Novel retractor for endoscopic and microsurgical spinal interventions

Retractors play an important role in surgery, especially using endoscopic techniques like microendoscopic discectomy. As a consequence of the minimally invasive approach the working space is frequently very restricted. All currently available systems still use tubular retractors with limitations regarding flexibility, stability and accessible working space. This paper discusses the technical aspects of a newly designed circular retractor system for endoscopic and microsurgical spinal interventions (SpineGate) and presents first clinical results in a series of 20 consecutive patients. The autoclavable system consists of a circular base plate and several valves varying in length. The variable fixation of the valves from different directions within the 360 degrees geometry of the base plate allows a continuously adjustable working space, depending on the individual anatomy. An additional fixation device is not necessary. The retractor is suitable for microendoscopic and microsurgical techniques. It is easy and safe to handle. The retractor system was successfully used in all cases without complications or instrumental malfunctions. All patients experienced good to excellent relief of their preoperative symptoms.

Primary melanocytic lesions of the CNS: report of five cases

Primary melanocytic tumours of the central nervous system (CNS) form a rare entity which is histologically and clinically distinct from metastatic cutaneous or retinal malignant melanoma. They can be classified into diffuse melanocytosis (diffuse melanosis), malignant melanoma and benign melanocytoma with a small number of intermediate variants. In this paper, 5 cases treated neurosurgically in our department for spinal or cerebral primary CNS malignant melanoma are reported. Primary tumors and further metastases were ruled out. Radiological, histological and clinical features are discussed. Compared to metastatic disease, primary CNS malignant melanoma shows a more benign clinical course with long-term tumour control and a good quality of life. A review of the literature which mainly consists of individual case reports, confirms this assessment. Although therapeutic experience for primary melanocytic lesions of the CNS is based on a small number of published cases, prognosis seems highly dependent on complete tumour resection. Adjuvant radiation seems to be of additional therapeutic benefit. Except for meningeosis melanomatosa chemotherapy must be regarded as experimental. Unfortunately, a standardised therapy concept is still lacking.

Anatomy of the cerebral ventricular system for endoscopic neurosurgery: a magnetic resonance study

BACKGROUND

Endoscopy has developed into an integral part of minimally invasive neurosurgery. For further technological innovations, detailed knowledge about the pathological anatomy is essential. The gross anatomy of the cerebral ventricular system has been meticulously investigated with ventriculography and casts. Extensive volumetric measurements based on neuroradiological images have been performed, but only little is known about the surgically relevant linear distances in patients with hydrocephalus.

METHOD

Thirty healthy volunteers and thirty patients suffering from hydrocephalus were scanned with high-resolution 3-D magnetic resonance imaging sequences. The image volumes were sliced identically with the help of Siemens Prominence software. Individual anatomical measurements of the ventricular system were carried out, mean values and standard deviations were calculated, and different endoscopic approaches were investigated.

FINDINGS

In healthy volunteers the measurements confirmed the results obtained from ventriculography and anatomic casts. In hydrocephalic patients the ventricular system was found to be enlarged asymmetrically. The optimal neuroendoscopic approach showed considerable, interindividual variation.

INTERPRETATION

This 3-D magnetic resonance imaging study revealed surgically and clinically relevant aspects of the pathologic anatomy of hydrocephalic patients, in comparison to healthy volunteers. Individualized planning of the endoscopic approach appears to be warranted. Finally, the data provided a sound basis for the further development of neuroendoscopes.

Relevance of image fusion for target point determination in functional neurosurgery

BACKGROUND

For the treatment of medically refractory movement disorders such as Parkinson's disease, essential tremor and primary dystonia, deep brain stimulation (DBS) has become one of the main treatment options. The targets for implantation of the stimulation electrodes are various nuclei within the basal ganglia or the thalamic and subthalamic area. Accurate target localisation is of major importance for outcome and patient safety. The goal of this study was to evaluate the role of image fusion in the determination of target co-ordinates.

METHOD

We conducted a retrospective study on 10 patients in whom 17 DBS electrodes had been implanted. Coordinates of the anterior and posterior commissures and of the DBS targets were compared on pre- and postoperative computerised tomography (CT) and fused CT/magnetic resonance scans. The targets as defined on the images were further compared with the targets derived intra-operatively with microelectrode recordings (MER) and macrostimulation.

FINDINGS

The achievable mean target accuracy was of the order of the diameter of the DBS electrode and of the accuracy of the image fusion algorithm, i.e. about 1 mm. However, the maximal differences were between 1.8 mm and 3.2 mm.

