[Catheterization of the inferior petrosal sinus. Its role in the diagnosis of Cushing's syndrome. Experience with 23 explorations]. / Le cathétérisme des sinus pétreux inférieurs. Sa place dans le diagnostic du syndrome de Cushing. Expérience de 23 explorations.

Selective catheterization of the inferior petrosal sinus has been performed in 23 patients: 11 Cushing's disease, 5 lung carcinoid tumors whose diagnosis has been confirmed by surgery and 7 ACTH-dependent hypercortisolism whose final diagnosis has not yet been proved. The pituitary origin of hormone secretion is accepted if the central-to-peripheral ratio (C/PR) is equal or greater than 2 on basal values and/or during CRF test. On basal values, all subjects but one with confirmed pituitary lesions exhibited a C/PR > or = 2; the carcinoid tumors never exceeded the value of 1.3. After CRF injection, all the pituitary tumors showed an increase in C/PR; one patient with a lung carcinoid tumor (CRF-negative) showed a pituitary ACTH secretion (C/PR = 3.7). The localization of pituitary adenoma by the lateralization of hormone secretion is disappointing, except, perhaps, for very small extremely lateral adenomas. No accident occurred in our series, nor in the literature. This investigation seems the most reliable approach to prove the pituitary origin of hormonal hypersecretion. We recommend it to be performed in ACTH-dependent Cushing's syndrome when the secretory pattern is not typical and/or pituitary imaging is normal.

Long-term suppression of tremor by chronic stimulation of the ventral intermediate thalamic nucleus.

The usefulness of high-frequency stimulation of the ventral intermediate nucleus (Vim) as the first neurosurgical procedure in disabling tremor was assessed in 26 patients with Parkinson's disease and 6 with essential tremor. 7 of these patients had already undergone thalamotomy contralateral to the stimulated side, and 11 others had bilateral Vim stimulation at the same time. Chronic stimulating electrodes connected to a pulse generator were implanted in the Vim. Tremor amplitude at rest, during posture holding, and during action and intention manoeuvres was assessed by means of accelerometry. Of the 43 thalami stimulated, 27 showed complete relief from tremor and 11 major improvement (88%). The improvement was maintained for up to 29 months (mean follow-up 13 [SD 9] months). Adverse effects were mild and could be eradicated by reduction or cessation of stimulation. This reversibility and adaptability, allowing control of side-effects, make thalamic stimulation preferable to thalamotomy, especially when treatment of both sides of the brain is needed.

[Memory disorders following rupture of anterior communicating artery aneurysm. 22 cases]. / Troubles mnésiques après rupture d'anévrysme de l'artère communicante antérieure. 22 cas.

Twenty-two patients who underwent surgery for ruptured aneurysm of the anterior communicating artery were investigated by a battery of neuropsychological tests, including memory evaluation tests. According to the results obtained at these tests the patients were divided into three groups: 1) 7 patients had no memory disorders; 2) 10 patients presented with memory disorders affecting memory; their complaints concerned behavior, and the memory deficit was discovered at neuropsychological examination; 3) 5 patients presented with an obvious amnesic syndrome, and the tests confirmed a severe learning deficit and a severe forgetting while recognition remained normal in 4 patients. Age, residual lesions at CT and electrophysiological signs of focalization correlated well with the residual neuropsychological disorders. Leaving aside quantitative aspects, the memory deficits observed in the second and third groups seemed to be qualitatively different and might correspond to different anatomical and functional sequelae.

[Association of 5-FU, CDDP and hypofractionated radiotherapy in recurrences of subtentorial astrocytomas and malignant gliomas in adults]. / L'association 5-FU/CDDP/radiothérapie hypofractionnée dans les récidives des astrocytomes et des gliomes malins sustentoriels de l'adulte.

Twenty-seven patients who had a relapse of astrocytomas or supra-tentorial malignant gliomas, previously treated by radio-surgical combination or exclusive irradiation, underwent a combination of 3 courses of 5-FU, cis-platyl and hypofractionated irradiation. No objective response was observed, but there was a progression of the tumor in 33% of the cases, and no change in 67%. Overall median survival was 7 +/- 1.5 months. The 20 patients with grade III or IV astrocytomas had a lower median rate than the 7 patients with grade II astrocytomas or oligodendrogliomas: 6 +/- 1.8 months versus 18 +/- 3.2 (P = 0.16). Median survival was 14 +/- 2.7 months for neurological responders and 6 +/- 2.1 months for non-responders (P = 0.017).

