Effect of home-based rehabilitation of purposeful activity-based electrical stimulation therapy for chronic stroke survivors: a crossover randomized controlled trial

2.1Study design

The study design was a crossover randomized controlled trial. This study was conducted in accordance with the Declaration of Helsinki. It was approved by the Ethics Committee of Osaka Kawasaki Rehabilitation University (OKRU30-A018). The study was registered as a clinical trial in the University Hospital Medical Information Network (UMIN ID. 39663). This study was carried out from November 2018 to the end of November 2019.

2.2Participants

We recruited community-dwelling chronic stroke survivors who were receiving home-based visiting occupational therapy. They were included after providing written informed consent. Preliminary tests (motor function test on the paretic side and cognitive function tests) were performed on candidate stroke survivors for screening against the inclusion and exclusion criteria. Inclusion criteria were as follows: (i) patients at least three years after stroke onset, (ii) patients with BRS I–III upper limb motor function, (iii) patients who could not extend their paretic wrist voluntarily toward dorsal for 10 degrees or more, (iv) patients receiving occupational therapy once per week, and (v) patients having sufficient cognitive functions to enable daily conversation. Exclusion criteria encompassed the following: (i) patients using a demand-type cardiac pacemaker, (ii) patients having a malignant tumor at the site of electrical stimulation, (iii) patients having fractures at the body site where electrical stimulation is applied, and (iv) patients whose physician did not permit them to receive electrical stimulation. In addition, the general health condition was targeted at those who were judged to be in good health. There were no restrictions on the type of stroke. There were no restrictions on taking medications to prevent secondary stroke.

All participants received home-based visiting occupational therapy at least once a week. The occupational therapy consisted of 40-min sessions that included range of motion training, strength training, and exercise involving occupational activities with the aim of maintaining and recovering daily life. The occupational therapy was continued during PA-EST or stretching/exercise intervention in this study.

2.3Randomization and study schedule

For this crossover randomized controlled trial, the stroke survivors who matched the selection criteria were randomly assigned to group A or B using stratified block randomization technique. Participants were stratified by sex, age (<50 or≥50 years), and motor function of the paretic limb (Fugl–Meyer Assessment upper extremity [FMA-U]<30 or≥30 points). Then, randomization was conducted in each block using random numbers generated by Excel (Microsoft, Redmond, WA, USA). When a block of subjects was assembled, it was assigned to the group that would result in the smallest between-group difference in the initial FMA-U points.

The study schedule was follows: In group A, participants received PA-EST for 3 months as phase 1, and then received standard stretching and exercise for 3 months as phase 2. In group B, participants received standard stretching and exercise for 3 months as phase 1, followed by PA-EST for 3 months as phase 2. For both groups, 1-month washout period was provided between the phase 1 and 2 to avoid carry-over effect.

The occupational therapist confirmed manner of the PA-EST or stretching and exercise, and evaluated unpleasant subjective and objective symptoms during intervention and daily life, when a weekly home-based visiting occupational therapy was performed. When necessary, additional instructions for method of the PA-EST or stretching and exercise were provided by occupational therapist.

2.4PA-EST

The electrical stimulator used in the PA-EST was an orthosis-type assisted functional electrical stimulator, NESSH200® (Bioness Inc., Valencia, CA, USA). This device has been classified as a medical device by the Japanese Ministry of Health, Labor, and Welfare. This electrical stimulator ensures quality, effectiveness, and safety of medical devices. As for the specifications, it can be a functional electrical stimulator that elicits complex movements by means of five pole electrodes. The five electrodes were arranged in the following muscles: extensor digitorum, extensor pollicis brevis, flexor digitorum superficialis, flexor pollicis longus, and thenar muscles. The electric stimulus was performed with the stimulation frequency of 36 Hz.

As the first step of PA-EST, the occupational therapist interviewed the participants to understand their subjective values, motives, and abilities accumulated through patients’ experiences as well as to grasp the participants’ thought and emotional patterns. This was based on the occupational behavior model, named as “the model of human occupational therapy” at the foundation of the practical theory of occupational therapy (Kielhofner & Forsyth, 2008). In PA-EST, each individual was assessed while being engaged in a voluntary activity, and the assessment focused on and respected the individual’s ADL and behavioral patterns, uniqueness, and their preferred way of performing tasks. More specifically, we assessed whether their environment could meet daily tasks and maintain ADL, and whether the individual could feel his(her) identity and execute daily life behavior.

