Technology and Health Care 22 (2014) 751–758 DOI 10.3233/THC-140836 IOS Press
751
FES for abnormal movement of upper limb during walking in post-stroke subjects C.-H. Choua , Y.-S. Hwanga,1 , C.-C. Chenb,1 , S.-C. Chenc,1 , C.-H. Laic,1 and Y.-L. Chend,e,∗ a Department
of Electronic Engineering, National Taipei University of Technology, Taipei, Taiwan of Management Information System, Hwa Hsia University of Technology, Taipei, Taiwan c Department of Physical Medicine & Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan d Department of Digital Technology Design, National Taipei University of Education, Taipei, Taiwan e Department of Information Management, Nursing and Management College, Yilan, Taiwan b Department
Received 19 March 2014 Accepted 2 May 2014 Abstract. BACKGROUND: Hemiplegia can cause accidental falls, as the patients place their arms in front of their chests or next to the hips when they walk. This is due to limitations in the ability to swing their arms during walking. OBJECTIVE: This study proposes a functional electrical stimulator approach in order to improve the foot drop and abnormal movement of the upper limbs during walking. The goal of this study is to verify the feasibility of improving the foot drop and arm swing problems of hemiplegic patients using electrical stimulators in a clinical trial. METHODS: The present study utilizes a functional electrical stimulator found on the market. The stimulator is controlling the gait and arm swing of the patient while the patient is walking. It can help him or her restore regular gait cycles and arm swings. The FES device can also train the patient to walk safely and regain control of his or her arm swing. After the four-week training, the subjects had to walk 10 meters without the FES system. The step length, step time, and joint goniograms were recorded in order to determine whether there was any improvement. RESULTS: After the four-week training was concluded, the three post-stroke patients showed an improvement in arm swing angle when walking. The improvement was found to be 7.16% in the first patient, 43.06% in the second, and 54.66% in the third. These results are all statistically significant. The t-test had a p-value 0.012 (p < 0.05), which demonstrated that the method used in the present study had the potential to significantly improve the arm swing of post-stroke patients. CONCLUSIONS: The present study showed that a traditional foot drop functional electrical stimulator providing stimulation also to the patient’s upper limbs, while being triggered by a foot switch under his or her heel, can help the patient to swing the arms and reduce the foot drop. The method has significant effect on traditional foot drop therapy. The subjects’ high degree of acceptance and willingness to commit to long-term use showed that the method is indeed worthy of further research. Keywords: Functional electrical stimulation, gait analysis, drop foot, hemiplegia, goniometter
1
These authors contributed equally to this study and should all be considered first authors. Correspondence author: Y.-L. Chen, No.134, Sec.2, Heping E. Rd., Da-an District, Taipei City 106, Taiwan. Tel.: +886 2 2732 1104; Fax: +886 2 6639 6688; E-mail: [email protected]. ∗
c 2014 – IOS Press and the authors. All rights reserved 0928-7329/14/$27.50
752
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
1. Introduction In modern society, there has been an increase in cases of cerebral vascular accident, also known as stroke. This may be in part due to people’s busy work schedules, the propensity towards eating processed foods and a lack of physical exercise. A stroke may have numerous sequelae, the most common of which being hemiplegia. In mild cases, the patient can lose control of one half of his or her body. The condition is often accompanied by the loss of speech, sense of taste, and other senses. This can not only affect the patient’s life functions, but also impacts his mental state. Hemiplegia has a tremendous impact on a person’s everyday life. For example, when walking, the patient can suffer from foot drop i.e. the lack of dorsiflexion, which means that the patient’s toes drag over the ground. As a result, patient’s walking becomes awkward and tiresome, causing the patient to trip or fall easily. This makes the condition very dangerous to patients who have suffered a stroke. Hemiplegia affects the upper and lower limbs simultaneously, causing the patients to place their arms in front of their chests or next to the hips when they walk. While the extent of the arm swing is limited or even non-existing, the patient is in danger of falling when walking. In stroke rehabilitation therapy, the current focus is on correcting the foot drop in the lower limbs. In addition, rehabilitation training often focuses also on restoring the grasping function of the paralyzed hand. The applications of functional electrical stimulation (FES) are very comprehensive. Based on the location of the electrodes, FES can be categorized as transcutaneous, percutaneous, or totally implanted [1]. Functional rehabilitation is a type of rehabilitation designed to restore certain functions, such as