[Surgery of acoustic neurinoma. Apropos of a personal series. Development of techniques and results]. / La chirurgie du neurinome de l'acoustique. A propos d'une série personnelle. Evolution des techniques et résultats.

Between 1973 and 1987, 125 acoustic neurinomas were operated on in oto-neuro-surgery. The sub-occipital approach route was used for Stages III and IV up to 1982 (30 cases). Subsequently, surgery for all the neurinomas used the translabyrinthine approach route (82 cases), except for those cases where an attempt was made to preserve hearing by a supra-petrosal route (6 cases) or a retrosigmoid route (6 cases). The translabyrinthine approach route provided the simplest sequellae and the best preservation of the function of the facial nerve: grades I and II in 68% of cases (in 80% of cases by excluding Stage IV). Preservation of hearing was perfect in 2 cases, and partial in 2 cases, out of 12 attempts. The use of a facial nerve monitor proved highly satisfactory.

[Treatment of Parkinson tremor by chronic stimulation of the ventral intermediate nucleus of the thalamus]. / Traitement du tremblement parkinsonien par stimulation chronique du noyau ventral intermédaire du thalamus.

Stereotactic ventral intermediate nucleus (Vim) thalamotomy may improve drug resistant severe parkinsonian tremor. However, tremor may recur and bilateral thalamotomy is known to induce unacceptable side effects in a proportion of patients. A high frequency (130 Hz) chronic Vim stimulation was performed in 4 parkinsonian patients, 2 of them having previously undergone a thalamotomy on the other side. Tremor was suppressed in all patients at the price of slight paresthesias. This improvement has been lasting from 2 to 14 months. Beneficial and adverse effects were suppressed at once each time the stimulation was stopped. These preliminary results are encouraging but a longer delay and more patients are obviously needed.

[Multiple correlative studies of stereotaxic biopsies of brain tumors]. / Etudes correlatives multiples sur biopsies stéreótaxiques de tumeurs cérébrales.

The opportunity of having several samples at the same site which could be spatially localized allows an intensive exploitation of stereotactic biopsies of brain tumors: the pathological data may be correlated to other measures, performed at the same site (electrical impedance X ray absorption coefficient) or on other samples (NMR relaxation times, water content, nucleic acids). These samples are available for oncology experiments in cellular biology (cell cultures, grafts on nude mice) or in molecular biology (DNA and RNA hybridization with specific nucleic acid probes). We were therefore able: 1) to study the diagnostic homologies between pathology and histology examinations; 2) to show that T1 and T2 NMR relaxation times are 2 times longer in tumor tissues than in normal brain; 3) to show that the electrical impedance is decreased by a factor 2 in brain tumors; 4) to show the absence of integrated viral genomic sequences and the existence of oncogenes association patterns in brain tumors by hybridization of specific sequences; 5) to establish permanent cell lines, the tumorigenicity of which is assayed by grafting on nude mice. Therefore, stereotactic biopsies appear to be, provided they are intensively and rationally exploited, a major research tool in an area which remains unsensitive to the various therapeutic approaches.

Removable, adjustable and reusable implants for stereotactic interstitial radiosurgery of brain tumors.

Sixty primary brain tumors (gliomas) were treated by interstitial radiosurgery using 192Ir according to a protocol based on the size of the tumor. In all cases, the radioactive wires were left in place for periods ranging from 5 to 10 days, according to dosimetry calculations, and then removed, which was made possible by the use of removable implants. The stainless steel tubes are occluded on their inner side and adjustable in length depending on the depth of the tumor, and are introduced through screws inserted into the skull in an array depending on the preliminary dosimetry. The tubes were afterloaded with 192Ir and removed at the end of the calculated time. Forty-six patients (18 low-grade and 28 malignant gliomas) were treated using this method. One small hematoma was evacuated and no sepsis occurred.

