems implanted for the treatment of chronic pain or spasticity.

RESULTS

Twelve patients (23.5%) presented a total of 22 complications. The main type of complication in our series was catheter-related (50%), followed by pump failure, infection, and inappropriate refilling. Fluoroscopy and conventional CT were used in 12 cases. High-resolution 3D CT VRT scan was used in 35 instances with suspected yet unclear complications. Using 3D-CT (VRT) the sensitivity was 58.93% - 100% (CI 95%) and the specificity 87.54% - 100% (CI 95%).The positive predictive value was 58.93% - 100% (CI 95%) and the negative predictive value: 87.54% - 100% (CI 95%).Fluoroscopy and axial CT as a combined diagnostic tool had a sensitivity of 8.3% - 91.7% (CI 95%) and a specificity of 62.9% - 100% (CI 95%). The positive predictive value was 19.29% - 100% (CI 95%) and the negative predictive value: 44.43% - 96.89% (CI 95%).

LIMITATIONS

This study is limited by its observational design and the small number of cases.

CONCLUSION

High-resolution 3D CT VRT is a non- invasive method that can identify IDD-related complications with more precision than axial CT and fluoroscopy.

MRI-based radiation-free method for navigated percutaneous radiofrequency trigeminal rhizotomy

BACKGROUND/STUDY AIMS: Percutaneous radiofrequency trigeminal rhizotomy (RTR) is a standardized treatment for trigeminal neuralgia, yet it has been associated with serious complications related to the cannulation of the foramen ovale. Some of these complications, such as carotid injury, are potentially lethal. Neuronavigation was recently proposed as a method to increase the procedure's safety. All of the techniques described so far rely on pre- or intraoperative computed tomography scanning. Here we present a simple method based on magnetic resonance imaging (MRI) (radiation free) used to target the foramen ovale under navigation guidance.

PATIENTS/MATERIAL AND METHODS

We retrospectively analyzed nine patients who had undergone navigated percutaneous RTR based solely on preoperative MRI and compared them with 35 patients who underwent conventional RTR guided by fluoroscopy. We analyzed immediate and late outcome and categorized the results into pain free, > 70% pain reduction, and persistent pain. We also compared groups in terms of the duration of the procedure and the complication rates. Here we describe the navigation method in detail and review the anatomical landmarks for target definition.

RESULTS

The duration of the surgical procedure was similar in both groups (32.1 in the standard technique versus 34.5 minutes with navigation; p = 0.5157). There was no significant difference between groups regarding pain reduction at the immediate (p = 1.0) or late follow-up (p = 0.6284) time points. Furthermore, no serious complications were observed in the navigated group.

CONCLUSIONS

We present a simple radiation-free method for neuronavigation-assisted percutaneous RTR. This method proved to be safe and effective, and it is especially recommended for young, inexperienced neurosurgeons.

Stem cells in neurology--current perspectives

Central nervous system (CNS) restoration is an important clinical challenge and stem cell transplantation has been considered a promising therapeutic option for many neurological diseases.

OBJECTIVE

The present review aims to briefly describe stem cell biology, as well as to outline the clinical application of stem cells in the treatment of diseases of the CNS.

METHOD

Literature review of animal and human clinical experimental trials, using the following key words: "stem cell", "neurogenesis", "Parkinson", "Huntington", "amyotrophic lateral sclerosis", "traumatic brain injury", "spinal cord injury", "ischemic stroke", and "demyelinating diseases".

CONCLUSION

Major recent advances in stem cell research have brought us several steps closer to their effective clinical application, which aims to develop efficient ways of regenerating the damaged CNS.

Current perspectives in stem cell therapy for spinal cord repair in humans: a review of work from the past 10 years

Spinal cord injury (SCI) and amyotrophic laterals sclerosis (ALS) are devastating neurological conditions that affect individuals worldwide, significantly reducing quality of life, both for patients and their relatives.

OBJECTIVE

The present review aims to summarize the multiple restorative approaches being developed for spinal cord repair, the use of different stem cell types and the current knowledge regarding stem cell therapy.

