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OBJECTIVE: Unilateral strength training has been shown to be more effective than bilateral training to increase strength in healthy people. The aims of this study were to test the feasibility of unilateral strength training during total knee arthroplasty (TKA) rehabilitation and compare it with standard bilateral training. METHODS: Twenty-four TKA patients from an inpatient rehabilitation programme were randomly assigned to unilateral and bilateral strength training groups. Both groups completed 6 strength training sessions during 3 weeks of rehabilitation. Isometric strength, knee joint flexibility, knee circumference, chair rise and walking abilities, and perceived exertion and pain were assessed before and after the training period. RESULTS: Both training groups increased isometric strength of both legs (+17-25%) and flexibility of the affected leg (+7.6%). Improvements in isometric strength of the healthy leg (+23% vs +11%) and flexibility of the affected leg (+10.7% vs +4.5%) were greater in the unilateral training group. Chair rise and 2-min walk test results improved in both groups, to the same extent. Perceived exertion decreased only in the unilateral training group (-20%), while perceived pain did not change in either group. CONCLUSION: This study showed the feasibility of unilateral strength training in TKA rehabilitation. Strength and flexibility improved similarly or better with unilateral strength training compared with standard bilateral strength training. Future studies should analyse the efficacy of prolonged unilateral strength training following TKA.
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Artroplastia de Reemplazo de Rodilla , Osteoartritis de la Rodilla , Entrenamiento de Fuerza , Humanos , Artroplastia de Reemplazo de Rodilla/rehabilitación , Entrenamiento de Fuerza/métodos , Proyectos Piloto , Fuerza Muscular , Articulación de la Rodilla/cirugía , Dolor , Osteoartritis de la Rodilla/cirugíaRESUMEN
This article describes the development of a temporary protective glenoid prosthesis placed between the augmentation and humeral head prosthesis during the healing phase of shoulder prosthesis revision with necessary reconstruction of the bony structure of the glenoid. The glenoid protection prosthesis ensures the fixation of the augmentation material and protects the screws from contact with the metallic humeral head prosthesis. Another approach of the development is a reduction of the resorption of the augmentation by targeted mechanical stimulation of the tissue. The aim should be to achieve significantly improved conditions for the implantation of a new glenoid component at the end of the healing phase of the augmentation material in comparison to the current standard method. The development of the protective prosthesis was carried out according to specific needs and includes the collection of requirements and boundary conditions, the design and technical detailing of the implant, the verification of the development results as well as the validation of the design. For the verification, FEM simulations (Finite Element Analysis) were performed to estimate the mechanical stability in advance. Mechanical tests to confirm the stability and abrasion behavior have been carried out and confirm the suitability of the protective implant. The result of the present work is the detailed technical design of two variants of a glenoid protective prosthesis "GlenoProtect" for use in revision procedures on shoulder joints-with large-volume defects on the glenoid-treated by arthroplasty and the necessity of augmenting the glenoid, including a description of the surgical procedure for implantation.
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It is often suggested that stretching-related changes in performance can be partially attributed to stretching-induced neural alterations. Recent evidence though shows that neither spinal nor cortico-spinal excitability are susceptible of a long-lasting effect and only the amplitude of stretch or tap reflex (TR) is reduced up to several minutes. Since afferents from muscle spindles contribute to voluntary muscle contractions, muscle stretching could be detrimental to muscle performance. However, the inhibition of muscle spindle sensitivity should be reversed as soon as the stretched muscle contracts again, due to α-γ co-activation. The present work evaluated which type of muscle contraction (static or dynamic) promotes the best recovery from the inhibition in spindle sensitivity following static stretching. Fifteen students were tested for TR at baseline and after 30 s maximal individual static stretching of the ankle plantar flexors followed by one of three randomized interventions (isometric plantar flexor MVC, three counter movement jumps, and no contraction/control). Ten TRs before and 20 after the procedures were induced with intervals of 30 s up to 10 min after static stretching. The size of the evoked TRs (peak to peak amplitude of the EMG signal) following stretching without a subsequent contraction (control) was on average reduced by 20% throughout the 10 min following the intervention and did not show a recovery trend. Significant decrease in relation to baseline were observed at 9 of the 20 time points measured. After MVC of plantar flexors, TR recovered immediately showing no differences with baseline at none of the investigated time points. Following three counter movement jumps it was observed a significant 34.4% group average inhibition (p < 0.0001) at the first time point. This effect persisted for most of the participants for the next measurement (60 s after intervention) with an average reduction of 23.4% (p = 0.008). At the third measurement, 90 s after the procedure, the reflexes were on average still 21.4% smaller than baseline, although significant level was not reached (p = 0.053). From 120 s following the intervention, the reflex was fully recovered. This study suggests that not every type of muscle contraction promotes a prompt recovery of a stretch-induced inhibition of muscle spindle sensitivity.
