Background
Acquired Brain injury (ABI) is the main cause of death and disability among young adults [
1]. ABI can cause from mild to severe impairments in cognitive, motor or psychological functions leading to difficulties in familiar, vocational and social reintegration which diminishes health-related quality of life [
2]. Among them, ABI can cause different levels of paralysis, such as hemiplegia or hemiparesis, which dramatically affect the balance control and, consequently, the performance of activities of daily living (ADL). Traditional balance training is based on the automatic repetition of specific movements. These methods can become repetitive and aimless, and thus reduce the motivation and adherence to treatment. Balance control, as the complex constellation of impairments following ABI, demands a multidisciplinary rehabilitation approach that, with the aid of new technologies, could maximize functional recovery.
In the last few years, there has been increasing research interest in the application of virtual reality (VR) technology to rehabilitation [
3]. In contrast with traditional rehabilitation procedures, which may be tedious, resource-intensive and costly, VR provides patients with ABI opportunities to engage in meaningful, intensive, enjoyable and purposeful tasks related to real-life interests and ADL [
4]. The published clinical results indicate that the recovery of motor function in ABI patients with motor difficulties appears to be enhanced by using VR technology [
5‐
7]. Although most of these studies still consist of small experiments without randomized control trials [
8], they demonstrate the feasibility of the application of VR technology in this clinical field.
In regard to standing balance, systems based on force platforms are particularly interesting, since they enable to estimate the weight distribution of the patients by means of pressure sensors [
9,
10]. These devices are expensive and require a dedicated area in the clinical facilities due to their size, weight and set-up. In this respect, computerized dynamic posturography can assess the ability of the automatic motor system to quickly recover from an unexpected external disturbance. Some of these systems even offer interactive and functional training exercises that fit the patients' conditions. In comparison with these platforms, the Nintendo
® WBB (a peripheral of the Nintendo
® Wii gaming system) is an inexpensive interface (less than $100USD) that has widespread availability. The WBB also has the advantage of being portable, easy and comfortable to handle thanks to its small size (0.511 m. wide by 0.316 m. long by 0.053 m. thick) and weight (3.5 kg. without batteries). Furthermore, it is a device with Bluetooth wireless connectivity that is battery operated. The WBB contains four force sensors (located in each corner) that are used to measure the user's center of balance and weight. Following the Nintendo
® gaming philosophy, users can interact naturally with the game (by means of weight transferences).
The number of studies that include Nintendo
® Wii or WBB in the rehabilitation process is increasing but still limited. Saposnik et al. evaluated the feasibility, safety and efficacy of VR rehabilitation using the Nintendo
® Wii gaming system with entertainment software to improve arm motor recovery in stroke patients [
11]. Since the study is focused on improving arm recovery, the WBB was not used. Deutch et al. also use commercial software (Wii sports) to describe the feasibility and clinical efficacy of Nintendo
® Wii to augment the rehabilitation of an adolescent with cerebral palsy [
12]. Loh et al. use this system as well and reported improvement in a group of patients with stroke in a non-controlled study [
13]. Sugarman et al. report the feasibility and outcome of the WBB with a commercial program for balance training after stroke [
14]. Although this software is not designed for balance recovery after stroke, they highlight its potential to be used in clinical settings in order to improve balance. In this sense, Clark et al. [
15] demonstrated the convergent validity and the clinical utility of the WBB compared to a laboratory-grade force platform, which is considered the gold standard measure of balance. The results suggest that the WBB could be considered as a valid portable low-cost tool for assessing standing balance. However, the Nintendo
® Wii and WBB are entertainment systems oriented to healthy people that offer a gaming experience that differs from the therapy required by patients with ABI [
16,
17]. This fact has encouraged different authors to develop custom made applications oriented to diminished people using the WBB [
18‐
22]. However, they are still very conceptual designs or lack more powerful studies to evaluate their efficacy.
Therefore, we designed eBaViR, a virtual rehabilitation system for balance recovery that provides motivational task oriented exercises specifically designed for ABI people by clinical therapists. The system can fit the patients' impairment to provide a particular training session, allowing the therapists to customize the duration and difficulty of exercises to the needs of the patients in each session.
The aim of this study is to evaluate the efficacy of the eBaViR system as a rehabilitation tool for balance recovery. In this contribution, we present a randomized and controlled single blinded trial to evaluate the influence of eBaViR on balance rehabilitation of ABI patients. We hypothesize that eBaViR is feasible, safe and potentially efficacious in enhancing standing balance.
Results
No significant differences in demographical (age and gender) or clinical (chronicity, etiology and laterality) variables at inclusion were detected between groups (Table
1).
