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Biomedical subjects

R Merletti

Publications and source records attributed to R Merletti.

69 records · Page 4Linked to original sources
PubMed1986

Size and X-ray density of normal and denervated muscles of the human leg and forearm.

An accurate assessment of muscle size and tissue density can be obtained by X-ray computed tomography. CAT scans of the extensor and flexor muscle compartments of the leg and forearm were performed on normal subjects to establish: normal ranges of muscle densities, and the effect of sex and side dominance on muscle size and density. The same muscle groups were studied in patients with nerve damage resulting in either total or very extensive denervation of the corresponding muscle compartments. In normal subjects muscle density is significantly lower in females and the effect of side dominance is more marked in the upper extremity. Denervated muscle compartments show reduced cross-section and density. Electrotherapy does not appear to be effective in preventing muscle atrophy.

Absorptiometry, Photon↗
PubMed1984

Median frequency of the myoelectric signal. Effects of muscle ischemia and cooling.

A study was performed to investigate the changes that occur in the median frequency of the myoelectric signal during local ischemia or reduction of intramuscular temperature produced by surface cooling. Data was obtained from experiments which involved the first dorsal interosseous muscle of 10 female and 16 male subjects. These subjects were asked to perform isometric constant-force abduction contractions of the index finger at 20% and 80% of maximal voluntary contraction level. The initial median frequency (IMF) of the myoelectric signal during the first 0.5 s of contraction was calculated. Results showed a significant reduction of the IMF in contractions performed under ischemic conditions; upon release, the IMF recovered quickly. At 80% maximal voluntary level of contraction, a greater decrease of the IMF was recorded. Similar results were demonstrated during reduction of intramuscular temperature with gradual recovery of the IMF after cooling. These results demonstrate that the median frequency of the myoelectric signal displays behavior similar to that reported for conduction velocity and this is consistent with the notion that accumulation of metabolic byproducts in muscle tissue causes a decrease in the conduction velocity of the muscle fibers.

Adult↗
PubMed1981

Tomographic evaluation of size and X-ray density of normal and denervated human muscles.

Neuromuscular disease will lead to size changes, degeneration or destruction of muscle fibres. However, fat or connective tissue infiltration occurs and this prevents the use of simple measures to assess wasting. Computerized tomography will allow accurate assessment of this wasting. Five normal subjects and five patients with total traumatic denervation of radial or peroneal origin were examined. Denervated muscle was shown to have lower than normal cross-section and X-ray density. These reductions were not paralleled in circumference or limb volume. Recovery could be followed by tomography.

Absorptiometry, Photon↗
PubMed1980

A critical appraisal of neuromuscular stimulation and electrotherapy in neurorehabilitation.

The problems of neuromuscular electrostimulation in patients affected by central or peripheral nervous system chronic lesions have been analysed during an interdisciplinary meeting held in Pavia on Dec. 9, 1978 and evolved to the discussion of two previous workshops concerning the same topic. The effective value of functional electrical stimulation, especially for the lower limbs, seems to be proved in some patients with upper motor neuron lesions. However, a clear definition of patient selection criteria has not been given yet, while a comparison with the results with vibratory techniques is still be carried out. With regard to the so-called electrotherapy of denervated muscles. it has been stressed that the trophic state can also be promoted by vibratory mechanical stimulation while the electrical stimulation could partly reduce the diffuse type of membrane excitability present in the devervated muscle fibres; this effect might interfere negatively with the process of collateral nerve sprouting.

Electric Stimulation Therapy↗
PubMed1979

Clinical experience of electronic peroneal stimulators in 50 hemiparetic patients.

Fifty hemiparetic subjects were selected from a population of 250 patients according to criteria forsuitable candidates for peroneal stimulation. The patients received from 10 to 120 hours of treatment during 2--5 weeks. The therapeutic results obtained were classified into four groups, ranging from none to excellent improvement of voluntary movement and reduction of spasticity. The clinical results were correlated to different variables where time from lesion, spasticity, and extent of treatment appeared to be the most important ones. The percentage of excellent results decreased with increasing time from lesion and spasticity, and increased with increasing treatment. Orthotic validity (i.e. the beneficial effect of the orthosis) was observed in 76% of the selected cases and in most of them it was very significant. Preliminary tests performed on 9 subjects showed that in cases with orthotic validity the peroneal brace slightly reduces the oxygen consumption of patients and improves their motivation. This work gives a more quantitative perspective of the validity of functional peroneal stimulation and a better indication of criteria for patient selection. The overall validity of an electronic peroneal brace appears to apply to 15% of the total ambulatory hemiparetic population and its therapeutic value is relevant in two-thirds of such cases if sufficient treatment is provided. Application of functional electrical stimulation to non-ambulatory subjects in the acute phase may however lead to a higher percentage of cases of therapeutic validity.