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BACKGROUND: Peripheral nerve defects (PND) often cause lifelong physical disability, and the available treatment options are often not satisfactory. PND are usually bridged with an autologous nerve transplant or a nerve guidance conduit (NGC), when coaptation as preferred technique is not possible. The aim of this experimental study was to determine the effectiveness of a novel NGC for regeneration in the treatment of PND. MATERIALS AND METHODS: A conduit made of gelatin with an innovative interior structure was tested for the repair of a 6-mm gap versus direct microsurgical suture repair without gap. RESULTS: We found that bridging the defect with this conduit was as effective as direct microsurgical coaptation without a defect. CONCLUSIONS: This nerve conduit, effective in bridging neural defects, appears as an alternative to autologous nerve grafts, avoiding the problems related to nerve graft harvesting, host-donor differences in diameter, mismatches in number and pattern of fascicles, cross-sectional shape and area, and morbidity of the donor area.
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Regeneración Nerviosa , Traumatismos de los Nervios Periféricos/cirugía , Prótesis e Implantes , Nervio Ciático/lesiones , Animales , Atrofia , Potenciales Evocados Motores , Análisis de la Marcha , Gelatina , Modelos Animales , Músculos/inervación , Músculos/patología , Músculos/fisiología , Regeneración Nerviosa/fisiología , Procedimientos Neuroquirúrgicos/métodos , Traumatismos de los Nervios Periféricos/fisiopatología , Diseño de Prótesis , Distribución Aleatoria , Nervio Ciático/fisiología , Porcinos , Porcinos Enanos , TitanioRESUMEN
OBJECTIVES: Corticospinal tract excitability and spinal reflex pathways are transiently affected by short applications of static stretching. However, it remains unclear whether the duration and magnitude of these neurophysiological responses can be increased with a longer duration of the applied stretch. The purpose of this study was to investigate alterations in cortical and spinal excitability following five minutes static stretching. METHODS: Seventeen participants (22.8±2.3 years old) were tested for the tendon tap reflex (T-reflex), Hoffman reflex (H-reflex) and motor-evoked potentials (MEPs) after transcranial magnetic stimulation (TMS) of the ankle flexor muscles in two separate occasions: before and after 5 minute static stretching or 5 minute control period, in a randomized order. RESULTS: No changes were observed following the control condition. H/M ratio increased by 16.2% after stretching (P=.036). Furthermore, immediately after stretching it was observed a strong inhibition of the T-reflex (57.6% inhibition, P=.003) that persisted up to five minutes after stretching (16.2% inhibition, P=.013) but returned to baseline following 10 minutes. MEPs were not affected by stretching. CONCLUSIONS: This study suggests that the neuromuscular responses that follow five minute of static stretching do not influence the excitability of the corticospinal tract and follow a different time course within spinal reflex pathways.