standing, walking, grasping, and pedaling. FES can be utilized to restore the aforementioned physical functions. Liberson and Holmquest (1961) were the first to introduce the concept of treating the foot drop in patients suffering from cerebral vascular diseases using electrical stimulators [2]. The treatment involves placing one of the stimulation electrodes over the calf nerve, while detecting foot displacement using a foot switch (FS) under the heel, correcting thus the foot drop during the swing phase. Moe and Post (1962) named the procedure functional electrotherapy [3]. Kralj (1979) introduced the six-channel electrical stimulator that can control the movement of three muscle groups simultaneously. This device was designed to be used in clinical experiments [4]. Currently, there are many low-cost, portable, low voltage versions of electrical stimulators on the market. Because of improvements in microprocessor technology [5], FES devices are no longer limited to one single function. The same FES system can be used for DFS [6], hand rehabilitation [6], standing [7], cerebral palsy intervention [8], and functional electrical stimulation cycling [9]. Because the processing power of microprocessors has improved, it is now possible to insert artificial intelligence and control into FES devices [10]. It is also possible to store physiological signals (i.e. EMG, ENG), detected by sensors, into the memory of the FES device, as well as use the signals to control electrical stimulation output [11]. The present study utilized a commercially available functional electrical stimulator that has the ability to adjust and control trains of electrical stimuli using a microprocessor and foot switch. This study was conducted in order to verify the feasibility of improving simultaneously the foot drop and arm swing problems of hemiplegic patients using electrical stimulators in a clinical trial. 2. Materials and methods The present study utilized a commercially available functional electrical stimulator that has the ability to adjust and control the durations of gait cycles using a microprocessor and foot switch. Figure 1
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
753
Fig. 1. FES system.
illustrates the FES system used in the study. The FES device, by controlling the lower limb and arm swing of the patient, while the patient is walking, can help him or her restore the normal gait cycle. The device can also be used to train the patient to walk safely and regain control of his or her arm swing [12]. The treatment can improve the patient’s confidence in his or her rehabilitation and re-integration into society [13]. The present study used the 2-channel electrical stimulator (Trio-300 MuIti-Mode Electrical Stimulator, Ito Co. Ltd, Japan). The two channels of the device can operate independently. The system is controlled by an 8-bit microprocessor. The operation mode can be selected on an LCD screen. The thin leather foot switch (Heel/foot Switch for Respond II 1/bx, Empi Inc, USA), was placed under the heel inside the shoe on the patient’s healthy side. When the heel comes in contact with the ground, the pressure on the switch breaks the circuitry, and the microprocessor sends electrical stimulation to the affected side. The microprocessor-controlled stimulator device utilizes an electrical stimulation timing control device based on a PIC18F4520 microcontroller. Every patient’s condition and his or her gait cycle vary, but the device is adjusting electrical stimulation output and timing in order to improve the patient’s gait. When the microprocessor receives a signal from the foot switch, it will automatically adjust the optimal delay time and stimulation off time for the patient. The delay time is the period between receiving the signal and providing the stimulation, and the off time is the time when the stimulation ends. The times are adjusted based on patient’s clinical gait evaluation, with the goal to restore the patient’s walking as much as possible. Figure 2 shows the stimulation pattern control of gait cycles. In the figure, the person’s left foot (white) is the healthy side, while the right foot (black) is the affected side. The foot switch is installed under the heel of the healthy side. After the microcontroller receives the signal from the foot switch, it outputs the electrical stimulation to help the patient raise his foot and swing his arms. The electrical stimulation is discontinued when the healthy heel leaves the ground. Figure 3 shows the patient during the experiment. On the affected side, the electrodes were placed on the triceps of the upper limb and the tibialis anterior muscle of the lower limbs. Electrical stimulation applied to these two locations can help restore arm and foot movement when the patient is walking. In order to measure the angular movement of elbow and ankle joints, a goniometer (Twin Axis Goniometers SG110, Biometrics Ltd, UK) was placed close to the center of joint rotation. Four goniometers were placed on the patient’s elbows and ankles in order to record the angular joint rotations on the healthy and the affected side. The differences between the healthy and the affected sides were analyzed.
