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M de Carvalho

Publications and source records attributed to M de Carvalho.

At least 19 recordsLinked to original sources
PubMed2006

Upper limb tremor induced by peripheral nerve injury.

We report a patient with proximal right upper limb tremor, secondary to direct peripheral nerve lesion caused by prior thoracic surgery. Electromyography demonstrated neurogenic abnormalities and tremor in muscles innervated by the thoracodorsal and long thoracic nerves. Somatosensory evoked potentials, transcranial magnetic stimulation, and MRI of the cervical and thoracic spine were normal. Tremor persisted in REM and non-REM sleep. These findings suggest a peripheral generator.

Arm↗
PubMed2006

Does caffeine modify corticomotor excitability?

AIMS: To test the influence of caffeine on the lower and upper motor neuron excitability. METHODS: In Experiment A, 18 healthy subjects received 200 mg of caffeine or placebo, in a randomized, double-blind, placebo-controlled design protocol. Mean F-waves amplitude, amplitude of the motor response evoked by magnetic stimulation (MEP), MEP duration, cortical silent period (CSP), central conduction time, and cortical threshold were evaluated. In Experiment B, 6 healthy controls received 400 mg of caffeine, the peripheral silent period (PSP) and CSP were evaluated. CSP was recorded bilaterally in biceps brachii (intensity 10% above threshold) and abductor digiti minimi (ADM) (intensity at 10% and 50% above threshold). Muscle contraction was above 50% of the maximum force in both experiments. Latencies were defined by a technician who was not aware of this investigation. Serum caffeine level was evaluated. RESULTS: In Experiment A, only the CSP, recorded in both ADM with intensity at 10% above threshold showed a significant change after caffeine (decrease of 17.1+/-34.0 ms, about 12% reduction). In Experiment B, PSP did not change, but CSP tested with intensities 10% above threshold was significantly decreased by 20.8+/-34.4 ms in ADM and 13.5+/-13.8 ms in biceps (about 13 and 16%, respectively). Serum caffeine level clearly increased after consumption but no correlation could be found between these levels and CSP reduction. CONCLUSIONS: In our investigation, caffeine elicited a consistent decrease of the CSP, suggesting that caffeine increases cortical neuronal excitability.

Adult↗
PubMed2006

Amplitude, area and duration of the compound muscle action potential change in different ways over the length of the ulnar nerve.

OBJECTIVE: To study physiological changes of the compound muscle action potential (CMAP) obtained from stimulation at different sites over the full length of a motor nerve and to study possible effects of anthropometrical factors. METHODS: Multicentre study of ulnar motor nerve conduction in five segments to Erb's point performed bilaterally on 100 healthy subjects aged 17-83 years. RESULTS: CMAP amplitude decreased linearly with conduction distance (0.31%/cm) from wrist to Erb's point. CMAP area decreased with the square of conduction distance. Decrease in area was smaller than decrease in amplitude especially distally. CMAP duration increased linearly (0.17%/cm). Amplitude decay correlated with age, height and BMI and dispersion correlated with age and height. There were no correlations between area decay and anthropometrical factors. There was no significant inter-examiner variation. CONCLUSIONS: Area decay may be preferred to amplitude decay in the evaluation of conduction block over short segments due to smaller physiological changes and independence of anthropometrical factors. The absence of inter-examiner variation indicates that the results are robust and may be used by other laboratories. SIGNIFICANCE: This study provides knowledge of physiological changes of CMAP parameters that may be of importance in the evaluation of nerve pathology, in particular conduction block.

Action Potentials↗
PubMed2006

The onset of amyotrophic lateral sclerosis.

Two patients in whom both the neurological examination and electromyography (EMG) were normal prior to the onset of amyotrophic lateral sclerosis (ALS) are reported. In each patient, the onset of ALS some 18 months later was clearly defined clinically and confirmed by subsequent EMG studies. These unique observations show that ALS commences at a defined time, and that there is early generalisation with an initial phase of rapid progression.

Aged↗
PubMed2005

Chronic inflammatory demyelinating polyneuropathy, phrenic nerve and respiratory symptoms.

