Pedunculopontine nucleus stimulation induces monocular oscillopsia.

Two patients with Parkinson's disease with pedunculopontine nucleus (PPN) stimulation for gait impairments reported "trembling vision" during the setting of the electrical parameters, although there was no clinically observable abnormal eye movement. Oculomotor recordings revealed frequency locked voltage dependent vertical or oblique movements of the eye ipsilateral to the active contact, suggesting current spreading to the mesencephalic oculomotor fibres. These results emphasise the difficulty of stimulating this mesencephalic region.

Analysis of brain metabolism changes induced by acute potassium cyanide intoxication by 31P NMR in vivo using chronically implanted surface coils.

Chronic implantation of surface coils on the skull has been developed to record 31P NMR spectra of the brain in unanesthetized rats. Intraperitoneal sublethal potassium cyanide doses induce strong and reversible changes in high-energy phosphate compounds in the brain, similar in part to those induced by ischemia. These effects are dose-dependent as far as phosphocreatine, inorganic orthophosphates and pH are concerned; ATP does not seem to be altered by KCN doses ranging from 3 to 5 mg/kg but starts decreasing at a dose of 6 mg/kg. The fraction of Mg2+ complexed ATP which could be estimated as about 90% was not affected by KCN intoxication. For high doses (6 mg/kg) a new peak, appearing on the upfield side of the inorganic phosphate peak, may correspond to an acidic compartment, the significance of which is discussed.

Deep brain stimulation of the corpus luysi (subthalamic nucleus) and other targets in Parkinson's disease. Extension to new indications such as dystonia and epilepsy.

Chronic high frequency (130 Hz) stimulation (HFS) of the thalamic target Vim, first used in our group in 1987 as a treatment of tremor of various origins, has been used over the last ten years in 137 patients. Since 1993, this method has been extended to two other targets (subthalamic nucleus (STN): 137 patients and the medial pallidum (GPi): 12 patients), based on recent experimental data in rats and monkeys. STN appears to be a target of major interest, able to control the three cardinal symptoms and to allow the decrease or suppression of levodopa treatment, which then also suppresses levodopa induced dyskinesias. The stereotactic technique is based on the determination of the target using ventriculography, MRI and electrophysiology, with both microrecording of single neuron activity and microstimulation inducing therapeutic symptom suppression and side effects. Chronic electrodes are then placed bilaterally at the best physiologically defined location and then connected to implantable stimulators (either 2 Itrel II or the new double channel Kinetra), operated at 130-185 Hz, 60 ms pulse width, 2.5 to 3.5 volts. There was no operative mortality and permanent morbidity was observed in 3 patients. The mechanisms of action of HFS are not fully understood, but are definitely related to high frequency and are probably different depending on the target. Inhibition of cellular activity or of neural network functions could be induced, by jamming of a retroactive loop for tremor, or by shutdown of neurotransmitter release in STN. Mechanisms within an individual target are also probably different for tremor or for other symptom alleviation. All cardinal symptoms are alleviated from tremor to akinesia and rigidity. This strong improvement allows the decrease of the drug dosage to approximately 30% of the preoperative level, which suppresses the levodopa-induced dyskinesias. The off period dystonias are also suppressed as well as freezings and falls. The effects remain stable over more than 5 years and in the same period, the off stimulation-off medication UPDRS remains stable and does not increase at the usual rate The low rate of permanent complications, the minor side effects and their immediate reversibility, the possibility of bilateral implantation in one session and the long-term persistence of symptom relief are strong arguments which support chronic HFS of STN as the method of choice when a surgical procedure is indicated for the treatment of Parkinson's disease and even more when a bilateral procedure is necessary. Recent data show that STN stimulation could be useful in the treatment of dystonia as well as some forms of epilepsy. It is therefore possible that DBS in STN as well as in other targets could become a potent therapeutic tool in the near future for neurological disorders.

Discrimination between cross-country and downhill skiers by pulmonary and local 31PNMR evaluations.