INTERPRETATION

Image fusion is a helpful tool for accurate determination of target point co-ordinates in DBS. In combination with intraoperative, electrophysiological recordings and stimulation which are still considered to be the most reliable localisation methods, image fusion may help to discern the anatomical and functional three-dimensionality of the target nuclei. Image fusion may reduce the number of trajectories needed for intraoperative electrophysiological determination of the optimal electrode localisation and thus lower the risk of complications.

Combined therapy of cerebral arteriovenous malformations: histological differences between a non-adhesive liquid embolic agent and n-butyl 2-cyanoacrylate (NBCA)

OBJECTIVE

Based on 2 casuistics, the intraoperative qualities of a new, non-adhesive liquid embolic agent (Onyx, Micro Therapeutics. Inc., Irvine, CA, USA) are to be compared to those of n-butyl 2-cyanoacrylate (NBCA) with regard to the histopathological results after preoperative embolization of a cerebral arteriovenous malformation (AVM).

PATIENTS AND METHODS

In a case example, the intraoperative quality of the nidus after embolization of a parieto-occipital AVM with Onyx--a new, non-adhesive liquid embolic agent--consisting of ethylene-vinyl alcohol copolymer (EVOH), dimethyl sulfoxide (DMSO) and tantalum, is described. In the second patient, embolization of a frontal high-flow AVM was performed with NBCA. Both patients underwent surgery with complete resection ofthe AVM.

RESULTS

From a neurosurgical point of view, Onyx is suitable for preoperative embolization of AVMs, because the nidus intraoperatively remains elastic and formable and can be dissected from the surrounding brain tissue quite well by microsurgical technique. Inflammatory reactions can be found mainly in the lumina of the vessels.

CONCLUSIONS

Onyx promises to be an embolic agent well suitable for subsequent neurosurgical resection. Further studies considering various intervals of time between embolization and resection as well as histopathological and electron microscopical examinations are necessary for evaluation of our first experience with this new embolization agent.

New virtual system for planning of neuroendoscopic interventions

OBJECTIVE

The demands on virtual planning systems are increasing, particularly for technically pretentious surgical interventions such as intracranial endoscopy. In this article, a new virtual system for neuroendoscopy (VIVENDI) is presented. The main purpose of this system is to provide support for planning and training in neuroendoscopic interventions.

MATERIALS AND METHODS

The software is applied for virtual endoscopic visualization of three-dimensional magnetic resonance datasets, using a clinical magnetic resonance scanner. Rendering is performed on a Hewlett-Packard UNIX workstation.

RESULTS

Virtual endoscopy provides a three-dimensional view of the cerebral ventricles, with good visualization of anatomic details. The rendering system used allows the generation of fly-through sequences for the entire ventricular system in real time. Navigation is controlled by mouse movements, and the visualization of the computer-generated intraventricular spaces is adapted to the characteristics of the optical endoscope.

CONCLUSIONS

The presented virtual neuroendoscopy system is a promising tool for planning and training in neuroendoscopic procedures. It enables these procedures to be simulated prior to surgery based on the patient's individual anatomy.

Overexpression, purification, and characterization of a thermostable chitinase (Chi40) from Streptomyces thermoviolaceus OPC-520

A new procedure for the large-scale purification of the recombinant thermostable chitinase (Chi40) cloned from Streptomyces thermoviolaceus in various expression vectors in Escherichia coli is described. Chi40 was overproduced in the cytosolic and secreted forms. The cytosolic form (Chi40c) was highly overproduced and purified by metal-affinity and ion-exchange chromatography in large amounts. The protein was highly active and thermostable but not homogeneous, since a considerable proportion of the Chi40c protein was not correctly folded as determined by native polyacrylamide gel electrophoresis. The Chi40 protein secreted into the culture medium (Chi40s) was purified by hydrophobic interaction and ion-exchange chromatography and high amounts of correctly folded and active Chi40 protein could be recovered in a short time. The enzymatic activity of Chi40s on a synthetic and on its natural substrate, chitin, was studied. Thermostability measurements showed that Chi40 has a T(m) of 60.7 degrees C at neutral pH. (13)C-(15)N double-labeled recombinant Chi40s was also produced and purified from the pECHChi40-9 construct introduced into BL21trxB(DE3) cells grown in minimal medium in the presence of the paramagnetic elements [(13)C]glucose and (15)NH(4)Cl. The presented data open the possibility of an extensive structural study on Chi40s by X-ray crystallography and on enzyme-substrate interaction by NMR spectroscopy.