Respiratory involvement in chronic inflammatory demyelinating polyneuropathy (CIDP) has been very recently described. Phrenic nerve conduction studies have been described as useful to detect respiratory impairment in these patients. This study describes two patients with CIDP, in whom neurophysiological studies of the respiratory muscles were performed. The first patient had severe respiratory insufficiency, and phrenic nerve studies disclosed no motor responses and electromyography (EMG) of the diaphragm confirmed severe loss of motor units, bilaterally. On treatment, we documented clinical and neurophysiological improvement. In the second patient, phrenic nerve studies showed abnormal results; however, EMG of the diaphragm ruled out loss of motor units. The first case represents the risk of phrenic nerve involvement in this disorder, and the potential recovery on treatment. The second case illustrates that the temporal dispersion of the motor responses can be misleading, and EMG of diaphragm should be performed to confirm the loss of motor units.

Aged↗
PubMed2003

Variation in the classification of polyneuropathies among European physicians.

OBJECTIVE: Considerable debate still exists regarding the classification of polyneuropathies (PNPs) into predominantly demyelinating, predominantly axonal loss, mixed or unclassified. This study was designed to determine the variation among physicians in the classification of PNPs by using the European Standardized Telematic tool to Evaluate Electromyography knowledge-based systems and Methods (ESTEEM) multicenter database. METHODS: Seven physicians from 6 laboratories in Europe sent a total of 156 prospectively collected cases of PNP with electromyography (EMG) data including diagnosis (examination diagnosis) to the database. Each physician interpreted the electrophysiological data from all cases (interpretation diagnosis) and a final diagnosis was given at the consensus meetings of the group (consensus diagnosis). RESULTS: Comparison of each physician's examination diagnosis with his/her interpretation diagnosis, i.e. intra-physician variation, showed a change towards less classified PNPs (P < 0.05). Interpretation diagnoses showed large inter-physician variation in the classification of PNPs. The consensus group was more cautious than individual physicians in classifying PNPs as mixed and axonal. The probability of the consensus diagnosis increased with increasing number of abnormal motor and sensory segments tested. CONCLUSIONS: Recognition of variation in classification of PNP as shown in this study and suggesting standards of good clinical practice developed by a consensus group may increase the quality of EMG practice.

Consensus↗
PubMed2003

Motor-axonal polyneuropathy associated with hepatitis C virus.

The association between hepatitis C virus (HCV) infection, the presence of mixed cryoglobulinemia and peripheral neuropathy is well-documented (Apartis et al., 1996). HCV is the chief cause of essential mixed cryoglobulinemia (type II cryoglobulinemia) with cryoglobulins present in up to half of patients with HCV infection (Akriviadis et al., 1997). More recently it has been stated that peripheral polyneuropathy may be associated with HCV chronic infection without mixed cryoglobulinemia (Lidove et al., 2001). Patients usually present with a clinical and electrophysiology--predominantly sensory axonopathies (Apartis et al., 1996; Heckmann et al., 1999) or less frequently with fulminating vasculitis and mononeuropathy multiplex syndrome (David et al., 1996)--especially when associated with cryoglobulinemia. We report, for the first time, the association between pure motor-axonal polyneuropathy and HCV infection without cryoglobulinemia.

Aged↗
PubMed2002

Estimation and diversity of phylloplane mycobiota on selected plants in a Mediterranean-type ecosystem in Portugal.

Mediterranean ecosystems have not been consistently investigated as natural habitats for microbes in general, and fungi in particular. Here we present the results of a survey of epiphytic mycobiota (filamentous fungi and yeasts) on the phylloplane of selected plants in the Arrábida Natural Park, an ecosystem of Mediterranean characteristics in Portugal, using conventional culture-dependent isolation methods. Leaves from the species Acer monspessulanum and Quercus faginea (deciduous trees) and Cistus albidus, Pistacia lentiscus, and Osyris quadripartita (evergreen shrubs) were collected twice a year for two consecutive years, at two distinct locations of Serra da Arrábida: the more humid northern slope and the drier southern slope. A total of 1029 strains of filamentous fungi and 540 strains of yeasts were isolated, which represented at least 36 and 46 distinct species, respectively. Total counts were higher on the plants from the northern slope and there was a general increase from spring to autumn, notably on the deciduous trees for the yeasts. Plant species that had higher numbers of leaf colonists (A. monspessulanum, C. albidus, and Q. faginea) also yielded a wider range of species. Among the filamentous fungi there was a predominance of species of ascomycetous affinity, whereas basidiomycetous species dominated among yeast isolates. Some of the taxa recovered were common to other phylloplane studies (e.g., ubiquitous molds and yeasts such as Cladosporium spp. and Cryptococcus spp., respectively), but less common species were also found, some of which appeared to represent undescribed taxa. Interestingly, a few species seemed to be associated with a particular plant, notably in the case of the evergreen shrub C. albidus. However, for a considerable number of fungi and yeasts the same taxon was recovered throughout the year from more than one plant and at both sites, suggesting that such species might be genuine phylloplane inhabitants (or at least of aerial plant surfaces) even though they appeared not to display host specificity.

