Based on this retrospective cohort study, therapy utilizing DBWS during inpatient rehabilitation yields larger gains in function compared to SOC in patients with acute ischemic stroke. Patients whose therapy incorporated the DBWS demonstrated a significantly higher improvement in total FIM at completion of inpatient rehabilitation. Additionally, patients using the DBWS achieved significant improvements in bowel and bladder function based on FIM subscores.
Previous studies have supported the functional benefits of high-dose gait training in stroke populations, but its implementation is not without barriers. Klassen et al. performed a prospective and randomized study to evaluate the dose-relationship of walking exercises during inpatient rehabilitation after stroke . They concluded that higher doses of gait training can yield greater functional outcomes, greater endurance, and higher quality of life compared to SOC and to lower dose of training. While the study by Klassen et al. demonstrated crucial data to optimize training protocols during inpatient rehabilitation, all participants included in their study were able to ambulate at least 5 m with the assistance of a maximum of one person. This requirement may exclude a substantial number of patients as previous literature suggests up to 25% of stroke survivors are unable to walk without full assistance . In order to implement higher doses of gait training for a wider spectrum of stroke survivors during inpatient rehabilitation, it may be necessary to utilize technologies. This is particularly relevant considering regions of the country that face high patient-therapist ratios and patient populations with increased comorbidities [25, 26].
Various technologies are available to overcome barriers to higher training doses. Robotic rehabilitation devices which were designed with clinical applications in mind have been shown to maintain patient safety while allowing activity programs with sufficient intensity and repetitions [27, 28]. However, there is a lack of clinical evidence demonstrating that these robotic devices can in fact augment functional recovery particularly in inpatient rehabilitation settings. Furthermore, in spinal cord injury research, a large systematic review applying robotic rehabilitation together with treadmill training did not show superior outcomes compared to over-ground therapies .
DBWS systems, among a newer set of technologies, offer several features that may be important to higher doses of gait training and of other task-based activities during post-stroke rehabilitation. Firstly, they allow for static and dynamic weight unloading with remarkably natural ground-reaction forces during a therapy intervention . This is important because aberrancies in afferent feedback may contribute to less functional patterns of leg muscle activation during human locomotion . DBWS also offers an advantage over treadmill training with BWS because it allows safe performance of a variety of functionally relevant activities. These include transfers, over-ground gait, activities of daily living, ascending or descending stairs, and balance tasks. That is, salience across a number of tasks is achievable with DBWS systems versus treadmill-based systems, and this salience can be achieved without jeopardizing participant safety and without overburdening a therapist team.
The DBWS incorporated in this study may also benefit functional recovery through real-time feedback. Feedback has been previously recognized for its importance to neuroplasticity . In recent studies using static BWS methods, a visual feedback feature has been associated with improved functional recovery after stroke . The DBWS technology in the present study includes a fully instrumented robotic trolley with sensors capable of detecting participant movements, both side to side and up and down. The device software can then manipulate this sensor data into real-time visual feedback that the patient can use to understand trends in their performance. This visualization may then benefit the process of motor learning. Learning to perform a motor task entails processes of encoding motor memory, including both explicit and implicit motor learning . Visual feedback from the DBWS may support one or both of these motor learning processes.
With regards to bowel and bladder function, prior literature has suggested the potential of DBWS to improve outcomes in individuals with non-traumatic spinal cord injury . For spinal cord injury, the link between DBWS and sphincter control may be attributable to shared neural pathways, which has been supported in animal studies . Thus, interventions targeting locomotion may be beneficial to bowel and bladder function. Indeed, human studies have shown locomotor training may play such a role . The concept of shared neural pathways may also extend to the level of the brain, and previous functional MRI study has shown the extensive cortical representation shared between locomotion and pelvic floor activity . Interestingly, in studies of healthy adults, regular physical activity contributes to better pelvic floor function , and conceivably stroke survivors may benefit similarly with increased activity of locomotion training. The potential benefits between locomotion and sphincter control may, however, be dependent on characteristics of the stroke. For example, prior literature has suggested a potential dependence of sphincter outcomes on the laterality of stroke, which was not accounted for in the current study and should be considered in the future . The evidence from our study again suggests a potential benefit of DBWS on bowel and bladder function, and future studies on this would be worthwhile.
There were no reports of adverse events related to the DBWS technology used in this study. The absence of adverse events may be attributable to the safety of the DBWS during over-ground task-oriented therapy performed by patients. The implications of this include improved patient-perceived safety, reduced patient fear of falling, improved patient attention to task, and minimized disruptions to motor learning.
Of note, the DBWS system in this study seemed well accepted by both the therapy personnel and by the participants—an observation supported by the cohort of patients that willingly used this system multiple times during their IRF hospitalizations. The short duration and inpatient setting of this study limits discussion about the outpatient utility of DBWS and the long-term acceptance of this technology among providers and patients. Long-term acceptance is crucial for successful deployment of new technologies. Literature suggests an alarming rate of abandonment of technologies, which is especially concerning when technology grows more complex and more expensive [40,41,42,43].
In summary, our preliminary results indicate the potential of the DBWS systems to promote greater functional improvement in patients with ischemic stroke. This potential might be explained by higher-dose training, the real-time feedback, and/or the reduced fear of falling enabled by this system, which are conducive to the principles of neuroplasticity. Furthermore, the potential of this technology could be realized without increasing burden on a limited therapy workforce. Future longitudinal studies of interest should explore the impact of DBWS on a variety of outcomes including: (a) return to community ambulation; (b) reduction of secondary complications related to modifiable cardiovascular risk factors and/or immobility; (c) increase in balance, patient-perceived safety, and decrease of falls; (d) reduction of spasticity and related medications; (e) enhancement of general quality of life, including decrease in depression; and f) reduction of caregiver burden.
While our preliminary data suggests evidence of greater functional recovery compared to the control group, several notable limitations are identified. For instance, one limitation was the lack of a standardized training protocol (including length of stay, number of sessions, and intensity). Because data was collected during inpatient rehabilitation, the training protocol was dictated by the regulatory and insurance requirements of an inpatient rehabilitation facility. A lack of standardized dosage of the DBWS system was also a limitation. In our retrospective study, the initiation of and dosing of DBWS was at the discretion of the patient’s therapy team. While the principle of inpatient rehabilitation was kept the same as much as possible considering time constraints of therapy sessions (typically 60-min) and accounting for patient factors (e.g. safety, device acceptance, fatigue), there is opportunity for further standardizing a dosing protocol based on identified “active ingredients” (e.g. step counts) . Furthermore, the retrospective study examined a relatively small number of data elements from the patient chart, and future studies may benefit from further data extraction including time since stroke, patient demographics beyond age, and interruptions to rehabilitation. Additionally, as the present study focused on the acute stroke population, the relevance of our initial findings to subacute and chronic stroke survivors is uncertain. We encourage future prospective, randomized controlled studies that account for factors such as stroke chronicity, patient comorbidities, and rehabilitation setting. Additionally, optimal DBWS parameters, dose–response relationships of this novel intervention, long-term acceptance of this technology, and the implications of this technology on rehabilitation economics and human resources should also be explored in the future.