METHOD

Review of the literature from the past 10 years of human studies using stem cell transplantation as the main therapy, with or without adjuvant therapies.

CONCLUSION

The current review offers an overview of the state of the art regarding spinal cord restoration, and serves as a starting point for future studies.

Neuroprotective effects of erythropoietin during deep hypothermic circulatory arrest

OBJECTIVE

Permanent mild-to-severe brain injury with neurologic sequelae remains a significant source of postoperative morbidity in cardiovascular surgery. There is increasing evidence that erythropoietin confers neuroprotective effects in various conditions of neuronal damage, such as hypoxia and cerebral ischaemia. Using a surviving porcine model, this study evaluates whether systemic treatment with erythropoietin induces brain protection in deep hypothermic circulatory arrest (DHCA).

METHODS

Sixteen pigs (42+/-3 kg) randomly assigned into two groups (n=8) were subjected to 60 min of DHCA at an intracerebral temperature of 20 degrees C. The animals of the erythropietin group were treated perioperatively with 500 IU kg(-1) of recombinant human erythropoietin on 3 consecutive days beginning the day before surgery. Intracerebral monitoring was performed by subcortical microdialysis, brain tissue oxygenation, measurement of brain temperature and intracranial pressure. Neurologic recovery was evaluated daily. Perioperative S100 beta protein serum level was determined. The brains were harvested on the postoperative day 6 after perfusion fixation. Multiple brain regions were investigated histologically for hypoxic-ischaemic damage.

RESULTS

The subcortical brain microdialysis detected significant increase of glycerol and lactate concentrations in both groups (P=0.0001) with considerably higher concentrations in the brain of control animals (P=0.011). There were no significant differences in neurological outcome (P=0.15). Erythropoietin-treated animals tended to a more complete and rapid neurological recovery. By contrast, none of the animals in the control group achieved complete neurological recovery. S100 beta protein as a putative marker of cerebral injury tended to be higher in the control group. Brain infarction was detectable in all control animals but only in two erythropoietin-treated animals.

CONCLUSION

These results suggest some beneficial neuroprotective effects of erythropoietin in this model of global brain ischaemia induced by 1h of hypothermic circulatory arrest.

Do antibiotic-impregnated shunts in hydrocephalus therapy reduce the risk of infection? An observational study in 258 patients

BACKGROUND

Shunt infection in hydrocephalus patients is a severe, even life-threatening complication. Antibiotic-impregnated shunts (AIS) have been developed in an attempt to reduce rate of shunt infection. The study was performed to analyze if AIS can diminish the rate of shunt infection. The pathogenic nature of shunt infection in patients with AIS systems and those without antibiotic impregnated shunts (non-AIS) was compared.

METHODS

Over a period of 24 months in the Department of Neurosurgery at University Hospital of Tübingen shunt surgery was performed in 258 patients. In 86 patients AIS systems were implanted. Shunt catheters were commercially impregnated with clindamycin and rifampicin. Analysis of the clinical data included sex, age, classification of hydrocephalus, shunt types and risk factors for shunt infection [age (< 1 year and > 80 years), prematurely born patients, external ventricular drainage, former shunt infection, former systemic infection, disturbance of consciousness, former radiation-/chemotherapy]. Infection rates and underlying bacterial pathogens of patients with AIS were compared to patients with implanted non-AIS systems (172 patients).

