Audio-Biofeedback training for posture and balance in Patients with Parkinson's disease
© Mirelman et al; licensee BioMed Central Ltd. 2011
Received: 16 November 2010
Accepted: 21 June 2011
Published: 21 June 2011
Patients with Parkinson's disease (PD) suffer from dysrhythmic and disturbed gait, impaired balance, and decreased postural responses. These alterations lead to falls, especially as the disease progresses. Based on the observation that postural control improved in patients with vestibular dysfunction after audio-biofeedback training, we tested the feasibility and effects of this training modality in patients with PD.
Seven patients with PD were included in a pilot study comprised of a six weeks intervention program. The training was individualized to each patient's needs and was delivered using an audio-biofeedback (ABF) system with headphones. The training was focused on improving posture, sit-to-stand abilities, and dynamic balance in various positions. Non-parametric statistics were used to evaluate training effects.
The ABF system was well accepted by all participants with no adverse events reported. Patients declared high satisfaction with the training. A significant improvement of balance, as assessed by the Berg Balance Scale, was observed (improvement of 3% p = 0.032), and a trend in the Timed up and go test (improvement of 11%; p = 0.07) was also seen. In addition, the training appeared to have a positive influence on psychosocial aspects of the disease as assessed by the Parkinson's disease quality of life questionnaire (PDQ-39) and the level of depression as assessed by the Geriatric Depression Scale.
This is, to our knowledge, the first report demonstrating that audio-biofeedback training for patients with PD is feasible and is associated with improvements of balance and several psychosocial aspects.
Postural instability, gait disturbances and falls are a leading cause of morbidity and mortality among older adults [1–6], especially among patients suffering from a neurodegenerative disease like Parkinson's disease (PD). Because of the tremendous impact of falls on functional independence, health care economics, social function and health-related quality of life, much effort has been dedicated to identify the physiologic factors that contribute to fall risk. This includes prospectively monitoring those individuals with an increased fall risk and developing interventions for improving balance control and reducing falls [1–6].
In PD, postural instability and falls usually occur during the more advanced stages of the disease and are among the most disabling motor symptoms . These deficits are most probably due to an accumulation of factors such as stooped posture and decreased postural reflexes, hypokinesia, diminished and fragmented postural responses, and impaired cognitive ability [8–11]. While much is known at the present about the multi-factorial nature of gait disturbances and falls in PD, there are still many questions regarding the best therapeutic means of improving these impairments and thus reducing fall risk. Specific forms of exercise have been recommended as elements of fall-prevention programs for older adults, for example, aerobic-type exercises and exercises that target balance, strength and gait are common elements of multi-factorial fall prevention interventions [12–14]. However, typically, these interventions report a reduction in fall risk by only 10% to 20% [15, 16] and are not yet optimal. Moreover, these programs do not always address the specific needs for parkinsonian symptoms that give rise to poor balance and gait.
The use of biofeedback has been offered in the past as an instrument for training that enables an individual to learn how to change physiological activity or behavior for the purposes of improving performance. Biofeedback training of balance and posture has shown to be effective for posture control in adolescents with scoliosis  and has decreased fall rate in elderly patients with peripheral neuropathy . In patients with bilateral vestibular loss , biofeedback training was also found useful in enhancing postural stability even under challenging standing conditions (e.g., tandem walking), beyond the effect of practice alone [19–21]. Based on these previous studies, we hypothesized that deficits in postural control in patients with PD can be positively influenced by Audio Bio-Feedback (ABF) -based dynamic balance training. The aims of this study were to investigate the manner and tasks in which the ABF system can be used to enhance postural control in PD, to explore the feasibility of using an ABF system for training stability of those patients, and to preliminary assess the usability and efficacy of a new ABF-based paradigm on a small group of patients with PD.
Participants and Design
Audio Bio-Feedback (ABF) system
The training program followed three major objectives: (1) to improve body posture and static balance (2) to improve dynamic balance, and (3) to improve activities of daily living (ADLs), i.e., sit to stand abilities and reaching. The intervention included a variety of exercises from six categories of posture and balance with increasing difficulty and complexity. These included: (1) static posture control-achieving better upright position while sitting and in standing (improving upper limb and shoulder girdle range of motion and endurance while maintaining the predefined positions), (2) transfers (improving sit-to-stand and stand-to-sit activities), (3) sway (quiet standing, weight shifting to all directions, loading/unloading, additional upper body movements, differences in the base of support; e.g., foot position, foam), (4) reaching in different directions with movement of the trunk, (5) stepping in different directions and onto steps in different heights. Both reaching and stepping exercises were sometimes performed with additional upper body movements, and 6) obstacle clearance.
