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Journal Articles Microelectronics Journal Year : 2018

Toward the monitoring of the spinal cord: A feasibility study

Sylvain Feruglio

Abstract

The usual imaging techniques providing only limited information, there is an unmet need for methods, firstly, to monitor in real time the functional status of the Spinal Cord (SC) and, secondly, to assess the functional consequences of the SC Injuries (SCI) and the effect of therapeutic interventions. To meet these needs, our project aims to investigate a new imaging approach, through the realization of a device for measuring the SC activity. This approach will establish locally and specifically the functional state of the SC in real time, which will provide a breakthrough in surgery, as well as in the care and therapeutic trials for SCI. This paper presents the first results of this research project on pig subjects, focusing on the opto-electrical part, based on Near-InfraRed Spectroscopy (NIRS). Firstly, the pig SC optical characterization was performed in different conditions, using a portable spectrophotometer in order to define the wavelengths of interest and their corresponding optical attenuation. In transmission mode, the Optical Density (OD) was evaluated between 3.5 and 6.5 in the [500; 950] nm range. In reflection mode, a figure between 11 % and 33 % is obtained in the same wavelength range. We find that wavelengths between 600 nm and 940 nm are good candidates to monitor the SC functional activity. Secondly, thanks to these results, a specific opto-electrical system has been designed for the transmission mode only, with adapted light sources and custom probes with its front-end to observe the autonomic functions in the SC. 2 Results on the measured haemodynamic variations, at rest and under stimulation, show in real time the impact of a global stimulus on a local section of the SC. However, with a low AC-to-DC ratio (around 1 %), the SC PhotoPlethysmoGram (PPG) acquisition isn't simple and the best trade-off between power consumption and Signal-to-Noise Ratio (SNR) must be found in the perspective of the Embedded System (ES) development. This study demonstrates, for the first time, the feasibility of the SC activity monitoring using NIRS in transmission mode in a big animal model, where the perfect alignment of the light emitter and receptor isn't necessary due to the diffusive property of the biological media. It contributes to heading towards the use of the Internet of Things (IoT) for medical applications, through the monitoring of the SC during highly invasive processes, such as the stabilization of the spine, in the form of implants and other surgeries, such as that of the aorta, with the use of specific minimally invasive catheters.
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Dates and versions

hal-01782182 , version 1 (01-05-2018)

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Sylvain Feruglio, Olivier Tsiakaka. Toward the monitoring of the spinal cord: A feasibility study. Microelectronics Journal, 2018, ⟨10.1016/j.mejo.2018.01.026⟩. ⟨hal-01782182⟩
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