754
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
Fig. 2. The stimulation pattern control of gait cycles [14]. (Colours are visible in the online version of the article; http://dx. doi.org/10.3233/THC-140836)
Fig. 3. The patient during the experiment. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ THC-140836)
The Institution Review Board of Taipei Medical University approved the experimental design of the present study, and all of the participants signed an informed consent form. The subject’s inclusion criteria for the clinical trial were as follows: 1. The onset of acute stroke must have been within the past 6–24 months. 2. The subject must suffer from hemiplegia. 3. The subject must have had a FAC level between three and four and be able to walk 10 meters independently without assistance. 4. The subjects must not have been able to extend the upper limbs while walking. 5. In order to avoid interference with the study’s treatment plan, the subjects should not have participated in other rehabilitation training at the time of the current study. The clinical trial lasted for four weeks, with participants contacts occurring twice a week during the study period. The subjects were required to participate in pre-test, mid-test and post-test phases, which involved the following:
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
755
Table 1 Hemiplegic patients general data Subject Item
A
B
Sex Age 70 62 FAC level 4 4 Time past injury(m) 48 20 Affected side L R Used assistive device AFO AFO Note: FAC = functional ambulation category; (m) = month.
C
41 3 18 L AFO
Fig. 4. The test history of patient A. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
1. Pre-Test: The subjects’ basic data were collected in order to confirm electrical stimulation delay time, off time and intensity for the upper and lower limbs. 2. Mid-Test: After training each time twice a week, every subject was asked to walk with FES assistance for 10 meters distance. The step length and total time were recorded. 3. Post-Test: After the four-week training was concluded, the subjects had to walk 10 meters without the FES system. The step length, time, and angles of joint rotations were recorded in order to determine whether there was any improvement.
3. Results Table 1 shows the demographic data of the three patients with acute stroke that participated in the present study. Their FAC level was either three or four. Figure 4 shows the test history of patient A. In terms of the time required to walk 10 meters, the difference between the pre-test and the post-test showed that there was an improvement of 3.5%. Patient A suffered a foot injury in week two, which resulted in
756
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
Fig. 5. The test history of patient B. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
Fig. 6. The test history of patient C. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
a decrease in the average step length of the left and right foot (left: 12.39%, right: −13.31%). However, the pre-test and post-test step length showed an improvement (Pre-test: 14.52%, Post-test: 13.32%). Figure 4 shows the joint angles, and the results revealed that there was significant improvement in the elbow joint of the affected side (7.16%) and little improvement on the healthy side (0.81%). In terms of dorsiflexion, there was no improvement due to the foot injury. Figures 5 and 6 are the test histories of patients B and C. Table 2 shows the pre-test and post-test results for the subjects B and C, including
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
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Table 2 The pre-test and post-test results for Subject B and Subject C Lower limb
Record item Average step length Difference in step length Time required to walk 10 meters Dorsiflexion angle
Upper limb
Arm swing angle
Healthy side Affected side
Subject B +17.68% +7.11% +16.57% +6.1% +21.93% −0.16% +17.55%
Subject C +14.92% +3.31% +5.1% +5.1% +3.44% +7.56% +8.65%
Healthy side Affected side
+460.67% +43.06%
+5.3% +54.66%
Healthy side Affected side Healthy side Affected side
Table 3 Results of the joint angles on the affected side Subject Pre-Test (degree) Post-Test (degree) Difference (degree) Improvement∗ Paired sample t-test P(T t)
A 31.57 33.83 +2.26 7.16%
B 4.25 6.08 +1.83 43.06% 0.012
C 5.8 8.97 +3.17 54.66%
Note: Improvement∗ = Difference/Pre-Test.
