The effects of virtual reality-based bilateral arm training on hemiplegic children’s upper limb motor skills

Abstract

Background:

Hemiplegic cerebral palsy is a neurological symptom appearing on the unilateral arm and leg of the body that causes affected upper/lower limb muscle weakening and dysesthesia and accompanies tetany and difficulties in postural control due to abnormal muscle tone, and difficulties in body coordination.

Objectives:

The purpose of this study was to examine the impact of virtual reality-based bilateral arm training on the motor skills of children with hemiplegic cerebral palsy, in terms of their upper limb motor skills on the affected side, as well as their bilateral coordination ability.

Methods:

The research subjects were three children who were diagnosed with hemiplegic cerebral palsy. The research followed an ABA design, which was a single-subject experimental design. The procedure consisted of a total of 20 sessions, including four during the baseline period (A1), 12 during the intervention period (B), and four during the baseline regression period (A2), For the independent variable bilateral arm training based on virtual reality, Nintendo Wii game was played for 30 minutes in each of the 12 sessions. For the dependent variables of upper limb motor skills on the affected side and bilateral coordination ability, a Wolf Motor Function Test (WMFT) was carried out for each session and the Pediatric Motor Activity Log (PMAL) was measured before and after the intervention, as well as after the baseline regression period. To test bilateral coordination ability, shooting baskets in basketball with both hands and moving large light boxes were carried out under operational definitions, with the number of shots and time needed to move boxes measured. The results were presented using visual graphs and bar graphs.

Results:

The study’s results indicated that after virtual reality-based bilateral arm training, improvement occurred in upper limb motor skills on the affected sides, and in bilateral coordination ability, for all of the research subjects. Measurements of the effects of sustained therapy after completion of the intervention, during the baseline regression period, revealed that upper limb motor skills on the affected side and bilateral coordination ability were better than in the baseline period for all subjects.

Conclusion:

This study confirmed that for children with hemiplegic with cerebral palsy, bilateral arm training based on virtual reality can be an effective intervention method for enhancing the upper limb motor skills on the affected side, as well as bilateral coordination ability.

Keywords

Bilateral arm training hemiplegic cerebral palsy virtual reality

1 Introduction

Cerebral palsy is defined as a clinical syndrome that causes motor skill and postural control disorders due to non-progressive lesions occurring in fetuses’ or infants’ unmatured brains and is characterized by resultant kinetic restrictions (Bax et al., 2005). Among the symptoms of cerebral palsy, hemiplegia is a neurological symptom appearing on the unilateral arm and leg of the body that causes affected upper/lower limb muscle weakening and dysesthesia and accompanies tetany and difficulties in postural control due to abnormal muscle tone, and difficulties in body coordination (Cooper et al., 1995). Hemiplegic cerebral palsy children show difficulties in performing daily living activities for which both hands should be used because their upper limb skills decline particularly more than their lower limbs and not only movement timing control ability but also bilateral hand coordination ability is lacking (Sgandurra et al., 2011).

Diverse methods are presented to improve the upper limb motor skills of children with hemiplegia. Among them, bilateral arm training is emerging as one of effective intervention methods. Bilateral arm training refers to a method that induces the patient to symmetrically move both affected and unaffected upper limbs simultaneously or alternately to lead to the recovery of motor skills based on the neural signal crossing model theory (Cauraugh & Summers, 2005; Luft et al., 2004; Sabaté et al., 2004). The neural signal crossing model theory argues that when both side upper limbs are symmetrically moved simultaneously, the homologous muscle groups on both sides are activated and the neural networks on the cerebral hemispheres on both sides that control the muscles are activated. However, if exercise is performed focusing on the movements of the hemiplegic upper limb, the unaffected cerebral hemisphere will be excessively activated leading to suppression of the affected cerebral hemisphere. The abnormal compensatory mechanism appearing in the process of recovery of hemiplegic patients’ upper limb motor skill recovery is also attributable to the unbalanced activation of the cerebral hemispheres on two sides due to such a mechanism (Shimizu et al., 2002). Therefore, bilateral arm training can promote the recovery of the affected upper limb because it reduces cerebral hemisphere suppression through simultaneous activation of both cerebral hemispheres (Stinear & Byblow, 2002).

