Biomedical subjects

M Carvalho

Publications and source records attributed to M Carvalho.

At least 55 records · Page 3Linked to original sources

PubMed1996

Motor neuropathies mimicking amyotrophic lateral sclerosis/motor neuron disease.

We report three patients in whom the initial diagnosis was of possible A myotrophic lateral sclerosis (ALS/MND) according to the 'El Escorial Criteria'. All of them presented with monomelic paresis, atrophy of the paretic muscles and generalised brisk reflexes. The initial electromyograms showed a neurogenic pattern in the limbs with normal sensory and motor conduction velocities. Laboratory evaluation and imagiological investigations were normal in all of them. The previous diagnosis was changed in to demyelinating motor neuropathy with conduction block in 2 patients and tomaculous neuropathy in one after clinical and electromyographic follow-up and nerve biopsy. Patients 1 and 2 were given intravenous immunoglobulin treatment and showed moderate improvement.

Amyotrophic Lateral Sclerosis↗

PubMed1996

[Neurocardiogenic syncope: its pathogenesis, diagnosis and treatment].

Neurocardiogenic syncope seems to be the most common cause of syncope. It is believed to be triggered by paradoxical autonomic reflexes, beginning in the ventricular mechanoreceptors of the heart, modulated by the brain stem and terminating in the autonomic efferent pathways (parasympathetic stimulation with bradycardia or asystole and sympathetic inhibition with severe hypotension). Tilt test has been used recently, as a safety and effective tool to identify subjects prone to syncope. Although the pathophysiology of this syndrome is not completely understood, pharmacological therapeutics seems very effective in resolving symptoms.

Autonomic Nervous System↗

PubMed1996

Reliability of carnitine concentrations measured in single postprandial urine samples from dogs.

OBJECTIVE: To evaluate the reliability of urine carnitine concentrations measured in single postprandial samples, compared with carnitine concentrations measured in 24-hour urine samples. ANIMALS: 19 healthy Beagles. PROCEDURE: After emptying the urinary bladder by catheterization, dogs were fed a canned canine maintenance diet. Approximately 8 hours later, urine, plasma, and serum samples were obtained for determination of urinary carnitine fractional excretion and urine carnitine-to-creatinine concentration ratio. Results were compared with 24-hour urinary carnitine excretion rate. RESULTS: Fractional excretion of carnitine and urine carnitine-to-creatinine ratios correlated poorly with 24-hour urinary carnitine excretion. CONCLUSION: Determination of 24-hour urinary carnitine excretion is recommended to measure urine carnitine concentrations in dogs.

Animal Nutritional Physiological Phenomena↗

PubMed1995

Involvement of the external anal sphincter in amyotrophic lateral sclerosis.

In amyotrophic lateral sclerosis the striated pelvic floor sphincter muscles are functionally uninvolved, and pathological studies have confirmed the relative resistance of the Onuf nucleus motor neurons. We have evaluated the external anal sphincter (EAS) muscle in 16 patients with ALS using single fiber EMG, and compared the results with the findings in the semimembranosus-semitendinosus (SM-ST) muscles that have innervation from the L-5, S-1, and S-2 segments. The results were compared with a group of controls matched for age and sex. None of the patients or controls had symptomatic sphincter involvement and none of the 4 women studied were parous. Eight patients with ALS showed an increased fiber density in the EAS; 6 had an abnormal neuromuscular jitter. In 1 there was fibrillation in the EAS. In the SM-ST muscle 11 patients showed an increased fiber density, and 7 had an abnormal neuromuscular jitter. In 3 patients with ALS in whom there were abnormal findings in the EAS the bulbocavernosus reflex and pudendal nerve evoked potentials were normal. Neurogenic change was more marked in the SM-ST than in the EAS muscle. These findings show that the EAS is not normal in ALS. However, the relative resistance of the EAS to ALS is sufficient to prevent incontinence, even in the longer-surviving older patients.

Adult↗

PubMed1995

Respiratory assistance with a non-invasive ventilator (Bipap) in MND/ALS patients: survival rates in a controlled trial.

