RESUMO
Quadriplegic subjects present extensive muscle mass paralysis which is responsible for the dramatic decrease in bone mass, increasing the risk of bone fractures. There has been much effort to find an efficient treatment to prevent or reverse this significant bone loss. We used 21 male subjects, mean age 31.95 ± 8.01 years, with chronic quadriplegia, between C4 and C8, to evaluate the effect of treadmill gait training using neuromuscular electrical stimulation, with 30-50 percent weight relief, on bone mass, comparing individual dual-energy X-ray absorptiometry responses and biochemical markers of bone metabolism. Subjects were divided into gait (N = 11) and control (N = 10) groups. The gait group underwent gait training for 6 months, twice a week, for 20 min, while the control group did not perform gait. Bone mineral density (BMD) of lumbar spine, femoral neck, trochanteric area, and total femur, and biochemical markers (osteocalcin, bone alkaline phosphatase, pyridinoline, and deoxypyridinoline) were measured at the beginning of the study and 6 months later. In the gait group, 81.8 percent of the subjects presented a significant increase in bone formation and 66.7 percent also presented a significant decrease of bone resorption markers, whereas 30 percent of the controls did not present any change in markers and 20 percent presented an increase in bone formation. Marker results did not always agree with BMD data. Indeed, many individuals with increased bone formation presented a decrease in BMD. Most individuals in the gait group presented an increase in bone formation markers and a decrease in bone resorption markers, suggesting that gait training, even with 30-50 percent body weight support, was efficient in improving the bone mass of chronic quadriplegics.
Assuntos
Humanos , Masculino , Aminoácidos , Densidade Óssea , Terapia por Estimulação Elétrica , Terapia por Exercício , Osteoporose/prevenção & controle , Quadriplegia/reabilitação , Absorciometria de Fóton , Fosfatase Alcalina/sangue , Biomarcadores/sangue , Estudos de Casos e Controles , Doença Crônica , Osteocalcina/sangueRESUMO
Blood pressure pattern was analyzed in 12 complete quadriplegics with chronic lesions after three months of treadmill gait training. Before training, blood pressure values were obtained at rest, during treadmill walking and during the recovery phase. Gait training was performed for 20 min twice a week for three months. Treadmill gait was achieved using neuromuscular electrical stimulation, assisted by partial body weight relief (30-50 percent). After training, blood pressure was evaluated at rest, during gait and during recovery phase. Before and after training, mean systolic blood pressures and heart rates increased significantly during gait compared to rest (94.16 ± 5.15 to 105 ± 5.22 mmHg and 74.27 ± 10.09 to 106.23 ± 17.31 bpm, respectively), and blood pressure decreased significantly in the recovery phase (86.66 ± 9.84 and 57.5 ± 8.66 mmHg, respectively). After three months of training, systolic blood pressure became higher at rest (94.16 ± 5.15 mmHg before training and 100 ± 8.52 mmHg after training; P < 0.05) and during gait exercise (105 ± 5.22 mmHg before and 110 ± 7.38 mmHg after training; P < 0.05) when compared to the initial values, with no changes in heart rate. No changes occurred in blood pressure during the recovery phase, with the lower values being maintained. A drop in systolic pressure from 105 ± 5.22 to 86.66 ± 9.84 mmHg before training and from 110 ± 7.38 to 90 ± 7.38 mmHg after training was noticed immediately after exercise, thus resulting in hypotensive symptoms when chronic quadriplegics reach the sitting position from the upright position.
Assuntos
Adulto , Humanos , Masculino , Pressão Sanguínea/fisiologia , Terapia por Estimulação Elétrica/métodos , Terapia por Exercício/métodos , Marcha/fisiologia , Quadriplegia/reabilitação , Débito Cardíaco/fisiologia , Frequência Cardíaca/fisiologia , Quadriplegia/fisiopatologia , Descanso/fisiologia , Fatores de TempoRESUMO
Neuromuscular electrical stimulation (NMES) has been used in upper limb rehabilitation towards restoring motor hand function. Quantitative evaluation of the artificially generated movement is necessary to achieve proper muscle activation. Custom-made gloves instrumented with force and position transducers were used to evaluate artificial quadriplegic grasping for a drinking activity. In spite of different sensor position, stimulation parameter dependence and lack of repeatability, grasp patterns achieved with the application of NMES follow the same patterns previously obtained with normal subjects, regarding force distribution among fingers and the shape of force curves. Larger forces were exerted by the thumb (average ranged from 2.8 to 4.5 N) following by index or long finger (average ranged from 1.8 to 3 N). The forces exerted ranged within the same interval as those previously measured and were sufficient to grasp an object of 10 N. Finger position achieved by interphalangeal joint status indicated the opening size of the hand throughout the range of movement. The instrumented gloves offer an alternative force and position feedback system for use in cylindrical grasp evaluation. The gloves can be used in a closed-loop control system, allowing on-line adjustment or in a clinical application to evaluate the results of a rehabilitation programme.