The purpose of the present study was to correlate data on calf muscle metabolism using 31P nuclear magnetic resonance spectroscopy with measurements of whole body maximal oxygen consumption and maximal power output, and to determine whether the combination of these data could be used to predict athletic ability. Experiments were performed in a 2.35 Tesla, 35 cm diameter electromagnet on the leg muscle of sedentary human subjects (N = 6) and groups of athletes trained for endurance (cross-country skiers, N = 7) or strength performance (downhill skiers, N = 5). The exercise protocol consisted of successive plantar flexions performed at graded fractions of the maximal voluntary contraction (MVC). The results obtained from NMR investigation (changes in content of inorganic phosphate: Pi, phosphocreatine: PC and muscle ATP, and intracellular pH) were then compared with those of maximal O2 consumption (VO2max) and maximal power (MP). When the data on athletes were compared with those obtained on sedentary subjects, the curves illustrating the relationship between the imposed load and the Pi/PC ratio were significantly shifted toward high output power for a given Pi/PC value. It also appeared from this study that specific training in force development (downhill skiing) induced a slighter decrease in PC level than for endurance (cross-country skiers) despite improvement in physical performance. A slight but significant intracellular acidification was observed in the muscles of sedentary subjects and downhill skiers for contraction at, respectively, 50% and 80% of MVC, but not in the skeletal muscles of cross-country skiers.(ABSTRACT TRUNCATED AT 250 WORDS)

Coexistence of plasma cell granulomas of lung and central nervous system.

A rare case of concurrent plasma cell granulomas (PCG) of the lung and the central nervous system (CNS) is reported. A 30-year-old man was presented with recurrent left headaches lasting for two years. Computerized tomographic (CT) scan and magnetic resonance imaging (MRI) of the head disclosed a process extending from the lateral aspect of the left cavernous sinus to the tentorium cerebelli and the infratemporal fossa through the foramen ovale. At the same time, chest-X ray and CT scan showed three symptomless masses of the pulmonary right lower lobe. Histological examination of cerebral samples and of one of the pulmonary nodules revealed the presence of a fibrous tissue containing numerous lymphocytes and plasma cells as well as remnants of vascular and respiratory structures. Immunohistochemical study proved these cells to be polyclonal. Ultrastructural analysis confirmed the presence of lymphoid cells and failed to disclose any argument for meningioma or histiocytosis X. The differential diagnostic problems of PCG are discussed as well as considerations about clinicopathological features, histogenesis and pathogenesis of inflammatory pseudotumours (IPT).

Percutaneous intradiscal radio-frequency thermocoagulation. A cadaveric study.

STUDY DESIGN: This study examined the effect of radio-frequency thermocoagulation on cadaveric disc material. Radio-frequency lesions are induced to decompress the nerve root by coagulating the nucleus pulposus. OBJECTIVES: The purpose of this study was to assess the potential of the radio-frequency lesion technique for treating lumbar disc herniation percutaneously. The effect of radio-frequency thermocoagulation on cadaveric disc material was studied. SUMMARY OF BACKGROUND DATA: An intradiscal bipolar electrode is used for the thermocoagulation of the nucleus pulposus. METHODS: Lumbar discs of 27 adult cadavers were used for the experiments within 72 hours of donors' deaths. The physical and thermal parameters of intradiscal radio-frequency thermocoagulation were determined experimentally. Acute macroscopic and histologic changes before and after thermocoagulation were investigated. The temperature distribution of the tissue surrounding the disc was measured during the operation using thermocouples to evaluate potential heat damage. Also, computed tomography and magnetic resonance imaging of the disc were performed before and after thermocoagulation. RESULTS: Macroscopic observation showed that the lesion induced by radio-frequency thermocoagulation is homogeneous and intense without necrosis, and is limited to the nucleus pulposus. Histologically, the endplates and vertebral bodies were unaffected and an architectural disorganization of the stroma of the nucleus pulposus was seen. The temperature increase of the tissue surrounding the discs did not exceed 3-4 C. CONCLUSION: A bipolar electrode and a radio-frequency alternating current permits percutaneous intradiscal thermocoagulation for destruction of a portion of disc material in a cadaveric spine.

The use of a semi-customized phantom for verification of conformal plans.

