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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In the rat brain, the presynaptic 5-hydroxytrypt-amine (5-HT) autoreceptors located on 5-HT terminals correspond to the 5-HT1B subtype. The presence of a 5-HT receptor probably located on 5-HT nerve endings and modulating transmitter release in the human neocortex has been reported, but its detailed pharmacological characterization is not yet available. On the other hand, receptor binding and autoradiographic results indicate that the 5-HT1B receptor subtype is not present in the human brain. We, therefore, studied the modulation of the electrically evoked release of [3H]5-HT by various 5-HT receptor agonists and antagonists in preloaded slices of human neocortex obtained from 18 patients undergoing neurosurgery. The nonselective 5-HT1A/1B/1D receptor agonist 5-carboxamidotryptamine produced a potent inhibition (70% at 0.03 μM) of the electrically evoked release of [3H]5-HT which was blocked by 5-HT receptor antagonists with the following relative order of potency: methiothepin 〉 metergoline = methysergide 〉 propranolol. The selective 5-HT1A receptor agonist 8-hydroxy-2–(di-n-propylamino)tetralin at 0.1 μM did not modify the electrically evoked release of [3H]5-HT. The 5-MT1A/1B receptor agonist RU 24969 was 10 times more potent at inhibiting [3H]5-HT overflow in the rat frontal cortex than in the human neocortex. The potent 5-HT1B receptor antagonist cyanopindolol did not modify the 5-carboxamidotryptamine-induced inhibition of the electrically evoked release of [3H]5-HT in slices of the human neocortex, but produced by itself a small inhibition of [3H]5-HT overflow. The α2-adrenoceptor antagonist yohimbine, which possesses affinity for the 5-HT1D receptor subtype, decreased the release of [3H]5-HT, but only in the presence of the selective α2-adrenoceptor antagonist idazoxan, which by itself increased significantly [3H]5-HT overflow. Taken together, these results support the view that the 5-HT receptor modulating the electrically evoked release of [3H]5-HT in slices of the human neocortex could be of the 5-HT1D subtype. Moreover, preliminary results obtained with idazoxan confirm the existence of a presynaptic α2-adrenoceptor modulating the release of [3H]5-HT in the human neocortex. These α2-heteroreceptors could exert a tonic inhibitory modulation on 5-HT neurotransmission in the human neocortex.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 5 (1990), S. 241-244 
    ISSN: 1435-604X
    Keywords: CO2 laser ; Nd-YAG laser ; Endoscopic laser ; Stereotaxic laser surgery ; Intracranial tumours ; Intraorbital tumours ; Intraspinal tumours
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The early 1970s saw the birth of microscopic neurosurgery and the late 1970s the birth of laser neurosurgery. For more than 10 years now, laser radiations have been used during neurosurgical procedures: mostly for tumoral removal concerning essentially benign lesions. The reference laser has been and still is the CO2 laser, which has a limited penetration into CNS tissues. Until recently the Nd-YAG laser was used with its normal spectral transition, 1.064 μm. Because of its important diffusion in the CNS, it cannot be widely used except for shrinking large vascularized tumours such as meningiomas. The technological evolution has brought the laser specialists—physicists, medical doctors and surgeons—new concepts and new wavelengths which will progressively broaden laser applications and surgical procedures towards greater effectiveness, security and simplification. Holmium-YAG (2.1 μm), Erbium-YAG (2.9 μm) or long Nd-YAG wavelengths (1.44 or 1.32 μm) have been studied by different teams. The 1.32 μm Nd-YAG transition has been clinically used for about 2 years by a few neurosurgical teams (Beck in Munich, Roux in Paris, and more recently Lombard and Fasano in Torino, Ascher in Gratz). Laser radiations can be useful essentially during the removal of benign tumours, mostly if they are well vascularized and placed near functional structures such as the brain stem, the cranial nerves, the spinal cord: the CO2 laser is most efficient for vaporization; 1.06 Nd-YAG is effective for coagulation; 1.32 Nd-YAG provides very satisfactory photoevaporation effects if used with a superpulsed emission, and/or with a focusing handpiece, it also has good haemostatic properties with a c.w. output. The development of new optic fibre conducted wavelengths appears to be a possible answer to new requisites which should lead to the development of endoscopic neurosurgery (intraventricular tumours, discal herniations) and sterotaxic laser surgery (deep-seated intra-cerebral lesions).
