## 3 Treatments for Spinal Cord Injury
### Brain-Computer Interface Technology Using AI  
The Defense Advanced Research Projects Agency (DARPA) has innovated a brain-computer interface (BCI) that bridges the gap in spinal cord injury [44]. The process of bridging the gap involves an electrode on the spinal cord just above the damaged site that collects the information the brain is sending and feeds it back to a computer. This computer then uses machine learning to recognise the signals and match them to various motor and sensory actions in the body. Once the action is calculated, it is sent back to the spinal cord through another electrode that is attached to the other side of the spinal cord damage. Messages are received by the computer, sent down the spinal cord, and relayed to the muscles. The device itself is a 64-channel electrode (as shown in Figure 7) with two wires coming out of the device externally on either side of the spinal cord injury and allowsfor the bidirectional flow of information. Though this device is revolutionising spinal cord injury treatments by using machine learning to directly decode brain waves into motions on the other side of the damage, there is still a major limitation. The device has two wires that protrude from the body and are connected to a computer. To increase the usability and discreteness of this device, it would require battery power to also be implanted with the electrode and embedded in a wireless connection to a computer.  
Additionally, a study was conducted by researchers at Tsinghua University and Xu-anwu Hospital that focused on using epidurals for a minimally invasive brain-computer interface (BCI) to reclaim motor functions after complete SCI [46]. The BCI included a wireless device called NEO, comprising a titanium implant and two electrode adaptors sealed in silicone, which was implanted into the brain with the electrode adaptors facing outwards. Externally, the epidural electrodes are connected to the implanted adaptors, which allows the device to record and stimulate pulses. The electrodes do this through two sets of coils embedded into the device. One of the sets used near-field coupling for the power supply, and the other set used Bluetooth to transmit and collect neural signals. This means the first device does not require a battery, which allows for the longevity of the device. The device was trialled on a patient with complete C4 SCI from a car accident 10 years prior, which resulted in limited movement and motor functions in the hands. Post implantation of the device, the calibration time took less than 10 min and was able to maintain a significantly high grasping score over the nine-month evaluation period of home use. Other tests performed included object manipulation, in which the patients achieved a 100% success rate in the object transfer test and the action research arm test (ARAT), which illustrated significant functional gains [46]. Though the outcomes of this approach were deemed increasingly positive, this was a single-patient clinical trial, limiting the generalisability. Furthermore, despite the procedure being minimally invasive, brain surgery still comes with high risk factors such as infection and device migration. As the process is still in the early development stages, widespread clinical implantation may not be feasible yet. This study presents a promising new approach for spinal cord injury rehabilitation, yet further clinical trials with larger sample sizes are needed to confirm its effectiveness.