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Rossi S.,University of Rome La Sapienza | Rossi S.,Childrens Hospital Bambino Ges IRCCS | Patane F.,University of Rome La Sapienza | Patane F.,Childrens Hospital Bambino Ges IRCCS | And 4 more authors.
Measurement Science and Technology | Year: 2010

The centre of pressure (CoP) measurement is a very important evaluation tool in posturography. Several papers have been focused on the estimation of CoP accuracy with a pressure matrix (PM) and a force platform (FP) in static conditions, while a few works reported analyses in dynamic conditions. Here, the previous sensors were compared in terms of relative and absolute error during two dynamic sessions: with a rigid bipod and with a healthy adult. Trials were conducted placing the PM and FP in series over a three-axial rotating base, programmed with sinusoidal trajectories of amplitude 10°and frequencies 0.2 Hz and 0.5 Hz. In order to compute the absolute errors of the PM and FP, a further estimation of the bipod CoP was done from the moving base rotation and bipod position gathered by an optoelectronic system. The CoP relative error between the two sensors was about 7-8 mm. Because the relative errors obtained during the bipod session were comparable with the ones obtained during the subject sessions, the absolute errors estimated with the bipod, <7 mm, can be reasonably extended to the dynamic posturography tests performed with the subject. The accuracies were estimated checking all the possible error sources, such as the sensors' alignment and the inertial artefacts; because these are rarely considered parameters in clinical routine, they can decrease the overall CoP accuracy if not carefully controlled. © 2010 IOP Publishing Ltd.

Frascarelli F.,Childrens Hospital Bambino Ges IRCCS | Frascarelli F.,University of Rome La Sapienza | Di Rosa G.,Childrens Hospital Bambino Ges IRCCS | Bisozzi E.,Childrens Hospital Bambino Ges IRCCS | And 2 more authors.
European Journal of Paediatric Neurology | Year: 2011

In the last few years botulinum toxin type A (BTX-A) has been widely used in the management of spasticity in children with cerebral palsy in order to reduce hypertonicity and improve functional outcomes enhancing motor skill development. The botulinum toxin injection seems to interact with intrafusal and extrafusal fibers producing a reduction of hypertone both through synaptic blockade and inhibition of stretch reflex loop and these changes may influence not only the spinal cord but also the central nervous system (CNS). The purpose of our study was to determine the neurophysiological changes induced by the BTX-A through an evaluation of cortical somatosensory Evoked Potential (SEP) and Soleus H wave, that is the index of excitability of stretch reflex loop. Eighteen children with Cerebral Palsy (CP), aged between 5 and 12, were recruited at Children's Hospital "Bambino Ges" of Rome. All children were evaluated with appropriate clinical scales before and 1 month after the BTX-A injection. Neurophysiological measurements were performed before, and 1 month after botulinum toxin injection through lower limb SEPs, M-wave and Soleus H wave recording. After the injection the results showed a statistically significant improvement both of clinical scales and the neurophysiological variables. These findings suggest that spasticity itself can be considered as a factor affecting the cortical SEPs. And even though it seems that BTX-A does not have any direct central effect on sensory pathways we suppose an indirect mechanism on modulation of afferent fibers Ia due to the modification induced by BTX-A to central loop reflex. © 2010 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

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