Early activation of the primary somatosensory cortex without conscious awareness of somatosensory stimuli in tumor patients

The primary sensory cortex has usually been regarded as a necessary step in the information processing stream leading to conscious awareness. Recently, it has been proposed that that higher order associative areas rather than the primary sensory areas are the neural basis of conscious perception. In two patients with tumors near the central region we recorded magnetic somatosensory evoked fields. Magnetic source imaging revealed early (40 ms) neural activation in primary somatosensory cortex and absence of later (>60 ms) neural activation in the primary and associative areas in these patients. None of the patients showed conscious awareness of somatosensory stimuli applied to the corresponding body site although the first component of the evoked field was within normal limits. The time course of the magnetic responses and additional evidence on intensity ratings of somatosensory stimuli suggest that early activity in the primary somatosensory cortex is not sufficient for conscious experience to emerge.

Combined treatment effects after embolization and radiosurgery in high-grade arteriovenous malformations. Case report and review of the literature

In recent years the multimodal therapy concept has been established for high-grade intracerebral arteriovenous malformations (AVM). One strategy of a multimodal treatment approach for patients with AVM (Spetzler grade V) is reported. After endovascular embolization, the patient underwent radiosurgical treatment of the remaining nidus with a linear accelerator, after which he developed a left-sided hemiparesis in conjunction with severe edema. Angiographic control 44 months after radiation showed an occlusion of the radiosurgically treated nidus. The remaining nidus could be removed by microsurgery. The combination of embolization and radiosurgery may provoke prolonged edema and permanent neurological deficits due to inflammatory perivascular changes.

Quality planning for minimally invasive procedures in neurosurgery

Parallel to the introduction of a minimally invasive method in a department, a documentation system should be introduced for quality management. The first step of quality management of an innovation is quality planning. During the course of patients being treated neuroendoscopically, the pre- and postoperative imaging, the intraoperative video recording, the patient-relevant files and the data of the planning have to be documented. These amounts of data require a multimedial documentation concept. We found the CD-ROM as an optimal documentation media because the discs are both cheap and easily accessible and once stored extremely robust against external influences. Therefore, every neuroendoscopically treated patient is documented with all relevant pictures, files and video sequences on a single CD-ROM.

Recurrence of a cerebral arteriovenous malformation after surgical excision

Complete resection of a cerebral arteriovenous malformation (AVM) should eliminate the future risk of an associated intracranial bleeding. Because total removal of an AVM may be difficult to assess at the time of surgery, postoperative angiography has become the accepted standard for documenting that complete removal has been achieved. However, even angiographically confirmed excision of an AVM does not completely exclude the possibility of rebleeding. Regrowth of an AVM with subsequent haemorrhage has been documented in children and is attributed to forces acting on the immature vasculature. The authors report the case of a 21-year-old man whose AVM recurred 5 years after angiographically proven complete excision. According to the presented case, the authors emphasise that, even in adults, angiographic documentation of total removal does not always eliminate the risk of reformation of an AVM.

In vivo expression of insulin-like growth factor-binding protein-2 in human gliomas increases with the tumor grade

Human central nervous system tumors and glioma cell lines highly express the insulin-like growth factor-binding protein (IGFBP)-2. As IGFBP-2 can affect tumor growth, we studied the relationship between IGFBP-2 expression and the malignancy of brain tumors in vivo. To do so, we investigated by immunohistochemistry the accumulation of IGFBP-1, -2, and -3 in 50 human gliomas classified by the WHO Malignancy Scale. Double labeling using anti-CD68 (monocytes/macrophages), antiglial fibrillary acidic protein, and anti-CD3 (T cells) antibodies was performed to further characterize the IGFBP-1, -2, and -3(+) cells. The expression of IGFBP messenger RNAs (mRNAs) was tested by RT-PCR in tumor samples from nine gliomas of different grades and in eight cell lines representing the cellular composition of human glioma. As controls, the accumulation of IGFBP-2 was investigated in normal brain and in the rat C6 glioblastoma model. IGFBP-1 and -3 accumulated in endothelial and macrophage/microglial cells. IGFBP-2(+) macrophage/microglial and glioma cells clustered in the immediate vicinity of focal necrosis of the human gliomas as well as of the rat C6 glioblastoma. The labeling score of IGFBP-1 accumulation in endothelial cells correlated negatively (P: = 0.0229), and that of IGFBP-2 accumulation in glioma cells correlated positively (P: < 0.0006) with the tumor grade of the gliomas. In addition, RT-PCR analysis confirmed mRNA expression of IGFBP-1, -2, and -3 by the gliomas and glial cells. Small amounts of IGFBP-1 and -3 mRNA, but high amounts of IGFBP-2 mRNA, were detectable in macrophage-like and glioma cell lines. The results suggest cell type-specific accumulation of IGFBP-1, -2, and -3 in human glial tumors of the brain. The increase in IGFBP-2 expression with this malignancy suggests a role of IGFBP-2 in the biology of human gliomas.