Previous studies that examined the effects of bilateral arm training have reported not only the improvement of stroke patients’ affected upper limb motor skills but also significant effects in terms of the speed and quality of movements of the affected upper limb (Hesse et al., 2003; Summers et al., 2007). In addition, some studies reported that bilateral upper limb exercise applied to stroke patients improved body symmetry, reduced abnormal muscle tone, improved daily living ability, and increased the use or the affected upper limb in daily living (Lee, 2008, 2010; Luft et al., 2004). In addition, some study results were also reported indicating that when bilateral upper limb exercise was grafted on a robot upper limb movement apparatus and used in intervention for hemiplegic patients, the patients’ ankyloses and pain were reduced and upper limb motor skills were improved (Hesse et al., 2003).

Although many studies on the treatment effects of bilateral upper limb exercise on hemiplegic patients are being conducted as such, most studies are conducted with adult hemiplegic patients and studies conducted with children are very rare. In addition, exercise programs presented in previous studies on the effects of bilateral upper limb exercise are composed of simple repetitions of bilateral upper limb motions. Therefore, they are not sufficient to attract interest of children with hemiplegia and have reduced treating effects when patients’ interest in treatment is low (Flynn et al., 2007; Forkan et al., 2006). Therefore, bilateral upper limb exercise programs that arouse hemiplegic children’s interest are necessary so that the children with hemiplegia can voluntarily participate in bilateral upper limb exercise.

Based on this necessity, virtual reality systems implemented in the form of games have been reported as positive means of intervention that arouse children’s interest and fun to motivate them for treatment in studies conducted with children with cerebral palsy. In addition, other study results were also reported indicating that virtual reality systems can provide visual and auditory feedback while the subject is perfoming tasks thereby not only helping effective movement control but also enhancing the effect of motor learning (Flynn et al., 2007). To review previous studies that used such virtual reality systems as intervention tools for upper limb rehabilitation, some studies reported that when cerebral palsy children were trained with upper limb reaching exercise using a virtual reality system, the subject children’s upper limb exercise performing ability was improved (Chen et al., 2007). In addition, studies that used virtual reality systems on hemiplegic adult patients as intervention tools reported results indicating that virtual reality systems were effective for not only the improvement of subjects’ upper limb functions and upper limb muscle strength but also the improvement of through visual perception functions (Song et al., 2011; Levin et al., 2009; Merians et al., 2009).

Although cases where studies of virtual reality and studies of bilateral arm training conducted separately have been reported as above, no case where virtual reality based bilateral arm training was implemented on children with hemiplegia has been reported yet. If the advantages of virtual reality systems as intervention tools are grafted on bilateral arm training and implemented on hemiplegic cerebral palsy children, it should be effective for improvement of the children’s upper limb motor skills. Therefore, the purpose of the present study was to verify whether virtual reality based bilateral upper limb exercise is effective for improvement of hemiplegic cerebral palsy children’s affected upper limb functions and bilateral hand coordination ability.

2 Methods

2.1 Subjects

In the present study, permission for experiment was received from the research ethics committee of Yonsei University and the experiment was conducted with three hemiplegic cerebral palsy children who were receiving rehabilitation treatment as outpatients at university hospoital located in Daejon. The subjects were recruited through a notice on the bulletin board in the hospital and the experiment was conducted with those children among the recruited subjects that satisfied the following selection conditions after explaining the purpose and schedule of the study, traning and test methods, and personal information protection to the children and their guardians and receiving written agreements for participation from the children’s parents.

The subject selection criteria used in the present study are as follows.

Children diagnosed with spastic hemiplegic cerebral palsy

Children who can understand and cooperate with researcher’s instructions

Children with no visual or hearing impairment

Children who can voluntarily move the affected upper limb

Children who can catch and throw a basketball

Children whose guardians agreed to the study

Subject 1 was a seven year old right hemiplegic boy in the first year of elementary school who was receiving ambulatory physical therapy and occupational therapy after being diagnosed with cerebral palsy and was independently attending the school as he could walk. Although he could voluntarily move his right upper limb, he clearly showed functional declines in the right upper limb. In a Pediatric Motor Activity Log (PMAL) test, his scores for the amount of use (AOU) and the quality of movement (QOM) of the affected upper limb were 0.42 and 2.02 points respectively. According to his guardian’s report, he was rarely or hardly using the affected upper limb. In terms of the quality of movements, although he was using the affected sometimes but he was doing so with help by the unaffected hand.