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Potenciales Evocados Motores/fisiología , Reflejo H/fisiología , Ejercicios de Estiramiento Muscular , Tractos Piramidales/fisiología , Femenino , Humanos , Masculino , Adulto JovenRESUMEN
During the period when the ankle joint is kept in a dorsiflexed position, the soleus (SOL) H-reflex is inhibited. The nature of this inhibition is not fully understood. One hypothesis is that the decrease in spinal excitability could be attributed to post-activation depression of muscle spindle afferents due to their higher firing rate during the stretch-and-hold procedure. As the static stretching position is maintained though, a partial restoration of the neurotransmitter is expected and should mirror a decrease in H-reflex inhibition. In the present study, we explored the time course of spinal excitability during a period of stretching. SOL H-reflex was elicited during a passive dorsiflexion movement, at 3, 6, 9, 12, 18, 21, and 25 s during maximal ankle dorsiflexion, during plantar flexion (PF) and after stretching, in 12 healthy young individuals. Measurements during passive dorsiflexion, PF and after stretching were all performed with the ankle at 100° angle; measurements during static stretching were performed at individual maximal dorsiflexion. H-reflex was strongly inhibited during the dorsiflexion movement and at maximal dorsiflexion (p < 0.0001) but recovered during PF and after stretching. During stretching H-reflex showed a recovery pattern (r = 0.836, P = 0.019) with two distinct recovery steps at 6 and 21 s into stretching. It is hypothesized that the H-reflex inhibition observed until 18 s into stretching is the result of post-activation depression of Ia afferent caused by the passive dorsiflexion movement needed to move the ankle into testing position. From 21 s into stretching, the lower inhibition could be caused by a weaker post-activation depression, inhibition from secondary afferents or post-synaptic inhibitions.
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Spinal excitability in humans is inhibited by both passively holding a static position with the muscle lengthened (static stretching) and by a single non-active lengthening movement. However, whilst immediately after a passive lengthening movement the inhibition persists for several seconds, there seem to be an immediate recovery following static stretching. This result is counter intuitive and could be attributed to methodological procedures. Indeed, differently to what has been done until now, in order to study whether static stretching has a transient effect on the neuromuscular pathway, the procedure should be repeated many times and measurements collected at different time points after stretching. In the present study we repeated 60 times 30 s static stretching of ankle plantar flexors and measured tap reflex (T-reflex), Hoffman reflex (H-reflex), and motor evoked potentials (MEPs) from the Soleus muscle at several time points, starting from immediately after until 30 s following the procedure. T-reflex was strongly inhibited (range 31-91%, p = 0.005) and the inhibition persisted for 30 s showing a slow recovery (r = 0.541, p = 0.037). H-reflex was not affected by the procedure. Stretching increased the size of the MEPs (p < 0.0001), differences at times 0 and 2 s after stretching (p = 0.015 and p = 0.047, respectively). These results confirm that static stretching reduces muscle spindle sensitivity. Moreover it is suggested that post-activation depression of Ia afferents, which is commonly considered the cause of H-reflex depression during both dorsiflexion and static stretching, vanished immediately following stretching or is counteracted by an increased corticospinal excitability.
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BACKGROUND: Patient compliance with lower limb partial weight bearing (PWB) instructions during post-surgical early mobilization is often low and many are unable to adhere to the prescribed limits without the implementation of concurrent biofeedback. OBJECTIVES: A real-time feedback system based on eSHOE instrumented insoles was tested in order to preliminarily quantify its efficiency at improving geriatric patients' compliance. METHODS: In order to gain a proof of concept, measurements with one patient after a hip fracture were carried out. The compliance with the prescribed load restriction was measured on four measurement dates, first without and then with the feedback. The number of correctly loaded steps (NCS), the mean peak load (MPL) and the maximal load (ML) were considered. RESULTS: Preliminary results of one patient show that NCS was nearly doubled and the MPL was reduced to acceptable limits, while the ML was reduced on three of the four days. CONCLUSION: The results indicate that the developed system is easily implementable into the rehabilitative routine and has a positive effect on PWB performance of geriatric subjects while walking.