Assuntos
Terapia por Estimulação Elétrica , Força da Mão , Quadriplegia/reabilitação , Biorretroalimentação Psicológica , Fenômenos Biomecânicos , Estudos de Avaliação como Assunto , HumanosRESUMO
Although many efforts have been put forth, fecal incontinence of colostomates is still an unsolved problem. Among the techniques available to improve continence, the use of electromagnetic/mechanical power has not been explored. Our work looks at the characteristics needed by the components of an artificial sphincter where the power of sphincteric muscles is substituted with electromagnetic/mechanical power, and the mechanical absence of muscles is replaced by a plastic band. Experimental work was done with isolated colon of 26 mongrel dogs, and all of them became continent by an intraluminal gas pressure over 80 mm Hg when a final perimeter between 3.7 and 4.7 cm was reached. No macroscopic lesions were noted on the guts' surface beneath the plastic band. The largest band displacement was 4.2 cm, and the traction force was under 50 N.
Assuntos
Colostomia , Próteses e Implantes , Animais , Cães , Estimulação Elétrica , Estudos de ViabilidadeRESUMO
With the goal of investigating artificial proprioception elicited by electrical stimulation, we have developed a tactile phi phenomenon-based stimulator. This two-channel microprocessed pulse amplitude modulation system generates two different envelope waveforms (triangular and elliptical) and allows programming and visualizing of its main parameters: pulse with (0.1-10 ms), pulse frequency (0.1-10 kHz), modulation frequency (0.3-10 Hz), current intensity (up to 20 mA), and the amplitude modulation index (0-100%). In vivo experiments with 5 normal persons have shown that it is possible to elicit a moving fused phantom image with good resolution. A triangular envelope is good for straight line sensations while the elliptical one is more comfortable and has better resolution for all kinds of moving images.
Assuntos
Estimulação Elétrica , Propriocepção , Auxiliares Sensoriais , Biorretroalimentação Psicológica , Simulação por Computador , HumanosRESUMO
The use of neuromuscular electrical stimulation for restoration of gait in spinal cord injured subjects has been seriously pursued by many investigators for the past 15 years. By and large, however, systems to date require the intervention of a person, be it the patient or an observer, and are restricted to control of stimulation onset and termination. Further, existing systems are not adaptable to environmental and patient variations. This work proposes a system that relies on neural computing to determine proper muscle activation patterns from biomechanical signals. The intelligent system is trained to perform gait under supervision, after which it can be used to control muscle stimulation in an unknown environment. Computer simulations suggest that the best neural architecture for control of gait is a neural network including units corresponding to movement history. Separate networks for the stance and swing phases, respectively, were found to work better than a single neural network trained on the entire gait cycle. The artificial neural device proposed here also includes a voice recognition system that will allow for voluntary locomotion. A safety circuit has been designed to preclude acceptance of unwanted vocal commands in the latter system.
Assuntos
Estimulação Elétrica , Locomoção , Redes Neurais de Computação , Simulação por Computador , Marcha , Humanos , Músculo Esquelético/fisiologia , VozRESUMO
The use of neuromuscular electrical stimulation (NMES) for rehabilitation of gait in spinal patients is widely known. The best results can be obtained with the use of biomechanical sensors and a closed loop NMES system. One of the biggest problems faced in the design of control systems for closed-loop operation, in gait rehabilitation, is the variation of the mechanical conditions during the phases of gait. This work presents a new approach to ease the design of rule-based closed loop systems for operation in conditions such as gait rehabilitation.