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.

Heme oxygenase (HO)-1 expressing macrophages/microglial cells accumulate during oligodendroglioma progression

Heme oxygenase (HO-1, HSP32) catalyzes the oxidation of heme to biliverdin and carbon monoxide, a putative neurotransmitter. In the brain, HO-1 expression has been associated with neuroprotection during oxidative stress and hypoxia. However, consecutive downstream mediation is involved in neoangiogenesis and consequent neoplastic outgrowth. We have analyzed HO-1 expression in 69 oligodendroglioma tissue samples, in rat intracranially transplanted C6 gliomas, and neuropathologically unaltered control brains by immunohistochemistry. Double labeling experiments confirmed the nature of HO-1 expressing cells. Reverse transcription-polymerase chain reaction was used to demonstrate HO-1 gene expression. HO-1 immunoreactivity was predominantly observed in macrophages/microglial cells. The number of HO-1 expressing macrophages/microglial cells was significantly lower in primary oligodendrogliomas than in their matched relapses (P<0.0001) and lower in primary anaplastic oligodendrogliomas than in their relapses (P=0.0006). Prominent accumulation of HO-1 expressing macrophages/microglial cells was observed in perinecrotic areas of both experimental rat and human glioblastoma relapses. HO-1 expressing neurons, macrophages/microglial cells and astrocytes were scattered in areas of infiltrative tumor growth. Surprisingly, HO-1 mRNA was detected in only one glioblastoma multiforme relapse. We conclude from these data that HO-1 expressing macrophages/microglial cells accumulate during oligodendroglioma progression in areas of focal necrosis. However, overall biological function of this phenomenon remains to be determined.

A new thermoactive pullulanase from Desulfurococcus mucosus: cloning, sequencing, purification, and characterization of the recombinant enzyme after expression in Bacillus subtilis

The gene encoding a thermoactive pullulanase from the hyperthermophilic anaerobic archaeon Desulfurococcus mucosus (apuA) was cloned in Escherichia coli and sequenced. apuA from D. mucosus showed 45.4% pairwise amino acid identity with the pullulanase from Thermococcus aggregans and contained the four regions conserved among all amylolytic enzymes. apuA encodes a protein of 686 amino acids with a 28-residue signal peptide and has a predicted mass of 74 kDa after signal cleavage. The apuA gene was then expressed in Bacillus subtilis and secreted into the culture fluid. This is one of the first reports on the successful expression and purification of an archaeal amylopullulanase in a Bacillus strain. The purified recombinant enzyme (rapuDm) is composed of two subunits, each having an estimated molecular mass of 66 kDa. Optimal activity was measured at 85 degrees C within a broad pH range from 3.5 to 8.5, with an optimum at pH 5.0. Divalent cations have no influence on the stability or activity of the enzyme. RapuDm was stable at 80 degrees C for 4 h and exhibited a half-life of 50 min at 85 degrees C. By high-pressure liquid chromatography analysis it was observed that rapuDm hydrolyzed alpha-1,6 glycosidic linkages of pullulan, producing maltotriose, and also alpha-1,4 glycosidic linkages in starch, amylose, amylopectin, and cyclodextrins, with maltotriose and maltose as the main products. Since the thermoactive pullulanases known so far from Archaea are not active on cyclodextrins and are in fact inhibited by these cyclic oligosaccharides, the enzyme from D. mucosus should be considered an archaeal pullulanase type II with a wider substrate specificity.

Crystallization and preliminary X-ray crystallographic studies of the thermoactive pullulanase type I, hydrolyzing alpha-1,6 glycosidic linkages, from Fervidobacterium pennivorans Ven5

Crystals of the thermoactive recombinant F. pennivorans type I pullulanase, purified from the supernatant of a Bacillus subtilis culture, have been obtained by the vapour-diffusion method in the presence of the inhibitor beta-cyclodextrin (2 mM) by mixing protein (15 mg ml(-1)) with an equal volume of crystallization solution containing 0.1 M bis-tris propane pH 6.5, 50 mM MgCl(2) and 15% polyethylene glycol 3350. Crystals diffracted to 3.0 A using conventional Cu Kalpha radiation and belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 76.8, b = 96.2, c = 98. 5 A. The asymmetric unit contains one monomer. A preliminary 26% complete data set has been collected at 2.2 A resolution using synchrotron radiation.

