Abstract
BACKGROUND:
Functional electrical stimulation is a widely used technique for rehabilitation.
OBJECTIVE:
To assess the efficacy of walking-pattern-based four-channel functional electric stimulation and its influence on the gait features of stroke patients with hemiplegia.
METHODS:
A total of 21 stroke patients with hemiplegia were enrolled into the study. The walking gaits of patients were investigated before, during and after walking-pattern-based FES treatment using the gait analysis system. The changes of gait indexes were comparatively analyzed.
RESULTS:
After walking-pattern-based FES therapy, the pace, stride rate, gait cycle, and step length of stroke patients with hemiplegia were 50.19 ± 14.45 cm/s, 36.85 ± 5.85 time/min, 1.6643 ± 0.2626 sec, 80.3333 ± 15.1438 cm, respectively. The motion range of hip and knee joint were 47.5238 ± 10.7453, 56.7619 ± 14.5255, respectively. We found these indexes were significantly improved compared with those before FES treatment (P < 0.05). The single swing rate (injured extremity/uninjured extremity) after FES treatment was 1.5589 ± 0.4550. The statistical results showed that the gait cycle, pace, stride rat, and single swing rate (injured extremity/uninjured extremity) were significantly improved after FES treatment (P < 0.05).
CONCLUSIONS:
Our results demonstrate that walking-paradigm based FES we developed is effective for treating stroke patients during rehabilitation.
Introduction
Along with social progress and improvement of people’s living standards, the incidence of cerebrovascular disease increases year by year. Among them, stoke is a common disease in clinical rehabilitation medicine and neurological medicine, which has become the third fatal (Gresham et al., 1995) and the first disabling (Pearson et al., 2002) disease in developed countries. According to statistics, the incidence of stroke is about 180/100,000 in developed countries (Kolominsky-Rabas & Heuschmann, 2002); 80% survivals developed hemiplegia in acute phase; more than 87% patients developed upper limb motor dysfunction within 2 weeks after stroke onset (Parker et al., 1986) and 30% –60% patients still suffer severe upper limb movement disorder 6 months after stroke onset (Kwakkel et al., 2003); more than 50% patients lost walking ability during acute phase, and suchdisability can last as long as 3 months after (Wade et al., 1987; Friedman et al., 1990). Those disabilities can severely influence daily life and life quality of patients and are becoming severe burden for family and society. Delayed and improper rehabilitation and treatment not only leads to failure in recovery of lower limb in affected body side, but also results in further complications such as shrinkage of soft tissues and muscle, decline of angle moving range and so on, which will worsen patients’ suffering and increase burden for society and family. So it is of great importance to apply proper and in time rehabilitation treatment for improving patients’ living quality.
Functional electrical stimulation (FES) is a widely used technique for rehabilitation that applies electrical currents to activate nerves innervating extremities affected by paralysis resulting from spinal cord injury, head injury, stroke and other neurological disorders. FES is primarily used to restore function in people with disabilities. During FES, low-frequency electrical pulses are programed and applied to stimulate a single or several muscle groups to induce muscle movements or simulate normal autonomous movements to improve and ameliorate muscle function.
In this study, we firstly accessed reliability of gait analyzer for evaluating walking function, and then we applied FES, through an instrument developed by ourselves, to stroke patients with hemiplegia. We found that gait analyzer is a powerful way to evaluate walking function and FES can ameliorate lower limb gate of stroke patients with hemiplegia. The FES we developed can be combined with gait analyzer for evaluating walking function and ameliorating walking defects in stroke patients with hemiplegia in clinics.
Subjects and methods
Subjects
Twenty one patients suffered cerebral infarction or cerebral hemorrhage were hospitalized in the Department of Rehabilitation, People’s Hospital in Jiangmen and the Department of Rehabilitation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University. Subjects were included or excluded based on the following criteria. Thirteen healthy subjects without walking and cognitive disorders, including 8 males and 5 females with average age of 53 were included.
Criteria for including: 1. With cerebral infarction or cerebral hemorrhage. Diagnosis was made following the standards for stroke in diagnostic criteria for cerebrovascular diseases defined in the Fourth National Conference on Cereberavascular Diseases in 1995 (Chin J Neuro, 1996). Further verification was made by head CT or MRI scan; 2. Suffered recent attack or without neurological dysfunction in early attack and with single lesion; 3. With limb in one body side paralyzed; 4. Aged from 45 to 80 years old; 5. Condition is steady, staged as III∼IV according to Brunnstrom staging and staged above stage III according to Holden walking staging; 6. Well informed and signing written consent.