Every training session included different exercises from each category. Sessions were individualized to fit each patient's specific needs and were based on performance in the previous session, gradually progressing with intensity and complexity. For example, a session could begin with a posture task in standing with the patient trying to maintain an erect upright posture; this would then progress to a reaching exercise in different directions while the patient would still be required to maintain the upright posture when returning to the standing position after reaching his target. A possible progression could then include a stepping exercise over obstacles of different heights while maintaining minimal sway after the obstacle was negotiated. The system provided feedback during the exercises. The order of the exercises within the training sessions was pre-defined for all participants, but the progression within the categories was determined individually based on the patient's ability and needs, continuously adjusting and challenging the patient. The rational for this training program was based on motor learning paradigms aimed at providing demanding tasks for the patient and allowing knowledge of performance and results to enhance practice and learning . Mean exercise duration was between 2 and 3 minutes depending on the patient's ability, tolerance and endurance, with total net training time of 30-45 minutes in each session.
Assessments included standardized tests of balance and, postural control as well as ADL's to evaluate the effects of training. Balance tests that were used included: 1) The Berg-Balance Scale (BBS) which consists of 14 different balance tasks such as standing, reaching, bending, and transferring abilities, and has an overall score range from 0 (severely impaired) to 56 points (excellent) ; 2) The Timed Up-and-Go (TUG) test was used to assess the ability to perform sequence movements of functional mobility. Patients were instructed to stand up from a chair, walk for a distance of 3 meters at comfortable speed, turn, walk back, and sit down on the chair . Time was measured with a stopwatch and the average of two trials was taken; 3) the 5 chair rise (5CR) test was used to assess the ability to perform sit-to-stand and stand-to-sit transfers. Patients were instructed to stand up and sit down five times as fast as possible starting in the sitting position and stopping after sitting down the fifth time . Here too, the average duration of two trials was taken. The scores of the sub items and the total score of the Parkinson's disease questionnaire (PDQ-39) were used to determine health-related quality of life. The eight sub items of this questionnaire cover mobility, activity of daily living, emotional well-being, stigma, social support, cognitive impairment, communication, and bodily discomfort .
To quantify extra-pyramidal signs and disease severity, the Unified Parkinson's Disease Rating Scale (UPDRS) was used  and to assess the confidence in daily activities and the level of fear of falling, we used the Activities-specific Balance Confidence (ABC) scale . Finally, The Geriatric Depression Scale short form (GDS-15) was used for the assessment of emotional wellbeing and depressive mood .
Descriptive statistics were used to evaluate the effects of training on balance and postural control. Average, standard deviations and ranges were extracted as well as the percent change after training and at follow up from the initial baseline evaluation. Training effects (pre vs. post and pre vs. follow-up) were evaluated using the Wilcoxon signed rank test and were assumed to be significant at p < 0.05 (two-sided). All analyses were conducted with SPSS version 16 software (SPSS Inc., Chicago, IL, USA).
N = 7
Age of disease onset [yrs]
Duration of disease [yrs]
Hoehn and Yahr
Immediate and long term training effects
Berg Balance test
49.0 ± 7.2 (35-55)
50.4 ± 6.7 (37-55)*
49.6 ± 9.2 (30-55)
Timed Up & Go (sec)
13.2 ± 4.1 (9.4-20.0)
11.7 ± 2.9 (9.2-17.1)
10.8 ± 2.4 (9.0-16.1)*
5 Chair Rise Test (sec)
16.6 ± 3.4 (14.3-21.4)
15.3 ± 1.0 (12.2-16.8)
UPDRS (part III)
25.3 ± 11.7 (12-48)
24.4 ± 10.6 (12-45)
23.4 ± 10.4 (12-44)
Posture (UPDRS item 28)
2.3 ± 0.6 (1-3)
2.2 ± 0.7 (1-3)
2.2 ± 0.7 (1-3)
Activities-specific Balance Confidence Scale (%)
73.2 ± 15.4 (49.8-97.5)
73.3 ± 15.9 (49.4-100)
73.7 ± 18.9 (40.9-100)
Geriatric Depression Scale
5.8 ± 5.0 (1-13)
3.8 ± 3.5 (0-10)
6.1 ± 5.3 (0-14)
33.4 ± 18.7 (15.1-62.5)
31.7 ± 18.5(12.3-58)
36.8 ± 17.5(16.1-51.6)
41.8 ± 19.9 (12.5-67.5)
40 ± 17.3 (12.5-70)
37.5 ± 14.9 (12.5-50)*
48.2 ± 20.4 (20.8-70.8)
46.4 ± 17.6 (20.8-75)
46.6 ± 22.5 (20.8-75)
39.5 ± 27.6 (6.2-75)
26.8 ± 15.6 (6.2-50)*
33.7 ± 20.5 (6.2-62.5)
Changes in the TUG, BBS and UPDRS scores were maintained at follow-up and some measures even continued to improve compared to baseline (recall Table 2). Interestingly, there was deterioration in the PDQ-39 and GDS scores at follow-up from those measured immediately post training, however scores on the PDQ-39 were still better than at pre-training values.