Subject 2 was a six year old left hemiplegic boy who was receiving ambulatory physical therapy and occupational therapy after being diagnosed with cerebral palsy and could independently walk. He clearly showed functional declines in the left upper limb and could voluntarily move the affected hand but could do so very slowly and with hard effort. In a Pediatric Motor Activity Log (PMAL) test, his scores for the amount of use (AOU) and the quality of movement (QOM) of the affected upper limb were 1.76 and 1.85 points respectively. According to his guardian’s report, he was very rarely using the affected upper limb. In terms of the quality of movements, it was reported that his use of the affected hand was not helpful for activities.

Subject 3 was a five year old right hemiplegic girl, who was receiving ambulatory physical therapy and occupational therapy after being diagnosed with cerebral palsy, could walk and passively move all four limbs in the range of movements of joints. She showed voluntary use of the right hand but only at the level of assisting the left hand in most cases. When she was instructed to pick up and release small objects using the right hand, the motions were slow and not smooth and she filed sometimes. In a Pediatric Motor Activity Log (PMAL) test, her scores for the amount of use (AOU) and the quality of movement (QOM) of the affected upper limb were 2.23 and 2.42 points respectively. According to her guardian’s report, she was using the affected upper limb approximately in 25% of cases in daily living. In terms of the quality of movements, she was usding the affected hand but needed help from the unaffected hand.

The study subjects’ general characteristics are as follows Table 1.

2.2 Set up and measurement

2.2.1 Affected upper limb motor skill evaluation tool

(1) Wolf Motor Function Test: WMFT

The WMFT is an upper limb and hand function evaluation tool developed in 1989 by Wolf at Emory Medical College in the USA that evaluates upper limb movements with simple movement tasks and evaluates hand movement ability with complicated movement tasks (Wolf et al., 1989). The WMFT consists of a total of 17 items that instructs designated task movements and the time taken to perform the movementsd and the qualitative aspect of the movements are measured as function scores. The time to perform each item of this evaluation tool is set to 120 sec. and the function scores consist of 6-point scales ranging from 0 to 5 points. The WMFT is widely used not only in foreign countries but also in South Korea because its validity and reliability have been proved (Park et al., 2004). The inter-rater reliability and test-retest reliability of the performance time of this evaluation tool have been reported as 0.97 and 0.95 respectively (Morris et al., 2001). In the present study, to examine whether the performance time of affected upper limb movements and the qualitative aspect of movements have been improved by the effect of intervention, excluding evaluation items 7∼17 for hand function evaluation, WMFT’s evaluation items 1∼6 were measured in all sessions in each of the baseline period, the intervention period, and the period of regression to the baseline.

(2) Pediatric Motor Activity Log: PMAL

The PMAL is an evaluation tool intended to examine how independently the subject children use their affected upper limb through inteviews with the subject children or their guardians. The PMAL was made by modifying the motor activity log (MAL) developed for stroke patients to fit children. It consists of movements in actual living environments and is known to be a tool that can best evaluate daily living movements (van der Lee, 2003). This evaluation tool evaluates hand functions and coordination ability through functional daily living activities by measuring the amount of use (AOU) and the quality of movement (QOM) of the affected upper limb during daily life. In the PMAL, AOU and QOM scores consist of 6-point scales respectively ranging from 0 point (cannot use at all) to 5 points (uses well). The inter-rater reliability and test-retest reliability of this evaluation tool are r = 0.90 and r = 0.94 respectively (Taub et al., 2004). In the present study, to examine how much the frequency of use and the quality of movement of the affected upper limb in daily life improved after intervention, out of the 22 evaluation items of the PMAL, 21 items related to upper limb functions were selected and used in the evaluation (Kim & Park, 2007). For this evaluation, the guardian of the children were requested to answer the evaluation item once in the baseline period, once after the intervention, and once after the period of regression to the baseline and the scores for the amount of use (AOU) and the quality of movement (QOM) of the affected upper limb during daily life of the children were obtained from the resultant answers.