We have developed a technique for inverse treatment planning of prostate therapy designed to improve the degree of conformation between the dose distribution and the target volume. We compared the inverse plan with a "standard" four-field box technique as well as a four-field technique using oblique fields ("cross technique"). We validated the dosimetry of the inverse plan using Fricke gel solution in phantom specifically designed for this purpose. The phantom is a Plexiglas tank with a cross section, which approximates the dimensions of the pelvis. Anatomical data from computed tomography (CT) images of a patient were used to simulate organs in our phantom. This allows us to calculate dose distributions with the external geometry of the phantom and internal anatomy of the patient. Dose-volume histograms (DVHs) for the three different plans were calculated. The phantom containing the Fricke gel was irradiated according to the inverse plan. Magnetic resonance (MR) images was used to determine the dose distribution delivered to the phantom. We observe, on DVHs, that the inverse plan significantly reduces the dose to the rectum and the bladder but slightly increases the inhomogeneity inside the target volume. Correlation is good between isodoses on MR images and calculated isodoses. We conclude that inverse planning software can greatly improve the conformal degree of treatment to the prostate. This technique could be applied to other complex anatomic sites at which dose to organs at risk is a limiting factor and increased dose to the target volume is indicated. Our phantom and the Fricke gel solution are convenient to carry out validation of conformal treatments.

[Detection of parietal lesions using magnetic resonance imaging in arrhythmogenic dysplasia of the right ventricle]. / Mise en évidence par l'IRM des lésions pariétales au cours de dysplasies arythmogènes du ventricule droit.

Seven patients with arrhythmogenic right ventricular dysplasia were explored by magnetic resonance imaging (MRI), using the spin-echo technique (TR = the patient's own RR cycle; TE = 28 ms, 56 ms, 84 ms) with multiple, contiguous, 7 to 10 mm thick sections performed in two planes: axial plus sagittal or frontal planes. In 5 out of 7 patients, MRI showed dysplastic lesions in the right ventricular wall presenting typically as fat-like high signals contrasting with the normal myocardium. In 2 patients, no lesion was clearly visualized. The parietal lesions were located in the anterior wall of the right ventricle and conus arteriosus in 5 cases and in the lower wall of the right ventricle in one patient who had two dysplastic areas. In 3 patients the lesions extended up to the tip of the interventricular septum and of the left ventricle. In the 2 patients whose lesions were most extensive, their predominance in the subepicardial region and the concordance between the sites of abnormalities at MRI and angiography were clearly observed. Thus, despite its present technical limitations MRI seems to be one of the first techniques capable of visualizing the parietal lesions in patients with arrhythmogenic right ventricular dysplasia.

[Magnetic resonance imaging in dissection of the aorta]. / Imagerie par résonance magnétique au cours des dissections de l'aorte.

In order to evaluate the usefulness of this new exploratory method in dissection of the aorta, 13 patients (10 men and 3 women, mean age 58 +/- 14 years) were examined by means of an 0.5 Tesla Magniscan 5000 nuclear magnetic resonance machine. Fifteen examinations were performed: 5 in patients with actual aortic dissection (type A 4 including one acute, type B1), 5 in patients previously operated upon for type A dissection and 5 for suspected acute aortic dissection unconfirmed by other examinations. Magnetic resonance imaging (MRI), synchronized with electrocardiography, was carried out using spin-echo techniques with 1 to 3 echoes and multiple contiguous sections along several planes. In the 5 patients with actual dissection the 2 channels separating the membrane could be demonstrated, thus providing a firm diagnosis (MRI proved superior to angiography in 2/5 patients). All 5 patients could be classified as either type A or type B. Extension to the cervical vessels was observed in 3 cases and the portal of entry was seen in one case, but the origin of the coronary arteries was never visualized. In the 5 patients previously operated upon MRI provided detailed analysis of the prosthesis of the supra-coronary ascending aorta implanted in all cases, of the aorta proximal and distal to that segment and of the periaortic mediastinum. By studying the signal from the false channel distal to the prosthesis information was obtained as to the presence in it (2 patients) or absence of circulating blood.(ABSTRACT TRUNCATED AT 250 WORDS)

[Carotid stenoses. Non-invasive exploration]. / Sténoses carotidiennes. Apport des explorations non traumatisantes.

