Right in Comparison to Left Cerebral Hemisphere Damage by Stroke Induces Poorer Muscular Responses to Stance Perturbation Regardless of Visual Information.

OBJECTIVE: Fast and scaled muscular activation is required to recover body balance following an external perturbation. An issue open to investigation is the extent to which the cerebral hemisphere lesioned by stroke leads to asymmetric deficits in postural reactive responses. In this experiment, we aimed to compare muscular responses to unanticipated stance perturbations between individuals who suffered unilateral stroke either to the right or to the left cerebral hemisphere. METHODS: Stance perturbations were produced by releasing a load attached to the participant's trunk, inducing fast forward body oscillation. Electromyography was recorded from the gastrocnemius medialis and biceps femoris muscles. Muscular activation from age-matched healthy individuals was taken as reference. RESULTS: Analysis indicated that damage to the right hemisphere induced delayed activation onset, and lower rate and magnitude of activation of the proximal and distal muscles of the paretic leg. Those deficits were associated with stronger activation of the nonparetic leg. Comparisons between left hemisphere damage and controls showed deficits limited to activation of the biceps femoris of the paretic leg. Manipulation of visual information led to no significant effects on muscular responses. CONCLUSIONS: These results suggest that right cerebral hemisphere damage by stroke leads to more severe deficits in the generation of reactive muscular responses to stance perturbation than damage to the left cerebral hemisphere regardless of visual information.

Young and older adults adapt automatic postural responses equivalently to repetitive perturbations but are unable to use predictive cueing to optimize recovery of balance stability.

Processing of contextual cues has been proposed to modulate the generation of automatic postural responses to unanticipated balance perturbations. In this investigation, we compared young and older individuals in responses to sudden rotations of the support base inducing either planti- or dorsiflexion of the ankles. Assessment was made in conditions resulting from the combination of visual directional cueing of the forthcoming platform rotation, and block versus random sequences of platform rotation directions. Results showed that, for both rotation directions, the block sequence led to reduced magnitude of activation of distal agonist muscles and direction-specific modulation of ground reaction forces to recover body balance. Visual directional cueing, conversely, failed to modulate either muscular responses or forces applied to the support base through the feet for balance recovery. Effects were similar between ages, suggesting that aging does not increase the influence of cognition on the generation of automatic postural responses, and that adaptation to repeated postural perturbations over trials is preserved in healthy older individuals.

Light touch leads to increased stability in quiet and perturbed balance: Equivalent effects between post-stroke and healthy older individuals.

Cerebral damage provoked by stroke may lead to deficits of quiet balance control and of the recovery of body equilibrium following an unanticipated postural perturbation. In this investigation we aimed to evaluate the effect of light touch (LT) of an earth-fixed surface on balance stability in individuals with post-stroke hemiparesis, taking performance of age-matched healthy participants as reference. Evaluations were made in conditions of full and no visual information. Analysis of quiet balance showed that LT induced higher balance stability, with reduced amplitude and velocity of postural sway. Evaluation of the effect of LT on automatic postural responses was made in the task of recovering body equilibrium following a mechanical perturbation of balance leading to fast forward body sway. Results showed that LT led to reduced amplitude of center of mass displacement following the perturbation, in addition to reduced amplitude and velocity of center of pressure under the feet, and lower activation of the lower legs muscles. Those effects of LT were observed in both the post-stroke and control groups, and did not interact with vision availability. Our results indicated then that individuals who suffered a cerebral stroke can stabilize perturbed and non-perturbed postural responses by lightly touching a stable surface to a similar extent of healthy older individuals.

Right cerebral hemisphere specialization for quiet and perturbed body balance control: Evidence from unilateral stroke.

Our aim in this investigation was to assess the relative importance of each cerebral hemisphere in quiet and perturbed balance, based on uni-hemispheric lesions by stroke. We tested the hypothesis of right cerebral hemisphere specialization for balance control. Groups of damage either to the right (RHD, n=9) or the left (LHD, n=7) cerebral hemisphere were compared across tasks requiring quiet balance or body balance recovery following a mechanical perturbation, comparing them to age-matched nondisabled individuals (controls, n=24). They were evaluated in conditions of full and occluded vision. In Experiment 1, the groups were compared in the task of quiet standing on (A) rigid and (B) malleable surfaces, having as outcome measures center of pressure (CoP) amplitude and velocity sway. In Experiment 2, we evaluated the recovery of body balance following a perturbation inducing forward body oscillation, having as outcome measures CoP displacement, peak hip and ankle rotations and muscular activation of both legs. Results from Experiment 1 showed higher values of CoP sway velocity for RHD in comparison to LHD and controls in the anteroposterior (rigid surface) and mediolateral (malleable surface) directions, while LHD had lower balance stability than the controls only in the mediolateral direction when supported on the rigid surface. In Experiment 2 results showed that RHD led to increased values in comparison to LHD and controls for anteroposterior CoP displacement and velocity, time to CoP direction reversion, hip rotation, and magnitude of muscular activation in the paretic leg, while LHD was found to differ in comparison to controls in magnitude of muscular activation of the paretic leg and amplitude of mediolateral sway only. These results suggest that damage to the right as compared to the left cerebral hemisphere by stroke leads to poorer postural responses both in quiet and perturbed balance. That effect was not altered by manipulation of sensory information. Our findings suggest that the right cerebral hemisphere plays a more prominent role in efferent processes responsible for balance control.