RESULTS

AIS and non-AIS patients did not differ in sex, etiology of hydrocephalus and the shunt type. In the AIS group 72 out of 86 patients had at least one risk factor (83.7 %), compared to 126 patients in the non-AIS group (73.3 %). There was no significant difference between the two groups (p = 0.0629; Fisher's exact test). In patients with no risk factors, only one patient with non-AIS suffered from shunt infection. In patients with one or more risk factors the rate for shunt infection was 7.14 % in patients with non-AIS and 6.94 % in patients with AIS. Former shunt infection (p = 0.0124) was related to higher risk for shunt infection. The use of AIS had therefore no significant advantage (p = 0.8611; multiple logistic regression). Significantly related to a shunt infection was the number of shunt surgeries. 190 interventions in the AIS group (2.21 interventions per patient) and 408 in the non-AIS group (2.37 interventions per patient) had been performed (p = 0.3063; Wilcoxon). There was no shunt infection in the group of patients on whom only one shunt surgery was performed. In patients with at least two shunt surgeries the infection rate was 9%. The infection rate in AIS patients was 5/52 (9.6 %) and in the non-AIS 10/114 (8.77 %), (p = 1.0; Fisher's exact test). Staphylococcus epidermidis was the most frequent pathogen for shunt infection. Fourteen out of 15 infections occurred within the first 6 months of surgery. The most frequent pathogen for shunt infection was S. epidermidis. No toxic or allergic complications were seen using the AIS shunt systems. The presented data show a remarkably low infection rate of 5.8 % in the non-AIS group compared to other studies which demonstrated a significant decrease in the infection rate by AIS.

CONCLUSION

AIS did not significantly reduce shunt infection in hydrocephalus patients in the presented study. In the AIS group three patients suffered from shunt infections caused by skin ulceration or neurosurgical procedures with exposure of the cerebrospinal liquor after shunt implantation. AIS was not developed to prevent infection in such cases, therefore an advantage of AIS can not be excluded. In view of the presented data and the small number of reported studies a prospective randomized multicenter study is required.

The blockade of endothelin A receptor protects astrocytes against hypoxic injury: Common effects of BQ-123 and erythropoietin on the rejuvenation of the astrocyte population

In the present study the role of endothelin (ET) and its receptors (ETA-R and ETB-R) in cellular mechanisms underlying the resistance of astroglial cells to low oxygen level and development of hypoxia has been investigated. To define the influences of ET and its receptors on survival and on antigenic as well as morphologic differentiation of rat astroglial cells in normoxic (NC) and hypoxic culture (HC) the selective antagonists of ETA-R (BQ-123) and ETB-R (BQ-788) were used. Treatment of HC with BQ-123 caused an increase in cell number and inhibited the hypoxia-induced apoptosis by 37%. BQ-123 decreased the hypoxia-induced cytotoxicity in HC. These effects of BQ-123 were abolished in cultures simultaneously treated with BQ-123 and BQ-788. Administration of BQ-788 alone decreased the number of living cells in NC, but not in HC. The activity of caspase-3/-7 was not changed by exposure of NC and HC to BQ-788. The protection provided by BQ-123 to astroglial cells against cytotoxicity in NC and HC was similar to that of erythropoietin (EPO), a cytokine with established neuroprotective effects. The functional improvement of astroglial cells and slowing down of their differentiation under exposure to BQ-123, or EPO, or BQ-123 + EPO has been evidenced by an increased number of nestin+/glial fibrillary acidic protein-positive (GFAP+) astrocytes accompanied by decrease of nestin-/GFAP+ cells. The simultaneous treatment with BQ-123 and EPO additionally decreased the activities of caspase-3/-7 (64%) and release of LDH into the medium (94%). The benefits in the functional states of astrocytes obtained by combined treatment of HC with BQ-123 and EPO suggest a new therapeutic strategy in treatment of hypoxic brain injury.

Spinal nerve root ganglionitis as a cause of disc herniation: case report

The authors report on a patient in whom monoradicular pain was caused by ganglionitis of a spinal nerve. Neuroimaging and intraoperative findings identified what were thought to be tumorlike changes in the affected nerve root. The neuropathological examination, however, revealed typical signs of ganglionitis. This rare inflammation usually appears with viral infections, as part of paraneoplastic symptoms, or in the presence of Sjögren disease. Because all of these differential diagnoses were negative in the treated patient, chronic nerve root compression due to disc herniation was suspected as the causative factor for the spinal ganglionitis.