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Biorretroalimentación Psicológica , Retroalimentación , Soporte de Peso , Sistemas de Computación , Humanos , CaminataRESUMEN
OBJECTIVES: Rotation of a static magnet over the motor cortex (MC) generates a transcranial alternating magnetic field (tAMF), and a linked alternating electrical field. The aim of this transcranial magnetic stimulation (TMS) study is to investigate whether such fields are able to influence MC excitability, and whether there are parallels to tACS induced effects. METHODS: Fourteen healthy volunteers received 20â¯Hz tAMF stimulation over the MC, over the vertex, and 20â¯Hz tACS over the MC, each with a duration of 15â¯min. TMS assessments were performed before and after the interventions. Changes in motor evoked potentials (MEP), short interval intra-cortical inhibition (SICI) and intra-cortical facilitation (ICF) were evaluated. RESULTS: The tACS and the tAMF stimulation over the MC affected cortical excitability in a different way. After tAMF stimulation MEP amplitudes and ICF decreased and the effect of SICI increased. After tACS MEP amplitudes increased and there were no effects on SICI and ICF. CONCLUSIONS: The recorded single and paired pulse MEPs indicate a general decrease of MC excitability following 15 min of tAMF stimulation. SIGNIFICANCE: The effects demonstrate that devices based on rotating magnets are potentially suited to become a novel brain stimulation tool in clinical neurophysiology.
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Potenciales Evocados Motores/fisiología , Campos Magnéticos , Imanes , Corteza Motora/fisiología , Estimulación Magnética Transcraneal/métodos , Adulto , Estudios Cruzados , Electromiografía/métodos , Femenino , Humanos , Masculino , Método Simple Ciego , Estimulación Magnética Transcraneal/instrumentaciónRESUMEN
Clinical gait analysis contributes massively to rehabilitation support and improvement of in-patient care. The research project eSHOE aspires to be a useful addition to the rich variety of gait analysis systems. It was designed to fill the gap of affordable, reasonably accurate and highly mobile measurement devices. With the overall goal of enabling individual home-based monitoring and training for people suffering from chronic diseases, affecting the locomotor system. Motion and pressure sensors gather movement data directly on the (users) feet, store them locally and/or transmit them wirelessly to a PC. A combination of pattern recognition and feature extraction algorithms translates the motion data into standard gait parameters. Accuracy of eSHOE were evaluated against the reference system GAITRite in a clinical pilot study. Eleven hip fracture patients (78.4 ± 7.7 years) and twelve healthy subjects (40.8 ± 9.1 years) were included in these trials. All subjects performed three measurements at a comfortable walking speed over 8 m, including the 6-m long GAITRite mat. Six standard gait parameters were extracted from a total of 347 gait cycles. Agreement was analysed via scatterplots, histograms and Bland-Altman plots. In the patient group, the average differences between eSHOE and GAITRite range from -0.046 to 0.045 s and in the healthy group from -0.029 to 0.029 s. Therefore, it can be concluded that eSHOE delivers adequately accurate results. Especially with the prospect as an at home supplement or follow-up to clinical gait analysis and compared to other state of the art wearable motion analysis systems.
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Técnicas Biosensibles/instrumentación , Marcha , Zapatos , Adulto , Anciano , Anciano de 80 o más Años , Algoritmos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Procesamiento de Señales Asistido por Computador , Caminata/fisiologíaRESUMEN
NEW FINDINGS: What is the central question of this study? What mediates neural responses following static stretching, and how long do these influences last? What is the main finding and its importance? This study shows that 1 min of static stretching inhibits the tendon tap reflex and facilitates the H reflex without influencing motor-evoked potentials. The results indicate that at least two different mechanisms mediate neural responses after static stretching. The purpose of this study was to determine whether the neural responses observed after static stretching are mediated by sensitivity of muscle spindles, spinal excitability or cortical excitability and how long these influences last. Nineteen volunteers (25.7 ± 5.6 years old) were tested for the tendon tap reflex (T-reflex), H reflex and motor-evoked potentials on ankle flexors and extensors immediately, 5 and 10 min after 1 min static stretching applied at individual maximal ankle dorsiflexion, as well as immediately, 5 and 10 min after a control period of the same duration. Comparison of measurements collected immediately after stretching or control conditions revealed that the T-reflex was weaker after stretching than after control (-59.2% P = 0.000). The T-reflex showed a slow recovery rate within the first 150 s after stretching, but 5 min after the inhibition had disappeared. The H reflex increased immediately after stretching (+18.3%, P = 0.036), showed a quick tendency to recover and returned to control values within 5 min from stretching. Motor-evoked potentials were not affected by the procedure. These results suggest that 1 min of static stretching primarily decreases muscle spindle sensitivity and facilitates the H reflex, whereas effects on the motor cortex can be excluded.
