# HAL Training in Spinal Cord Injured Patients: A Narrative Review of 10 Years Experience
## 3 Results
### Clinical Trials
In addition to these results, the authors reported on seven participants with increased muscle volume as measured by the circumferences 10/20 cm cranial of the inner knee joint gap and 15 cm distal of it. One patient lost muscle volume. Furthermore, one participant with spinal spasticity was able to reduce Ashworth scale from four to two for a few hours after training. One patient switched from AIS B to C after treatment. Seven of these eight patients from the [PERSON] et al. [9] study were also part of a study by [PERSON] et al. [10] to investigate whether body weight supported treadmill training with HAL affects cortical excitability in the primary somatosensory cortex (S1) in SCI patients, as measured by paired-pulse somatosensory evoked potentials (ppSEP) stimulated above the level of injury. These seven patients were supplemented by four additional patients (8.5 months to 17 years since SCI) performing the same intervention protocol as described for a total of eleven participants. No electrophysiological results of these eleven patients were published until then. Nerve stimulation was conducted successively on both sides with a block electrode placed on the wrist. ppSEP was assessed before and after the HAL training period and compared with a healthy control group (\(n=11\)). Additionally, electroneurography (ENG), somatosensory evoked potentials (SEP) of the tibial nerves, and motor evoked potentials (MEP) of anterior tibial muscles were performed before and after the training period. The authors present a statistical difference between SCI patients and healthy control group at baseline. After intervention, this difference was no longer present. Comparison of patient's data pre- and post-training showed a significant statistical training effect. ENG, SEP of tibial nerves and MEP showed no significant differences after training. Functional outcomes consequently to the previous study from [PERSON] et al. [9] were statistical significance for 10 MWT-speed, 6 MWT, TUG, LEMS. These results show that SCI patients had increased cortical excitability in the hand area of S1 prior to training and that this was normalized following 12 weeks HAL training accompanied by significant improvements in walking abilities [10]. However, a correlation analysis revealed no relationship between the extent of changes in excitability and time since injury, functional walking parameters, or LEMS. The authors, anyway, conclude that walking improvements may be related to a renewed S1 and M1 representation of impaired lower extremities likely related to the recruitment and more effective use of remaining somatosensory afferent pathways and corticospinal tracts [10]. The missing correlation between functional abilities and changes of excitability in S1 might indicate that either other cortical areas or even a complex supraspinal network is required for walking rehabilitation [10]. In 2017, [PERSON] et al. [11] published a proof of concept to the pilot study from [PERSON] et al. [9] and expanded the collective to 21 chronic SCI (1-19 years since SCI) patients. All of them improved significantly in respect to treadmill associated data (walking distance, speed) and in functional tests assessed by standardized over-ground walking tests (10 MWT, TUG, 6 MWT) without HAL, which therefore confirms findings of the pilot study [9; 11]. In addition to these results, this study revisits the issue of spasticity and states that in eight subjects with spastic motor behavior intervention led to a temporary relief. This was already discussed for one patient in the pilot study [9]. Furthermore, the authors indicate that 18 of 21 patients reported improvements of their bowel and bladder dysfunctions after the training period with two of them able to discontinue self-catheterization [11]. However, both spasticity and bowel and bladder improvements were not supported by statistical data. A question often discussed in the SCI literature is in which patient population improvements are most likely to occur and in which less so. According to [PERSON] et al.