Light touch modulates balance recovery following perturbation: from fast response to stance restabilization.

Light fingertip touch of a static bar generates extra somatosensory information used by the postural control system to reduce body sway. While the effect of light touch has been studied in quiet stance, less attention has been given to its potential benefit for reactive postural responses. In the present study, we tested the effect of light fingertip touch of a stable surface on recovery of postural stability from a mechanical perturbation. Participants stood upright on a force plate touching a static rigid bar while being pulled backward by a load. Unpredictable release of the load induced fast anterior body sway, requiring a reactive response to recover balance. Effect of light touch on postural responses was assessed as a function of vision and malleability of the support surface, analyzing different epochs ranging from the pre-perturbation period to recovery of a relatively stable quiet stance. Results showed that light touch induced lower magnitude of muscular activation in all epochs. Center of pressure (CoP) displacement/sway was affected by interaction of light touch with manipulation of the other sensory information. For the periods associated with quiet stance, light touch led to decreased CoP sway in the malleable surface in the pre-perturbation epoch, and in the condition combining no vision and malleable surface in the balance restabilization and follow-up quiet stance epochs. For the fast reactive response epoch, light touch induced smaller amplitude of CoP displacement across conditions, and lower CoP maximum velocity in the condition combining no vision and rigid surface. These results showed that light touch modulates postural responses in all epochs associated with an unanticipated mechanical perturbation, with a more noticeable effect in conditions manipulating sensory information relevant for balance control.

Precueing time but not direction of postural perturbation induces early muscular activation: comparison between young and elderly individuals.

In this study, we evaluated the effect of precueing characteristics of an impending perturbation to upright stance on reactive responses of distal leg muscles. Young and older individuals were compared in a task of recovering stable upright stance following rotation of the supporting platform to induce anterior or posterior body sway. Directions of the supporting platform rotation were randomized across trials. Immediately before postural perturbation participants were cued about direction and/or time of platform rotation, or performed the task under directional and temporal uncertainty of the impending perturbation. Results showed that precueing time of perturbation led to earlier muscular activation onset, while precueing perturbation direction did not modulate either latency or magnitude of muscular activation. Those effects were similar between age groups. Our findings suggest that awareness of the perturbation time favored shorter response latencies in both the young and older individuals.

Aging increases flexibility of postural reactive responses based on constraints imposed by a manual task.

This study compared the effect of stability constraints imposed by a manual task on the adaptation of postural responses between 16 healthy elderly (mean age = 71.56 years, SD = 7.38) and 16 healthy young (mean age = 22.94 years, SD = 4.82) individuals. Postural stability was perturbed through unexpected release of a load attached to the participant's trunk while performing two versions of a voluntary task: holding a tray with a cylinder placed with its flat side down (low constraint) or with its rolling round side down (high constraint). Low and high constraint tasks were performed in alternate blocks of trials. Results showed that young participants adapted muscular activation and kinematics of postural responses in association with previous experience with the first block of manual task constraint, whereas the elderly modulated postural responses based on the current manual constraint. This study provides evidence for flexibility of postural strategies in the elderly to deal with constraints imposed by a manual task.

Alterações dos parâmetros da marcha e déficit sensório-motor associado à neuropatia diabética periférica / Changes in gait parameters and sensory-motor deficit associated with peripheral diabetic neuropathy