2.2.2 Bilateral hand coordination ability evaluation tool

(1) Putting a basketball through the hoop

In the present study, to measure the subject children’s bilateral hand coordination ability, putting a basketball through the hoop was operantly defined and evaluated. The hoop used in the experiment was a simplified hoop for children that could be adjusted in height and the basketball was a 14 cm diamer and 150 g basketball for children. This evaluation was conducted by having each subject child make 20 shots using both hands in a standing position from a point 1 m away from the hoop and measuring the number of successful shots. In this evaluation, the number of successful shots made using one hand instead of both hands was excluded from the results. This evaluation was conducted in all sessions in each of the baseline period, the intervention period, and the period of regression to the baseline and the results were recorded.

(2) Moving large lightweight boxes

The evaluation of moving large lightweight boxes was conducted the present study to meaure subject childrens’ bilateral upper limb coordination ability. In this evaluation, the time taken for each subject to take five 18*18*15 (width*length*height) empty paper boxes and put them on 1 cm thick boards one by one was measured. This evaluation was conducted in each of the baseline period, the intervention period, and the period of regression to the baseline and all the results were recorded.

2.2.3 Intervention tool

(1) Bilateral upper limb exercise program applied to virtual reality Nintendo Wii

The virtual reality system ‘Nintendo Wii (Nintendo company Ltd, Japan. 2008)’ used in the present study consists of a monitor, a desktop, a remote controller that senses upper limb movements, and a Nunchuk. In Nintendo Wii, when the program has been excuted, objects on the screen can be pointed with the pointer at the control element of the remote controller within 5 m from the monitor as the motion sensors senses the angles of hand movements and changes in the movements three dimensionally and makes the virtual avatar on the screen move in the directions desired by the subject thereby playing the role of a visual feedback device. The Nintendo Wii program used in the present study had the subject move the upper limbs while holding the remote controller using both hands following the commands appearing on the screen such as brandish a sword, playing golf, rowing, and depressing a pedal to train bilateral upper limb movements using the sensing of movements following the movements of the remote controller.

In the present study, bilateral upper limb exercise was grafted on Nintendo games played using both hands such as canoe, golf, swordsmanship, and cycling in the Sports resort software program of the virtual reality system NintendoWii and was implemented as an intervention for rehabilitation of the upper limbs of the subjects. Bilateral upper limb exercises are largely divided into symmetric bilateral upper limb exercises and asymmetric bilateral upper limb exercises. In the present study, among the selected four Nintendo Wii games, the canoe, golf, and swordmanship were organized into symmetric bilateral upper limb exercises to hold the remote controller using both hands and move the affected upper limb and the unaffected upper limb simultaneously in the same direction and the cycling game was organized into asymmetric bilateral upper limb exercise to hold the remote controller using one hand and the Nunchuk using another hand and move the affected upper limb and the unaffected upper limb alternately. Detailed upper limb movements and performing postures for individual games are presented below.

In the canoe game, in a standing position looking straight ahead, the subject holds the Nintendo Wii remote controller using both hands and rows the remote controller alternately to the right and left as if pulling an oar to train for symmetric bilateral movements of the affected upper limb and the unaffected upper limb. One thing that requires attention is that the subject should hold the remote controller using both hands and move both hands simultaneously in the same direction.

In the golf game, in a position turned approximately 90° away from the monitor, the subject holds the Nintendo Wii remote controller using both hands as if holding a golf club and swings the affected and unaffected upper limbs simultaneously in one direction in the form of a golf swing to train for symmetric bilateral upper limb movements. One thing that requires attention during the golf game is that the subject should hold the remote controller using both hands and move both hands simultaneously in the same direction.

In the swordmanship game, in a standing position facing the monitor, the subject holds the Nintendo Wii remote controller using both hands as if holding a sword and wields the remote controller as if wileding a sword in the directions of arrows presented on the monitor. The arrows are presented in diverse directions including downward, leftward, rightward, and diagonal directions. The swordmanship game trains the subject for symmetric bilateral movements to move the affected upper limb and the unaffected upper limb simultaneously in the same direction. One thing that requires attention during the swordmanship game is that the subject should hold the remote controller using both hands and move both hands simultaneously in the same direction.