Direkte CT-Arthrographie versus direkte MR-Arthrographie bei chronischer Schulterinstabilität: Ein Methodenvergleich nach Einführung der Multidetektor-CT-Technik

PURPOSE

To evaluate the diagnostic accuracy of direct multidetector CT arthrography (CTA) and direct MR arthrography (MRA) in patients suffering from chronic shoulder instability.

MATERIALS AND METHODS

Twenty-nine patients suffering from chronic shoulder instability were included into a prospective study. In all cases, the indication for direct CTA and arthroscopy was set by the orthopedic surgeon. Prior to the imaging procedures, 10 to 20 ml of a special combination of contrast media (including saline, Isovist(R) and Magnevist(R) in a relation of 125 : 125 : 1) was injected into the joint under sterile conditions. First, CTA was performed with a multidetector CT, with images reconstructed in the axial, semi-coronal and semi-sagittal planes. Thereafter, MRA was performed. Axial images were obtained using a T1-weighted, fat-saturated spin echo sequence and semi-coronal images using a T1-weighted FLASH-3D GRE sequence. The results of CTA and MTA were compared with results obtained from arthroscopy or arthrotomy.

RESULTS

MRA was superior to CTA in the detection of labral lesions. The sensitivity of MRA was 96 % and the specificity 96 %, compared to a sensitivity of 76 % (p < 0.05) and specificity of 92 % for CTA. Both methods showed the same effectiveness concerning the assessment of capsule distension (sensitivity for both techniques: 91 %).

CONCLUSIONS

MRA seems to be superior to CTA in the diagnostic workup of chronic shoulder instability even when using a multidetector CT technique.

Antigen processing and presentation in human muscle: cathepsin S is critical for MHC class II expression and upregulated in inflammatory myopathies

The immunological properties of muscle cells are of critical importance for both the pathogenesis of inflammatory muscle disorders as well as for understanding and controlling novel therapeutic strategies. Muscle cells can present antigens to both CD4 and CD8 cells. However, the cellular biochemistry of antigen processing and presentation by muscle cells is not clear. Cathepsins play a central role in the generation of antigenic peptide and control transport and maturation of MHC class II molecules. To further elucidate the molecular basis for the MHC class II-mediated antigen presentation by muscle cells, we here analyzed cultured human myoblasts and biopsies from inflammatory myopathies with respect to the expression and function of the constituents of the MHC class II antigen presentation machinery. We identified cathepsin S (CatS) as the dominant endocytic protease that is specifically upregulated under inflammatory conditions to significant mRNA levels, synchronously with HLA-DR, -DM and the class II invariant chain (Ii), both in muscle biopsies from affected individuals with inflammatory myopathies and in human myoblasts cultured in the presence of IFN-gamma. This led to translation of the mature CatS polypeptide that was enzymatically active in human myoblasts under inflammatory conditions. By contrast, expression of CatL and CatB was unaffected by IFN-gamma at both the expression and activity levels. CatS activity is required for efficient surface display of MHC class II in this cell type: functional inhibition of CatS using a CatS-selective inhibitor reduced the levels of surface class II alphabeta:peptide complexes on stimulated myoblasts by almost 50%. Surprisingly, and in contrast to B cells and dendritic cells, this was not due to inefficient processing of Ii in the absence of CatS, which was unaffected by the elimination of CatS activity. We therefore conclude that CatS is involved in the regulation of class II expression in human myoblasts independently from Ii processing.

Cyclooxygenase-1 and -2 in brains of patients who died with sporadic Creutzfeldt-Jakob disease