Doppler flowmeter and ultrasound imaging techniques, currently associated (duplex), have made important contributions to the simple and early non invasive diagnosis of carotid stenosis lesions in the cervical region for more than 20 years. These exploratory methods are reliable when a significant degree of stenosis (greater than about 60%) exists. Moderate degrees of stenoses or plaques are evaluated morphologically, calcifications and ulcerations being enhanced by staining techniques. But the evaluations have not really demonstrated exact correlations between anatomicopathologic and ultrasound images. The intracranial arteries and the circle of Willis are explored indirectly during the cervical examination by cautious compressive maneuvers or directly by trans-cranial Doppler. Whereas angiography competes with ultrasound imaging as a standard examination in the neck region, it nevertheless remains effective for the study of the intracranial arteries. Newer techniques, such as high-field MRI angiography, tridimensional ultrasonography or ultrasound recording of vascular flow rate without Doppler, will doubtlessly transform the diagnosis of symptomatic or asymptomatic carotid stenosis. From the strategic point of view, ultrasound imaging techniques will retain their role of a decisional pivot, since they are simple to use and are of very wide accessibility to competent vascular physicians in the context of an organized care network.

[Acute aortic dissection and peripheral ischemia. Diagnostic and therapeutic problems. Remote control using nuclear magnetic resonance]. / Dissection aortique aiguë et ischémie périphérique. Problèmes diagnostiques et thérapeutiques. Contrôle à distance par résonance magnétique nucléaire.

This study concerns 7 cases of acute aortic dissection associated with visceral and/or lower limb ischemia. Only those cases are included which raised diagnostic and therapeutic problems. Patients were excluded who had purely angiographic involvement of an aortic branch and minor rapidly resolving ischemic syndromes. Five of the 7 patients presented type B (type III or distal) and 2 type A (type I or proximal) dissection. All patients received anti-hypertensor medical treatment. All but one had undergone surgery at least once at the acute stage. Five had been followed up and monitored by magnetic resonance imaging (MRI). One type A and 4 type B dissections were thus reviewed between the 15th month and the 9th year. Diagnostically, aortography was found to be inaccurate twice because of incomplete exploration of the thoracoabdominal aorta. Therapeutically, a case of intraoperative death occurred during replacement of the ascending aorta. Thus, out of the 6 patients who survived the acute stage, 4 are alive and asymptomatic, one has been lost sight of and the other died in year 5 after surgery for chronic dissecting aneurysm of the aortic arch. Among the 5 patients examined by MRI, 4 presented aortic ectasia, chronic dissecting aneurysm of the aortic arch and/or a descending aorta with a diameter between 45 and 65 mm. The patient with subnormal aortic diameter had his ascending aorta replaced (the follow-up period at this writing is only 27 months). Among 3 patients who were examined twice, one showed improvement after a year's interval, with a 5-mm increase in the caliber of the dissected aorta.(ABSTRACT TRUNCATED AT 250 WORDS)

[Magnetic resonance imaging in multiple sclerosis. Sensitivity and correlation with the clinical picture]. / L'imagerie par résonance magnétique dans la sclérose en plaques. Sensibilité et corrélations avec la clinique.

The aim of imaging the brain in Multiple Sclerosis (MS) is to prove the dissemination of lesions, so critical for the diagnosis and so difficult to ascertain clinically. Our study included 21 patients with clinically definite (12) and probable (9) MS. A 21 patients underwent a neurological standard examination, a double-dose delayed CT scan and a Magnetic Resonance Imaging with a superconducting 0.5 Tesla magnet. Jointed slices were performed with a T2-weighted Spin-Echo sequence (TE 60, 120; TR 2000 msec). MRI detected 640 lesions in 20 patients while CT scan detected only 24 lesions in 9 patients. Technical limiting factors are discussed. Abnormalities in MRI were high-intense spots, blotches and streaks, located predominantly in the periventricular area. Capping lesions were common around the ventricular horns. "Plaques" were visualized in the posterior fossa. For each patient, the total surface of the lesions was calculated and was found to be related with the presence of lesions and with the cortical atrophy on CT scan. A correlation between the surface of lesions calculated by MRI and the disability scale was found especially in the group of patients with clinically proven cerebral lesions, while patients with predominantly spinal forms had a significantly lower surface of lesions. This finding could yield a new quantitative evaluation of the MS pathologic process which could be used to assess therapeutic efficacy.