Ecosystem↗
PubMed2001

Allgrove syndrome in adulthood.

A 35-year-old man with a past history of achalasia developed progressive spastic tetraparesis, distal limb atrophy, dysarthria, and dysphagia. A clinical diagnosis of amyotrophic lateral sclerosis (ALS) was considered before neurophysiological investigation, which disclosed a polyneuropathy and a prolonged central conduction time. One year later, the patient developed dysautonomic symptoms. Following confirmation of adrenal insufficiency, a diagnosis of Allgrove syndrome was made. This is a rare case, and we emphasize its clinical similarity with ALS.

Adult↗
PubMed2001

Reproducibility of neurophysiological and myometric measurement in the ulnar nerve-abductor digiti minimi system.

Reliability in strength and neurophysiological measurements is important in evaluating progression of neuromuscular diseases. No data are available on the variability of neurophysiological parameters as compared with maximal voluntary isometric contraction (MVIC) in the same muscles, in healthy subjects. A control population of 26 healthy subjects was studied twice on different days. We evaluated the reliability of neurophysiological parameters obtained from bilateral ulnar nerve stimulation, recording the response over the abductor digiti minimi (ADM) muscle, including distal motor latency, compound muscle potential amplitude and area, F-wave frequency and mean F-wave latency, and the derived neurophysiological index that we have described previously. MVIC force was measured in each session in both ADM muscles. The variances between the grouped data obtained in the two recording sessions were identical, indicating a low intrinsic variability with this experimental methodology. Comparison of the mean values obtained in the two sessions revealed no statistically significant differences. The reliability of these neurophysiological and strength measurements in the same nerve/muscle system suggests they may be useful in comparing the dynamics of weakness and neurophysiological change in neuromuscular disease.

Adult↗
PubMed2001

Medical technology assessment. Electrodiagnosis in motor neuron diseases and amyotrophic lateral sclerosis.

In motor neuron diseases/amyotrophic lateral sclerosis (MND-ALS), electrodiagnostic techniques are essential in supporting the diagnosis and excluding other conditions that clinically resemble MND-ALS. Electrodiagnostic techniques can also monitor disease progression and provide prognostic information. Electromyography has an important role in the diagnosis of MND-ALS, but some drawbacks should be borne in mind. Although internationally accepted electrophysiological criteria have been defined to support MND-ALS diagnosis, differences in different laboratories can raise unexpected difficulties in application of diagnosis criteria. Much work needs to be done to increase standardisation of the electrodiagnosis of MND-ALS in order to improve quality. Differential diagnosis with motor axonal neuropathies may be particularly difficult. EMG is an essential tool for the early diagnosis of MND-ALS, which increases potential benefit of therapeutic interventions. A wide discussion among neurophysiologists from different schools could create a sound consensus on early diagnosis of MND-ALS.

Amyotrophic Lateral Sclerosis↗
PubMed2001

Sympathetic sudomotor function and amyotrophic lateral sclerosis.