Criteria for excluding: 1. With subarachnoid hemorrhage, secondary cerebral infarction, lumbar vertebra disease, lower-limb osteoarticular disease, other neurological diseases and vestibule or cerebellar dysfunction; 2. With deteriorated condition, such as new stroke or cerebral hemorrhage; 3. Suffered recent epileptic attack without effective treatment; 4. With functional retardation or failure in heart, lung, liver, kidney and so on; 5. Failed in effective evaluation for disorder in cognition and communication; 6. Refused to sign the informed consent.
Treatments
Functional electrical stimulation (FES): FES is delivered by a four-channel FES instrument based on normal walking paradigm (designed by the Department of Rehabilitation, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Patent NO: 2006200588870). The instrument is with four output channels and one foot switch. Treatment parameters: bidirectional symmetry square wave, frequency: 36 Hz, wave length: 210us, periodic intermittent output mode, 5 s per cycle and stimuli strength was set as strong as it evoked walking movements of lower limbs. Sequence of stimulation from each channel were designed according to the gait cycles and shown in Fig. 1.
Electrodes were placed without regard for polarity. Anterior and posterior muscles of the thigh and posterior muscles in the lower leg were stimulated by 6 cm×9 cm electrodes while anterior muscles of the lower leg were stimulated by 4 cm×4 cm electrodes. According the involvement of muscles during walking, four FES electrodes were placed on motor points of musculi quadriceps femoris, hamstring tendon, musculi tibialis anterior and musculi gastrocnemius, respectively. The motor points were localized with electrical stimulation with peripheral nerve stimulator. The strongest contraction-evoking points were determined and marked on muscle belly of the four muscle groups in paralyzed leg.
Gait evaluation
Evaluation was carried out with the brand-new second generation GaitWatch 3D Gait Analyzer from Jumho Electric Corporation. In accordance with the marker points for stimulation, electrodes were pasted, power cables were connected and the foot-switch shoe-pads were laid in patients’ shoes. Then the sensors of gait analyzer were placed on back waist, frontal side of the two thighs, frontal inner side of the two calves and the two acrotarsiums. Gait indexes were firstly recorded before, then during (5 min after FES onset) and after (30 minutes after FES termination) four-channel FES stimulation.
Statistics
Quantitative data were represented as percentage and Mean ± SD. Parameters from same patient at different time points and parameters from different patients at same time point were proceeded for intraclass correlation coefficient, ICC for testing reliability. The variance homogeneity and distribution normality were firstly tested, those showing normal distribution were tested with paired t-test. χ2-test was used for rate test. Significance was accepted if P < 0.05. All statistics were analyzed with SPSS13.0 software.
Results
Intra-subjects and inter-subjects reliability
Indexes from same patient at different time points and indexes from different patients at same time point were proceeded for ICC test for evaluating the reliability. ICC were 0.20∼0.91 (excluding ICC of ankle activity, 0. 75∼0.91) and 0.31∼0.96 (excluding ICC of ankle activity, 0. 72∼0.96) for a same subject and different subjects, respectively. These results indicate that the analyzing for 15 different gait indexes, except for 2 related to ankle motion, are reliable (see Tables 1 and 2) and the can be applied for assessing walking gait function.
Gait indexes before and during FES
Compared with indexes before, during stimulation, pace, stride rate, step length, motion range of hip and knee joint significantly increased; gait cycle, rate of double support time, and single swing rate (injured extremity/uninjured extremity) significantly decreased (P < 0.05). The step distance in different phase, rate of single support time and ankle motion range did not show significant amelioration (P > 0.05, see Table 3). These results demonstrate that walking gait is improved during FES.
Gait indexes after and before FES
Compared with indexes before, after FES stimulation, pace, stride rate, step length, motion range of hip and knee joint significantly increased; gait cycle, double support, single swing rate (injured extremity/uninjured extremity) and single support duration of affected leg significantly decreased (P < 0.05). The step distance and distance ratio in different phase, rate of single support time, single swing phase and ankle motion range did not show significant amelioration (P > 0.05, see Table 4). These results demonstrate that walking gait is improved after FES.