Noninvasive ventilatory assistance, in ALS patients, with the bilevel intermittent positive air pressure (Bipap) was studied, in a prospective and controlled trial, by the authors. Twenty ALS bulbar patients, fulfilling El Escorial criteria for probable or definite disease, were selected. For the follow-up all patients were submitted to evaluation with the Norris scale, modified Barthel score and an analog scale of life satisfaction, every 3 months. All patients were also submitted to respiratory functional testing (RFT). Ten of these patients were treated with palliative management (group I), the remaining ten patients received Bipap support (group II). Clinical evolution curves and clinical parameters were not statistically different in both groups, except for the percentage of actual predicted value of vital capacity (p < 0.03), showing a more advanced disease in group II patients. Analog scale of life satisfaction showed improvement in the group II, even after the beginning of respiratory insufficiency, though without significance probably due to the small sample size (p < 0.1). Since 6 patients in group II are still alive survival rates were compared with log rank test considering cumulative survivals with Kaplan-Meier estimates. Total survival and survival from diurnal abnormalities in gas exchange (survival 1) were significantly longer for group II (p < 0.006 and p < 0.0004, respectively). In spite of the small number of patients, preliminary results strongly support the importance of BIPAP in ALS patients, though further studies must go on in order to optimize the best time for introducing Bipap.

Aged↗

PubMed1995

Phrenic nerve conduction in amyotrophic lateral sclerosis.

Respiratory failure accounts for the majority of deaths in amyotrophic lateral sclerosis (ALS). The main cause of respiratory failure is probably diaphragmatic weakness. In order to test the correlation between respiratory impairment and diaphragmatic function we studied the phrenic nerve conduction in 31 ALS patients. Our results showed that patients with respiratory symptoms, and decreased forced vital capacity with arterial PaO2/PaCO2 abnormalities, had more commonly increased phrenic nerve latencies or absent response due to severe diaphragm denervation than ALS patients without respiratory complaints. Diaphragmatic paresis commonly occurs during the course of ALS, and its presence and severity can be assessed by phrenic nerve studies. It is important to recognize the development of impairment in diaphragmatic function in order to prevent life-threatening complications.

Adolescent↗

PubMed1995

Variation in performance of the EMG examination at six European laboratories.

The quality of the EMG examination might be improved by standardization. However, knowledge about interlaboratory differences in the performance of the EMG examination is a prerequisite for standardization. The aim of this study was to describe differences in EMG techniques used and number of muscles and nerves examined per patient at 6 European EMG laboratories. The EMG results of 595 patients were prospectively sampled. The average number of muscles examined per patient in different disorders varied from laboratory to laboratory, for example from 3.0 to 10.8 muscles in anterior horn cell disorders and from 2.0 to 5.5 muscles in myopathies. The average number of muscles examined by quantitative EMG varied from 0 to 4.3 in anterior horn cell disorders and from 0.0 to 4.5 in myopathies. Also the average number of nerve segments examined per patient varied from laboratory for example from 2.7 to 17.7 for motor segments and from 3.1 to 9.0 for sensory segments in polyneuropathies. The laboratories that used needle electrodes for nerve conduction studies and quantitative analysis of individual motor unit potentials examined a smaller number of muscles and nerves than laboratories using surface electrodes for nerve conduction studies and qualitative EMG studies. The results of this study may have impact on guidelines and examination protocols as well as on quality assurance.

Electromyography↗

PubMed1995

The clinical value of tissue factor assays.

Tissue factor (TF) is now considered to be the primary physiologic activator of the blood coagulation system. Coupled with recent advances in our understanding of the biochemistry of TF this has heightened interest in measuring aspects of TF activity in disease states. Expression of TF by blood monocytes in various diseases is an established trigger for intravascular coagulation and there is now a considerable body of experience with its measurement. This has considerable clinical potential although more widespread application awaits a consensus on the most appropriate methodologic approach to its measurement. TF can be detected in urine and may reflect the activation state of renal macrophages. Urinary TF is increased in cancer and could have diagnostic and prognostic value in a variety of malignant diseases. Finally, it is now possible to measure soluble TF in plasma. One such assay is commercially available and is technically simple to perform. The clinical value of such assays, however, must await better understanding of the source and function of soluble TF in plasma.

Blood Coagulation↗

PubMed1995

Quality assurance in clinical neurophysiology: the ESTEEM project example.

This paper describes the current status of the utilisation of clinical practice guidelines (protocols) in the ESTEEM project as one form of the clinical quality assurance procedures considered in the project. The performance of electrodiagnostic studies, in terms of which types of conclusions need to be inferred during the examination plan, is briefly described. The main focus of the paper is a description of an European multicentre clinical audit in the field of Clinical Neurophysiology, using a common data-entry protocol for prospective EMG case collection and assessment with the ultimate objective of building up a multicentre reference database of EMG cases.

