# HAL Training in Spinal Cord Injured Patients: A Narrative Review of 10 Years Experience
## 4 Discussion  
The studies shown in this review on the use of HAL in patients with SCI demonstrate a wide range of use from acute patients to chronic patients and from patients with well-preserved residual functionality to severely affected patients. With the exception of skin reddening at the site of the electrodes, leg cuffs or shoes, no other adverse events or injuries were reported. The vast majority of patients improved functionally, showing increased walking distances, walking speeds, and endurance. In addition, a variety of other advances were described, such as temporary decrease in spasticity, improvement in bladder and bowel management, pain reduction, and change in muscle activity. Nevertheless, no clear recommendation can be made as to which patient population is most likely to benefit from this innovative training. It seems that in principle its application is feasible and effective in many types of SCI, but whether it is superior to other training and therapies remains unclear. To date, there are no published controlled randomized trials with firstly, other similar exoskeleton systems and secondly, conventional therapy of the same extent and frequency. This is imperative to differentiate the potential benefits of HAL therapy from others and should be done in the future.  
Accessibility to HAL training is mentioned in only a few studies. [PERSON] et al. [18] states that in Germany, HAL training is only funded for patients within the scope of the employers' liability insurance association, and in Japan, government support is provided for patients with neuromuscular diseases. Thus, access to training for a wide range of patients still seems to be a problem which should be solved. In addition to the insurance and thus financial hurdle, the availability for people of different constitutions must also be mentioned. Limitations for the application of this exoskeletal system, as with other manufacturers, are restrictions on patient's height and weight, contractures, insufficient cardiopulmonary capacity, and spasticity that does not decrease with the use of the system.  
The following limitations of the present work should be considered. The underlying selective literature search remains incomplete, and a possible bias cannot be excluded with certainty. Some of the authors of the review are also authors of included studies. The studies found are partly limited in their methodological quality. HAL was developed in Japan and is most widely used there. There might be studies published in Japanese journals that were not included in this review. Seven of the included studies [8; 9; 14; 23; 24; 26; 27] list Professor [PERSON], the inventor of HAL and CEO of Cyberdyne Inc. as a co-author. However, most state that Professor [PERSON] and Cyberdyne were not involved in conducting the study, data collection and analysis, writing, or submission. Different versions of HAL may have been used in the early studies than in the later studies. It was not always documented which other therapies were made and if medication was changed in the course of the training. Many of the studies presented have mixed collectives including chronic, acute, incomplete, and complete SCI.