[Magnetic resonance imaging in menisco-ligamentous lesions. Comparison with arthroscopy. Apropos of 37 cases]. / L'imagerie par résonance magnétique dans les lésions ménisco-ligamentaires du genou. Comparaison avec l'arthroscopie. A propos de 37 observations.

Results of magnetic resonance imaging of 37 cases of lesions of meniscus and ligaments of knee are reported and compared with arthroscopy findings. Use of MRI appears to be an excellent non-invasive diagnostic method, with current major indications in acute knee injuries and for evaluation of chronic laxity. It also allows guidance of surgical procedures. In the future, MRI should replace the more aggressive arthrography, this with a relatively short examination time, since sagittal section imaging in TI permits detection of the majority of lesions.

[Computed tomography of the mediastinum: normal anatomy and non pathologic variations in the adult (author's transl)]. / Aspects normaux et variations non pathologiques en tomodensitométrie du médiastin chez l'adulte.

This work is based on the separate study of a triple material: axial gross body sections from cadavers (4); normal and conventional radiographs with or without opacification; in vivo scans (210). Authors have selectionned thriteen scans patterns according to several regional levels: supra-aortic scans (n08 1, 2, 3); scan through the horizontal part of aortic arch (n0 4B); the scan of the aorto-pulmonary window (n0 4B); supra-cardiac scans through intra and extra-pericardic parts of great vessels: vena cava, aorta and pulmonary artery (n08 5, 6, 7); heart and cardiac cavities scans (n08 8, 9, 10, 11); scan through the retro-crural space (n0 12). Knowing these regional scan patterns, makes it possible to the radiologist to manage a topographic approach quite adapted to the technical mode of direct scannography through the area of interest, already tested by some constructors. The non pathologic variations are numerous. Mediastinal lipomatosis, dilated and tortuous great vessels in the older and atheromatic individual, constitutional variations of the vessels topography. Limits found out during this work concern heart examination and hilum study; great strides are to be achieved in these fields because of the unceasing technical improvments.

[Fatty masses in the mediastinum. A report on 21 cases including 16 after computer tomography investigations (author's transl)]. / Les amas graisseux du médiastin. A propos de 21 observations, dont 16 avec tomodensitométrie.

The authors use this term to describe collections of fatty material in the tissues, circumscribed or not, which may cause permanent deformity of the mediastinum. This definition may not be based upon histological examinations but it is perfectly appropriate following the recent use of computer tomography (CAT) investigations. The authors base their comments on the study of 21 cases divisible into two groups of unequal size: in 5 cases, studied without using CAT, diagnosis was made during operation; in the 16 other cases it was made by CAT. The masses may be circumscribed or not, but mixed forms have been observed. Among the circumscribed masses. Those in the right cardiophrenic region appear to be the frequent and are observed mainly in women: a retrocardiac location implies than an associated hiatus hernia must be searched for; the mediastinoparietal reduplicated form being rarely seen. The spreading types are noted mainly in men and occur usually in the superior or median part of the mediastinum. These masses can be demonstrated and diagnosis simplified by the use of CAT, as it is a truly specific radiological examination which eliminates the use of tomography, pneumomediastinum, and angiography as diagnostic procedures. Surgical operation is no longer practiced for diagnostic purposes and can be avoided in very many cases.

[Oesophageal cancer extension. Diagnostic contribution and effects on therapy of computed tomography. Report on 40 cases (author's transl)]. / L'apport de la tomodensitométrie au bilan d'extension des cancers de l'oesophage. Incidences thérapeutiques. A propos de 40 observations.