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Reflejo H/fisiología , Corteza Motora/fisiología , Reflejo de Estiramiento/fisiología , Adulto , Tobillo/fisiología , Articulación del Tobillo/fisiología , Potenciales Evocados Motores/fisiología , Femenino , Humanos , Masculino , Contracción Muscular/fisiología , Husos Musculares/fisiología , Músculo Esquelético/fisiologíaRESUMEN
This study examines with transcranial magnetic stimulation (TMS) and with functional magnetic resonance imaging (fMRI) whether 20 min of repetitive peripheral magnetic stimulation (rPMS) has a facilitating effect on associated motor controlling regions. Trains of rPMS with a stimulus intensity of 150% of the motor threshold (MT) were applied over right hand flexor muscles of healthy volunteers. First, with TMS, 10 vs. 25 Hz rPMS was examined and compared to a control group. Single and paired pulse motor evoked potentials (MEPs) from flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles were recorded at baseline (T0), post rPMS (T1), 30 min post (T2), 1 h post (T3) and 2 h post rPMS (T4). Then, with fMRI, 25 Hz rPMS was compared to sham stimulation by utilizing a finger tapping activation paradigm. Changes in bloodoxygen level dependent (BOLD) contrast were examined at baseline (PRE), post rPMS (POST1) and 1 h post rPMS (POST2). With TMS facilitation was observed in the target muscle (FCR) following 25 Hz rPMS: MEP recruitment curves (RCs) were increased at T1, T2 and T3, and intracortical facilitation (ICF) was increased at T1 and T2. No effects were observed following 10 Hz rPMS. With fMRI the BOLD contrast at the left sensorimotor area was increased at POST1. Compared to inductions protocols based on transcutaneous electrical stimulation and mechanical stimulation, the rPMS induced effects appeared shorter lasting.
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Preservation of mobility in conjunction with an independent life style is one of the major goals of rehabilitation after stroke. The Rehab@Home framework shall support the continuation of rehabilitation in the domestic area. The framework consists of instrumented insoles, wireless linked to a tablet PC, a server and a web-interface for medical experts. The rehabilitation progress is estimated via automated analysis of movement data from standardized assessment tests which are executed via the tablet PC application designed according to the needs of stroke patients. Initial evaluation of the analysis algorithms shows reproducible results for the overall time of the Timed Up & Go Test. Therefore it is assumed that the Rehab@Home framework is applicable as monitoring tool for the gait rehabilitation progress in stroke patients.