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 77 (1985), S. 37-40 
    ISSN: 0942-0940
    Keywords: CO2-laser neurosurgery ; tumoural haemostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors have been using CO2-laser radiation routinely for more than 2 years. After having recalled the basic thermal properties of this beam, they present their experience. The goal of this work is to point out the particular benefit of CO2-laser cautery to perform tumoral haemostasis. The technical data of this CO2-laser haemostasis are detailed for 3 main indications: 1. In cases of a precise origin of the haemorrhage, the coagulation of small intratumoural vessel necessitates a low output power: 2–4 watts in continued emission; 10–15 watts in the pulsed mode. The beam must be defocussed so as to be as large as the aimed vessel. A micro-manipulatotor is necessary for deeply located tumours. Basal meningiomas, neurinomas, giant adenomas are the best indications. 2. If a diffuse bleeding is encountered in the operative cavity the output must be a little higher: 3–8 watts in continuous mode or 15–30 watts in the pulsed mode; first the cavity is swept with a defocussed CO2-laser ray; then the few larger vessels which have not been cauterized are coagulated one by one either by laser or by bipolar coagulation. 3. The insertion zone of a meningioma can be efficiently coagulated by CO2-laser: a 150–200 watts output in the pulsed mode is necessary if the attachment is dural, a 300–400 watts pulsed output in the case of bony infiltration.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: 1.32 Nd-YAG Laser ; 1.06 Nd-YAG Laser ; stereotaxy ; endoscopic neurosurgery ; tumour removal
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors present their clinical experience with 1.32 μm NdYAG Laser. After a series of experimental studies which demonstrated the adaptability of such a wavelength to central nervous surgery, they used such a Laser during current neurosurgical procedures. The MC 2100 unit combines two wavelengths 1.32 μm and 1.06 μm, and two emission modes: continuous wave (c.w.) and pulsed. This Laser has been used during 70 procedures: 54 supra-tentorial, 8 infra-tentorial, 5 intra-spinal, 3 intra-orbital. 600 μm and 400 μm fibers were preferred in most cases, either with a telescopic light handpiece or-less often—with a focussing handpiece. The quality of vaporization—close to that of CO2 Laser—and of haemostasis —close to that of 1.06 μm Nd-YAG Laser—makes this 1.32 μm wavelength very suitable for neurosurgery. The manoeuverability due to the optic fibers is most interesting. Furthermore, such a Laser should have in the near future large applications in stereotactic and/ or endoscopic neurosurgery.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 138 (1996), S. 1019-1026 
    ISSN: 0942-0940
    Keywords: Brain tumours ; laser surgery ; MRI ; photocoagulation ; stereotaxy ; ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary One of the most recent laser treatment modalities in neurosurgery is interstitial laser thermotherapy (ILTT). In this review, experimental and clinical studies concerning intracranial ILTT are discussed. Two methods for intra-operative control of the laser induced lesions are described; i.e., computer-controlled power delivery, using a thermocouple that is positioned interstitially at the periphery of the tumour to maintain the desired temperature at that point, and MRI, to visualise the extent of the thermal lesions induced by ILTT. The results show that ILTT using a Nd:YAG laser is easy and relatively effective in the treatment of small deepseated brain tumours with minimal risk and complications. This review is concluded with suggestions for further improvement of this treatment modality.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 138 (1996), S. 1135-1147 
    ISSN: 0942-0940
    Keywords: Lasers ; tumour removal ; stereotaxy ; neuro-endoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary From initial experiments of ruby, argon and CO2 lasers on the nervous system so far, dramatic progress was made in delivery systems technology as well as in knowledge of laser-tissue interaction effects and hazards through various animal experiments and clinical experience. Most surgical effects of laser light on neural tissue and the central nervous system (CNS) are thermal lesions. Haemostasis, cutting and vaporization depend on laser emission parameters — wavelength, fluence and mode — and on the exposed tissues optical and thermal properties — water and haemoglobin content, thermal conductivity and specific heat. CO2 and Nd-YAG lasers have today a large place in the neurosurgical armamentarium, while new laser sources such as high power diode lasers will have one in the near future. Current applications of these lasers derive from their respective characteristics, and include CNS tumour and vascular malformation surgery, and stereotactic neurosurgery. Intracranial, spinal cord and intra-orbital meningiomas are the best lesions for laser use for haemostasis, dissection and tissue vaporization. Resection of acoustic neuromas, pituitary tumours, spinal cord neuromas, intracerebral gliomas and metastases may also benefit from lasers as accurate, haemostatic, non-contact instruments which reduce surgical trauma to the brain and eloquent structures such as brain stem and cranial nerves. Coagulative lasers (1.06 μm and 1.32 μm Nd-YAG, argon, or diode laser) will find an application for arteriovenous malformations and cavernomas. Any fiberoptic-guided laser will find a use during stereotactic neurosurgical procedures, including image-guided resection of tumours and vascular malformations and endoscopie tumour resection and cysts or entry into a ventricle. Besides these routine applications of lasers, laser interstitial thermotherapy (LITT) and photodynamic therapy (PDT) of brain tumours are still in the experimental stage. The choice of a laser in a neurosurgical operating room implies an evaluation of the laser use (applications, frequency), of the available budget and costs-including purchase, maintenance and staff training-, and material that will be necessary: unit, peripherals, safety devices and measures, training programme. Future applications of lasers in neurosurgery will come from technological advances and refined experimental applications. The availability of new wavelength, tunable, small sized and “smart” laser units, will enlarge the thermal and non-thermal interactions between laser energy and neural tissue leading to new surgical applications. Tissue photo-ablation, photohynamic therapy using second generation of photosensitizers, updated thermotherapy protocols, are current trends for further use of lasers in neurosurgery.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 133 (1995), S. 201-205 