Quando há dano no sistema nervoso periférico, com prejuízos sensoriais e motores, como observado em neuropatas diabéticos, podem ocorrer graves repercussões sobre o equilíbrio e a locomoção nesta população. Objetivo: Avaliar o desempenho da marcha e alterações sensório-motoras, decorrentes da neuropatia diabética periférica. Método: Participaram 24 indivíduos neuropatas diabéticos e 28 indivíduos saudáveis sem alterações glicêmicas indicativas de diabete. Osparticipantes foram submetidos inicialmente a avaliações clínicas para confirmação de diagnóstico de neuropatia diabética por meio de teste de sensibilidade tátil da sola dos pés com monofilamentos. Posteriormente, foram submetidos à avaliação da variação angular do tornozelo, em condição estática e durante a marcha, por meio de cinemetria. A força muscular do tornozelo foi investigada por meio de dinamometria digital. Resultados: Foi demonstrado maior duração nos períodos deduplo apoio e apoio total da marcha em indivíduos com neuropatia diabética quando comparados com o grupo controle, confirmando uma maior dificuldade no equilíbrio dinâmico destes indivíduos. Para o grupo experimental de indivíduos neuropatas foi evidenciado redução da força muscular, tanto para os músculos dorsiflexores, quanto para os plantiflexores de tornozelo. Conclusão: As perdas sensório-motoras decorrentes da NDP podem implicar em prejuízo no desempenho da marcha, com consequente perda de equilíbrio.

Peripheral nervous system impairment, with sensory and motor loss, as observed in diabetic neuropathy, can induce serious effects on balance control and gait in this population. Objective: To evaluate the performance of the gait and the sensory-motor changes, stemming from peripheral diabetic neuropathy (PDN). Method: Twenty-four individuals with PDN participated along with twenty-eight healthy individuals with no glycemic alterations indicative of diabetes. Participants were first subjected to clinical evaluations to confirm the clinical diagnosis of diabetic neuropathy by testing the tactile sensitivity of the soles of the feet with a monofilament test. Subsequently, ankle angle variations in static posture and during the gait were investigated through kinematics. The ankle muscle strength was investigated using a digital dynamometer. Results: The diabetic neuropathy group showed longer duration in double support and full support periods of gait than the control group, confirming greater difficulty in dynamic balance for these individuals. The group with neuropathy demonstrated reduced muscle strength, as much in the dorsiflexors as in the plantar flexors of the ankle. Conclusion: The sensory-motor losses stemming from PDN may cause impairment in gait performance, with consequent loss of balance.

Muscle strength and ankle mobility for the gait parameters in diabetic neuropathies.

AIMS: To evaluate the spatio-temporal variables of gait and the isometric muscle strength component of the ankle in patients with peripheral diabetic neuropathy. Also, verify the relationship between these variables and gait parameters. METHODS: This study involved 25 diabetic peripheral neuropathy (DPN) participants (62.4±8.36 years) and 27 age-matched healthy control individuals (64.48±6.21 years). The assessment of the spatio-temporal parameters of gait was performed using an electronic baropodometry treadmill. Prior to the collection data, each participant was instructed to walk on the treadmill in her/his habitual self-selected speed. RESULTS: Diabetic neuropathy group showed impairment of gait, with a smaller stride and length speed of the cycle, and increased duration of support time. Restricted dorsiflexion mobility and increased plantarflexion mobility were found, with a decrease in muscle strength of the dorsiflexors and plantiflexors. There was a significant relationship between plantiflexor muscle strength and the length and speed of the gait cycle. Also the muscle strengths of the plantiflexors and dorsiflexors, and the range of motion of dorsiflexion were predictors of gait performance. CONCLUSIONS: The ankle, muscle strength and ankle mobility variables could explain changes in gait speed and range of motion in patients with DPN, allowing for the application of preventive strategies.

Força muscular isométrica nas neuropatias diabética e hansênica / Isometric muscle strength on diabetic and leprosy neuropathies

Este estudo tem por objetivo avaliar a força muscular do tornozelo de portadores de hanseníase ou diabetes mellitus acometidos por neuropatia periférica (NP), comparando-os com sujeitos sadios e, assim, verificar se NPs com fisiopatologias distintas culminam em déficit muscular semelhante. Cinquenta indivíduos (60,72 ± 8,36 anos de idade), sendo 21 do grupo diabético (GD), nove do grupo hansênico (GH) e 20 do grupo controle (GC), participaram do estudo. Inicialmente coletou-se os dados gerais, seguido do teste de sensibilidade somatossensitiva com os monofilamentos Semmes-Weinstein da Sorri-Bauru® e, por fim, realizou-se o teste de força muscular do tornozelo, por meio de dinamômeto isométrico digital. No GD e no GH houve insensibilidade ao monofilamento de 10g, confirmando a presença de NP. A dinamometria muscular, em ambos os tornozelos acusou déficits da força muscular de dorsiflexores e plantiflexores no GD e mais acentuadamente no GH em comparação ao GC. A plantiflexão apontou alterações mais significantes porque, além de referir alteração da variável em relação ao GC, também indicou diminuição da força muscular do GH em relação ao GD. Ao final, verificou-se diminuição da força muscular do tornozelo de neuropatas, no entanto, esse déficit divergiu entre os grupos analisados sugerindo-se, assim, que o motivo da alteração pode estar relacionado à sua respectiva etiopatologia, uma vez que os dados indicaram maior agressividade da NP hansênica no comprometimento neuromuscular em relação à NP diabética. Torna-se evidente, portanto, considerar esse fator no planejamento de intervenções.

