3D modelling and monitoring of denervated muscle under functional electrical stimulation treatment and associated bone structural changes

Abstract

The main goals of the PhD study are develop novel methods, based on medical images and special processing tools, in order to monitor growth in denervated and degenerated muscles (DDM) and allow a better understanding of the restoration process induced by Functional Electrical Stimulation (FES).<br />A novel clinical rehabilitation method for patients who have permanent and non recoverable muscle denervation in the legs was developed in the frame of European Project RISE. The technique is based on FES and the project results shows, in these severely disabled patients, restoration of muscle tissue and muscle function.<br />The restoration process in DDM it is an important object of discussion since there isn't yet a complete understanding of the mechanisms regulating growth in denervated muscle. This study approaches the problem from the macroscopic point of view, developing 3 dimensional models of the whole stimulated muscles and following changes in volume, geometry and density very accurately. The method is based on the acquisition of high resolution Spiral CT scans from patients who have long-term flaccid paraplegia and the use of special image processing tools allowing tissue discriminations and muscle segmentation. Three patients were measured at different points of time during 4 years of electrical stimulation treatment. In this study it is demonstrated quantitatively the different influence, produced by the stimulation treatment, on quadriceps muscle. The Rectus Femoris muscle shows to be the most sensible to the induced stimulation, in compliant patient, Rectus Femoris doubled his volume during the treatment period while in other muscle bellies changes were minimal.<br />Beside the analysis of the density shows clearly a restoration of the muscular structure in the growing muscle. The remarkable increase of muscle mass and the improved quality of the muscle was observed and measured analysing density distribution on whole muscle volume. The 3-dimensional approach proposed in this work also allows to evaluate changes in muscle shape. Geometrical changes in the muscle are measured and compared with a normal muscle and the differences quantified. The results show a correlation in between restoration of shape and muscle growth. Furthermore, the induced effect of muscle contraction is measured on the patella bone. The bone densities which reduce drastically in paraplegic subjects benefit as well from the stimulation. The density in patella bone increases slightly but the raise is clear. Finally, the method developed in this research study allows a unique way of monitoring growth and muscle restoration. It provides qualitative and quantitative information on the denervated degenerate muscle behaviour otherwise hidden contributing in understanding the dynamics involved.<br />Moreover, the results can be used as base of new development and improved technology for stimulation of denervated muscles.