Cyclooxygenases (COXs) mediate inflammation, immunomodulation, blood flow, apoptosis, and fever in various diseases of the brain. Whereas COX-2 is cytokine inducible, COX-1 is expressed by macrophages/microglial cells that accumulate in pathological foci. We analyzed the localization of COX-1 and COX-2 in postmortem cortex slices of eight patients who died with sporadic Creutzfeldt-Jakob disease (CJD) and four neuropathologically unaltered controls by immunohistochemical double-labeling, reverse transcriptase polymerase chain reaction (RT-PCR), and Western blotting experiments. In healthy brains, COX-1 was expressed by single macrophages/microglial cells and COX-2 by disseminated neurons. In patients with CJD, significantly (p = 0.0195) more COX-1-expressing macrophages/microglial cells were detected adjacent to neurons. COX-2 expression was predominantly observed in neurons, and their number was significantly higher (p < 0.0001) compared to controls. RT-PCR and Western blotting revealed more COX-1 and COX-2 mRNA and protein in one CJD patient than in one control patient. These data show that accumulation of COX-1-expressing macrophages/microglial cells and COX-2-expressing neurons might represent important regulatory mechanisms in the complex process of neuronal degeneration in CJD patients.

[MRI of intraosseous fistulous systems and sequesters in chronic osteomyelitis with standard spin echo sequences, highly selective chemical-shift imaging, diffusion weighted imaging, and magnetization-transfer]

PURPOSE

To study and test the impact of modern MRI techniques in diagnostic imaging in the evaluation of intra-osseous fistulous systems and sequesters.

MATERIALS AND METHODS

In a prospective study, nine patients with chronic osteomyelitis of the legs were examined by MRI. Patients with clinical signs of osteomyelitis requiring surgery were included in the study. T1-weighted spin echo (SE) sequences, proton density (PD) and T2-weighted fast spin echo (FSE) sequences, water- and fat-selective FSE sequences, and diffusion weighted (DW) PSIF sequences were used preoperatively. Furthermore, magnetizing transfer (MT) with gradient echo (GRE) sequences was evaluated.

RESULTS

Water selective sequences revealed the highest sensitivity for the detection of fistulas (100%), providing the best delineation of the extent of the entire fistulous systems. Fat-selective sequences (sensitivity 55.6%) and T1-weighted sequences (sensitivity 77.8%) displayed fistulas as hypointense bands, which, however, cannot be well differentiated from cortical bone in the transcortical areas. PD and T2-weighted images were found to have a poor sensitivity (55.6% and 66.7%) for fistulas in any location. The sensitivity of water-selective sequences to demonstrate intraosseous sequesters was 100%. The sensitivity was low for the other sequences. In 4 of 5 patients with surgically proven infection, DW and MT revealed an abnormal spatial distribution, with high diffusion in the central parts of the fistulas and high MT effect peripherally surrounding a weak MT effect centrally.

CONCLUSION

Water-selective sequences are superior when demonstrating fistulous systems and intraosseous sequesters. The combined use of MT and DW sequences seems to allow a differentiation between solid granulation tissue and liquid pus.

Alterations in diffusion and perfusion in the pathogenesis of peritumoral brain edema in meningiomas

Magnetic resonance perfusion and diffusion studies were undertaken to clarify the significance of ischemia in the pathogenesis of peritumoral brain edema in patients with meningiomas. Included in this study were 26 patients with 27 meningiomas and 5 gliomas. Perfusion-weighted imaging (PWI) was performed using a gradient-echo, echo-planar-imaging (EPI) sequence for calculation of the relative regional cerebral blood volume (rrCBV) and the relative regional cerebral blood flow index (rrCBFi). Furthermore, multi-slice spin-echo EPI sequences were applied in order to obtain anisotropic and isotropic diffusion-weighted imaging (DWI). Apparent diffusion coefficient (ADC) values were then calculated for peritumoral brain parenchyma from tumors, with and without edema, using various diffusion sensitivities. Meningiomas without edema demonstrated a minimal increase of perfusion parameters in the peritumoral brain tissue. In contrast, cases with brain edema had highly significant ( p<0.0005) lower rrCBV and rrCBFi. The edema index (EI) correlated strongly with the rrCBV. A fitting procedure resulted into the following mathematical relation: EI=0.1/rrCBV(2). The DWI showed a significantly larger ADC value within areas of brain edema, compared with the normal white matter (0.74 x 10(-3) vs 1.55 x 10(-3) mm(2)/s; p<0.0001). Increases in EI correlated with increases in ADC values. In 31% of the meningiomas associated with edema, areas with increased signal, probable ischemia, demonstrated significantly lower ADC values, in comparison with the rest of the edematous areas. These areas were confined to tissue immediately adjacent to the tumor. In general, the decrease in rrCBV in brain edema represents a consequence from, rather than a cause of, vasogenic edema. Ischemic alterations can be regarded as secondary, facultative phenomena in the pathogenesis of meningioma-related brain edema.