the average step length, difference in step length, time required to walk 10 meters, dorsiflexion angle, and the arm swing angle. For patient B, the test revealed that all variables, except for the dorsiflexion angle on the healthy side, improved significantly. Patient B is making a large stride from the affected side first and then swings the healthy leg forward, which resulted in a longer step length on the affected side. Patient B also habitually puts his hands in the pockets when he walks, which resulted in a smaller arm swing angle on the healthy side. Table 3 shows the results of the joint angles on the affected side. The aforementioned results of the study showed that the patients demonstrated significant improvement in arm swing angles. After completing the training sessions, the three patients showed an improvement of 7.16%, 43.06% and 54.66%, which are all significant. The t-test had a p-value of 0.012 (p < 0.05), which demonstrated that the method used in the present study has the potential to significantly improve the arm swing of post-stroke patients. 4. Discussion and conclusion The data from the clinical trials conducted in this study revealed that after completing a comprehensive electrical stimulation training for upper and lower limbs, there can be expected a significant improvement in patients walking. When there is no outside interference, the FES device can improve the foot drop and prevent the patient from falling. The difference in step length between the left and the right leg also showed a significant decrease. Furthermore, the intervention by the electrical stimulation system also improved arm swing angle significantly after one month of therapy. The multichannel electrical stimulator is beneficial for improving the lack of coordination between the left and right limbs when the patient is walking. Furthermore, the patients showed very high confidence and interest in the system. All of the participants expressed interest in obtaining the system for training at home or for assisting them while walking outside.
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C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
The present study showed that a traditional foot drop functional electrical stimulator can be efficiently upgraded by simultaneous stimulation of to the upper limb, helping the patient to swing his or her arm. This method has a more significant effect on patients outcomes than does the traditional passive foot drop correction. The subjects’ high degree of acceptance and willingness to commit to long-term use showed that the method is indeed worthy of pursuing further. Acknowledgements This work is supported by the Ministry of MOST 102-2221-E-152-001, and clinic help from department of physical medicine and rehabilitation, Taipei Medical University and Hospital. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
Y. Lazorthes and A. R. M. Upton, Neurostimulation: An overview: Futura Pub. Co., 1985. W. T. Liberson, H. J. Holmquest, D. Scot, et al., Functional electrotherapy: stimulation of the peroneal nerve synchronized with the swing phase of the gait of hemiplegic patients, Archives of physical medicine and rehabilitation, 42, 1961, p. 101-105. J. H. Moe and H. W. Post, Functional electrical stimulation for ambulation in hemiplegia, The Journal-lancet, 82, 1962, p. 285-288. P. Strojnik, A. Kralj and I. Ursic, Programmed six-channel electrical stimulator for complex stimulation of leg muscles during walking, IEEE transactions on bio-medical engineering, 26, 1979, p. 112-116. A. Kralj, T. Bajd, R. Turk, et al., Gait restoration in paraplegic patients: A feasibility demonstration using multichannel surface electrode FES, Journal of rehabilitation R&D / Veterans Administration, Department of Medicine and Surgery, Rehabilitation R&D Service, 20, 1983, p. 3-20. J. Chae, L. Sheffler and J. Knutson, Neuromuscular electrical stimulation for motor restoration in hemiplegia, Topics in stroke rehabilitation, 15, 2008, p. 412-426. T. Bajd, M. Munih and A. Kralj, Problems associated with FES-standing in paraplegia, Technology and health care: Official journal of the European Society for Engineering and Medicine, 7, 1999, p. 301-308. S. Galen, L. Wiggins, R. McWilliam, et al., A combination of Botulinum Toxin A therapy and Functional Electrical Stimulation in children with cerebral palsy – a