Visuo-postural dependency index (VPDI) in human postural control.

BACKGROUND: Computerized stabilometry has been utilized to investigate the effect of vision on the neuromechanisms of human postural control. However, this approach lacks operational methods to quantify visual dependency during upright stance. This study had three goals: (1) To introduce the concept of visuo-postural dependency indices (VPDI) representing balance sway characteristics in multiple analytical domains (spatial, temporal, frequency, and structural), (2) To investigate the age and gender effects on VPDIs, and (3) To investigate the degree of relationships between VPDI and both subjective visual vertical and horizontal perception (SVV and SVH, respectively). METHODS: 102 participants (16 to 80 years old) performed bipedal stances on a force platform with eyes open and closed. Response variables included the VPDIs computed for each postural index. In addition, 29 participants also performed SVV and SVH assessments. RESULTS: Fifteen VPDIs showed to be robust indicators of visual input modulation, and the variation across their magnitudes of modulation revealed a non-homogeneous response to changes in visual stimuli. Gender and age were not found to be a significant factor to VPDI modulation. CONCLUSIONS: VPDIs revealed to be potential measures capable to quantitatively assess visuo-postural dependency and aid the assessment of fall risks and balance impairments.

Upright balance control strategies during pregnancy.

BACKGROUND: Morphological and physiological changes during pregnancy are considered to interfere with the mechanisms of postural control and potentially increase the risk of falling. A clear understanding of these mechanisms is important to improve pre-natal care and reduce the fall risk in this population. OBJECTIVES: This study focused on investigating how pregnancy affects postural control in each trimester of pregnancy by analyzing pelvic inclination and body sway behavior. Our main hypothesis was that balance control and posture would change during pregnancy. More specifically, pregnancy would increase sway amplitude, anterior pelvic tilt, and body sway regularity in time. STUDY DESIGN: Forty women formed four groups: non-pregnant women (NP) and women at their first, second, and third trimester of pregnancy (P1, P2, and P3, respectively). All participants performed (1) postural evaluation of the pelvic inclination using a digital system of postural analysis and (2) instrumented posturography using a force platform to collect the coordinates of the body's center of pressure (COP) during quiet bipedal stance for 120 s. Kruskal-Wallis H test and post-hoc Mann-Whitney U tests were used to investigate the effects of pregnancy (NP, P1, P2, and P3) on pelvic inclination angle and postural indices computed from the COP signals. RESULTS: Results revealed significant larger body sway accompanied by a more regular medial-lateral pattern of oscillation and a more synchronized anterior-posterior and medial-lateral sway already at the first trimester of pregnancy. The averaged COP migrated posteriorly at third trimester of pregnancy and the anterior pelvic tilt increased at second and third trimesters. CONCLUSIONS: Our results indicate the existence of changes in posture and balance metrics even at early stages of pregnancy. We suggest the use of posturography as one of screening tools for postural instability and fall risk during pregnancy.

Translation and validation of the Brazilian version of the Cerebral Palsy Quality of Life Questionnaire for Children – child report / Tradução e validação da versão brasileira do questionário de qualidade de vida de crianças com paralisia cerebral - autorrelato

Abstract Objective: To verify the psychometric properties of the Cerebral Palsy: Quality of Life Questionnaire Children – child report (CPQol-Child) questionnaire, after it was translated and culturally adapted into Brazilian Portuguese. Methods: After the translation and cultural adaptation of the tool into Brazilian Portuguese, the questionnaire was answered by 65 children with cerebral palsy, aged 9–12 years. The intraclass correlation coefficient and Cronbach's alpha were used to assess the reliability and internal consistency of the tool and its validity was analyzed through the association between CPQol-Child: self-report tool and Kidscreen-10 using Pearson's correlation coefficient. Results: Internal consistency ranged from 0.6579 to 0.8861, the intraobserver reliability from 0.405 to 0.894, and the interobserver from 0.537 to 0.937. There was a weak correlation between the participation domain and physical health of CPQol-Child: self-report tool and Kidscreen-10. Conclusion: The analysis suggests that the tool has psychometric acceptability for the Brazilian population.

