RESUMO
Spasticity is a sensorimotor disorder widely recognized as one of the features that contribute to patients' disability. Transcutaneous electric neural stimulation (TENS/SES) has been adopted in spasticity rehabilitation as an alternative to pharmacological agents. Although previous studies have reported clinical benefits of TENS/SES in relieving spasticity, there is no clarity on how and whether this therapeutic modality affects specific neural circuitries. Thus, this systematic review aimed to verify the efficacy of TENS/SES in the control of spasticity and its consequences in spinal and corticospinal excitability. This study was carried out according to PRISMA recommendations using SCOPUS, PubMed, BVS, Google Scholar and BASE databases screening, which provided 483 references. Six additional records were found from other sources. All these records were submitted to a filtering process following the eligibility criteria, and 44 studies were selected for further analysis. Ten were replicas. Consequently, 34 studies were read in full with the aim of checking their eligibility criterion, which resulted in 10 manuscripts for qualitative synthesis. Even though they evaluated the effects of TENS/SES both at the spinal and/or corticospinal levels, the electrophysiological results seem to be inconsistent, corroborating the lack of agreement between them and with clinical outcomes.
Assuntos
Espasticidade Muscular/terapia , Estimulação Elétrica Nervosa Transcutânea/métodos , Humanos , Resultado do TratamentoRESUMO
Evidence suggests that somatosensory electrical stimulation (SES) may decrease the degree of spasticity from neural drives, although there is no agreement between corticospinal modulation and the level of spasticity. Thus, stroke patients and healthy subjects were submitted to SES (3 Hz) for 30' on the impaired and dominant forearms, respectively. Motor evoked potentials induced by single-pulse transcranial magnetic stimulation were collected from two forearm muscles before and after SES. The passive resistance of the wrist joint was measured with an isokinetic system. We found no evidence of an acute carry-over effect of SES on the degree of spasticity.
Assuntos
Potencial Evocado Motor/fisiologia , Músculo Esquelético/fisiologia , Acidente Vascular Cerebral/fisiopatologia , Estimulação Elétrica , Humanos , Projetos Piloto , Estimulação Magnética Transcraniana , PunhoRESUMO
BACKGROUND: Contemporary theories of motor control propose that motor planning involves the prediction of the consequences of actions. These predictions include the associated costs as well as the rewarding nature of movements' outcomes. Within the estimation of these costs and rewards would lie the valence, that is, the pleasantness or unpleasantness of a given stimulus with which one is about to interact. The aim of this study was to test if motor preparation encompasses valence. METHODOLOGY/PRINCIPAL FINDINGS: The readiness potential, an electrophysiological marker of motor preparation, was recorded before the grasping of pleasant, neutral and unpleasant stimuli. Items used were balanced in weight and placed inside transparent cylinders to prompt a similar grip among trials. Compared with neutral stimuli, the grasping of pleasant stimuli was preceded by a readiness potential of lower amplitude, whereas that of unpleasant stimuli was associated with a readiness potential of higher amplitude. CONCLUSIONS/SIGNIFICANCE: We show for the first time that the sensorimotor cortex activity preceding the grasping of a stimulus is affected by its valence. Smaller readiness potential amplitudes found for pleasant stimuli could imply in the recruitment of pre-set motor repertoires, whereas higher amplitudes found for unpleasant stimuli would emerge from a discrepancy between the required action and their aversiveness. Our results indicate that the prediction of action outcomes encompasses an estimate of the valence of a stimulus with which one is about to interact.
Assuntos
Emoções/fisiologia , Força da Mão/fisiologia , Adolescente , Adulto , Córtex Cerebral/fisiologia , Eletroencefalografia , Humanos , Masculino , Adulto JovemRESUMO
The authors collected and compared mechanomyo-graphic (MMG) signal behavior from the biceps brachii of left and right arms of right-handed men (n = 19) and women (n = 20) who performed isometric contractions at 5 contraction levels. Mean frequency (MF) and RMS values were calculated from the MMG signals that arose from lateral oscillations of muscle fibers. Across genders and arms, RMS values increased with contraction level and MF values decreased with increase in muscle contraction. The authors found no significant difference in those parameters between dominant and nondominant arms. Therefore, summation of muscle twitches obtained from the MMG signal collected in biceps brachii muscle does not reveal any difference between dominant and nondominant arms.
Assuntos
Braço/fisiologia , Lateralidade Funcional/fisiologia , Contração Isométrica/fisiologia , Movimento/fisiologia , Músculo Esquelético/fisiologia , Adolescente , Adulto , Análise de Variância , Eletromiografia/métodos , Feminino , Humanos , Masculino , Valores de Referência , Estresse MecânicoRESUMO
The ability to identify safety and danger is critical to survival. However, not much is known about human somatic body reactions in these contexts. We performed a posturographic study comparing body reactions to the sight of pictures of smiling babies and families (affiliative) versus matched neutral people, and to pictures depicting body envelope violations (mutilation) versus matched neutral people. The participants stood on a force platform and heart rate and displacement of the center of pressure were recorded while the pictures were presented. Pictures of mutilation induced a freezing-like reaction consisting of a medial-lateral (M-L) decrease in the amplitude of sway (immobility) and increase of the mean power frequency (rigidity), associated with bradycardia. Affiliative stimuli also induced an immobility and rigidity behavior but in the anterior-posterior (A-P) axis. This resembles the "immobility-without-fear reaction" proposed to occur when, upon detection of safety cues, mammals including humans are involved in pro-social activities. We conclude that the sight of visual cues of affiliation and danger produce distinct body somatic reactions.
Assuntos
Emoções/fisiologia , Equilíbrio Postural/fisiologia , Postura/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Eletroencefalografia/métodos , Feminino , Humanos , Masculino , Estimulação Luminosa/métodosRESUMO
Mental simulation of movements has been widely used to infer about representational aspects of action. On a daily basis, motor planning and execution depends crucially both upon vision and kinesthesia. What if the former is lost? In this study we investigate the physiological changes induced during a mental simulation task in subjects with early and late onset blindness, analyzing simultaneously stabilometric (body sway), electromyographic (EMG, lateral gastrocnemius) and eletrocardiographic (ECG) signals. Subjects were asked to stand up on a force platform and instructed either to: rest during 20s; count mentally from 1 to 15; imagine themselves executing a bilateral plantar flexion 15 times and execute the same movement 15 times. Discriminant analysis was employed to have access to the differences in the groups with respect to heart rate variability (HRV), EMG and body sway measurements for each condition. We found an overall correct classification of 100 and 90.9%, respectively, for the stabilometric parameters and HRV. This result was found only for the mental simulation task (p<0.05), being absent for resting, counting and executing. Previous studies have shown that motor simulation in a kinesthetic mode strongly associates with somatic and autonomic changes. In late blind subjects, however, movement simulation would tend to unfold with the use of both visual and kinesthetic representations. Thus, our results suggest that early and late blind subjects make use of distinct body representations during motor imagery.