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By-passes of the sagittal sinus-which is 2,5 mm in diameter-were carried out with autogenous arterial or venous grafts, in 34 dogs, using the classical microtechniques (operative microscope, micro-instruments, micro-sutures...). Controls were done both 1 degree by angiography (direct sinography was the only convenient procedure to visualize the sinus and the by-pass) during survival, and 2 degrees by anatomical and histological examination after sacrifying the animals, on an average the 40th post-operative day (from the 10th to the 75th day). The early patency rate (within the first post-operative month) was 76 p. 100. All cases of early thromboses, which affected especially venous autografts, were related to technical insufficiencies. The late patency rate (after a one month follow-up) was only 64 p. 100, because of the secondary occlusion of some arterial autografts. All these late thromboses were related to an extensive fibrosis of the arterial wall.

Authors performed in two patients a macroscopically complete exeresis of a panspinal ependymoma. The first case concerns a 27 years old woman, submitted to surgery in 1971, soon after a delivery, who exhibited a tumor in all points identical to the one described by G. Horrax an D. Henderson (1939). The second case concerns a male subject submitted to surgery in May 1973 because of a lesion extending from C2 to L2 and corresponding to a dorsal fleshy ependymoma, surrounded by two voluminous pseudosyringomyelic cysts, with respectively cervical and dorsal-lumbar localization. Such cases rare, with sometimes difficult clinical and roentgenologic diagnosis, raise before all problems of surgical tactics. We are dealing here with benign ependymomas, few favourable to roentgentherapy. Their management is surgical, i.e. complete exeresis. The few common extent of some of these tumors to the totality of the spinal cord does not modify in any manner such a principle. The same may be said of some etiologic circumstances, such as pregnancy, that often enough constitute a postponing of diagnosis and mangement detrimental for the patient. Only, the march of the surgical procedure may be object of discussion. The here reported experience lets appear that, when necessary, complete exeresis may be performed in one session under the same conditions and with the same spinal risks than for a less extensive analogous tumor. At long term the problem of spasticity of lower extremities has to be considered. However, in spite of extensive laminectomy, no major deformity of the vertebral column is to be noted.

Prognosis of cancerous tumors of the spine depends above all on their neurological consequences. The authors have wondered whether osteosynthesis of the spine -- in addition to decompressive surgery -- can improve patient's survival and fonctional results. 23 patients, 20 with a metastatic tumor and 3 with a plasmocytoma were treated in this way. All of them had neurological deficits, 4 had isolated radicular symptoms, 1 a cauda equina syndrome and 18 a spinal cord compression (7 of which were complete). 20 of these patients suffered intractable pain of the spine. All the patients underwent decompressive surgical removal of tumor through laminectomy, associated with a bilateral posterior metallic osteosynthesis. The type of osteosynthesis consisted of two metallic plates placed along each articular column and screwed into the articular processes and the vertebral body through the pedicles of the adjacent normal vertebrae. Cobaltotherapy was added in 14 cases, hormonotherapy in one case and radioactive 131 1 in one another patient. Selective spinal angiography, performed in one case of thoracolumbar tumor was found useful in the location and avoidance of Adamkiedwicz's artery. With regard to the complication, there were two operative wound infections requiring reoperation. Our series -- in comparaison with others -- prove the effectiveness of the combined procedure. Patients without complete spinal deficit had a 20 months survival average. Patients with complete deficit had the same survival as in comparative group. But all the 20 patients suffering pain in the spine were substantially relieved. Such a combined procedure is indicated in cases of tumors involving the vertebrae, whether or not the epidural space is invaded especially when there are riskes of unstable fracture and only partial neurological deficits. The technique may be extended even to complete paraplegia because of its worth while antalgic effects. Thus this method -- by consolidating the spine -- relieving pain and consequently allowing kinesitherapy to be resumed earlier is able to improve the functionnal status and increase survival of the patients.

The authors have carried out serial section analysis in an attempt to elucidate the fiber organization at the posterior spinal cord-rootlet junction in Man. In the peripheral segment of the rootlet, large and small caliber fibers have no particular organization. On the contrary, at the level of the spinal cord-rootlet junction, small caliber fibers are re-grouped in the ventro-lateral region, whilst the large fibers are central and dorso-medial. After consideration of published experimental data, which show that the small caliber fibers activate the nociceptive system, the authors have carried out in Man selective sections of the small fibers for antalgic reasons. These selective posterior rootlet sections - operation called selective posterior rhizidiotomy - result in an analgesia without suppression of tactile epicritic and conscious proprioceptive sensitivities.

The most important results concerning the mechanisms of cortical electrogenesis have been achieved with animals thanks to transcortical bipolar investigations (Bishop and Clare 1952, Calvet and Scherrer 1961 a, b, Calvet et al. 1964, Jami et al. 1965, Fourment et al. 1965). These researches revealed that only the technique of transcortical derivation could give an accurate account of cortical activity. This is in accordance with the histological radiate structure of the cortex. The best proof of this is the parallelism between the phenomena of EEG type that this technique records and the unitary activity of neuronal volume explored. Moreover stratigraphic explorations enable these phenomena to be linked with the existence of generators. Experiments on human beings have been made with simple transcortical derivation by Hirsch et al. (1961, 1965, 1966) in particular. To our knowledge there have not been stratigraphic experiments with humans.