Resumo Objetivo: Verificar as propriedades psicométricas da versão traduzida e adaptada culturalmente para o português do Brasil do instrumento Cerebral Palsy Quality of Life Questionnaire for Children – Child report. Métodos: Após a tradução e a adaptação cultural do instrumento para o português, o questionário foi respondido por 65 crianças com paralisia cerebral, entre nove e 12 anos. Os coeficientes de correlação intraclasse e alfa de Cronbach foram usados para avaliar a confiabilidade e consistência interna do instrumento e a validade do instrumento foi analisada pela relação entre CPQol-Child: self-report toole a Kidscreen-10 por meio do coeficiente de correlação de Pearson. Resultados: A consistência interna variou de 0,6579 a 0,8861, a confiabilidade intraobservador de 0,405 a 0,894 e a interobservador de 0,537 a 0,937. Verificou-se uma fraca correlação entre o domínio participação e saúde física da CPQol-Child e Kidscreen-10. Conclusão: A análise feita sugere que o instrumento usado tem aceitabilidade psicométrica para a população brasileira.

Translation and validation of the Brazilian version of the Cerebral Palsy Quality of Life Questionnaire for Children - child report.

OBJECTIVE: To verify the psychometric properties of the Cerebral Palsy: Quality of Life Questionnaire Children - child report (CPQol-Child) questionnaire, after it was translated and culturally adapted into Brazilian Portuguese. METHODS: After the translation and cultural adaptation of the tool into Brazilian Portuguese, the questionnaire was answered by 65 children with cerebral palsy, aged 9-12 years. The intraclass correlation coefficient and Cronbach's alpha were used to assess the reliability and internal consistency of the tool and its validity was analyzed through the association between CPQol-Child: self-report tool and Kidscreen-10 using Pearson's correlation coefficient. RESULTS: Internal consistency ranged from 0.6579 to 0.8861, the intraobserver reliability from 0.405 to 0.894, and the interobserver from 0.537 to 0.937. There was a weak correlation between the participation domain and physical health of CPQol-Child: self-report tool and Kidscreen-10. CONCLUSION: The analysis suggests that the tool has psychometric acceptability for the Brazilian population.

Multi-muscle control during bipedal stance: an EMG-EMG analysis approach.

Posture and postural reactions to mechanical perturbations require the harmonic modulation of the activity of multiple muscles. This precision can become suboptimal in the presence of neuromuscular disorders and result in higher fall risk and associated levels of comorbidity. This study was designed to investigate neurophysiological principles related to the generation and distribution of inputs to skeletal muscles previously recognized as a synergistic group. Specifically, we investigated the current hypothesis that correlated neural inputs, as measured by intermuscular coherence, are the mechanism used by the central nervous system to coordinate the formation of postural muscle synergies. This hypothesis was investigated by analyzing the strength and distribution of correlated neural inputs to postural muscles during the execution of a quiet stance task. Nine participants, 4 females and 5 males, mean age 29.2 years old (±6.1 SD), performed the task of standing while holding a 5-kg barbell in front of their bodies at chest level. Subjects were asked to maintain a standing position for 10 s while the activity of three postural muscles was recorded by surface electrodes: soleus (SOL), biceps femoris (BF), and lumbar erector spinae (ERE). EMG-EMG coherence was estimated for three muscle pairs (SOL/BF, SOL/ERE, and BF/ERE). Our choice of studying these muscles was made based on the fact that they have been reported as components of a functional (synergistic) muscle group that emerges during the execution of bipedal stance. In addition, an isometric contraction can be easily induced in this muscle group by simply adding a weight to the body's anterior aspect. The experimental condition elicited a significant increase in muscle activation levels for all three muscles (p < 0.01 for all muscles). EMG-EMG coherence analysis revealed significant coherence within two distinct frequency bands, 0-5 and 5-20 Hz. Significant coherence within the later frequency band was also found to be significantly uniformly distributed across the three muscle pairs. These findings are interpreted as corroborative with the idea of a hierarchic system of control where the controller may use the generation of common neural inputs to reduce the number of variables it manipulates.