In vivo NIRS monitoring in pig Spinal Cord tissues

Little is known about the processes occurring after Spinal Cord damage. Whether permanent or recoverable, those processes have not been precisely characterized because their mechanism is complex and information on the functioning of this organ are partial. This study demonstrates the feasibility of Spinal Cord activity monitoring using Near Infra-Red Spectroscopy in a pig animal model. This animal has been chosen because of its comparable size and its similarities with humans. In the first step, optical characterization of the Spinal Cord tissues was performed in different conditions using a spectrophotometer. Optical Density was evaluated between 3.5 and 6.5 in the [500; 950] nm range. Secondly, adapted light sources with custom probes were used to observe autonomic functions in the spine. Results on the measured haemodynamics at rest and under stimulation show in real time the impact of a global stimulus on a local section of the Spinal Cord. The photoplethysmogram signal of the Spinal Cord showed low AC-to-DC ratio (below to 1 %).