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  • 1
    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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  • 2
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    ISSN: 1573-7373
    Keywords: stereotactic biopsies ; gliomas ; CT scanning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Histologic features of 100 supra-tentorial astrocytomas, oligodendrogliomas and oligo-astrocytomas obtained from serial stereotactic biopsies were compared with the corresponding CT scans. Topographic comparisons provided by visualization of the biopsy trajectories on post-biopsy CT scans were available in 24 cases. Areas of contrast enhancement and low attenuation were compared with the histologic grade of malignancy, tumor delimitation and structural type. The latter was determined as follows: Type I-solid tumor tissue without significant peripheral isolated tumor cells; Type II-solid tumor tissue associated with peripheral isolated tumor cells; Type III-isolated tumor cells only. There was a strong correlation between areas of contrast enhancement and tumor microvascularity. In addition, contrast enhancement occurred only in the solid tumor tissue component of the neoplasm. This correlation accounted for the relationship observed between CT images and the structural type of glioma. Contrast enhancement was constant in structural type I gliomas, inconstant in structural type II, and absent in structural type III. No correlation was found between malignancy and contrast enhancement. Contrast enhancement occurred in all grades of malignancy but was a constant feature of grade 4 gliomas. The volume of the tumors could not be reliably determined from CT images alone. Areas of low attenuation on contrast CT scans could correspond to either peritumoral edema or to edematous parenchyma infiltrated by isolated tumor cells. Serial stereotactic biopsies combined with calculations based on the CT scan provided a more precise definition of the tumor volume and identification of structural type. Such classification may prove useful in prospective analysis of various modes of therapy.
    Type of Medium: Electronic Resource
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