pilot study, Technology and health care: Official journal of the European Society for Engineering and Medicine, 20, 2012, p. 1-9. J. Verellen, Y. Vanlandewijck, B. Andrews, et al., Cardiorespiratory responses during arm ergometry, functional electrical stimulation cycling, and two hybrid exercise conditions in spinal cord injured, Disability and rehabilitation Assistive technology, 2, 2007, p. 127-132. P. C. Sweeney, G. M. Lyons and P. H. Veltink, Finite state control of functional electrical stimulation for the rehabilitation of gait, Medical & biological engineering & computing, 38, 2000, p. 121-126. W. L. Chen, S. C. Chen, C. C. Chen, et al., Patient-driven loop control for ambulation function restoration in a noninvasive functional electrical stimulation system, Disability and rehabilitation, 32, 2010, p. 65-71. G. Alon and H. Ring, Gait and hand function enhancement following training with a multi-segment hybrid-orthosis stimulation system in stroke patients, Journal of stroke and cerebrovascular diseases: The official journal of National Stroke Association, 12, 2003, p. 209-216. J. H. Cauraugh and S. Kim, Two coupled motor recovery protocols are better than one: Electromyogram-triggered neuromuscular stimulation and bilateral movements, Stroke; A journal of cerebral circulation, 33, 2002, p. 1589-1594. J. Perry and J. M. Burnfield, Gait Analysis: Normal and Pathological Function: Slack Incorporated, 2010.
751
FES for abnormal movement of upper limb during walking in post-stroke subjects C.-H. Choua , Y.-S. Hwanga,1 , C.-C. Chenb,1 , S.-C. Chenc,1 , C.-H. Laic,1 and Y.-L. Chend,e,∗ a Department
of Electronic Engineering, National Taipei University of Technology, Taipei, Taiwan of Management Information System, Hwa Hsia University of Technology, Taipei, Taiwan c Department of Physical Medicine & Rehabilitation, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan d Department of Digital Technology Design, National Taipei University of Education, Taipei, Taiwan e Department of Information Management, Nursing and Management College, Yilan, Taiwan b Department
Received 19 March 2014 Accepted 2 May 2014 Abstract. BACKGROUND: Hemiplegia can cause accidental falls, as the patients place their arms in front of their chests or next to the hips when they walk. This is due to limitations in the ability to swing their arms during walking. OBJECTIVE: This study proposes a functional electrical stimulator approach in order to improve the foot drop and abnormal movement of the upper limbs during walking. The goal of this study is to verify the feasibility of improving the foot drop and arm swing problems of hemiplegic patients using electrical stimulators in a clinical trial. METHODS: The present study utilizes a functional electrical stimulator found on the market. The stimulator is controlling the gait and arm swing of the patient while the patient is walking. It can help him or her restore regular gait cycles and arm swings. The FES device can also train the patient to walk safely and regain control of his or her arm swing. After the four-week training, the subjects had to walk 10 meters without the FES system. The step length, step time, and joint goniograms were recorded in order to determine whether there was any improvement. RESULTS: After the four-week training was concluded, the three post-stroke patients showed an improvement in arm swing angle when walking. The improvement was found to be 7.16% in the first patient, 43.06% in the second, and 54.66% in the third. These results are all statistically significant. The t-test had a p-value 0.012 (p < 0.05), which demonstrated that the method used in the present study had the potential to significantly improve the arm swing of post-stroke patients. CONCLUSIONS: The present study showed that a traditional foot drop functional electrical stimulator providing stimulation also to the patient’s upper limbs, while being triggered by a foot switch under his or her heel, can help the patient to swing the arms and reduce the foot drop. The method has significant effect on traditional foot drop therapy. The subjects’ high degree of acceptance and willingness to commit to long-term use showed that the method is indeed worthy of further research. Keywords: Functional electrical stimulation, gait analysis, drop foot, hemiplegia, goniometter
1