Gait indexes during and after FES
Compared with indexes during, after FES stimulation, pace and stride rate significantly increased; gait cycle significantly decreased (P < 0.05). The step length and step distance in different phases, rate of single support time, single swing rate (injured extremity/uninjured extremity), double support time, motion range of hip, knee and ankle did not show significant amelioration (P > 0.05, see Table 5). These results demonstrate that FES produces long-term after-stimulation effects on walking gait.
Discussion
Stroke can lead to hemiplegia, functional disorders in language, cognition and so on. Stroke patients with hemiplegia will suffer muscle weakness, hypermyotonia then complications such as soft tissue contracture, muscular atrophy, reduced joint motion range and so on, which can severely influence living and moving ability of patients in their daily life. Ameliorating walking defects is vital for improving working quality of stroke patients with hemiplegia. In the current study, we aimed to evaluate short-term effect of FES treatment on stroke patients with hemiplegia by monitoring walking gate indexes such as step length, stride rate, and pace, single support time and so on before, during and after FES treatment, which can be a reliable tool for assessing effect of rehabilitation treatments (Tenore et al., 2006). We analyzed walking gait via quantitative analysis that can be more objective and reliable compared with previous qualitative analysis (Sun et al., 2007). We found FES can ameliorate walking defects in patients with hemiplegia. Our study provided foundation for future in-depth studies.
Reliability of 3D gait analysis with GaitWatch
Reliability is used for evaluating stability of assessment (Hu et al., 2005) and includes inter-subjects reliability and intra-subject reliability. Inter-subjects reliability denotes the consistency among measurements on the same subjects from different observers; Intra-subject reliability denotes the consistency among measurements on the same subjects from same observer at two different time points. In current study, there is no significant difference among indexes from different intra- and inter-subjects tests, demonstrating the stability of currently used gait analyzing system and the reliability of data from this equipment. The analyzing for 15 different gait indexes, except for 2 related to ankle activity, is reliable (Tables 1 and 2). Davis and colleagues (Davis et al.,1991) found that reliability is better when measuring joint angle of hip and knee than ankle, this is in line with our finding, which may related to the specific characters of ankle movement. Our finding demonstrate that gait analyzer and quantitative analyzing paradigm we used in this study is reliable and can be extended for further clinic applications.
Ameliorating effects on walking gait of four channel FES developed ourselves
Pizzi and colleagues (Pizzi et al., 2007) found that pace, step length and PAP indexes significantly increased and stride rate, stride and single support time significantly decreased after treatment. Hu and colleagues (Hu et al., 2009) found that after rehabilitation, step length and pace significant increased while gait cycle, stride rate and supporting time did not show significant changes in patients with hemiplegia. Those results are consistent with part of our findings. Different from the two studies, either during treatment or after treatment with four-channel FES, pace, stride rate, step length, motion range of hip and knee significantly increased; gait cycle, rate of double support time, rate of single support time and single swing rate (injured extremity/uninjured extremity) significantly decreased, indicating FES not only improves walking ability during FES, but also produces lasting ameliorating effect after FES treatment. Moreover, compared with during stimulation, after stimulation, pace and stride rate further increased and gait cycle further decreased, indicating ameliorating effect is enhanced after FES termination. Those two effects points to that the four channel stimulation we developed can produce fine effect for improving walking ability in patients. Decline of walking ability is the main dyskinesia of patients with hemiplegia. Walking speed can be influenced by step length, pace, stride rate, support duration, and rate of mid-support time, swing and double support time. Decrement in step length of normal leg, increment in support time and decrement in swing time are key factors influencing walking efficiency of patients with hemiplegia. Four-channel FES can induce dorsiflexion in ankle and flexion in knee. Increment in motion range of hip is benefit for forward movement and step length which contributes to amelioration in stride rate and step length. Phase of leg & heel-touchdown clearance can be eased during swing phase and mopping of affected legs can be decreased or even avoided, which had been indicated in other study (Hu et al., 2009). Our study demonstrated that FES can ameliorate walking ability of lower limb in patients with hemiplegia.
In summary, we found that evaluating patients’ gait with the gait analyzer is reliable, which is of great relevance for clinic application. We developed software and hardware for walking-paradigm based FES. This treatment produces obvious ameliorating effect on lower limb gate of stroke patients with hemiplegia, especially in pace, stride rate, gait cycle, step length, single swing rate (injured extremity/uninjured extremity), motion range of hip and knee and so on. Further study should be focused on improving stimulation parameters for FES designed by ourselves to produce better and longer-term ameliorating effect in larger stroke population.