Cyclooxygenase (COX)-1 expressing macrophages/microglial cells and COX-2 expressing astrocytes accumulate during oligodendroglioma progression

Cyclooxygenases (COX, prostaglandin endoperoxide synthases, PGG/H synthases) are potent mediators of edema, impeding blood flow and immunomodulation in the pathologically altered brain. Two COX iso-enzymes have been associated with brain disease, the constitutively expressed COX-1 and the cytokine-inducible COX-2. We have used single and double labeling immunohistochemistry to analyse COX-1 and COX-2 expression in twenty-six primary WHO grade II oligodendrogliomas, sixteen primary WHO grade III anaplastic oligodendrogliomas, twenty-seven matched recurrences and ten neuropathologically unaltered brains. COX-1 immunoreactivity was predominantly observed in macrophages/microglial cells. The number of COX-1 expressing macrophages/microglial cells was significantly lower in primary oligodendrogliomas than in primary anaplastic oligodendrogliomas (P<0.0001) and in anaplastic oligodendroglioma relapses (P=0.011). Patients with low COX-1 labeling scores in the primary tumors had significantly longer time to progression and overall survival (P=0.0285) than those with high COX-1 labeling scores. COX-2 immunoreactivity was predominantly observed in disseminated neurons and astrocytes. In glioblastoma multiforme relapses, accumulation of COX-2 expressing astrocytes was observed surrounding areas of focal necrosis. The number of COX-2 expressing astrocytes was significantly (P=0.0471) lower in primary oligodendrogliomas than in high grade oligodendroglioma relapses. These data provide convincing evidence for the differential accumulation of cyclooxygenase isoforms during oligodendroglioma progression in vivo.

Role of hydrodynamic processes in the pathogenesis of peritumoral brain edema in meningiomas

OBJECT

In a prospective study, 28 patients with 32 intracranial meningiomas were examined to determine the role of hydrodynamic interaction between tumor and surrounding brain tissue in the pathogenesis of peritumoral brain edema.

METHODS

Gadolinium-diethylenetriamine pentaacetic acid (Gd-DPTA), an extracellular contrast agent used for routine clinical imaging, remains strictly extracellular without crossing an intact blood-brain barrier. Therefore, it is well suited for investigations of hydrodynamic extracellular mechanisms in the development of brain edema. Spin-echo T1-weighted magnetic resonance images were acquired before and after intravenous administration of 0.2 mmol/kg Gd-DPTA. Additional T1-weighted imaging was performed 0.6, 3.5, and 6.5 hours later. No significant Gd-DPTA diffused from tumor into peritumoral brain tissue in 12 meningiomas without surrounding brain edema. In contrast, in 17 of 20 meningiomas with surrounding edema, contrast agent in peritumoral brain tissue was detectable after 3.5 hours and 6.5 hours. In three of 20 meningiomas with minimum surrounding edema (<5 cm3), contrast agent effusion was absent. After 3.5 hours and 6.5 hours strong correlations of edema volume and the maximum distance of contrast spread from the tumor margin into adjacent brain parenchyma (r = 0.84 and r = 0.87, respectively, p < 0.0001) indicated faster effusion in larger areas of edema.

CONCLUSIONS

The results of this study show that significant contrast agent effusion from the extracellular space of the tumor into the interstitium of the peritumoral brain tissue is only found in meningiomas with surrounding edema. This supports the hypothesis that hydrodynamic processes play an essential role in the pathogenesis of peritumoral brain edema in meningiomas.

