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Biomedical subjects

M de Carvalho

Publications and source records attributed to M de Carvalho.

16 recordsLinked to original sources
PubMed1997

Magnetic stimulation in Alzheimer's disease.

Alzheimer's disease (AD) is a common cause of dementia in which some clinical motor abnormalities have been described. We used transcranial magnetic stimulation in order to test the hypothesis that the change in the motor cortex might cause modifications in motor excitability. Fourteen mildly to moderately affected AD patients were compared with 11 controls matched for age, height and sex. The motor evoked potential threshold value for the relaxed abductor digiti minimi was lower in the AD patients than in the control group for both left and right hemispheres (P < 0.05). No statistically significant difference was found comparing the left and the right hemispheres thresholds in each population. The mean interside threshold differences were small and not significantly different between patients and controls. The spinal motor neuron excitability, as evaluated by F/M and H/M waves amplitude ratios, showed no difference between the groups, reinforcing the motor cortex increased excitability hypothesis to explain this difference. Degeneration of inhibitory gabaergic terminals might be the basis for the increased cortical excitability in the motor cortex of the Alzheimer patients; postsynaptic changes in the GABAA receptors might also affect inhibitory gabaergic transmission. The increased excitability found by transcranial magnetic stimulation in the motor cortex is important for understanding the emergence of seizures and myoclonus in this disease.

Aged↗
PubMed1997

A new method for reproducible coil positioning in transcranial magnetic stimulation mapping.

A new method is presented for mapping the motor cortex by transcranial magnetic stimulation in which the position of the stimulation coil on the scalp is measured using a 3D digitizer. The reproducibility of the method was tested by mapping 3 times the left abductor digiti minimi of 6 right-handed subjects and calculating the position of the centre of gravity (CoG), the area and volume of the individual maps. For individual maps, the coordinates of the CoG were found to be reproducible within +/-3 mm and the map areas and normalized volumes to within +/-20%, when the induced current flows anteriorly. Six more subjects were mapped to estimate interindividual variability of the position of the CoG. The method's ability to differentiate the cortical representation of two close muscles was successfully tested by mapping the flexor carpi radialis and the biceps brachii in another subject. Coordinates are given in a Cartesian frame of reference defined by the two tragi and the nasion. This feature will facilitate the comparison of results and their superposition on MR images.

Adult↗
PubMed1997

Relapsing chronic low-dose corticosteroid-responsive multifocal motor neuropathy with conduction block.

Multifocal Motor Neuropathy (MMN) is a newly described disorder that might mimics the Motor Neuron Disease (MND). MMN is considered by some authors to be an entity distinct from Chronic Inflammatory Demyelinating Polyradiculoneuropathy (CIDP), nevertheless because a pure-motor variant of CIDP is well recognized and CIDP can present Partial Motor Conduction Block (PMCB), several authors believe that MMN can be a variant of CIDP. We describe a 27-year old male with a relapsing chronic low-dose corticosteroid-responsive MMN with conduction block. Our case stresses that MMN includes a wide range of motor neuropathies with different immunological profiles conditioning distinct treatment strategies.

Adrenal Cortex Hormones↗
PubMed1996

Motor neuron disease presenting with respiratory failure.

Respiratory failure accounts for the majority of deaths in amyotrophic lateral sclerosis (ALS) but only rarely is ALS diagnosed on the basis of respiratory insufficiency. We report four ALS patients presenting with acute respiratory failure. In three patients we have performed EMG needle examination of both hemidiaphragms which showed severe denervation. We reviewed 25 patients previously described presenting with respiratory failure. Almost all patients showed upper limbs weakness and diaphragm involvement; few patients had bulbar dysfunction. The prognosis of these patients is not always in permanent ventilator dependence. Rapidly progressive ventilatory failure may be a striking initial sign of ALS; the main reason is a weakened diaphragm. There are possibilities of significant improvement after a period of rest with ventilatory assistance. In the initial phase of the disease, bulbar dysfunction is not the more common reason of acute respiratory failure.