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Monitoreo Ambulatorio/instrumentación , Rehabilitación de Accidente Cerebrovascular , Telemedicina/métodos , Algoritmos , Manejo de la Enfermedad , Humanos , Internet , Evaluación de la Tecnología Biomédica , Tecnología InalámbricaRESUMEN
Transcranial direct current stimulation (tDCS) protocols applied over the primary motor cortex are associated with changes in motor performance. This transcranial magnetic stimulation (TMS) study examines whether cathodal tDCS prior to motor training, combined with anodal tDCS during motor training improves motor performance and off-line learning. Three study groups (n=36) were trained on the grooved pegboard test (GPT) in a randomized, between-subjects design: SHAM-sham stimulation prior and during training, STIM1-sham stimulation prior and atDCS during training, STIM2-ctDCS stimulation prior and atDCS during training. Motor performance was assessed by GPT completion time and retested 14 days later to determine off-line learning. Cortical excitability was assessed via TMS at baseline (T0), prior training (T1), after training (T2), and 60 min after training (T3). Motor evoked potentials (MEP) were recorded from m. abductor pollicis brevis of the active left hand. GPT completion time was reduced for both stimulated groups compared to SHAM. For STIM2 this reduction in time was significantly higher than for STIM1 and further off-line learning occurred after STIM2. After ctDCS at T1, MEP amplitude and intracortical facilitation was decreased and intracortical inhibition was increased. After atDCS at T2, an opposite effect was observed for STIM1 and STIM2. For STIM2 these neuromodulatory effects were retained until T3. It is concluded that application of atDCS during the training improves pegboard performance and that additional priming with ctDCS has a positive effect on off-line learning. These cumulative behavioral gains were indicated by the preceding neuromodulatory changes.
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Actividad Motora , Corteza Motora/fisiología , Plasticidad Neuronal , Desempeño Psicomotor/fisiología , Estimulación Transcraneal de Corriente Directa/métodos , Adulto , Potenciales Evocados Motores , Femenino , Humanos , Masculino , Músculo Esquelético/fisiología , Adulto JovenRESUMEN
To examine whether afferent stimulation of hand muscles has a facilitating effect on motor performance, learning and cortical excitability, healthy subjects were trained on the grooved pegboard test (GTP) while wearing a mesh glove (MG) with incorporated electrical stimulation. Three study groups (n=12) were compared in a between subjects design, the bare handed (BH), gloved (MG) and gloved with electrical stimulation (MGS) groups. Motor performance was assessed by the GPT completion time across 4 training blocks, and further one block was retested 7 days later to determine the off-line effects. On-line learning was obtained by normalizing the completion time values to the first training block, and off-line learning was obtained by normalizing the retest values to the last training block. Cortical excitability was assessed via single and paired-pulse transcranial magnetic stimulation (TMS) at pre-training, post-training and 30 min post-training. Motor evoked potential recruitment curve, short-latency intracortical inhibition and intracortical facilitation were estimated from the TMS assessments. Motor performance across all 4 training blocks was poor in the MG and MGS groups, while on-line learning was not affected by wearing the glove or by afferent stimulation. However, off-line learning, tested 7 days after training, was improved in the MGS group compared to the MG group. In addition, post-training corticospinal excitability was increased in the MGS group. It can be concluded that afferent stimulation improves off-line learning and thus has a positive effect on motor memory, likely due to LTP-like cortical plasticity in the consolidation phase.
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Potenciales Evocados Motores/fisiología , Guantes Protectores , Mano/fisiología , Memoria , Corteza Motora/fisiología , Plasticidad Neuronal/fisiología , Adolescente , Adulto , Estimulación Eléctrica/métodos , Femenino , Humanos , Masculino , Músculo Esquelético/fisiología , Pruebas Neuropsicológicas , Tiempo de Reacción , Estimulación Magnética Transcraneal , Adulto JovenRESUMEN
INTRODUCTION: Even the most modern technology has failed to induce satisfactory functional regeneration of traumatically severed peripheral nerves. Delayed neural regeneration and in consequence, slower neural conduction seriously limit muscle function in the area supplied by the injured nerve. This study aimed to compare a new nerve coaptation system involving an innovative prosthesis with the classical clinical method of sutured nerve coaptation. Besides the time and degree of nerve regeneration, the influence of electrostimulation was also tested. METHODS: The sciatic nerve was severed in 14 female Göttingen minipigs with an average weight of 40.4 kg. The animals were randomized into 2 groups: One group received the new prosthesis and the other underwent microsurgical coaptation. In each group, according to the randomization a part of the animals received postoperative electrostimulation. Postoperative monitoring and the stimulation schedule covered a period of 9 months, during which axonal budding was evaluated monthly. RESULTS: The data from the pilot study indicate that results with the nerve prosthesis were comparable with those of conventional coaptation. CONCLUSION: The results indicate that implantation of the nerve prosthesis allows for good and effective neural regeneration. This new and simple treatment option for peripheral nerve injuries can be performed in any hospital with surgical facilities as it does not involve the demanding microsurgical suture technique that can only be performed in specialized centers.