This study aims to evaluate ankle muscle strength in patients with leprosy or diabetes mellitus with peripheral neuropathy (PN), when compared to healthy subjects, and thus verify if PNs with different patho-physiologies culminate in similar muscular deficit. Fifty subjects (60.72 ± 8.36 years old), 21 of them from the diabetic group (DG), nine from the leprosy group (LG) and 20 from the control group (CG), have participated in the study. Initially, general data were collected, followed by the somatosensory test with Semmes-Weinstein monofilament (SORRI-BAURU®) and, finally, the ankle muscle strength was tested using an isometric digital dynamometer. In DG and LG groups, no sensitivity was found for the 10-g monofilament, confirming the PN diagnosis. The muscle dynamometry, in both ankles, presented strength deficits of the dorsal and plantar flexors in DG and more markedly in LG, when compared to CG. The deficit in plantar flexion was more significant because, in addition to demonstrating deficit in relation to the CG, it has also showed decreased muscle strength from LG in relation to DG. In the end, a decreased ankle muscle strength of subjects with neuropathy was noticed; however, this deficit differed among the groups suggesting, therefore, that the reason for such change may be related to their respective aetiopathology, since the data indicated more neuromuscular aggression in leprosy PN in relation to diabetic PN. Thus, this fact can be clearly considered when planning interventions.

Análise do alinhamento dos membros inferiores em crianças com excesso de peso / Analysis of lower limb alignment in overweight children

O sobrepeso e a obesidade (SO) têm atingido proporções epidêmicas, principalmente, em idade escolar, tornando-se um problema mundial de saúde. Muitas adaptações podem ocorrer na organização postural de crianças com SO, provocando, graves consequências. A avaliação postural pode colaborar para o entendimento destas alterações. Oobjetivo do presente estudo foi verificar alterações na postura dos membros inferiores de crianças com SO, através de metodologia específica. Vinte e dois indivíduos, sendo distribuídos de acordo com o sexo: 9 do feminino e 13 do masculino, com faixa etária entre 5-9anos, participaram do estudo. Na avaliação postural, foram utilizados a fotogrametria e o software SAPo. Foram analisados os ângulos articulares dos membros inferiores e a projeção plantar do centro de gravidade. Foi utilizada estatística não-paramétrica descritiva, alémdos testes de Kruskal-Wallis e de Mann-Whitney (p<0,05), para comparação entre os sexos. Ambos os sexos apresentaram anteroversão e leve rotação pélvica, à direita para o feminino e à esquerda para o masculino hiperextensão e valgismo de joelhos e valgismo tornozelos. O centro de gravidade apresentou 26,95% de anteriorização. Conclui-se que a avaliação postural nessa população foi congruente aos achados da literatura e a metodologia utilizadapossibilitou quantificar os dados para futuras comparações.

Overweight and obesity have reached epidemic proportions, especially among schoolchildren, and have become a global health problem. Many adaptations in postural organization are observed in overweight and obese children, which have serious consequences. Posture assessmentcontributes to the understanding of these changes. The aim of this study was to assess changes in lower limb posture of overweight and obese children using a specific method. Twenty-two subjects, 9 girls and 13 boys, aged 5-9 years participated in the study. Posture was assessed byphotogrammetry using the SAPo software. The lower limb joint angles and plantar projection of the center of gravity were analyzed. Nonparametric and descriptive statistics were used, in addition to the Kruskal-Wallis and Mann-Whitney tests (p < 0.05) for comparison between genders. Both groups showed anterior pelvic tilt and slight rotation (to the right in girls and to the left in boys), hyperextension, and valgus knees and ankles. The center of gravity presented 26.95% anteriorization. In conclusion, posture assessment in this population was consistent with literature findings and the method used permitted the quantification of data for future comparisons.

Stretch injuries of skeletal muscles: experimental study in rats' soleus muscle / Lesión por estiramiento de los músculos esqueléticos: estudio experimental con el músculo soleus de ratas

The study aimed to verify the physiological injury behavior by stretching the soleus muscle of rats, using a noninvasive experimental model. Twenty-four rats were used and divided into three groups of eight animals: control group (A), group that performed tetanus followed by electrical stimulation and a sudden dorsiflexion of the left paw performed by a device equipped with a mechanism of muscle soleus rapid stretching (B); and a group that only received the tetanus (C). Three days later, the animals were killed, and the soleus muscle was resected and divided into three segments. Morphological changes indicative of muscle damage appeared in all three segments of group B. In a lesser degree, similar changes were also detected in muscles subjected to only tetanus. This model was effective; reproducing an injury similar to what occurs in human sports injuries.