A repeated measures ANOVA at the beginning and at the end of the clinical trial revealed a significant time effect for the BBS (p = 0.000), BBA (p = 0.048), standing ART (p = 0.005), ST-paretic (p = 0.021), ST-non paretic (p = 0.046), 1MWT (p = 0.007), TUG (p = 0.004) and 30SST (p = 0.003) (Table
3). No group effect was detected for any outcome, which confirms the comparability of both groups. Finally, significant group-by-time interaction was detected in the scores of the BBS (p = 0.011) and the ART in standing position (p = 0.011). With respect to these variables, post-hoc analysis showed better improvement in trial patients when compared to control subjects throughout the therapy.
BBS
| | | | |
Control | 45.38 ± 7.35 | 46.88 ± 6.15 | 1.50 ± 1.31 | T**(p = 0.000) |
Trial | 41.22 ± 10.57 | 45.44 ± 8.62 | 4.22 ± 2.33 | GxT*(p = 0.011) |
BBA
| | | | |
Control | 11.00 ± .1.31 | 11.13 ± 1.13 | 0.12 ± 0.35 | T*(p = 0.048) |
Trial | 10.00 ± 2.00 | 10.33 ± 2.18 | 0.33 ± 0.50 | |
ART standing (cm)
| | | | |
Control | 25.44 ± 9.33 | 25.63 ± 9.74 | 0.19 ± 1.56 | T**(p = 0.005) |
Trial | 24.13 ± 7.70 | 27.25 ± 10.38 | 3.12 ± 2.36 | GxT*(p = 0.011) |
ART sitting (cm)
| | | | |
Control | 40.06 ± 6.87 | 40.13 ± 7.66 | 0.06 ± 6.35 | NS |
Trial | 34.83 ± 11.92 | 37.78 ± 12.34 | 2.94 ± 4.05 | |
ST paretic (n)
| | | | |
Control | 6.57 ± 2.30 | 7.57 ± 2.44 | 1.00 ± 1.29 | T*(p = 0.021) |
Trial | 6.75+3.58 | 7.63 ± 4.00 | 0.87 ± 1.46 | |
ST non-paretic (n)
| | | | |
Control | 8.17 ± 1.72 | 9.50 ± 3.39 | 1.33 ± 1.97 | T*(p = 0.046) |
Trial | 9.33 ± 2.81 | 10.50 ± 3.02 | 1.16 ± 1.83 | |
TST (s)
| | | | |
Control | 14.82 ± 9.42 | 12.13 ± 4.94 | -2.69 ± 6.19 | NS |
Trial | 15.38 ± 9.69 | 13.52 ± 9.60 | -1.86 ± 4.67 | |
1MWT (m)
| | | | |
Control | 31.13 ± 13.59 | 36.38 ± 15.39 | 5.25 ± 3.99 | T**(p = 0.007) |
Trial | 31.94 ± 12.47 | 42.69 ± 20.43 | 10.75 ± 13.78 | |
10MT (s)
| | | | |
Control | 14.57 ± 10.95 | 14.07 ± 9.02 | -0.50 ± 2.16 | NS |
Trial | 13.47 ± 8.29 | 13.47 ± 10.64 | -0.00 ± 2.60 | |
TUG (s)
| | | | |
Control | 24.00 ± 14.87 | 19.52 ± 10.91 | -4.48 ± 4.98 | T**(p = 0.004) |
Trial | 20.99 ± 15.11 | 18.69 ± 13.43 | -2.30 ± 2.33 | |
30SST (n)
| | | | |
Control | 6.88 ± 3.52 | 8.50 ± 3.12 | 1.62 ± 1.68 | T**(p = 0.003) |
Trial | 7.56 ± 4.19 | 9.00 ± 4.74 | 1.44 ± 1.81 | |
The mean ± SD SFQ score was 55.560 ± 5.940 over 65. In addition, all the patients remarked having had fun during the treatment. Only one case reported not being in control of the exercises. None of the patients suffered from spatial disorientation or cyber-sickness and no adverse symptoms were described by therapists.
Discussion
Balance difficulties are amongst the most frequent motor disorders of ABI patients [
39‐
41]. The recovery of this skill is an essential part of the rehabilitation process, since it is associated with a dramatic improvement in functional autonomy. The clinical study presented in this paper suggests that virtual rehabilitation provided significant improvement in static balance compared to traditional treatment. The homogeneity of the subject and their random assignment support the results.
According to BBS evolution, even though both groups show improvement over time, the results provide evidence of significant improvement in the trial group. As regards BBA evolution, the increase in BBA scores for both control and trial group is neglectable given de SD. Differences in the structure and content of the two measures may lead to this inconsistency; since the BBA score ranges from 0 to 14, this scale may not be as sensitive as the BBS to detect minor changes.