Claudin-1 and claudin-5 expression and tight junction morphology are altered in blood vessels of human glioblastoma multiforme

The aim of the study was to characterize the interendothelial junctions in tumor microvessels of five cases of human glioblastoma multiforme. In addition to morphological analysis, tumors were screened for the expression of junctional proteins, such as occludin, claudin-1, ZO-1 and catenins. The expression of the tight junction protein claudin-1 was lost in the majority of tumor microvessels, whereas claudin-5 and occludin were significantly down-regulated only in hyperplastic vessels. As shown by freeze-fracture analysis, under the conditions of tumor growth tight junction particles of endothelial cells were almost exclusively associated with the exocytoplasmic fracture face, providing evidence for a switch of the particles from the protoplasmic to the external leaflet of the endothelial membrane. These results suggest a relationship between claudin-1 suppression and the alteration of tight junction morphology, which is likely to correlate with the increase of endothelial permeability. Underlining the undifferentiated state of tumor microvessels, plakoglobin, a crucial protein for mature endothelial junctions, was not detectable in most microvessels, whereas beta-catenin was abundantly labeled. In this context, it is of particular interest that the majority of microvascular pericytes were negative for alpha-smooth muscle actin, which is a marker of differentiated pericytes, although pericytes were frequently found in electron micrographs. In conclusion, the data suggest that the increase in microvascular permeability in human gliomas, contributing to the clinically severe symptoms of brain edema, is a result of a dysregulation of junctional proteins.

Intracranial malignant B-cell lymphoma of the dura

OBJECTIVE

Malignant B-cell lymphomas of the dura mater are very rare. A case of primary centroblastic/centrocytic lymphoma of the dura mimicking a bilateral convexity meningioma is presented.

CLINICAL PRESENTATION

A 50-year-old woman was referred to our institution with a 6-month history of headache and two Jacksonian seizures. Computed tomography revealed a parafalcine and bilateral convexity lesion. Cerebral angiography and magnetic resonance imaging were performed prior to surgery. At surgery the tumor was removed subtotally. The patient was treated postoperatively by combined chemo- and radiotherapy.

CONCLUSION

Laboratory studies and follow-up examinations revealed no evidence of systemic lymphoma nor of any immunocompromised state. According to the presented case combined surgery and chemoradiotherapy seems to be an effective treatment for this rare lesion.

Activation of the anterior cingulate cortex by thalamic stimulation in patients with chronic pain: a positron emission tomography study

OBJECT

Deep brain stimulation (DBS) of the sensory thalamus has been used to treat chronic, intractable pain. The goal of this study was to investigate the thalamocortical pathways activated during thalamic DBS.

METHODS

The authors compared positron emission tomography (PET) images obtained before, during, and after DBS in five patients with chronic pain. Two of the five patients reported significant DBS-induced pain relief during PET scanning, and the remaining three patients did not report any analgesic effect of DBS during scanning. The most robust effect associated with DBS was activation of the anterior cingulate cortex (ACC). An anterior ACC activation was sustained throughout the 40 minutes of DBS, whereas a more posteriorly located ACC activation occurred at a delay after onset of DBS, although these activations were not dependent on the degree of pain relief reported during DBS. However, implications specific to the analgesic effect of DBS require further study of a larger, more homogeneous patient population. Additional effects of thalamic DBS were detected in motor-related regions (the globus pallidus, cortical area 4, and the cerebellum) and visual and association cortical areas.

CONCLUSIONS

The authors demonstrate that the ACC is activated during thalamic DBS in patients with chronic pain.

Pullulanase type I from Fervidobacterium pennavorans Ven5: cloning, sequencing, and expression of the gene and biochemical characterization of the recombinant enzyme