Age Factors↗
PubMed1978

A control study of muscle force recovery in hemiparetic patients during treatment with functional electrical stimulation.

A group of forty-nine hemiparetic patients with limited emotional, communication and sensibility involvement and with recent lesion of cerebrovascular aetiology was randomly divided into two groups of twenty-four and twenty-five subjects. Both groups received traditional physiotherapy treatment for one hour/day, one group received twenty min/day of peroneal nerve stimulation. The maximum voluntary dorsal flexion moments of the ankle joint of the affected and non affected extremities were measured with an isometric brace twice a week for one month and for both groups. The recovery of moment in the stimulated group turned out to be about three times greater than in the control group and considerably less dependent upon age, time from lesion, initial value, side of lesion. Three patients using a peroneal brace at home as an assisting device were again evaluated two months later and a further improvement was observed. This work gives statistical support to previous observations based on very few cases and provides a statistically reliable answer concerning the entity of FES induced recovery of muscle force in hemiparetic subjects.

Adult↗
PubMed1975

Electrophysiological orthosis for the upper extremity in hemiplegia: feasibility study.

A versatile two channel stimulator with cutaneous electrodes was designed and built to test the feasibility of multi-channel upper extremity functional electrical stimulation in hemiplegic patients. Preliminary experiments led to the choice of stimulation for hand opening (extensor carpi radialis and ulnaris, extensor digitorum communis) and elbow extension (triceps). Three channel stimulation including the deltoideus muscle was attempted successfully in one patient. Five of eight patients showed substantial improvement with the orthosis and three of these five showed some therapeutic effect over a period of two months. The stimulation was proportionally controlled by the patient by means of movement of the nonaffected shoulder. Functional tasks such as the shifting of an object between two specified areas on a desk were used for evaluation of performance. Tasks that were impossible without stimulation were easily performed with stimulation and after minimal training. The results obtained were significant for the functional rehabilitation of hemiplegic subjects. It is concluded that a more extensive clinical evaluation program including regular long term training of the subjects is justified.

Arm↗
PubMedDate not supplied

[PROCID: a project of the European Community for the study and prevention of muscular disorders in computer terminal operators].

This paper presents an EC funded concerted action aimed at studying the prevention of muscle disorders in the operation of computer input devices. About 40% the today's working population use computers in their daily work. This percentage is expected to increase dramatically in the coming years. At the same time health statistics indicate an increased incidence of work related musculoskeletal disorders among computer users. A deeper knowledge in this field may improve the health risk assessment approach, the design of computer input devices and the revision process of existing standards, norms and guidelines concerning computer work. Specific research objectives include: the development of intramuscular techniques suitable for mapping motor unit recruitment under operation of computer input devices; the evaluation of muscle fatigue and motor unit recruitment in dynamic tasks in normal subjects and in patients with pain syndromes; the experimental evaluation of stress induced muscular tension at the motor unit level, in operation of computer input devices; the formulation of recommendations for work with computer input devices.

Computer Terminals↗
PubMedDate not supplied

[Neuromuscular assessment of the elderly worker: the European NEW project].

Neuromuscular problems reduce working ability of aging workers, and increase cases of work loss and accidents. For this reason, elderly people throughout Europe are forced into early retirement, and fail to be self-supporting. There is a need to identify and monitor work related neuromuscular disorders in order to reduce their consequences by monitoring the most vulnerable individuals, identify the determinants of neuromuscular aging related to occupational conditions, prevent pathologies and their evolution. Preliminary results show the possibility of identification of neuromuscular problems through non invasive techniques, some of which, recently developed within the SENIAM and PROCID Concerted Actions, can provide quantitative indices of neuromuscular performance. Substantial field tests and training initiatives are required to demonstrate if these techniques can be used outside the research labs, if there may be a European market in the fields of ergonomics and occupational health, and if they can be routinely used with standardized methodology to monitor the relationship between occupational and neuromuscular system conditions in the working environment. The objective of the European Project Neuromuscular assessment in the Elderly Worker (NEW) is to answer these questions.

Aged↗