Byline: Xiao-Yan. Shen, Chun-Ling. Tao, Lei. Ma, Jia-Huan. Shen, Zhi-Ling. Li, Zhi-Gong. Wang, Xiao-Ying. Lu
Functional electrical stimulation is an effective way to rebuild hindlimb motor function after spinal cord injury. However, no site map exists to serve as a reference for implanting stimulator electrodes. In this study, rat models of thoracic spinal nerve 9 contusion were established by a heavy-impact method and rat models of T6/8/9 spinal cord injury were established by a transection method. Intraspinal microstimulation was performed to record motion types, site coordinates, and threshold currents induced by stimulation. After transection (complete injury), the core region of hip flexion migrated from the T13 to T12 vertebral segment, and the core region of hip extension migrated from the L1 to T13 vertebral segment. Migration was affected by post-transection time, but not transection segment. Moreover, the longer the post-transection time, the longer the distance of migration. This study provides a reference for spinal electrode implantation after spinal cord injury. This study was approved by the Institutional Animal Care and Use Committee of Nantong University, China (approval No. 20190225-008) on February 26, 2019.
Spinal cord injury (SCI) refers to structural or functional injury of the spinal cord resulting in movement, sensation, and autonomic dysfunction below the level of injury (Nakae et al., 2011). Whether the cause is trauma or disease, SCI has a high disability rate. The number of people suffering from SCI in China has exceeded one million and is surging at a rate of 140,000 annually (Zhou, 2013). In 2016, there were about 282,000 people suffering from SCI in the United States (Borrell et al., 2017), while the total number of people with SCI has exceeded 3 million worldwide (Nakae et al., 2011). Because it is difficult to recover injured neurons and restore conduction function of axons, treatment of SCI has become a worldwide problem (Borton et al., 2014).
Intraspinal microstimulation, a new form of functional electrical stimulation, exhibits potential to restore spinal motor function (Saigal et al., 2004). Studies of intraspinal microstimulation on the spinal cords of cats demonstrated that stimulating different lumbosacral regions can produce single muscle activity and selectively induce the required motion (Bamford et al., 2011; Holinski et al., 2011). Jackson and Zimmermann (2012) observed that if the spinal motor neuron network below the injury plane remains intact, it can activate its motor function during electrical stimulation. In addition, researchers have successfully rebuilt nerve function remotely in toads with microelectronic neural bridge technology (Wang et al., 2005; Shen et al., 2010).
Based on these findings, we developed a microelectronic neural bridge to repair spinal cord function (Shen et al., 2012). The main idea was to implant a microelectronic chip in the injured point, collect the motion control signal from the cerebral cortex, and then process and output this signal to the descending pathway to realize restoration of the body function (Huang et al., 2016). However, to successfully implement this new strategy for restoration of motor function in SCI, it is crucial to determine...