Combined (thalamotomy and stimulation) stereotactic surgery of the VIM thalamic nucleus for bilateral Parkinson disease.

Stereotactic thalamotomy of the thalamic nucleus ventralis intermedius (VIM) is routinely used for movement disorders. During this procedure, it has been observed that high-frequency (100 Hz) stimulation of VIM was able to stop the extrapyramidal tremor. In patients with bilateral tremor of extrapyramidal origin, who were resistant to drug therapy, the therapeutic protocol associated (1) a radiofrequency VIM thalamotomy for the most disabled side, and (2) a continuous VIM stimulation for the other side using stereotactically implanted electrodes, connected to subcutaneous stimulators. VIM thalamotomy relieved the tremor in all operated cases. Side effects were mild and regressive. VIM stimulation strongly decreased the tremor but failed to suppress it as completely as thalamotomy did. This was due in part to the fact that programmable stimulator frequency rate is limited to 130 Hz, while it appeared that the optimal stimulation frequency was 200 Hz. This therapeutic protocol appears to be of interest for patients with bilateral extrapyramidal movement disorders.

[Technical considerations on lumbar disk surgery. Results of a survey of 49 centers]. / Considérations techniques sur la chirurgie discale lombaire. Résultats d'une enquête portant sur 49 centres.

The lumbar discectomy, how do you see it? That could be the title of this inquiry which 49 neurosurgeons answered. At first we discuss the timing of the operation (as a rule sooner than the conventional indication of the third month) the use of operative microscope which is still uncommon (11 surgeons out of 49) and the operative policy. The more specific technical features regarding the different stages of the operation are then analysed. Opinions of neurosurgeons differ on many points particularly on the ligament and bone removal which exposes the disco-radicular conflict: whereas one third of the neurosurgeons refuse to open the lumbar facet joint, one third always open it widely and the remaining third take a mid-way position. On the whole, this inquiry points cut both a great diversity in technical details, but also a stagnation because this operation hardy improved and only slightly benefited from the technical progress.

[Our experience with surgery of neuromas of the 8th nerve]. / Notre expérience de la chirurgie des neurinomes du VIII.

Before 1982 the suboccipital approach was reserved for neurinomas larger than 2 cm diameter, whereas since that date the translabyrinthine approach has been employed in all cases where no attempt was made to preserve hearing. Of the 85 patients operated upon between 1978 and 1985, 5 were through a supra-petrous approach, 35 a retro-sigmoid approach, 44 a translabyrinthine approach and one by a transotic approach. Translabyrinthine approaches allowed the best postoperative course and conservation of normal facial motility in 22 patients of 33 with stages II and III lesions. An attempt was made to preserve hearing in 9 patients, with one reasonable result by the supra-petrous approach and 2 satisfactory results including one perfect operated upon using a rectosigmoid approach.

[The metastatic meningoradiculitis. An exceptional detection of a gastric cancer. Review of the literature about one case (author's transl)]. / La méningoradiculite métastatique: un mode de révélation exceptionnel de cancer gastrique. Revue de la littérature à propos d'un cas.

The authors relate a case of gastric cancer on a 47 years woman, revealed by the presence of nerve roots metastasis whose evolution was fatal in 13 months. They are pointing out the singularity of this pathology as only 29 cases have been published to date. The clinical and radiological diagnosis must cancel the existence of paraneoplasic polyradiculoneuritis, only by histological examination of the roots. The primary cancer concerns often the breast, the lungs and the stomach. But 25% of cases remain unknown. Among the various terms proposed to define this neurological complication of visceral neoplasms, the authors are selecting the expression of "metastatic meningoradiculitis", as the best reflecting of the anatomical scheme.

[Semiologic aspects of traumatic coma (author's transl)]. / Aspects séméiologiques des comas traumatiques.

After studying 85 patients with severe traumatic coma and reviewing the published literature, the authors propose a simple clinical procedure for the diagnostic of such cases. This classification is based on signs without any ambiguity, easily recognized by different physicians, and of pathognomonic significance. These include reaction to pain, testing four reflexes integrated at different levels in the brain stem, pupil morphology, and spontaneous ocular movements. The clinical features corresponding to different levels of dysfunction in the brain are described and their characteristics outlined. The importance of motor reactivity to pain associated to the brain stem reflexes (fronto-orbicular, photomotor, horizontal and vertical oculo-encephalic) is stressed.