INTRODUCTION: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder affecting motor neuron cells in the cerebral cortex, brain stem and spinal cord. Autonomic nervous system involvement is not a recognized feature of the disease; nonetheless, autonomic dysfunction has been reported in severely affected patients. The aim of this study was to evaluate sympathetic sudomotor function in ALS patients, employing the sweat imprint test. METHODS: Twenty-four ALS patients and 25 controls, matched for sex and age, were included. In total, 34 hands and 35 feet in controls, and 29 hands and 30 feet in the ALS population, were investigated. RESULTS: No inter-side difference was found in controls or in ALS patients. The mean number of sweat drops/cm2 was comparable in both populations. However, six ALS patients had a lower count on the hand than on the foot, which was never observed in controls. Furthermore, in the ALS population, five hands and three feet showed values below the lower limit of normal. The abnormalities were more frequent in very weak limbs, and could be ascribed to lack of use. CONCLUSION: Although significant sudomotor hypofunction does not occur in ALS, mild subclinical changes can be observed in weak limbs.

Adult↗
PubMed2000

Nerve conduction studies in amyotrophic lateral sclerosis.

We studied 137 ulnar nerves and abductor digiti minimi (ADM) muscles in 70 patients with amyotrophic lateral sclerosis (ALS), and correlated the results with ADM strength graded on the Medical Research Council (MRC) scale, to address the potential value of a standardized neurophysiological assessment of this nerve-muscle system. The ulnar nerves of 35 normal subjects matched for age, gender, and height served as controls. Reduced compound muscle action potential (CMAP) amplitude and area in the ADM muscle recordings correlated strongly with weakness. Distal motor latency, proximal conduction time, and F-wave frequency were abnormal with minimally detectable weakness. In weaker ADM muscles, conduction velocities and F-wave latencies were also abnormal. Conduction block was never observed and sensory potentials were normal. An "ALS neurophysiological index" was derived from these ulnar nerve studies and consisted of the expression: (CMAP amplitude/DML) x F frequency -, where F frequency was expressed as the number of F responses recorded in 20 trials. This index was strongly correlated with ADM weakness (r = 0.74, P < 0.001). Neurophysiological studies restricted to a single nerve-muscle system, the ulnar nerve/ADM, appear potentially useful in objectively assessing change in ALS.

Adult↗
PubMed2000

New transthyretin mutation V28M in a Portuguese kindred with amyloid polyneuropathy.

A 62-year-old Portuguese man, with no history of familial amyloid polyneuropathy (FAP), and a 2(1/2)-year history of tingling in the toes and sexual dysfunction was found neurophysiologically to have a sensory-motor axonal polyneuropathy. Autonomic tests showed slight sympathetic and marked parasympathetic involvement. Heart, kidney, and eyes were normal. Single strand conformation polymorphism (SSCP) mutation analysis for the transthyretin (TTR) gene was performed. The SSCP pattern suggested the presence of a mutation in exon 2, but was different from the pattern observed for a control representing the most common TTR mutation associated with FAP, i.e., TTR V30M. DNA sequencing analysis revealed an A-to-G transition in the first base of codon 28 normally encoding a valine, giving rise to a methionine residue. The presence of this extra methionine was confirmed by peptide mapping and mass spectrometry analysis. Biopsy of nerve and skin of the propositus showed amyloid deposits that were immunoreactive for TTR. This is a new variant TTR related to late-onset amyloid neuropathy with autonomic dysfunction. This case confirms that TTR mutation screening should be considered in patients with a clinical disorder consistent with amyloid neuropathy even in the absence of a family history.

Adult↗
PubMed2000

Neurophysiological features of fasciculation potentials evoked by transcranial magnetic stimulation in amyotrophic lateral sclerosis.

We report 13 patients with amyotrophic lateral sclerosis in whom fasciculation potentials (FPs) driven by transcranial magnetic stimulation (TMS) were recorded. A total of 18 different FPs were analyzed. TMS-driven fasciculations had a simple morphology and were stable. Complex potentials were never cortically driven. Recruitment by a slight voluntary contraction was verified in 7 of 13 tested FPs. FPs were driven by threshold stimuli in 7 of 10 patients and by stimuli 5% below threshold in 3 of 6. Mapping demonstrated that FPs were driven in an area close to the center of gravity of the muscle cortical area. In one case FPs were evoked from most of the cortical representation area of a very weak muscle. Three other patients with profuse fasciculations associated with other clinical conditions were also studied. No TMS evoked fasciculation was observed in this group. The results of this systematic study suggest that cortically evoked FPs arise centrally, at spinal cord or even more proximally, and can represent a marker of increased corticomotor excitability, which is predominant at an earlier phase but can persist as the disease progresses.

Adult↗