In the cycling game, in a standing position facing the monitor, the subject holds the remote controller using one hand and the Nunchuk using another hand. This game trains the subject for asymmetric bilateral upper limb movements as the subject moves the two hands alternately upward and downward as if depressing bicycle pedals. One thing that requires attention during the cycling game is that the subject should hold the remote controller using one hand and the Nunchuk using another hand and move both hands in the opposite directions.

2.3 Procedure

In the present study, ABA design was used which is a withdrawal design as a single-subject research design. The experiment was conducted with two sessions per week for a total of 20 sessions consisting of A1 as a baseline period for two weeks comprising four sessions, B as an intervention period for six weeks comprising 12 sessions of virtual reality based bilateral arm training, and A2 as a regression to baseline period for two weeks comprising four sessions in the same method as baseline A1 without intervention.

2.3.1 Baseline (A1)

During the baseline period in the present study, to measure basic data on subject children’s upper limb motor skills, the PMAL was conducted once with the guardians before intervention. During the same period, the subject children were evaluated on WMFT, putting a basketball through the hoop, and moving large light-weighted boxes in four sessions in total consisting of two sessions per week for two weeks.

2.3.2 Intervention period (B)

During the intervention period in the present study, the subject children visited the treatment room two times per week and implemented the given Nintendo Wii programs for 30 minutes. In the first session every week, they implemented canoe and golf for 15 minutes each during 30 minutes in total and in the second session, they implemented swordmanship and cycling for 15 minutes each during 30 minutes in total. As such, they implemented all of four programs once per week by performing two programs per session and the same was repeated for six weeks so that a total of 12 session of intervention were implemented during the intervention period. In the present study, even during the intervention period, after the intervention of 30 minutes in each session, WMFT, putting a basketball through the hoop, and moving boxes were evaluated and the scores in each evaluation were recorded. In addition, PMAL evaluation was conducted when all the 12 session in the intervention period were completed.

2.3.3 Regression to baseline (A2)

The regression to baseline period in the present study was set to examine whether the upper limb motor skills obtained through training are maintained when all the intervention has been completed. During this period, WMFT, putting a basketball through the hoop, and moving boxes were evaluated four times in total; two times per week for two weeks. Thereafter, PMAL evaluation was conducted with the guardians once again when the regression to baseline period had passed.

2.4 Data processing

In the present study, performances were recorded by session and the results were analyzed through visual graphs. The results of measurement in the evaluation of WMFT, putting a basketball through the hoop, and moving large light-weighted boxes were plotted on graphs to examine changes and the frequencies and skills of use of the affected upper limb obtained through PMAL were presented through comparison between values measured before and after intervention.

3 Results

3.1 Changes in affected upper limb motor skills

3.1.1 Changes in Wolf Motor Function Test (WMFT) performance scores

The performance scores of Wolf motor function test (WMFT) by time are presented by subject in Figs. 1–3. The performance scores of subject 1 were 22 points on average during the baseline period and 23.9 points on average during the intervention period with an increase by 1.9 points. The scores increased by 4 points to become 26 points during the regression to baseline period.

The performance scores of subject 2 were shown to be 15.5 points during the baseline period, increased by 3.5 points to become 19 points during the intervention period, and became 20 points on average during the regression to baseline period with an increase by 4.5 points compared to the baseline period. The performance scores of subject 3 were shown to be 24.2 points during the baseline period, increased by 2.4 points to become 26.6 points during the intervention period, and became 28 points on average during the regression to baseline period with an increase by 4.5 points compared to the baseline period. Therefore, the Wolf motor function test (WMFT) performance scores increased in the intervention period compared to the baseline period in all subjects and these increases continued in the regression to baseline period too.

3.1.2 Changes in Wolf Motor Function Test (WMFT) performance time

The Wolf motor function test (WMFT) performance times by period are presented by subject in Figs. 4–6. The performance times of subject 1 were 8.1 sec. on average during the baseline period but decreased by 2.3 sec. to 5.7 sec. on average during the intervention period, and decreased to 5.3 sec. during the regression to baseline period with a decrease by 2.8 sec. compared to the baseline period. The performance times of subject 2 were 15.7 sec. on average during the baseline period but decreased by 5.7 sec. to 10 sec. on average during the intervention period, and decreased to 9.7 sec. during the regression to baseline period with a decrease by 6 sec. compared to the baseline period. The performance times of subject 3 were 18 sec. on average during the baseline period but decreased by 10 sec. to 8 sec. on average during the intervention period, and decreased to 5.8 sec. during the regression to baseline period with a decrease by 12 sec. compared to the baseline period.