To our knowledge, this is the first intervention trial using an ABF system for training posture and balance in patients with PD. In this pilot study, we demonstrated that ABF training in patients with PD is feasible and that it appears to be well accepted. Adherence to the training protocol was high with no attrition. All patients also reported satisfaction and enjoyment during the training program while the therapist commented on the ease of use of the device. Some of the training sessions were conducted in the patients' home-environment with the rationale that behavior and performance may be altered in a clinical setting with unfamiliar surroundings and that training in the home could address the particular needs of each patient. The sessions at home were similar to the lab sessions in the provided exercise program and tasks performed. Patients commented that they felt comfortable during the home sessions and that they could foresee a need for such training in the future.
This training program demonstrated some potential therapeutic effects on postural control and psychosocial aspects of the disease. Small, but positive changes were observed in the BBS, 5 chair rise test, TUG and the pull test of the UPDRS rating scale. Components of these tasks were trained during the intervention and therefore, these effects could be considered a result of task specific training. Although statistically significant, the improvements on the BBS revealed only a mild change in actual function. This may be due to the fact that the patients had relatively high scores at baseline suggesting that the measure may not have been sensitive enough to detect minor changes in balance tasks. Some of these improvements were also observed at follow-up demonstrating initial support for retention of the effects of ABF training even in the presence of neurodegeneration.
Patients also reported improved mood after training however, without a control group, it is difficult to know if the improvement should be attributed to the participation in this research study and its weekly routine, or if this was a beneficial by-product of the ABF training. Interestingly, the sub items that were affected by the training on the quality of life questionnaire (PDQ-39) were mobility, ADL and cognition, which are all consistent with the specific training goals and the particular training effects. Although scores on the Activities-specific Balance Confidence scale (ABC) did not change, anecdotally, patients described that they were able to move more freely, with less assistance and more confidence after the training. Once more, this finding could be attributed to the insufficient sensitivity of the ABC as the sections that were scored low initially on this scale were not addressed in this training protocol.
A key limitation of this study is the small sample size. The present study aimed to explore if this training method is feasible for patients with PD. As such, the findings are encouraging. Future studies should include a larger sample of patients and compare them to an active control group. Training with the ABF device teaches participants new strategies of movement that could be applied in real life situations. In this sense, the ABF may have an advantage over other technologies used in PD such as external cueing, by enhancing motor learning through feedback on knowledge of performance and knowledge of results. Although, there is evidence in the literature on the positive effects of cueing strategies on gait in PD [32–34], gait training with the ABF has yet to be examined. Further studies are needed to look at the possibility of using ABF for independent, home training, and specifically for the purpose of improving gait in PD. The findings of our study should also encourage therapists to perform ABF-based physical training in other age-associated disorders such as elderly with higher level gait disorders and older adults with high fall risk or with Mild Cognitive Impairment.
In conclusion, the results presented here demonstrate that ABF-based physical training for posture and balance in PD is feasible and associated with quantitative improvements. This may be viewed as a promising first step to implement home-based training strategies for patients with PD, a cohort which does not yet have sufficient therapeutic options for improving postural instability and alleviating gait disturbances.
The authors would like to the patients for their willingness and availability to participate in this study and to the SensAction-AAL team for their help and support. The project was funded by the European Commission (FP6 project SENSACTION-AAL, IST-045622). McRoberts (The Hague, The Netherlands) provided the accelerometer based devices.
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