These authors contributed equally to this study and should all be considered first authors. Correspondence author: Y.-L. Chen, No.134, Sec.2, Heping E. Rd., Da-an District, Taipei City 106, Taiwan. Tel.: +886 2 2732 1104; Fax: +886 2 6639 6688; E-mail: [email protected]. ∗
c 2014 – IOS Press and the authors. All rights reserved 0928-7329/14/$27.50
752
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
1. Introduction In modern society, there has been an increase in cases of cerebral vascular accident, also known as stroke. This may be in part due to people’s busy work schedules, the propensity towards eating processed foods and a lack of physical exercise. A stroke may have numerous sequelae, the most common of which being hemiplegia. In mild cases, the patient can lose control of one half of his or her body. The condition is often accompanied by the loss of speech, sense of taste, and other senses. This can not only affect the patient’s life functions, but also impacts his mental state. Hemiplegia has a tremendous impact on a person’s everyday life. For example, when walking, the patient can suffer from foot drop i.e. the lack of dorsiflexion, which means that the patient’s toes drag over the ground. As a result, patient’s walking becomes awkward and tiresome, causing the patient to trip or fall easily. This makes the condition very dangerous to patients who have suffered a stroke. Hemiplegia affects the upper and lower limbs simultaneously, causing the patients to place their arms in front of their chests or next to the hips when they walk. While the extent of the arm swing is limited or even non-existing, the patient is in danger of falling when walking. In stroke rehabilitation therapy, the current focus is on correcting the foot drop in the lower limbs. In addition, rehabilitation training often focuses also on restoring the grasping function of the paralyzed hand. The applications of functional electrical stimulation (FES) are very comprehensive. Based on the location of the electrodes, FES can be categorized as transcutaneous, percutaneous, or totally implanted [1]. Functional rehabilitation is a type of rehabilitation designed to restore certain functions, such as standing, walking, grasping, and pedaling. FES can be utilized to restore the aforementioned physical functions. Liberson and Holmquest (1961) were the first to introduce the concept of treating the foot drop in patients suffering from cerebral vascular diseases using electrical stimulators [2]. The treatment involves placing one of the stimulation electrodes over the calf nerve, while detecting foot displacement using a foot switch (FS) under the heel, correcting thus the foot drop during the swing phase. Moe and Post (1962) named the procedure functional electrotherapy [3]. Kralj (1979) introduced the six-channel electrical stimulator that can control the movement of three muscle groups simultaneously. This device was designed to be used in clinical experiments [4]. Currently, there are many low-cost, portable, low voltage versions of electrical stimulators on the market. Because of improvements in microprocessor technology [5], FES devices are no longer limited to one single function. The same FES system can be used for DFS [6], hand rehabilitation [6], standing [7], cerebral palsy intervention [8], and functional electrical stimulation cycling [9]. Because the processing power of microprocessors has improved, it is now possible to insert artificial intelligence and control into FES devices [10]. It is also possible to store physiological signals (i.e. EMG, ENG), detected by sensors, into the memory of the FES device, as well as use the signals to control electrical stimulation output [11]. The present study utilized a commercially available functional electrical stimulator that has the ability to adjust and control trains of electrical stimuli using a microprocessor and foot switch. This study was conducted in order to verify the feasibility of improving simultaneously the foot drop and arm swing problems of hemiplegic patients using electrical stimulators in a clinical trial. 2. Materials and methods The present study utilized a commercially available functional electrical stimulator that has the ability to adjust and control the durations of gait cycles using a microprocessor and foot switch. Figure 1
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
753
Fig. 1. FES system.
