Guillain-Barré syndrome and plasma exchange.
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Biomedical subjects
Publications and source records attributed to J C Raphael.
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The Neuroleptic Malignant Syndrome (NMS) is a rare but severe affection (spontaneous mortality 30 to 50 per cent), associating fever, hypertonia with myolysis, and respiratory impairment. Its mechanism remains debatable: The origin of the hypertonia might be central (as phenothiazines and butyrophenones induce a blockade of dopaminergic receptors in the hypothalamus) or it might be muscular (with an impairment of the sarcoplasmic reticulum uptake of calcium in a genetically abnormal muscle, as is proven in malignant hyperthermia). Whatever the actual mechanism, the oral or intravenous administration of sodium dantrolene, a peripheral muscle relaxant agent which does not affect the neuromuscular transmission but prevents the calcium-dependent contraction of actin and myosine, has proved to be effective in three recent cases of NMS.
A typical case of glycyrrhizin-induced hypokalemic paralysis in a diabetic patient is presented. Hypokalemia was responsible for a generalized muscle weakness with a rise in serum muscular enzymes and cardiovascular disorders, which improved under potassium supplementation and spironolactone therapy. The pseudoaldosteronism syndrome with low plasma renin activity and aldosteron suggested aldosteron -like liquorice intoxication. Patient's interrogation revealed regular consumption of a common aperitive drink: a non-alcoholic pastis containing small amounts of glycyrrhizin. The discrepancy between the severity of clinical manifestations and the ingested amounts of glycyrrhizin is explained by the diabetic state.
A randomized study was carried out in 14 myasthenia patients to compare the long-term effects of two therapeutic regimens. Group I patients received prednisone 1 mg/kg/24 h for one month, then in decreasing dosage; in case of failure at the end of the first month, cyclophosphamide 2 mg/kg/24 h was added to the prednisone treatment. Group II patients received the same treatment associated with 3 plasma exchanges over a 10-day period; these were continued, if required, at the rate of once a week. The minimum follow up was one year. The results (greater improvement in muscular strength and vital capacity) were better after one month in group I and thereafter similar in both groups. However, the mean daily dose of prednisone was higher in Group I. The number of exacerbations of myasthenia was greater in group II (11 versus 2 in group I over a 24-months period). The mean fall in anti-R Ach ab was about the same in both groups. This study confirms the rapid effectiveness of plasma exchanges and their value in severe myasthenia. The higher incidence of exacerbations in Group II was probably due to a rebound phenomenon and points to the need for combined immuno-suppressive treatment.
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Two adults patients presenting Bartter's syndrome have been studied for 9 years in one case, 7 years in the other. Both were affected with chondrocalcinosis. This association does not seem to be coincididental but suggests a pathogenic link between Bartter's syndrome and chondrocalcinosis; the two patients presented hypomagnesemia which, inhibiting intrasynovial pyrophosphatase, induces calcium pyrophosphate crystals deposits on fibrocartilages. Otherwise, excessive daily urinary excretion of PG E2 and PG F2 alpha was found in both patients. Indomethacin (150 mg daily) decreased urinary excretion of PG to normal values in the two cases, Kalaemia was completely normalized in one case, partially in the other.
Redistribution of blood volume during orthostatism is followed by a reduction in venous return and therefore cardiac output. A drop in the blood pressure following postural changes is normally prevented by the action of the baroreceptor reflex, which leads to an increase in total peripheral resistance and heart rate. Orthostatic hypotension may arise from a variety of causes. In some cases, the disorder of postural regulation is due to an autonomic nervous system disease, and various tests are available that enable the diagnosis to be confirmed and the mechanism of action to be elucidated. Certain of these investigations explore the function of the complete baroreceptor reflex arc, while others enable selective study of either the efferent parasympathetic or sympathetic pathways. Central zones and afferent pathways cannot be explored directly. Individual tests are of limited value only, and the results of overall investigations are necessary for a better understanding and therefore more effective therapy of orthostatic hypotension due to autonomic nervous system disease.
We have explored the baroreceptor reflex on nineteen patients free of all cardiovascular diseases having contracted acute primary polyradiculitis. The tilt test (at 30 degrees from the horizontal line) demonstrates that, at the acute point of the disease, there is a dysregulation of the arterial pressure characterised by an orthostatic hypotension with a lack of normal increase of the peripheric arterial resistances. Once the motor activity restituted, this dysregulation disappears without sequelae. The clinical and pharmacological tests prove a failure in the baroreceptor arc and shows that sympathetic and parasympathetic pathways to the heart and vessels are functionally normal. Thus, this study localizes the defect on the afferent pathways conducting the local information perceived on the baroreceptors.
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Extracorporeal circulation with a membrane oxygenator (ECMO) was used in 11 patients with acute respiratory insufficiency who did not respond to conventional treatment. By pass was veno-arterial in every case, seven times with femoral artery return, three times with axillary artery return, and once with both femoral and axillary return. Five patients died on ECMO. Six patients were taken off ECMO and two of them are long-term survivors. In nine cases ECMO allowed short-term control of respiratory failure. The respective roles of oxygen supply from ECMO and the haemodynamic changes incurred by its use are discussed. Although use of ECMO for long periods seems less hazardous now, present results are restricted by the lack of therapy for the underlying pulmonary lesions.
The same protocol was used three times to produce a paralytic episode in a typical case of periodic familial paralysis with hypokalemia. This consisted of an effort together with a perfusion of hypertonic glucose serum and insulin. The first test provoked an attach of hypokalemic tetraplegia. The second test, two months after treatment with 500 mg daily of acetazolamide, produced no reaction. In the third test, the metabolic acidosis caused by acetazolamide was reduced by the injection of sodium bicarbonate, and a stronger effect than in the first test was observed. This confirms the efficacy of acetazolamide as a preventive treatment for paralytic attacks; the most reasonable hypothesis being that it acts through the metabolic acidosis that it induces. Metabolic and hemodynamic studies were carried out during the provoked attacks. Cardiac output and oxygen consumption are increased, while pulmonary capillary pressure and periopheral resistance are reduced. Diastolic pressure is lower when measured by an arm-cuff but shows no change when direct readings are taken in the blood-vessels. These results suggest that there is an increase in cellular energy needs, or that the smooth muscle in the vessel walls is paralyzed. The two tetraplegic attacks in tests 1 and 3 were associated with a metabolic acidosis, which is explained by a simultaneous transfer, though in the opposite direction, of H+ and K+ ions; the intra-cellular pH, as measured by the D.M.O. technique, was acid when there was not an attack, and this increased during paralysis.
A case of familial paralysis with hypokalemia is presented. Acetazolamide at a dose of 500 mg daily prevents the onset of acute attacks. Under acetazolamide, an oral glucose tolerance test is not followed by hypokalemia. The association of glucose and insulin is unable to trigger off a paralytic attack although without acetazolamide, the same protocol had 5 months previously precipitated tetraplegia with hypokalemia. These results are compared with those in the literature.
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