The gene encoding the type I pullulanase from the extremely thermophilic anaerobic bacterium Fervidobacterium pennavorans Ven5 was cloned and sequenced in Escherichia coli. The pulA gene from F. pennavorans Ven5 had 50.1% pairwise amino acid identity with pulA from the anaerobic hyperthermophile Thermotoga maritima and contained the four regions conserved among all amylolytic enzymes. The pullulanase gene (pulA) encodes a protein of 849 amino acids with a 28-residue signal peptide. The pulA gene was subcloned without its signal sequence and overexpressed in E. coli under the control of the trc promoter. This clone, E. coli FD748, produced two proteins (93 and 83 kDa) with pullulanase activity. A second start site, identified 118 amino acids downstream from the ATG start site, with a Shine-Dalgarno-like sequence (GGAGG) and TTG translation initiation codon was mutated to produce only the 93-kDa protein. The recombinant purified pullulanases (rPulAs) were optimally active at pH 6 and 80 degrees C and had a half-life of 2 h at 80 degrees C. The rPulAs hydrolyzed alpha-1,6 glycosidic linkages of pullulan, starch, amylopectin, glycogen, alpha-beta-limited dextrin. Interestingly, amylose, which contains only alpha-1,4 glycosidic linkages, was not hydrolyzed by rPulAs. According to these results, the enzyme is classified as a debranching enzyme, pullulanase type I. The extraordinary high substrate specificity of rPulA together with its thermal stability makes this enzyme a good candidate for biotechnological applications in the starch-processing industry.

3D spiral CT imaging of bone anomalies in a case of diastematomyelia

The case of a 48-year-old woman, suffering from a diastematomyelia, is presented. This case and the diagnostic findings are used to demonstrate the demands on imaging methods with respect to a new classification of split cord malformations (SCMs) recently published. Although MRI is the method of choice for imaging of the spinal cord generally, only X-ray methods and especially conventional computer tomography provide the information necessary for correct classification of SCMs. Additional 3D-reconstructions from suitable CT-data are helpful in visualizing complex anomalies of bony structures found in most cases of SCM.

Radiosurgery for the treatment of brain metastases in renal cell carcinoma

BACKGROUND

In the treatment of brain metastases using a stereotactically modified linear accelerator it could be shown that a single dose between 15 and 25 Gy leads to partial or complete remission of so-called radioresistant metastases from melanoma and hypernephroma. Radiosurgery of brain metastases then started in centers all over the world, however, experiences with brain metastases of renal cell carcinoma are yet limited. The aim of this analysis is therefore to present the treatment results of radiosurgery of brain metastases. Furthermore, in this paper prognostic subgroups shall be defined, in order to establish guidelines for an optimal therapy strategy.

MATERIALS AND METHODS

Radiosurgery means stereotactically guided high-precision irradiation methods by extremely focussing ionizing radiation within the target volume as a single dose application. The characteristic steep dose decrease allows the selective destruction of small intracranial lesions, while the surrounding brain tissue is optimally protected. Two methods, Gamma Knife and stereotactic modified linear accelerator are clinically available.

RESULTS

In larger studies from different groups all over the world, local tumor control rates from 85% to 95%, recurrence rates from 6% to 15% and side effects between 3% and 15% have been attained, independent of the system used. Prognostic factors, like volume of metastases < 10 ml, applied dose > 18 Gy, one or two metastases, absence of extracranial metastases, good patient performance with a Karnofsky score > 70%, primary treatment and more than one year between primary diagnosis and brain metastases showed a trend toward improved survival. Depending on the prognostic factors the median survival after radiosurgery ranged from 6 to 12 months. Retrospective comparison of radiosurgery and surgical series suggest that both modalities attain similar results. The dose can be applied with an accuracy of 0.3 mm.

DISCUSSION

Based on these experiences, brain metastases can be treated by radiosurgery, primarily in patients with one or two metastases or in combination with whole brain irradiation as a boost in patients with more than two metastases. Furthermore with radiosurgery a new treatment modality exists to re-irradiate patients who have been failed after surgery or whole brain irradiation.

[75 years after Dandy, Fay and Mixter--looking back on the history of neuroendoscopy]

The first neuroendoscopic operation was done in the year 1910 by the urologically practicing doctor Victor Darwin Lespinasse (1878-1946). Lespinasse never published this procedure. He only reported the case in front of a local surgical society. Several years later (1922/23) the first endoscopic operations in the brain were published by three neurological surgeons within one year (Dandy, Fay and Mixter). This 75 year anniversary is the background for the following historical overview.

Five years of stereotactic radiosurgery at the University of Tübingen--a critical review of the method

At the University of Tübingen a Linac based stereotactic system for radiosurgery has been used since 1991. The floorstand system (SRS 200, Phillips) developed at Gainsville is used in combination with a Cosman Roberts Weels system by Radionics. The floorstand enables the gantry to be rotated vertically and the table to be rotated in the horizontal plane. Additionally, patient's movements are reduced by the fixation of the stereotactic ring to the stereotactic floorstand. We report our experience with the first 50 patients treated between December 1991 and June 1995. The patients were treated with an interdisciplinary approach. This cooperation eases the transition from radiosurgery to other methods such as embolization, operation, and other radiooncologic treatment options.