illustrates the FES system used in the study. The FES device, by controlling the lower limb and arm swing of the patient, while the patient is walking, can help him or her restore the normal gait cycle. The device can also be used to train the patient to walk safely and regain control of his or her arm swing [12]. The treatment can improve the patient’s confidence in his or her rehabilitation and re-integration into society [13]. The present study used the 2-channel electrical stimulator (Trio-300 MuIti-Mode Electrical Stimulator, Ito Co. Ltd, Japan). The two channels of the device can operate independently. The system is controlled by an 8-bit microprocessor. The operation mode can be selected on an LCD screen. The thin leather foot switch (Heel/foot Switch for Respond II 1/bx, Empi Inc, USA), was placed under the heel inside the shoe on the patient’s healthy side. When the heel comes in contact with the ground, the pressure on the switch breaks the circuitry, and the microprocessor sends electrical stimulation to the affected side. The microprocessor-controlled stimulator device utilizes an electrical stimulation timing control device based on a PIC18F4520 microcontroller. Every patient’s condition and his or her gait cycle vary, but the device is adjusting electrical stimulation output and timing in order to improve the patient’s gait. When the microprocessor receives a signal from the foot switch, it will automatically adjust the optimal delay time and stimulation off time for the patient. The delay time is the period between receiving the signal and providing the stimulation, and the off time is the time when the stimulation ends. The times are adjusted based on patient’s clinical gait evaluation, with the goal to restore the patient’s walking as much as possible. Figure 2 shows the stimulation pattern control of gait cycles. In the figure, the person’s left foot (white) is the healthy side, while the right foot (black) is the affected side. The foot switch is installed under the heel of the healthy side. After the microcontroller receives the signal from the foot switch, it outputs the electrical stimulation to help the patient raise his foot and swing his arms. The electrical stimulation is discontinued when the healthy heel leaves the ground. Figure 3 shows the patient during the experiment. On the affected side, the electrodes were placed on the triceps of the upper limb and the tibialis anterior muscle of the lower limbs. Electrical stimulation applied to these two locations can help restore arm and foot movement when the patient is walking. In order to measure the angular movement of elbow and ankle joints, a goniometer (Twin Axis Goniometers SG110, Biometrics Ltd, UK) was placed close to the center of joint rotation. Four goniometers were placed on the patient’s elbows and ankles in order to record the angular joint rotations on the healthy and the affected side. The differences between the healthy and the affected sides were analyzed.
754
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
Fig. 2. The stimulation pattern control of gait cycles [14]. (Colours are visible in the online version of the article; http://dx. doi.org/10.3233/THC-140836)
Fig. 3. The patient during the experiment. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/ THC-140836)
The Institution Review Board of Taipei Medical University approved the experimental design of the present study, and all of the participants signed an informed consent form. The subject’s inclusion criteria for the clinical trial were as follows: 1. The onset of acute stroke must have been within the past 6–24 months. 2. The subject must suffer from hemiplegia. 3. The subject must have had a FAC level between three and four and be able to walk 10 meters independently without assistance. 4. The subjects must not have been able to extend the upper limbs while walking. 5. In order to avoid interference with the study’s treatment plan, the subjects should not have participated in other rehabilitation training at the time of the current study. The clinical trial lasted for four weeks, with participants contacts occurring twice a week during the study period. The subjects were required to participate in pre-test, mid-test and post-test phases, which involved the following:
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
755
Table 1 Hemiplegic patients general data Subject Item
A
B
Sex Age 70 62 FAC level 4 4 Time past injury(m) 48 20 Affected side L R Used assistive device AFO AFO Note: FAC = functional ambulation category; (m) = month.
C
41 3 18 L AFO
Fig. 4. The test history of patient A. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
1. Pre-Test: The subjects’ basic data were collected in order to confirm electrical stimulation delay time, off time and intensity for the upper and lower limbs. 2. Mid-Test: After training each time twice a week, every subject was asked to walk with FES assistance for 10 meters distance. The step length and total time were recorded. 3. Post-Test: After the four-week training was concluded, the subjects had to walk 10 meters without the FES system. The step length, time, and angles of joint rotations were recorded in order to determine whether there was any improvement.
