## 3 Treatments for Spinal Cord Injury
### Transcranial Magnetic Stimulation (TMS)  
Transcranial magnetic stimulation is a non-invasive technique that initiates cortical stimulation for the treatment of spinal cord injury [37]. The device itself, as shown in Figure 6, transmits magnetic pulses that affect the local neurons in the brain through the copper coils in the device. There are three methods of TMS. The first method is single-pulse stimulation, which results in single magnetic pulses that are released to simulate the primary motor cortex, in turn activating the contralateral muscle [38]. This generates motor-evoked potentials (MEPs) that allow for the analysis of cortical motor control, as well as the corticospinal conduction time. MEPs can be used for neuronavigational methods such as functional mapping, which is used for muscle representation inside the motor cortex. The second method is paired-pulse TMS, which aids in the analysis of intracortical or intercortical excitability with a paired simulation. The result of this method avoids affecting the cortex through nerve feedback as the TMS is focused on a singular point, for example, the motor cortex. This method is practical for evaluating cortical excitability; however, it is not effective if magnetic stimulation is given [37]. The final method is repetitive transcranial magnetic stimulation (rTMS), which is the most common simulation method. rTMS is widely used in therapeutic research to modulate cerebral cortex activity by varying stimulation parameters. Specifically, high-frequency rTMS (\(\geq\)5 Hz) increases motor cortex excitability, while low-frequency rTMS (\(\leq\)1 Hz) decreases it, making it useful for controlling overactivity in targeted brain regions [38]. Paired associative stimulation (PAS) combines single-pulse peripheral nerve electrical stimulation with single-pulse TMS of the related motor cortex to alter excitability along the corticospinal  
Figure 5: Example of an exoskeleton on a female patient [34]. pathway. The timing of these stimuli is critical: when peripheral stimulation reaches the cortex before or at the same time as TMS, corticospinal excitability increases; otherwise, it is reduced. PAS has demonstrated efficacy in promoting motor cortex plasticity and excitability, offering promising therapeutic potential. The type of coil used in TMS significantly affects stimulation depth and precision. Circular coils provide maximum stimulation at the coil's edge but none at the centre, resulting in broad but shallow stimulation limited to areas within 2-2.5 cm of the scalp. In contrast, Figure 6 coils deliver a more focused stimulation at the centre, also limited to superficial cortical regions. For deeper brain regions (3-6 cm), specialised coils like double cone, H-coils, and HCA coils have been developed, allowing greater penetration to target deeper neural structures. The choice of coil and stimulation parameters is critical in tailoring rTMS and PAS for specific therapeutic applications, maximising efficacy based on the target depth and desired effect [38]. A study was performed by [PERSON] and [PERSON] at the Poznan University of Medical Sciences, in which they evaluated the impact of rTMS as a treatment for patients with incomplete spinal cord injury (iSCI) [39]. The therapy protocol used rTMS on the motor cortex to enhance motor function for individuals with spinal cord injuries. The treatment averaged eight months, with patients receiving 3-5 sessions monthly. MagPro R30 and MagPro X100 stimulators were used to target lower limb regions in the motor cortex, applying frequencies between 15 and 25 Hz at an intensity of 70-80% of each patient's resting motor threshold (RMT). Each session delivered 800 pulses per hemisphere. Before therapy, RMT values were assessed individually to personalise the stimulation, ensuring that each patient received optimal intensity without exceeding 80% of their RMT.