A new endoscopic tool for the CRW Stereotactic System

A new endoscopic tool designed and manufactured specifically for the CRW Stereotactic System (Radionics) has a high definition optical system, with a single optical and light cable long enough to leave the sterile operating area. The diameter of the scope is 4.5 mm, which is small enough to pass through the foramen of Monro in occlusive hydrocephalus. In addition, several multifunctional instruments are comparable with the endoscope.

Primary Candida albicans empyema associated with epidural hematomas in craniocervical junction

The case of a 27-year-old patient with chronic candida empyema in the craniocervical junction is presented. Occlusive hydrocephalus at admittance, primary subdural candida empyema, and recurrent epidural bleedings are the outstanding features in the clinical course. Despite intact immunity this patient acquired primary candidosis of CNS. Pathological changes in dura, ventricular system, and CSF required multiple shunt revisions. Antimycotic therapy was performed with a combination of 3 antimycotics. The clinical improvement was prolonged by several complications.

Giant cell tumor of the occipital bone in a case of von Recklinghausen neurofibromatosis

Von Recklinghausen neurofibromatosis (NF1) is the most common hereditary syndrome predisposing to neoplasia. The most common symptomatic manifestation of NF1 is the plexiform neurofibroma. We describe the case of a patient with classical von Recklinghausen neurofibromatosis presenting with a giant cell tumor (GCT) of the occipital bone infiltrating a surrounding plexiform neurofibroma.

[Gamma knife versus stereotactic linear accelerator. Utilization, clinical results and cost-benefit relations]

INTRODUCTION

The principles of radiosurgery were developed in 1951 by Leksell. Their technical realization led to the development of the gamma knife and stereotactically modified linear accelerator.

METHODS

In addition to the gamma knife, we present the different principles of convergent beam irradiation (radiosurgery with linear accelerator), the further development to fractionated stereotactic conformal radiotherapy, and the necessary quality-assurance steps.

RESULTS

The greatest uncertainties in the precision of radiosurgery result from medical imaging (CT 0.7 x 0.7 x 1 mm; DSA 1-5 mm; MR angiography < 2 mm). The focusing accuracy of the gamma knife (+/- 0.3 mm) can also be achieved today by linear accelerators using a stereotactic floorstand. For the same indication and the same dosage for the target volume, there are no clinical differences between the gamma knife and the linear accelerator (AVM: 80% complete obliteration; metastases: 85% local tumor control; AN: 90% tumor control). However, there are greater differences in costs. There is no constellation where the gamma knife is just as expensive or more cost-effective than the linear accelerator treatment. The most cost-effective solution is modification of an available linear accelerator, resulting in treatment costs per patient of 9,201.25 DM (50 patients/year).

CONCLUSION

There seem to be no methodological, physical, clinical or cost reasons for using a gamma knife, especially because the trend is going towards fractionated conformation radiotherapy instead of the application of high single doses.

[Stereotaxic convergent-beam irradiation. Initial experiences with the SRS 200 system]

BACKGROUND

The system SRS 200 for the stereotactic convergent beam irradiation described in this paper has a stereotactic floor stand, which allows the high precision rotation of a secondary collimator around an isocenter. This system is used since 1991 at the University Hospital of Tübingen for the treatment of patients with solitary brain metastases, acoustic neurinomas and arteriovenous malformations.

PATIENTS AND METHODS

The attainable accuracy of the mechanics and dosimetry was studied within the scope of extensive quality assurance measures during its installation and before each patients' irradiation. The individual treatment steps from radiotherapy planning to irradiation were evaluated by means of a specially developed head phantom. Since the installation of the SRS 200 a total of 50 patients (21 solitary brain metastases, 12 acoustic neurinomas, 17 arteriovenous malformations) has been treated with the system.

RESULTS

With 0.3 mm +/- 0.2 mm an excellent accuracy of the target point transfer and isocenter stability during irradiation was attained. The difference between calculated dose and dosimetric control measurements was smaller than 3%. The physical accuracy, however, is limited by the imaging resolution (CT and digital subtraction angiography). Of the patients 15% with solitary brain metastases developed complete remission, 20% partial remission and with 50% no further neurological deterioration was observed. Imaging revealed for 88% of the patients a reduced uptake of contrast medium or a regression of the tumor size. Six patients with acoustic neurinoma had anacusis already before radiotherapy. Regarding the other patients in the follow-up, hearing improved in 1 patient, 1 patient showed hearing deterioration, and all other patients hearing remained constant. MR and CT imaging revealed in 10 patients with acoustic neurinoma a reduced uptake of contrast medium and in 1 patient a tumor diminution. From the patients with arteriovenous malformation only 4 have been followed for more than 2 years after treatment. Therefore, statements about the rate of obliteration are not possible yet. Concerning pretherapeutic symptoms (headache 22%, convulsion 28%, neurological deficits 11%) 8/17 (47%) of the arteriovenous malformation patients showed an improvement, in 8 patients clinical findings were unchanged and 1 patient showed neurological deterioration.