Thin and thick filament regulation of contractility in experimental cerebral vasospasm

OBJECTIVE

Cerebral vasospasm is a potentially fatal consequence of aneurysmal subarachnoid hemorrhage and influences the prognosis of the patient. The purpose of this study was to evaluate the status of thin (actin) and thick (myosin) filament regulation of smooth muscle contraction in the double-subarachnoid hemorrhage canine model of cerebral vasospasm and to determine the effects of a kinase inhibitor reported to be effective in vasospasm, HA1077, on thin and thick filament regulation.

METHODS

Cerebral vasospasm was assessed by vertebral angiography. Myosin regulatory light chain phosphorylation was measured using glycerol-urea gels, whereas protein levels of the thin filament-associated protein calponin were measured by Western blot.

RESULTS

The basilar arteries of dogs in which subarachnoid hemorrhage was induced narrowed to 36% +/- 2.0% of their size on the first day (n = 12). The phosphorylation of the regulatory light chain tended to increase, but the change did not reach statistical significance (35% +/- 5.9% [n = 12] versus 25% +/- 4.8% [n = 10] in control arteries). In contrast to this increase, significant degradation of calponin was observed in the samples from vasospastic dogs (85.4% +/- 5.45% [n = 5] versus 15.2% +/- 6.21% [n = 5]; P < 0.01). Prophylactic treatment with intravenous injections of HA1077 at 0.67 mg/kg b.i.d. significantly inhibited vasospasm (diameters, 65% +/- 10.2% of Day 1 diameters [n = 5]; P < 0.05), and calponin degradation (57.8% +/- 13.9% [n = 4]) was substantially reduced.

CONCLUSION

These data suggest that degradation of the thin filament-associated protein calponin plays a role in cerebral vasospasm and that the antivasospastic action of HA1077 is, at least in part, due to prevention of calponin degradation.

Angiogenesis and brain oedema in intracranial meningiomas: influence of vascular endothelial growth factor

The correlation between angiographic neovascularization, peritumoural brain oedema (PTBOe) and the expression of vascular endothelial growth factor (VEGF), was analysed in 30 patients with intracranial meningiomas. Pre-operative angiograms were examined for the existence of either an exclusively dural tumour blush or an additionally pial tumour supply from cerebral arteries. Furthermore the presence of macroscopic tumour-neovascularization and dysplastic changes of tumour-draining cerebral veins was evaluated. VEGF expression was investigated on histological tissue samples, using immunohistochemical techniques. VEGF immunohistochemistry and neuroradiological evaluations were performed in double blind fashion. Tumour volume and the amount of oedema were calculated by computerized tomography (CT) or magnetic resonance imaging (MRI). The oedema-tumour volume ratio was defined as oedema index (OeI). Compared to VEGF-negative meningiomas, tumours with striking VEGF staining revealed a significant higher mean oedema index (OeI = 4.2 vs. OeI = 1.5; p < 0.018), and a higher oedema incidence (91.7% vs. 44.4%; p < 0.046). Equally, meningiomas with additionally tumour supply from cerebral arteries were associated with a significant higher mean OeI (OeI = 4.1 vs. OeI = 1.2; p < 0.01) and oedema incidence (94.7% vs. 20.0%; p < 0.0023) than meningiomas with exclusively tumour supply from dural arteries. All meningiomas with striking VEGF-expression were associated with vascular tumour supply from cerebral arteries, but VEGF-negative tumours only in 50% (p < 0.029). These data suggest a link between VEGF-expression, arterial tumour supply and peritumoural brain oedema. The development of tumour supply from cerebral arteries may be important for formation of meningioma-related oedema. Therefore, VEGF may represent a potent mediator in the evolution of this type of vascularization in meningiomas.

Tumor-related venous obstruction and development of peritumoral brain edema in meningiomas

OBJECTIVE

The exact pathogenesis of peritumoral brain edema (PTBE) in meningiomas is still unknown. A number of different pathophysiological hypotheses have been considered. A detrimental effect of tumor-related venous obstruction has been suggested as one pathogenetic mechanism. We sought to characterize the significance of venous stasis in the development of PTBE in meningiomas.