Correlative study between computerized transverse scanning and stereoimpedoencephalography in space-occupying lesions of the brain.

Stereoimpedoencephalography (SIEG) is routinely used by the authors during stereotactic investigations of glial brain tumours prior to stereotactic implantation of isotopes or prior to conventional surgery: the brain tissue impedance is measured along a probe track according to the four electrodes impedance technique. The correlation between the tissue structures and the corresponding impedance values has been studied by comparison with the CATScan data reported on the stereotactic schedules; impedance values are influenced by changes in arterial pCO2 and also by other unknown factors; in order to avoid these uninterpretable changes of the impedance, the recorded values have been normalized with respect to the average impedance along a control track in the normal hemisphere. As a rule, the impedance profile exhibits a "hole" at the site of the pathological processes like tumours as well as surrounding oedema, and the delimitation of the pathological area is very similar to that obtained by the CATScan. There is a good linear correlation between the values of normalized impedance and the x-ray absorption as given by the computer listing of the CATScan. Lastly, statistical values of normalized impedances are determined for the main structures of the brain, showing that the tumour tissue has an impedance equal to half the impedance of the normal tissue.

[Intracranial pressure. IV - Relationships with post capillary vascular pressures (author's transl)]. / La pression intracrânienne. IV - Relation avec les pressions post-capillaires.

The authors have demonstrated experimentally in dogs that, in all cases, the cortical venous pressure (Pvco) is higher than the intracranial pressure (PIC), which always remains higher than the sagittal sinus venous pressure (PSLS). The difference between Pvco and PIC remains statistically equal to 8 mm Hg and can be explained by the "Vascular Waterfall" phenomenon; during Queckenstedt's test, the intracranial venous volume does not change, and is not the cause for the increase of PIC; this increase is due to the constancy of the difference between PIC and PSLS, which is induced by the resorption of CSF through the arachnoïd villi. Increases in Pvco and PIC are shown to be equal to 70% and &2% respectively of the change in PSLS. Any other factor that increases PIC (injections in the cisterna magna, pharmacological effects) does not change PSLS, which remains equal to zero. As long as the cerebral blood flow is constant, the increase in cerebro-vascular resistance of the veins at the site of their junction to the sagittal sinus must be compensated upstream by a vasodilatation, which leads to a new distribution of the pressures along the cerebro-vascular bed.

Electrical impedance brain scanner: principles and preliminary results of simulation.

In previous studies, the authors have shown the importance of impedance recording by stereotactic procedures for brain tumor detection. In this study they report the principles and the first results of an attempt to obtain the impedance value of any given point inside the brain by an external way. The experimental device is mainly made of a set of 128 electrodes, surrounded by an electrode guarding monitored by an operational amplifier the purpose of which is to made the electric field uniform and to enable a focused measure of the impedance by each of the 128 electrodes. The effect of this electrode guarding is demonstrated, and the present sensitivity of the prototype is shown on various obstacles. conductive or non-conductive; the influence of an impedance barrier on this sensitivity is the project of an impedometric scanner is described, and the problems due to the non-linear propagation of electric currents and to the anisotropic properties of the brain tissue are evaluated.

[Delineation of brain tumors by stereo-impedo-encephalography (SIEG) (author's transl)]. / Délimitation des tumeurs cérébrales par stéréo-impedo-encéphalographie (SIEG).

Authors describe the SEEG technique which is routinely used during stereotactic investigations of brain tumors. By the way of the Talairach's stereoencephalographic electrodes, the brain tissue impedance is measured along the probe trajectory with a four electrode impedancemeter (0.25 mA; 5 KHz). The impedance profile provides a good pattern of the brain structures which are crossed; in pathological areas, the impedance significantly decreases as well in gliomas as in edema; cysts and CSF spaces also decrease the recorded impedance. As a contrary, metastases and meningiomas increase the impedance. SEEG appears to be a sharp method for stereotactic delineation of the brain tumors; a larger series as well as the real-imaginary decomposition of the impedance are needed for a best selectivity of the method.