3.1.3 Changes in Pediatric Motor Activity Log (PMAL) scores

In the case of subject 1, the amount of use of the affected upper limb increased from 0.42 points in the baseline period to 2.57 points after the intervention period and was shown to be 2.47 points during the regression to baseline period indicating that the amount of use of the affected upper limb was maintained at higher levels compared to the baseline period. The quality of movement of the affected upper limb increased from 2.02 points in the baseline period to 3.21 points after the intervention period and was maintained at similar levels until the end of regression to baseline. In the case of subject 2, the amount of use of the affected upper limb increased from 1.76 points in the baseline period to 2.3 points after the intervention period and was shown to be 2.27 points during the regression to baseline period indicating that the amount of use of the affected upper limb was maintained at higher levels compared to the baseline period. The quality of movement of the affected upper limb increased from 1.85 points in the baseline period to 2.53 points after the intervention period and was shown to be 2.41 points during the regression to baseline period indicating that quality of movement of the affected upper limb was maintained at higher levels compared to the baseline period. In the case of subject 3, the amount of use of the affected upper limb increased from 2.23 points in the baseline period to 4 points after the intervention period and was maintained at similar levels until the end of regression to baseline. The quality of movement of the affected upper limb increased from 2.42 points in the baseline period to 4.04 points after the intervention period and the same score was maintained in the regression to baseline period.

3.2 Changes in bilateral hand coordination ability

3.2.1 Changes in the number of successful basketball shots

Changes in the number of successful basketball shots by the subjects using both hands are presented in Figs. 7–9. In the case of subject 1, the numbers of successful basketball shots were 4.2 on average during the baseline period, 8.6 on average during the intervention period with an increase by 4.4, and 7.7 on average during the regression to baseline period with an increase by 3.5 compared to the baseline period. In the case of subject 2, the numbers of successful basketball shots were 2 on average during the baseline period, 5.2 on average during the intervention period with an increase by 3.2, and 4 during the regression to baseline period with an increase by 2 compared to the baseline period. In the case of subject 3, the numbers of successful basketball shots were 1.7 on average during the baseline period, 5.2 on average during the intervention period with an increase by 3.5, and 7 during the regression to baseline period with an increase by 5.3 compared to the baseline period.

3.2.2 Changes in box moving performance time

Changes in the time taken for the subjects to move large light-weighted boxes using both hands are presented and Figs. 10–12. In the case of subject 1, the average times taken to move the boxes were 10.2 sec. on average during the baseline period, 6.4 sec. on average during the intervention period with a decrease by 3.7 sec., and 6.1 sec. on average during the regression to baseline period with a decrease by 4.1 sec. compared to the baseline period. In the case of subject 2, the average time taken to move the boxes decreased from 29.5 sec. on average during the baseline period to 21.2 sec. on average during the intervention period with a decrease by 8.3 sec and was shown to be 22.9 sec. on average during the regression to baseline period with a decrease by 6.6 sec. compared to the baseline period. In the case of subject 3, the average times taken to move the boxes were 31.2 sec. on average during the baseline period, 21.1 sec. on average during the intervention period with a decrease by 9 sec., and 18.1 sec. on average during the regression to baseline period with a decrease by 13 sec.

4 Discussion

In the midst of implementation of diverse upper limb rehabilitation programs intended to improve hemiplegic patients’ upper limb functions, studies of bilateral upper limb exercises that can overcome the side effects comning from the training concentrated on the affected upper limb have been actively conducted. In the present study, bilateral arm training grafted on virtual reality was implemented on children with hemiplegia to examine resultant changes in the subjects’ affected upper limb motor skills and bilateral hand coordination ability.