The results also showed a significant improvement of the sample in the ART over time with a better course of recovery for individuals in the trial group. According to the data, the trial group improved by 3 cm, which was considered a noticeable improvement. The functional reach test (FRT) has shown to improve over the course of rehabilitation, especially in the earlier stages of the recovery. Weiner et al. reported that the FRT is sensitive to changes in subacute patients undergoing traditional rehabilitation [
42]. Brooks et al. described similar results in acute geriatric patients after a rehabilitation program [
43]. Consequently, our results are promising considering the chronicity of our sample. In this sense, the FRT responsiveness for the experimental group was high (effect size: 1.3) compared to the control group (effect size: <0.1). Then, since this test is suggested to be a clinical measure of the stability and since it has correlation with balance abilities and risk of falls in the elderly [
30,
35], the clinical relevance of the improvement achieved during the present study should be considered.
Although the eBaViR system is designed to train static balance more specifically than dynamic balance, several outcome measures focused on balance abilities during gait and other complex motor tasks have also been considered. The results showed significant improvement over time in all these measures, but no significant group effect or group-by-time interaction was detected for any of them, which suggests that both groups improved in the same way. These results support the hypothesis that the system promotes the recovery of static balance, in which the system focuses on its exercises, while it has no significant effect in dynamic balance, since it is no specifically trained. Consequently, the therapy should be reinforced with dynamic exercises towards a comprehensive functional recovery, either through virtual or traditional therapy.
The significance of the
time effect is especially outstanding due to the chronicity of the sample. The improvement in both groups is remarkable in spite of the fact that the chronicity (570.9 ± 313.2 days) is several times higher than a 6-month period, which is traditionally considered as the period with maximum recovery (where spontaneous recovery takes place) [
44,
45]. This fact makes the eBaViR achievements more relevant and suggests that forthcoming systems should have their basis more on the lost function and not so much on the chronicity.
With regard to feedback data, the SFQ score was high and corroborates the positive feedback of the patients who underwent the virtual treatment, and no cyber-sickness effect was detected. In addition, the therapists highlighted the ease and speed of use of the system.
In the last decade the emerging literature has demonstrated that training can lead to an enhancement of both the function and structure of the neural mechanisms. New rehabilitative strategies regarding motor learning and plasticity principles are focused on high-intensity, repetitive, and task-specific practice. According to these principles, virtual rehabilitation systems are excellent tools to enhance motor recovery since they allow repetitive intense training and on-screen observation, practice and representation of task-specific activities [
46]. The eBaViR system has demonstrated to provide benefits to ABI patients affected by motor impairments and could be especially useful for balance rehabilitation under static conditions. In the field of skill learning and brain plasticity, the transfer of the skill acquired in the trained task to even other very similar tasks is generally the exception rather than the rule. This fact is well documented not only in the field of motor domain [
47] but also in those processes involving perceptual learning [
48] and cognitive recovery [
49]. According to these principles, the greatest effects of training in our sample were observed in tasks that most closely mirror the trained task (static balance), with limited transfer of gains to other skills or to everyday competence (dynamic balance activities). Thus, these results encourage us to reinforce the virtual treatment with new exercises in order to promote improvement in the dynamic balance of patients. Future studies involving larger samples and including the aforementioned new exercises will be designed to evaluate the validity of these assumptions.
Conclusions
eBaViR is a virtual rehabilitation system that uses the WBB with software that is specifically designed and developed in collaboration with clinical specialists for the rehabilitation of standing balance. This paper presents a single blinded study with two parallel groups. The study assessed the influence of a WBB-based virtual rehabilitation system (eBaViR) on standing balance rehabilitation with ABI patients and showed that virtual rehabilitation is capable of substantially improving the condition of the patients. However, interpretations of the results should be taken carefully considering the characteristics of our sample. The heterogeneous nature of acquired brain injury in our sample is also another limitation of the study.
The patients reported having had fun during the treatment without suffering from cyber side effects, which implies additional motivation and adhesion level to the treatment. Although no ergonomics test was considered, the specialists remarked on the ease and the speed of use. This makes it possible to spend most of the session on the treatment. As a token of their satisfaction, the therapists now continue using the eBaViR system on a daily basis for the standing balance rehabilitation of their patients and have encouraged us to add new exercises focusing on new issues. Currently, a second stage of eBaViR is being designed to incorporate all of their suggestions.
Acknowledgements
The authors wish to thank the staff and patients of the Servicio de Daño Cerebral from the Hospital Valencia al Mar for their time, confidence and suggestions, specially Dr. Enrique Noé. The authors want to mention specially Miriam González for her early work and great contribution to this work.
This study was funded in part by Ministerio de Educación y Ciencia Spain, Projects Consolider-C (SEJ2006-14301/PSIC), "CIBER of Physiopathology of Obesity and Nutrition, an initiative of ISCIII" and the Excellence Research Program PROMETEO (Generalitat Valenciana. Conselleria de Educación, 2008-157).
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
JG, RL and MA contributed to the design of the study, the software development and the interpretation of the results. CC contributed to the design of the study, to the assessment of patients, to the acquisition of data and to its interpretation. All the authors have revised the manuscript and have given their final approval for publication.