METHODS

Angiograms for 134 patients with 136 intracranial meningiomas were analyzed. Pathological changes affecting cortical veins, sylvian veins, bridging veins, deep veins, transmedullary veins, and dural sinuses were evaluated. From preoperative computed tomographic scans, the total tumor volume, the tumor/PTBE volume ratio (edema index [EI]), and the location of the edema were determined. For statistical evaluation, meningiomas associated with pathological venous drainage were compared with size-matched controls.

RESULTS

The edema incidence and the mean EI were not different for meningiomas with unselected signs of obstructed venous drainage, compared with controls. In particular, lesions with involvement of cortical veins, bridging veins, and dural sinuses showed no higher edema incidence. However, meningiomas associated with venous changes in sylvian veins (EI = 4.9 versus EI = 2.7; P < 0.004) and with dysplastic transmedullary veins (EI = 3.3 versus EI = 1.7; P < 0.04) showed significantly higher mean EI values, compared with meningiomas without involvement of these vessels.

CONCLUSION

Our data suggest that tumor-related venous obstruction does not play an essential role in the development of PTBE for the majority of meningiomas. For a small subgroup of meningiomas with involvement of sylvian veins or development of dysplastic transmedullary veins, changes in venous drainage may aggravate preexisting PTBE.

Peritumoural brain oedema in intracranial meningiomas: influence of tumour size, location and histology

Peritumoural brain oedema was examined retrospectively in 175 patients with 179 intracranial meningiomas. The influence of tumour size, location and histology were investigated. Tumour volume and localization, and the presence of peritumoural brain oedema (PTBOe) were determined by computed tomography (CT). The oedema-tumour volume ratio was defined as Oedema Index (Oel). All patients underwent microsurgical removal of the tumour. Surgically resected meningiomas were classified histopathologically based on criteria of the new World Health Organization (WHO) classification. A close relationship was found between the tumour size and the incidence of peritumoural oedema: with increasing size of the tumour the incidence of oedema also rises, the oedema index, however decreases. Frontobasal and temporobasal meningiomas showed a significant increase in the oedema incidence and the mean oedema index. If major parts of the surface of meningiomas were adjacent to subarachnoid cisterns only a slight tendency for the development of oedema was observed. WHO-III-meningiomas showed a significantly higher oedema incidence (61.1% vs. 94.4%; p < 0.004) and mean oedema index (Oel = 2.7 vs. 3.7; p < 0.0009) than WHO-I-meningiomas. Brain tissue was affected in 59 cases. 19 meningiomas with infiltration into adjacent brain parenchyma revealed a statistically significant increase in oedema incidence (94.7% vs. 51.7%; p < 0.0003) and mean oedema index (Oel = 3.9 vs. Oel = 2.2; p < 0.0001) when compared to tumours without any brain tissue involvement in the histopathological specimens. Tumours with large volume, fronto-temporo-basal location and anaplastic histology were not only associated with the highest incidence of oedema formation but also presented with an overproportionate infiltrative growth. Thus, a disruption of the arachnoid or a true brain infiltration may be an essential factor for the development of a PTBOe.

[Experimental studies and clinical aspects of cold-preserved allogenic spongiosa]

Different temperatures, freeze techniques, and durations of storage for cryopreservation of allogeneic spongious bone were studied in an experimental model. Low temperatures (-70 degrees C to 196 degrees C) without cryoprotectants proved to be favorable in micromorphological as well as scintigraphic analyses. These transplants seem to be equivalent to fresh autologous transplants - at least in animal experiments. Medium-term durations of storage (3 mo) at low temperatures yield the best osteoinductive capacity. Long term storage (12 months) and radiosterilization reduce the quality of the allogeneic bone. The clinical results in 495 transplantations of cryopreserved allogeneic spongious bone confirm the experimental findings.