Computer Communication Networks↗

PubMed1995

[Muscular diseases in hyperthyroidism].

Hyperthyroidism may present various muscular diseases, namely thyrotoxic chronic myopathy, myasthenia gravis, disthyroid ophthalmopathy and thyrotoxic periodic paralysis. Although infrequent, it is possible to find some of these clinical situations in a medical ward of a general hospital. Differential diagnosis must be made with chronic idiopathic polymyositis and certain congenital myopathies. We describe three patients with hyperthyroidism; one of these patients had chronic thyrotoxic myopathy and another had myasthenia gravis. The third had a thymolipoma and ocular changes probably corresponding to myasthenia gravis.

Adult↗

PubMed1995

[Lumbar spinal stenosis. Significance of neurophysiologic tests].

The authors review Lumbar Spinal Stenosis discussing the diagnostic criteria, the etiopathogenesis, and clinical manifestations. Imaging and neurophysiological investigations are also discussed. EMG, Sensory Evoked Potencials and Motor Stimulation are described stressing their role in differential diagnosis. The therapeutic approach is briefly commented.

Diagnosis, Differential↗

PubMed1994

A Caucasian family with the 3271 mutation in mitochondrial DNA.

The second most common mutation associated with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes) in Japan is the 3271 mutation. This mutation was found in a Brazilian family of Portuguese and Italian descent, indicating that this mutation also exists in a race other than Japanese. The propositus had mild clinical manifestations atypical of MELAS, suggesting that patients with the 3271 mutation exhibit heterogeneous phenotypic expression as seen in the 3243 mutation.

Acidosis, Lactic↗

PubMed1994

HLA antigens and lymphocytes in proliferative vitreoretinopathy.

An immunohistopathological study was performed on 33 epiretinal membrane specimens obtained during vitreoretinal surgery from patients with rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy (PVR). Immunofluorescence and immunoperoxidase methods were used to detect major histocompatibility complex or HLA antigens and immunocompetent cells, and to identify the cellular and the extracellular component of the proliferative tissue. The following antigens were detected in epiretinal membranes: cytokeratin in 18 (of 18 cases studied for this antigen), glial fibrillary acidic protein in 20 (of 20), vimentin in 20 (of 20), actin in 16 (of 18), fibronectin in 20 (of 20), macrophage CD68 in 16 (of 18), leukocyte common antigen in 12 (of 18), T-cell CD45R in 13 (of 22), HLA-ABC in 27 (of 33), HLA-DR in all the 33 membranes and HLA-DR alpha chain in 32 of 33 membranes. We observed the presence of macrophages and of an activated T-cell population in PVR membranes. HLA-DR antigen expression was found on pigmented and nonpigmented epithelial cells and on mononuclear cells in all epiretinal membranes. The HLA-DR expression on retinal pigmented epithelial cells could play a role in triggering a local immune response in PVR. These findings suggest the involvement of immunological phenomena and probable interactions between the immune system and peptide growth factors.

Cytoskeletal Proteins↗

PubMed1994

Immunohistochemical characterisation of probable intravascular haematopoiesis in the vasa rectae of the renal medulla in acute tubular necrosis.

Immunohistochemistry was applied to identify the nature of the nucleated cells that accumulate in the vasa rectae of the corticomedullary junction in acute tubular necrosis. In all 6 cases studied, there were intravascular cells that reacted with monoclonal antibodies to erythroblast, macrophages, myeloid cells, T and B lymphocytes and rare megakaryocytes. The findings are consistent with the occurrence of intravascular haematopoiesis in the renal medulla in acute tubular necrosis.

Adult↗

PubMed1994

Correlation between clinical, electromyographic and dysautonomic evolution of familial amyloidotic polyneuropathy of the Portuguese type.

To assess the correlation between the severity of clinical symptoms and sensorymotor and autonomic function in familial amyloidotic polyneuropathy of the Portuguese type (FAP-PT), clinical grade (CG), electromyographic score (ES), sympathetic (SS) and parasympathetic score (PS) were compared in 47 patients. SS and PS were both abnormal in 72% of patients with ES = 0% and in 73% of patients with CG = 0. When SS and PS were compared with either CG and ES, PS progressed more rapidly and stabilized earlier than SS. As a whole, SS and PS were greater as CG and ES were higher. This pattern of autonomic involvement should be taken into account when assessing the course of the disease and evaluating new forms of therapy.