In the present study, virtual reality based bilateral upper limb exercises were applied to three children with hemiplegia and changes in their affected upper limb motor skills and bilateral hand coordination ability between before and after the bilateral upper limb exercises were examined. In the case of WMFTs conducted to examine changes in affected upper limb motor skills, performance time decreased during the intervention period in all subjects and performance scores improved. In the case of evaluation of putting a basketball through the hoop and box moving conducted to examine changes in bilateral hand coordination ability, the number of successful basketball shots increased and the time taken to move boxes decreased in all subjects. This means that through bilateral upper limb exercises, not only affected upper limb motor skills but also bilateral hand coordination ability improved. The results of PMAL showed the the amount of use and the quality movements of the affected upper limb improved in all three subjects in the second evaluation conducted after the intervention period in the compared to evaluation at the beginning of the baseline period. This can be regarded as evidence indicating that thanks to the upper limb functions improved through bilateral upper limb exercises, the amount of use of the affected upper limb increased during daily living activities and the quality of movement improved.

On reviewing the results of WMFT evaluation, it could be seen that in all sessions, despite that the WMFT performance scores of subject 3 were higher compared to subject 1, the WMFT performance time of subject 3 was shown to be longer than that of subject 1. This is considered attributable to the fact that since subject 3 aged five years was younger than other subjects, her cognitive level to understand instructions was the lowest and took time in understanding the evaluation tasks. However, since the WMFT performance times of all subject decreased compared to the baseline period consistently with the results of studies conducted by Rose and Winstein (2004) and Cauraugh, Kim, and Duley (2005) indicating that affected limbs’ movement time statistically significantly decreased after bilateral arm training, it can be seen that, the virtual reality based bilateral upper limb exercises implemented in the present study positively affected upper limb movement speed.

On reviewing the results of the evaluation of bilateral hand coordination ability conducted in the present study, it can be seen that all three subjects showed improvement by at least 3 on average in the number of successful basketball shots in the intervention period compared to the baseline period when putting a basketball through the hoop was evaluated and box moving performance times decreased by 3 sec. on average in the intervention period compared to the baseline period indicating improvement in performing ability. In the case of subject 3, the results of evaluation were a little poorer in sessions 13 and 14 during the intervention period and this is considered attributable to the fact that the subject child had poor physical conditions during the experiments as she had a cold. However, given that all subjects showed improved performing ability in the intervention period compared to the baseline period in the evaluation of putting a basketball through the hoop and box moving, the virtual reality based bilateral arm training used in the present study can be regarded to have improved the subjects’ bilateral hand coordination ability.

When the results of the evaluation of affected upper limb motor skills and bilateral hand coordination ability conducted in the present study were compared, the results of evaluation of affected upper limb motor skills of subject 3 were the best with the WMFT performance score 26.6 points on average in the intervention period but the results of evaluation of bilateral hand coordination ability of subject 1 were shown to be higher with the putting a basket through the hoop score of 8 points on average in the intervention period compared to subject 3 that showed 6 points on average in the intervention period. Given these results, the levels of improvement in affected upper limb motor skill and bilateral hand coordination ability were a little different among the subjects but consequently, the affected upper limb motor skills and bilateral hand coordination ability of all subjects improved.

On reviewing the results of the present study for the regression to baseline period it can be seen that all subjects showed better results than baseline in evaluation. In particular, in the case of subject 3, the averages of the results of evaluation conducted in the regression to baseline period were higher than those of evaluation conducted in the intervention period. Through these results, the present study showed the possibility for the effects of virtual reality based bilateral arm training to remain even when intervention disappeared and presented evidence for whether treatment effects are maintained that is insufficient in previous studies on bilateral arm training.

The present study showed improvement in affected upper limb motor skills by implementing bilateral upper limb exercises on children with hemiplegia. These results support the results of a previous study conducted by Kim, Park, and Ahn (2003) on the effects of bilateral upper limb activities of children with hemiplegia on the affected upper limb’s movement performance and learning indicating that when tapping tasks were performed using the affected and unaffected upper limbs simultaneously significantly increased affected upper limb movement speed than when only the affected upper limb was used. In addition, results of the present study can be also regarded to be consistent with the results of a study in which adult hemiplegic patients were randomly assigned to a bilateral rehabilitation exercise group and a unilateral rehabilitation exercise group and rehabilitation exercises were implemented indicating that the bilateral rehabilitation exercise group showed significantly more improvement in the efficiency of affected upper limb movements compared to the unilateral rehabilitation exercise group (Kim et al., 2010). In addition, results of the present study are in the same context with previous studies indicating that bilateral rehabilitation exercises brought about positive results on hemiplegic adult patients’ bilateral hand coordination ability (Cauraugh & Summers, 2005; Stewart et al., 2006; Waller & Whitall, 2008).