El estudio tuvo como objetivo verificar el comportamiento fisiológico de la lesión por estiramiento de los músculos soleos de ratas, utilizando un modelo experimental no invasivo. Veinticuatro ratas se utilizaron y se dividieron en tres grupos de ocho animales: Grupo A control; Grupo B se realiza tetanización por la estimulación eléctrica seguida de una repentina flexión dorsal de la pierna izquierda, realizado por un dispositivo equipado con un mecanismo rápido de estiramiento del músculo sóleo y Grupo C los animales sólo recibieron la tetanización. Tres días después, los animales fueron sacrificados, el músculo sóleo fue resecado y dividido en tres segmentos. Cambios morfológicos indicativos de daño muscular aparecieron en los tres segmentos del grupo B. En menor grado, cambios similares se detectaron en los músculos sometidos solamente al tetanización. El modelo fue eficaz, la reproducción de la lesión fue similar a lo que ocurre en las lesiones deportivas humanas.

Avaliação do complexo do ombro em mulheres submetidas à intervenção cirúrgica para tratamento de câncer de mama / Assessing of the shoulder complex in women submitted to surgical intervention for breast cancer treatment

A cirurgia de câncer de mama está associada, em torno de 70% dos casos, a complicações que podem levar à limitação e diminuição da mobilidade do ombro. Considerando as alterações decorrentes das cirurgias mamárias, o objetivo deste estudo foi realizar uma avaliação física do ombro homolateral e contralateral à cirurgia, comparando os resultados obtidos nos dois ombros. Este estudo foi realizado com 21 mulheres submetidas à mastectomia ou quadrandectomia unilateral, incluídas, pelo menos há seis meses, em um programa de reabilitação em fisioterapia. Precedendo o início das avaliações clínicas, uma ficha de avaliação específica para esta população foi desenvolvida, identificando alterações agudas e crônicas. A idade média das pacientes foi 52,10 anos. De acordo com o exame físico, a aderência cicatricial estava presente em 14% das pacientes e o linfedema em 86% destas. Durante a palpação, 95% das pacientes apresentaram dor e pontos-gatilho nos músculos trapézio, esternocleidomastoideo, escalenos e romboides. As medianas da amplitude de movimento do ombro homolateral e contralateral à cirurgia foram: flexão, 130º/154º; extensão, 38º/40º; rotação lateral, 60º/85º; rotação medial, 70º/90º e abdução 115º/145º. De acordo com os resultados, houve uma diminuição significativa em todos os movimentos do ombro homolateral, quando comparado ao contralateral à cirurgia. Diante do exposto, pode-se concluir que a avaliação, por meio da ficha específica, elaborada para pacientes com câncer de mama, foi eficaz para identificar complicações pós-cirúrgicas no ombro desta população. Portanto, esta avaliação foi importante para identificar disfunções físicas, visando à reabilitação e independência nas atividades de vida diária destas mulheres.

The surgery of breast cancer is associated, in around 70% of cases, with complications which can lead to limitation and decrease in shoulder mobility. Considering the changes resulting from breast surgery, the aim of this study was to perform a physical assessment of homolateral and contralateral shoulder surgery, comparing the results obtained in both shoulders. This study was conducted with 21 women undergoing mastectomy or unilateral quadrantectomy including, at least, six months in a physical therapy rehabilitation program. Preceding the onset of clinical assessment, a specific evaluation form to this population was developed, identifying acute and chronic alterations. The average age of patients was 52.10 years. According to the physical examination, there was adherence scar in 14% of patients and in 86% of lymphedema of them. During palpation, 95% of patients had pain and trigger points in trapezius, sternocleidomastoid, scalene and rhomboids. The median of range of motion in homolateral and contralateral shoulder were: flexion, 130º/154º, extension, 38º/40º, external rotation, 60º/85º, medial rotation, 70º/90º and abduction, 115º/145º. According to the results, there were significant decreases in all movements of the homolateral shoulder when they are compared with the contralateral side of surgery. In conclusion, the assessment by the specific form for patients with breast cancer was effective to identify postoperative complications of the shoulder in this population. Therefore, this evaluation was important to identify physical disorders to be aimed at for the these women?s rehabilitation and independence in their daily life activities.