Adult↗

PubMed1994

[Stress echocardiography with dobutamine: the importance of adding atropine in inconclusive tests].

OBJECTIVES: To study the feasibility of adding atropine after dobutamine infusion in patients with known or suspected coronary artery disease not achieving 85% of predicted maximal heart rate. PATIENTS: We studied with dobutamine stress echocardiography 219 patients (174 men e 45 women; mean age +/- SD: 58 +/- 11 years), 126 patients with a previous myocardial infarction and 93 with angor. One hundred and thirty three (61%) also performed coronariography. METHODS: Dobutamine stress echocardiography protocol consisted of a step-wise infusion of dobutamine from 5 micrograms/kg/min to a maximal dose of 40 micrograms/kg/min or until a new or a worsening wall motion abnormality, 85% of predicted maximal heart rate or any indication for interruption. In patients not achieving any of these end points, intravenous atropine was administered up to 1 mg. Patients were divided in two groups: Group A: infusion of dobutamine alone and Group B: dobutamine plus atropine. RESULTS: With this protocol the test was interrupted in 41 patients (19%) because of adverse effects that were mild and short lived and resolved with discontinuation of the test. After dobutamine infusion 46% of the tests were nonconclusive, the majority were on beta blocker therapy. After atropine administration there was a significant reduction of the nonconclusive studies to 20% (p < 0.001). In patients with a normal rest echocardiogram the sensitivity and specificity of the test to diagnose significant coronary artery disease was respectively 89% e 100% after atropine. The capacity of the test to detect multivessel disease was also increased after atropine, allowing to reach a sensitivity of 85% and a specificity of 90%. CONCLUSIONS: Dobutamine stress echocardiogram supplemented with atropine is a safe and accurate method to diagnose significant coronary artery disease and to detect multivessel disease in patients with a previous myocardial infarction with rest wall motion abnormalities.

Aged↗

PubMed1993

Minimal residual coronary obstructions in patients who suffered a first myocardial infarction. A prospective study comparing coronary angiography and exercise thallium scintigraphy.

The purpose of the present study was to correlate the presence of minimal coronary obstruction (< or = 50%) assessed by coronary angiography with the presence of myocardial scar and ischemia detected by thallium-201 myocardial perfusion imaging. The study included 83 consecutive patients (74 men and 9 women) with a mean age 55.4 +/- 8.5 years who suffered a first myocardial infarction and did not undergo thrombolytic therapy. In all patients, coronary angiography, left ventriculography, and exercise thallium-201 tomographic scintigraphy were performed within 3 to 5 months of the myocardial infarction. Coronary arteriograms showed minimal residual obstructions in 37 (45%) patients. Of a total of 54 patients with < or = 50% obstruction, 18 showed persistent defects and 22 reversible defects on thallium scintigrams. The present study showing estimated angiographic stenosis of < or = 50% as being responsible either for myocardial scar or myocardial ischemia on postexercise thallium scintigrams leads us to conclude that percent value of stenosis does not accurately predict the pathophysiologic significance of coronary atherosclerotic lesions in patients who suffer a myocardial infarction. After a first myocardial infarction, coronary angiographies and thallium-201 scintigrams are complementary for an optimal treatment strategy for selected subsets of patients.

Adult↗

PubMed1993

Postexercise changes of the QTc interval in patients with recent myocardial infarction.

A lack of the QTc ratio decrease at maximal exercise is considered as an index of exercise-induced ischemia in patients with coronary artery disease. The authors studied 51 patients with recent myocardial infarction in order to evaluate the QTc changes with exercise in assessing the presence of remaining ischemic myocardium. All patients were submitted to exercise stress tests, coronary angiographies, and exercise thallium 201 scintigraphies within 3-5 months of the myocardial infarction. Of the patients studied, 18 showed one-vessel disease and 33 showed multivessel disease. All vessels were classified as patent or occluded. In all patients with reversible thallium 201 defects both at distance and in the infarct zone, the QTc interval following exercise either showed a prolongation or no change from the resting electrocardiogram. In patients with only fixed perfusion defects, the QTc shortened at the end of the test. This study showed a low sensitivity and specificity for inducible ST-segment depression compared with the delayed redistribution on the postexercise thallium 201 scintigram. QTc variations at the end of exercise electrocardiograms are valuable as a noninvasive, low-cost identification of residual ischemic myocardium in patients after myocardial infarction.

Coronary Angiography↗