In particular, the effects of treatment programs that repeat simple movements decrease because children’s interest in the treatment is low (Flynn et al., 2007; Forkan et al., 2006). Unlike studies on bilateral arm training that repeats simple movements, the present study grafted a virtual reality system that arouses children’s interest and fun was grafted on bilateral arm training performed by cerebral palsy children. In the results of a study conducted by Harris and Reid (2005) that measured cerebral palsy children’s motive for virtual reality system indicated that virtual reality systems could be an appropriate intervention tool that can arouse cerebral palsy children’s interest. In addition, many studies that used virtual reality systems as a treatment intervention for cerebral palsy children reported results indicating that virtual reality training improved not only balance ability but also daily living activities, voluntary control ability, and coordination ability of cerebral palsy children (Bryanton et al., 2006; Han, & Gho, 2010). These cases show that virtual reality systems are an appropriate intervention tool that enhances cerebral palsy children’s intervention effects. Therefore, given these special advantages of virtual reality systems, it can be seen that the effects of bilateral arm training were enhanced in the present study because subject children felt interest in the treatment and actively participated as bilateral arm training was implemented through the means of intervention termed virtual reality.

The clinical significance of the present study is that by identifying that bilateral arm training of which the effects were mainly identified in adult hemiplegic patients had positive effects on hemiplegic childrens’ affected upper limb functions and bilateral hand coordination ability, it could identify that bilateral arm training is effective upper limb rehabilitation training for not only adults but also children. In addition, unlike previous studies that simply repeated bilateral arm training without any separate program as an intervention, the present study implemented an intervention that grafted bilateral arm training on virtual reality games and through the results of the intervention that brought about improvement in hemiplegic childrens’ upper limb motor skills, it showed a possibility to apply bilateral arm training to diverse intervention tools.

Based on the above study results and discussion, this author would like to present several proposals in relation to the limitations of the present study and the direction of future studies. Considering that since existing studies on bilateral arm training were mainly conducted with adults, bilateral arm training might cause boredom to children, the present study grafted bilateral arm training on virtual reality games to implement it. However, since the effects of such bilateral arm training when it was grafted on virtual reality games and when it was not grafted on virtual reality games were not compared, follow-up studies should compare such effects. In addition, since the follow-up period after intervention was short with four sessions and evaluation was conducted from the immediate next session after the removal of the intervention in the present study, whether the effects would be maintained for a long time or not cannot be sufficiently identified. If studies that can supplement these limitations in the study design are conducted later, the effects of virtual reality based bilateral upper limb exercise on hemiplegic children’s affected upper limb function can be more clearly identified.

5 Conclusion

The present study examined the effects of virtual reality based bilateral arm training on hemiplegic cerebral palsy children’s affected upper limb motor skills and bilateral hand coordination ability. The training was conducted with three children diagnosed with hemiplegic cerebral palsy two times per week for 10 weeks in the pediatric occupational treatment room of the department of rehabilitation medicine of a university hospital located in Daejon. Virtual reality based bilateral arm training was implemented on all the subjects and intervention results were examined by examining changes in affected upper limb motor skills through WMFT and PMAL during baseline, intervention, and regression to baseline periods and changes in bilateral hand coordination ability were analyzed through evaluation of putting a basketball through the hoop using both hands and moving large light-weighted boxes.

According to the results of the studies all subjects showed improvement in WMFT performance scores and decreases in performance time after intervention. In the results of PMAL reported by the guardians too, the amount of use of the affected upper limb increased and the quality of movement improved after intervention. In the results of evaluation of putting a basketball through the hoop using both hands and moving large light-weighted boxes conducted to evaluate bilateral hand coordination ability too, all subjects showed positive changes after intervention.

Through the results of the present study, it could be identified that virtual reality based bilateral arm training had positive effects in improving hemiplegic cerebral palsy children’s affected upper limb motor skills and bilateral hand coordination ability.

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