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Regeneración Nerviosa/fisiología , Prótesis Neurales , Traumatismos de los Nervios Periféricos/cirugía , Nervios Periféricos/cirugía , Ingeniería de Tejidos/instrumentación , Potenciales de Acción/fisiología , Animales , Ingeniería Biomédica/instrumentación , Terapia por Estimulación Eléctrica , Femenino , Músculo Esquelético/fisiología , Proyectos Piloto , Porcinos , Porcinos EnanosRESUMEN
It has been recently shown that 20 min of mechanical flutter stimulation induces lasting motor cortical excitability changes, as assessed by transcranial magnetic stimulation in relaxed hand muscles. The present functional magnetic resonance imaging (fMRI) study aims to examine if such neuromodulatory changes are reflected in the BOLD signal during a motor test. Therefore, two groups were recruited: one group receiving whole-hand flutter stimulation with a frequency of 25 Hz (FSTIM group, n = 22) and a second group receiving no stimulation (NOSTIM group, n = 22). As motor test finger-to-thumb tapping was performed to activate a wide sensorimotor network during the fMRI measurements. Three fMRI measurements were obtained with this test: before stimulation (PRE), after stimulation (POST1), and 1 h after stimulation (POST2). Three regions of interest (ROIs) were defined: primary motor area (M1), primary somatosensory area (S1), and supplementary motor area. In the absence of baseline differences between both groups, the FSTIM group showed increased movement-related brain activations compared with the NOSTIM group, both at POST1 and POST2. ROI analysis revealed increased blood-oxygenation-level-dependent (BOLD) responses within contralateral S1 (+20%) and M1 (+25%) at POST1, which lasted until POST2. These poststimulatory effects within S1 and M1 obviously reflect neuroplastic changes associated with augmented cortical excitability. These findings are of high clinical relevance, for example, to improve the treatment of stroke patients.
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Corteza Motora/fisiología , Corteza Somatosensorial/fisiología , Adulto , Atención/fisiología , Mapeo Encefálico , Señales (Psicología) , Interpretación Estadística de Datos , Femenino , Dedos/fisiología , Mano/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Red Nerviosa/fisiología , Oxígeno/sangre , Estimulación Física , Desempeño Psicomotor/fisiología , Adulto JovenRESUMEN
OBJECTIVE: In a previous transcranial magnetic stimulation (TMS) study we demonstrated that suprathreshold mesh-glove (MG) whole-hand stimulation elicits lasting changes in motor cortical excitability. Currently, there is no consensus with regard to the optimal parameters for the induction of sensorimotor cortical plasticity using peripheral electrical stimulation. Thus, in the present study we explore the modulatory effects of MG stimulation at different stimulus intensities and different frequencies in order to identify an optimal stimulation protocol. METHODS: MG stimulation was performed on 12 healthy subjects in separate sessions at different stimulation levels: sub-sensory at 50 Hz, sensory at 50 Hz and motor at 2 Hz. To verify if stimulation at lower frequencies is less effective, an additional experiment at sensory level with 2 Hz was performed. TMS was used to assess motor threshold (MT), motor evoked potentials (MEPs) recruitment curve (RC), short latency intracortical inhibition (SICI) and intracortical facilitation (ICF) to paired-pulse TMS at baseline (T0), immediately after (T1) and 1h (T2) after 30 min of MG stimulation. F-wave studies were performed to assess spinal motoneuron excitability. RESULTS: MG stimulation at sub-sensory/50 Hz and sensory/2 Hz level determines no significant cortical excitability changes; at sensory/50 Hz level and at motor/2 Hz level we found decreased MT, increased MEP RC as well as reduced SICI and increased ICF at T1 and T2. CONCLUSIONS: MG stimulation at sensory/50 Hz and motor/2 Hz level induces similar long-lasting modulatory effects on motor cortical excitability. Both the strength of the corticospinal projections and the intracortical networks are influenced to the same extend. SIGNIFICANCE: The study provides further evidence that stimulation intensity and frequency can independently modulate motor cortical plasticity. The selection of optimal stimulation parameters has potentially important implications for the neurorehabilitation of patients after brain damage (e.g. stroke, traumatic brain injury) with hand motor deficits.