Aged↗
PubMed1995

Somatosensory evoked potentials in the differential diagnosis between spinal cord compression and amyotrophic lateral sclerosis.

Spinal cord compression (SCC) often presents a similar clinical picture to amyotrophic lateral sclerosis (ALS). An early differential diagnosis is important because SCC is a potentially treatable clinical disorder. We carried out a longitudinal study of 43 patients with an initial diagnosis of ALS, in order to ascertain the percentage of patients with SCC, and to evaluate the usefulness of somatosensory evoked potentials (SEPs) in early diagnosis. Thirty-three patients had a final diagnosis of ALS and 8 of SCC. SEPs central conduction was abnormal in 3 ALS and 7 SCC patients, respectively (Fisher exact test, p < 0.05). We concluded that SEPs investigation is useful in the differential diagnosis between ALS and SCC patients with pure motor signs.

Adult↗
PubMed1991

Analysis of the use of multiple technologies in neonatal care.

The use of 53 different technologies was studied in 82 patients in a neonatal intensive care unit. Using a coefficient of similarity based on the utilization pattern of these technologies, it was possible to identify five clusters of patients that can be correlated with the primary diagnostic groups and such other variables as birth weight (BW), gestational age, length of stay (LOS), and weight gain. Four interdependent models were identified by multiple regression analysis. The number of different therapeutic technologies applied to these patients can be explained (r = 0.67) by their Apgar scores, gestational age, and an index of severity of illness based on the diagnostic group. The number of different diagnostic technologies used is directly related to the number of therapies delivered (r = 0.63) and, jointly with BW, determines LOS (r = 0.73). Finally, weight gain is explained by LOS and BW (r = 0.65).

Cluster Analysis↗
PubMed1991

Estimating the effectiveness of perinatal care technologies by expert opinion.

The majority of technologies in use in perinatal care were organized into 45 technological functions. Forty-six experts from 19 different regions of Brazil and other Latin American countries then selected a "basic package" (BP) of 15 technological functions. Considering the 12 main causes of perinatal mortality in Brazil, the experts estimated the number of preventable deaths, assuming universal coverage by the BP and the additional reductions that could be obtained by gradually adding other technological functions to the BP. A simulation was performed for the 26 states of Brazil to identify regional priorities for the diffusion of technological functions. For most regions, the BP appears to be the most effective intervention, with the potential of reducing perinatal mortality by 33%, followed by "coordination of services and referral of pregnant women" (14%), and "treatment of respiratory conditions" (11.8%).

Attitude of Health Personnel↗
PubMed1982

Milk intake and frequency of feeding in breast fed infants.

To provide normative data for healthy full term infants in the United States when the mothers were encouraged to feed as often and as long as the infants wished, 46 mother-infant pairs were studied in the first month after delivery. Mothers recorded the length and time of each breast-feeding for the first 14 days postpartum, and weighed the infant before and after each feeding during a 24-48 h period at 1 month. The mean frequency of feeding during the first 2 weeks of life was 9.8 +/- 2.5 feeds/24 h and the mean duration of feeding was 162 +/- 50 min/24 h. Infants heavier at birth demanded significantly more feedings and nursed longer during the first 14 days of life. At one month the infants were nursing an average of 7.2 +/- 1.3 times/24 h and the mean duration of feeds was 158 +/- 63 min/24 h. Although the frequency of feeding during the first 14 days postpartum was significantly higher than at 1 month, the total duration of feeding in 24 h was similar. Daily milk intakes at 1 month ranged from 395 to 1011 ml (mean 681 +/- 136 ml) and were not significantly correlated with either the frequency or duration of feedings.

Body Weight↗
PubMed1981

Effects of water supplementation on physiological jaundice in breast-fed babies.

The effect of water supplementation in normal, term, breast-fed babies with physiological jaundice was studied. Water supplementation was given to 120 babies and 55 received no extra fluids. There was no significant difference between the two groups when peak serum bilirubin levels and incidence of phototherapy were compared.

Bilirubin↗