3. Results Table 1 shows the demographic data of the three patients with acute stroke that participated in the present study. Their FAC level was either three or four. Figure 4 shows the test history of patient A. In terms of the time required to walk 10 meters, the difference between the pre-test and the post-test showed that there was an improvement of 3.5%. Patient A suffered a foot injury in week two, which resulted in
756
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
Fig. 5. The test history of patient B. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
Fig. 6. The test history of patient C. (Colours are visible in the online version of the article; http://dx.doi.org/10.3233/THC140836)
a decrease in the average step length of the left and right foot (left: 12.39%, right: −13.31%). However, the pre-test and post-test step length showed an improvement (Pre-test: 14.52%, Post-test: 13.32%). Figure 4 shows the joint angles, and the results revealed that there was significant improvement in the elbow joint of the affected side (7.16%) and little improvement on the healthy side (0.81%). In terms of dorsiflexion, there was no improvement due to the foot injury. Figures 5 and 6 are the test histories of patients B and C. Table 2 shows the pre-test and post-test results for the subjects B and C, including
C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
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Table 2 The pre-test and post-test results for Subject B and Subject C Lower limb
Record item Average step length Difference in step length Time required to walk 10 meters Dorsiflexion angle
Upper limb
Arm swing angle
Healthy side Affected side
Subject B +17.68% +7.11% +16.57% +6.1% +21.93% −0.16% +17.55%
Subject C +14.92% +3.31% +5.1% +5.1% +3.44% +7.56% +8.65%
Healthy side Affected side
+460.67% +43.06%
+5.3% +54.66%
Healthy side Affected side Healthy side Affected side
Table 3 Results of the joint angles on the affected side Subject Pre-Test (degree) Post-Test (degree) Difference (degree) Improvement∗ Paired sample t-test P(T t)
A 31.57 33.83 +2.26 7.16%
B 4.25 6.08 +1.83 43.06% 0.012
C 5.8 8.97 +3.17 54.66%
Note: Improvement∗ = Difference/Pre-Test.
the average step length, difference in step length, time required to walk 10 meters, dorsiflexion angle, and the arm swing angle. For patient B, the test revealed that all variables, except for the dorsiflexion angle on the healthy side, improved significantly. Patient B is making a large stride from the affected side first and then swings the healthy leg forward, which resulted in a longer step length on the affected side. Patient B also habitually puts his hands in the pockets when he walks, which resulted in a smaller arm swing angle on the healthy side. Table 3 shows the results of the joint angles on the affected side. The aforementioned results of the study showed that the patients demonstrated significant improvement in arm swing angles. After completing the training sessions, the three patients showed an improvement of 7.16%, 43.06% and 54.66%, which are all significant. The t-test had a p-value of 0.012 (p < 0.05), which demonstrated that the method used in the present study has the potential to significantly improve the arm swing of post-stroke patients. 4. Discussion and conclusion The data from the clinical trials conducted in this study revealed that after completing a comprehensive electrical stimulation training for upper and lower limbs, there can be expected a significant improvement in patients walking. When there is no outside interference, the FES device can improve the foot drop and prevent the patient from falling. The difference in step length between the left and the right leg also showed a significant decrease. Furthermore, the intervention by the electrical stimulation system also improved arm swing angle significantly after one month of therapy. The multichannel electrical stimulator is beneficial for improving the lack of coordination between the left and right limbs when the patient is walking. Furthermore, the patients showed very high confidence and interest in the system. All of the participants expressed interest in obtaining the system for training at home or for assisting them while walking outside.
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C.-H. Chou et al. / FES for abnormal movement of upper limb during walking
The present study showed that a traditional foot drop functional electrical stimulator can be efficiently upgraded by simultaneous stimulation of to the upper limb, helping the patient to swing his or her arm. This method has a more significant effect on patients outcomes than does the traditional passive foot drop correction. The subjects’ high degree of acceptance and willingness to commit to long-term use showed that the method is indeed worthy of pursuing further. Acknowledgements This work is supported by the Ministry of MOST 102-2221-E-152-001, and clinic help from department of physical medicine and rehabilitation, Taipei Medical University and Hospital. References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
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