Based on a homogeneous series of 40 cases of thoracic or abdominal oesophageal cancer, of which 23 had been confirmed by operation, the authors analyse the contribution of the CT scan to the diagnosis of the extension of the cancer, and evaluate the effects on therapy of this technique. Computed tomography supplies much more precise and complete details of possible cancer extension than any other pre-operative investigation. Conducted after radiological and endoscopic examination of the oesophagus, it supplies rapid, perfectly readable, irreplaceable information on local, regional, and metastatic spread of the cancer. This only slightly aggressive examination enables evaluation of the size of the tumour and its direct relationships, effective exploration of the mediastinal and coeliac glands regions, and detection of possible pleural, pulmonary, or hepatic metastases. Its role in the decision to operate is a considerable one: true assessment of of local, regional, or metastatic extension assists the surgeon in his choice of either curative or palliative therapy. Better still, it enables a route of approach to be decided as a function of data concerning possible extension, as well as the best surgical tactic. As a support for radiotherapy or chemotherapy for this type of cancer, computed tomography greatly assists follow-up supervision.

[Straight azygos continuation of the inferior vena cava. Apropos of 3 cases using an NMR study]. / Continuation azygos droite de la veine cave inférieure. A propos de 3 observations avec étude IRM.

Three patients with straight azygos vein continuation of inferior vena cava (IVC) were studied by nuclear magnetic resonance (NMR) imaging. In all three cases the diagnosis had been established previously by ultrasound and/or computed tomography imaging, but NMR images provided better anatomical precision of the venous anomaly : visualization of the total trajectory of the major azygos vein, the caliber of which can exceed that of aorta, and absence of retrohepatic segment of IVC but presence of a short supradiaphragmatic segment towards which converge the suprahepatic veins; anastomotic etwork between IVC and major azygos vein contributing to ensure continuity of venous drainage superior to its renal segment. The advantages of NMR are described and the precise diagnostic role of this new method of imaging in the diagnosis of this type of anomaly discussed.

[The value of tomodensitometry in the diagnosis of dermoid cysts. Apropos of 5 cases]. / Apport de la tomodensitométrie au diagnostic des kystes dermoïdes. A propos de 5 observations.

Results of computed tomography before operation in 5 cases of dermoid cysts (mediastinal: 3; retroperitoneal: 1; ovarian: 1) are employed to assess the contribution of this technique, and to define its place in relation to other diagnostic radiological procedures (straight radiographs and ultrasonography). The CT scan enables three morphological types to be distinguished, and also supplies very precise data on the extension, limits, and relationships of the tumor. The effective place of this examination in the diagnosis of dermoid cysts depends upon two factors: data obtained from the straight radiograph and the initial site of the lesion. When the former supplies specific information, the only role of the CT scan and ultrasonography is to determine the precise extent of the tumor pre-operatively, the CT scan being superior to ultrasonography for this purpose. When straight radiographs do not reveal characteristic signs, the diagnostic assistance of the scanner appears to be irreplaceable, even in those abdominal or pelvic regions where ultrasonography is best conducted.

[Mediastinal lymph node extension in primary bronchial cancer: correlation of x-ray computed tomography, magnetic resonance imaging and mediastinoscopy. Apropos of 50 cases]. / L'extension ganglionnaire médiastinale dans le cancer primitif des bronches: corrélations entre la tomodensitométrie, l'imagerie par résonance magnétique et la médiastinoscopie. A propos de 50 observations.

Based on a homogeneous series of 50 cases investigated within less than a week by CT scan and NMR imaging with mediastinoscopic correlation, and in 32 of theses cases with correlation with operative findings, a critical study was carried out of modern imaging methods for detection of mediastinal gland invasion from primary bronchial cancer. Axial mediastinoscopy presented absolute specificity and very high sensitivity (93%) markedly superior to those of CT scan and NMR imaging. The two latter examinations were practically of equal efficacy: sensitivity of NMR (80%) was somewhat higher than that of CT scan (70%) whereas specificity of CT scan was 83% as against 70% for NMR. Lack of efficacy of axial mediastinoscopy was in cases with extra-axial lymphatic extension (anterior mediastinal chains) from primary cancer. These results suggest that, in view of current inconveniences of NMR imaging, the best means for local and regional exploration of primary bronchial cancer preoperatively is combined CT scan and mediastinoscopy. The diagnosis of glandular enlargement of anterior mediastinal lymphatic chains should lead to performance of an anterolateral mediastinoscopy.