    ISSN: 0942-0940
    Keywords: Cranial base repair ; bone substitute ; Madreporic Coral ; transmission of infections ; Creutzfeld-Jacob-disease ; AIDS ; hepatitis C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors, since 1985, have used 587 Madreporic Coral grafts as bone substitute in a total of 183 patients, among them in 80 cases for repair of cranial base bone defects. They report their long-term results. Partial resorption to about 40% of the initial volume occurred in almost all cases within 8 to 10 months, with complete resorption after about one year. 20% of the coral blocks moved spontaneously or split into pieces, but could easily be withdrawn rhinoscopically through the nostrils. No CSF leakage was noticed afterwards. The local infection rate was only 4%, always close to the basal coral graft. This is lower than the infection rate after using autologous bone harvested from the inner table of the bone flap (20%). Infections were cured by removal of the coral graft. Despite the mentioned draw backs, Madreporic Coral graft implants can be recommended as bone substitute in cranial base surgery: 1. The material simplifies the surgical procedure 2. Harvesting of autologous bone is no longer necessary 3. Transmission of infections like AIDS, Hepatitis C or Creutzfeld-Jacob-disease can be avoided with certainty.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 98 (1989), S. 129-134 
    ISSN: 0942-0940
    Keywords: Adenocarcinoma ; ethmoid sinus ; induction chemotherapy ; operative therapy ; tumour removal ; cranial base reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary New therapeutic modalities for Ethmoidal Adenocarcinomas are presented. Thirty three patients harbouring such a tumour have been treated during the last four years. Twenty three were included in the following protocol: —the first step consisted in inductive chemotherapy based on a four-day course of continuous cisplatine (CDDP) and 5-fluoro-uracyl (5-FU infusion)—the second step was the tumour removal, which was performed through a combined transfacial and subfrontal approach. A contralateral ethmoidectomy was always performed. The integrity of the sphenoidal sinus was systematically checked. The cranial base was reconstructed with madreporic coral grafts; then a large extra-dural pediculated galea flap was placed onto the anterior base to line the sub-frontal dura. The authors discuss the results of this series of rare tumours.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1920
    Keywords: Key words Arteriovenous malformation ; cerebral ; Haemorrhage ; Cerebral angiography ; Prognostic factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The overall haemorrhagic risk of a cerebral arteriovenous malformation (cAVM) is 2–4 % per year. However, the individual risk of haemorrhage has never been determined. This study was undertaken to assess the haemorrhage risk of an individual cAVM. Neuroangiographic findings of 160 cAVM were analysed retrospectively, looking at 30 angiographic features. A statistical model was established by logistic regression to evaluate the risk of an individual cAVM. We statistically correlated 15 parameters with the haemorrhage risk. The statistical model includes five independent parameters. Four are unfavourable: exclusively deep drainage, venous stenoses, venous reflux and the radio of afferent to efferent systems; one is favourable: venous recruitment. This model quantifies the individual risk of haemorrhage. When this model is applied to the population studied, the error rate is 5 %. This model can contribute to therapeutic strategy, and to a better understanding of the natural history of cAVM.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    International orthopaedics 14 (1990), S. 255-259 
    ISSN: 1432-5195
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Des implants de corail madréporaire ont été utilisés par les auteurs en chirurgie osseuse orthopédique et crânio-faciale depuis 1985, pour des indications préliminaires: comblement de trous de trépans crâniens et comblement de prises de greffe iliaque. Plus de 200 fragments de corail de l'espèce Porites, préparés industriellement selon un cahier des charges rigoureux, et pré-usinés selon des tailles standardisées, ont été implantés. Aucune complication imputable au corail n'a été observée. Le corail s'est avéré d'emploi pratique et est en outre facilement disponible et d'un coût faible. L'incorporation n'a pu être appréciée qu'indirectement, en fonction de l'aspect radiologique mais a paru se faire lentement. Les propriétés biologiques du corail sont rappelées, et les résultats cliniques analysés en fonction des données expérimentales connues.
    Notes: Summary The authors have used Porites coral as a bone substitute in more than 200 patients since 1985, initially for reconstruction after craniotomy or removal of graft from the iliac crest. Encouraging results have prompted wider use. No complications have occurred. The biological properties of coral are described. It is easily available and appears to be a promising bone substitute.
    Type of Medium: Electronic Resource
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