CONCLUSION

The stereotactic system SRS 200 allows an excellent mechanical accuracy in the radiosurgery with linear accelerators.

Percutaneous needle trephination for external CSF drainage: experience with 226 punctures

We report on our experience with 226 percutaneous needle trephinations in a total of 192 consecutive patients. Trephination was performed with a hand-driven drill. A special puncture needle was inserted into the anterior horn of the lateral ventricle. The main indication for this procedure was the treatment of occlusive hydrocephalus in an emergency. Duration of drainage ranged from 1 to 34 days and was 7 days on the average. We encountered 14 cases of infection (6.2%) and one case of symptomatic bleeding (0.4%). All these complications eventually resolved without permanent sequelae. In our opinion, ventricle puncture with this device is a simple and effective method and can especially be recommended for external CSF drainage in cases of emergency.

[Subacute and chronic epidural hematoma after craniocerebral trauma]

During an 8-year period, fifteen patients with subacute or chronic epidural haematoma were seen among 110 treated cases of extradural haematoma corresponding to a frequency of 13.6%. Increasing headache, nausea, vomiting, mild drowsiness and cranial nerve palsy were the symptoms resulting in the correct diagnosis in most cases. Clinical and pathological findings are described, and the factors influencing the course of events are discussed. The most important factors are cerebral atrophy, age, source of bleeding and location. By means of early CT (computed tomography) diagnosis of haematoma, fatal outcome could be prevented in most of the cases.

Assessment of Pediococcus acidilactici as a Potential Silage Inoculant

Eighteen Pediococcus strains were screened for their potential as silage inoculants. Pediococcus acidilactici G24 was found to be the most suitable, exhibiting a short lag phase on both glucose and fructose, a rapid rate of acid production, a high sugar-to-lactate conversion efficiency, no detectable breakdown of proteins or lactic acid, and the ability to grow within a broad range of pH and temperature. When tested in laboratory silos using grass with a water-soluble carbohydrate content of 24 g/kg of aqueous extract, P. acidilactici G24 stimulated the natural Lactobacillus plantarum population and accelerated the rates of lactic acid production and pH decrease. After 6 days of fermentation, the inoculated silage exhibited a 12% decrease in ammonia nitrogen and an 11% increase in crude protein levels compared with uninoculated controls. The use of an L. plantarum inoculant at a rate of 10 4 bacteria per g of grass in conjunction with P. acidilactici G24 produced no additional beneficial effect. Inoculation of grass with a water-soluble carbohydrate level of 8 g/kg of aqueous extract with P. acidilactici G24 led to no acceleration in the rate of L. plantarum growth or pH decrease. However, after 7 days of fermentation the inoculated silage had a 14% lower ammonia nitrogen protein content than did uninoculated controls. The results suggest that P. acidilactici G24 may be useful as a silage inoculant for crops with a sufficiently high water-soluble carbohydrate level.

[Surgical treatment of aseptic forearm shaft pseudarthrosis]

Non union of a lower arm fracture (without infection) is the result of inadequate immobilization or of too extensive devastation of the bone. Within 1975 to 1985 in the accident-hospital of Tübingen we saw 131 pseudarthroses of the ulnar or radius shaft in 111 patients. Among these a hypertrophic pseudarthrosis is mostly seen after conservative treatment or operative treatment with intramedullary nailing. Atrophic pseudarthroses or defect pseudarthroses mostly occur after open fractures, comminuted fractures or insufficient plate osteosynthesis. The operative treatment was regularly a plating of radius and/or ulna (mostly with the 3.5 mm AO-DC-plate) combined with correction of axis or rotation deformity. Depending on the type of the pseudarthrosis, decortication was also performed as well as an autogenous bone-grafting or an interposition of a cortical-cancellous-block. All but one of the pseudarthroses each of the ulna and radius, healed completely. Most patients had a reduction of pain, improvement of mobility of the elbow or wrist joint, especially an improvement of supination/pronation, regarded as an index of correction of a malrotation. Postoperative physiotherapy has to be most careful; the best physiotherapy is the everyday active use of the arm by the patient himself.