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Estimulación Eléctrica , Mano/fisiología , Corteza Motora/fisiología , Adulto , Potenciales Evocados Motores/fisiología , Femenino , Humanos , Masculino , Estimulación Magnética Transcraneal , Adulto JovenRESUMEN
The objective was to investigate if whole-hand mechanical stimulation (MSTIM) in the tapping-flutter frequency range induces outlasting post-stimulus changes in the hand region of the primary motor cortex. MSTIM was delivered to 12 healthy subjects for 20 min using a therapeutic stimulation device (Swisswing BMR 2000). Frequencies of 10 and 25 Hz were tested in separate sessions, and for control additionally the foot sole was stimulated at 25 Hz. Motor evoked potentials (MEPs) after single (recruitment curves) and paired-pulse transcranial magnetic stimulation (TMS) were recorded from FDI and APB muscles of the right hand. TMS assessments were carried out at baseline (T0), immediately after (T1), 30 min (T2), 1 h (T3) and 2 h (T4) after end of MSTIM. After MSTIM with 25 Hz, MEP recruitment curves were increased at all post-stimulation assessments in both muscles. The most significant effect was achieved at T3 (1 h). Intracortical inhibition was decreased within the first hour, while intracortical facilitation was increased at all post-stimulation assessments. No significant effects were found following MSTIM with 10 Hz and following foot vibration. We conclude that 20 min MSTIM with a frequency of 25 Hz induces outlasting plastic changes in the primary motor cortex. Paired-pulse stimulation further confirms that intrinsic intracortical mechanisms are involved in these changes. Spinal adaptation could be excluded (F-wave assessments). These results could be of relevance for hemiplegic patients with motor deficits, to improve the rehabilitation outcome with vibration exercise in combination with motor training.
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Potenciales Evocados Motores/fisiología , Mano/fisiología , Corteza Motora/fisiología , Músculo Esquelético/fisiología , Adulto , Estimulación Eléctrica/métodos , Electromiografía/métodos , Ejercicio Físico/fisiología , Femenino , Pie/fisiología , Mano/inervación , Humanos , Masculino , Contracción Muscular/fisiología , Estimulación Magnética Transcraneal/métodos , VibraciónRESUMEN
For quantitative somatosensory testing in the clinical environment a microprocessor controlled MR-compatible stimulation device was developed. A main feature of this device is the use of an inflatable cuff allowing the application of defined test pressures (0-1000 mbar) to the skin surface. The cuff is pressurized by a piezoelectric proportional valve with embedded closed loop controller. The distortion of the pressure pulses, introduced by the tube between valve and cuff (tube lengths of 2 and 6 m), was evaluated. Two kinds of stimulation patterns were implemented by the microprocessor: constant frequency stimulation (selectable between 1 and 20 Hz) and stimulation with stepwise changing frequencies according to a pseudorandom sequence. Imaging tests (n=8, index finger) showed more robust responses in S1 (contralateral) and S2 (bilaterally) if evoked by the random sequence. Both, the technical tests and the imaging results, demonstrate that this new stimulation system is well suited to set a standard for somatosensory stimulation in individual longitudinal studies or multicenter comparisons.