The training components were selected specifically to focus on the severely hemiparetic upper limb (for example, for making a hamburger that her husband liked, holding hands with her grandchild, and opening the lid of coffee). For instance, for making a hamburger, electrical stimulation was applied to the paretic upper limb to energize the muscles while the participants actually performed a practice of mimicking a hamburger (Minami et al., 2020). All exercises were performed with the participants in the sitting or standing position. Adequate instructions and demonstrations were given by an occupational therapist on the first day of the intervention. During 3-month intervention period, participants performed unsupervised PA-EST at least 3 days per week, and an additional supervised PA-EST with the occupational therapist was applied at least once a week. The implementation time was 10–20 min per session, and participants were allowed to perform the PA-EST in two sessions per day.

2.5Stretching and exercise

The training components were selected specifically to focus on the paretic side shoulder, elbow, and wrist. The exercise program included the following exercises: holding hands (i), shoulder lifting and lowing/stretching, (ii) elbow bending and extending/stretching, and (iii) wrist bending and extending/stretching. All exercises were done with the participants in a sitting position. Adequate instructions and demonstrations were provided by an occupational therapist on the first day of the intervention. During 3-month intervention period, each participant repeated the unsupervised stretching and exercise training at least 3 times per week. The implementation time was 10 to 20 min per session, and participants were allowed to perform the stretching and exercise in two sessions per day.

2.6Assessment items

The outcomes of interest were measured 4 times, before and after the phase 1 and phase 2. The primary outcome was FMA-U (Bohannon & Smith, 1987; Gregson et al., 1999), and the secondary outcomes were Motor Activity Log (MAL; amount of use [AOU] and quality of movement [QOM]) (Taub et al., 1993; Uswatte at al., 2005; Van der Lee et al., 2004), Goal attainment scale-light (GAS-light) (Turner-Stokes, 2009; Turner-Strokes, 2020), and ultrasound-derived muscle thickness of upper limb and abdominal muscles. The measurements were performed by a single investigator for all participants. FMA is a measure of the overall physical function of stroke patients, and the items include motor function, range of motion, pain, sensation, and balance (Bohannon & Smith, 1987; Gregson et al., 1999). In this study, the FMA of motor function included the upper limbs (maximum score, 66 points). MAL is a measure of quantifying the patients’ subjective functional level for the usage of the paretic side during daily life. The MAL consists of 14 items. For each item, AOU and QOM of the paretic upper limb were evaluated on a scale from 0 to 5, with higher score indicating greater use and quality. Subsequently, an average of 14 items was obtained for AOU and QOM, separately. GAS-light is a method of scoring how well a patient’s individual goals are achieved during the intervention. Goals were set by the therapist and patients (e.g., ability to hold down ingredients by the paretic hand when cooking). GAS-light was scored from -2 to+2 points, with higher score indicating greater achievement. Muscle thickness (cm) of biceps brachii, brachioradialis, rectus abdominis, external oblique, internal oblique, and transversus abdominis was measured using ultrasound (LOGIQ e V2, GE Healthcare UK, Chalfont, Buckinghamshire, UK). Transducer was placed at the largest muscle diameter at the two-third of the upper arm length for biceps brachii, at proximal third of the forearm length, just lateral to the umbilicus for rectus abdominis, and at mid-point between the inferior rib and the iliac crest for abdominal oblique muscles.

2.7Statistical analysis

Data were shown as the mean value±standard deviation (SD). Differences in age, time since stroke onset, BRS, and all outcome measures between the groups A and B at baseline were examined using unpared t test. A two-way repeated measures analysis of variance [type of intervention (PA-EST, stretching and exercise)×time (before and after intervention)] was performed to examine the effects of intervention. SPSS (ver. 26 IBM Japan, Inc.) was used as statistical processing software, and the significance level was set to 5% by a two-sided test.

3.1Participants

Figure 1 shows the study flow diagram. Fifteen chronic stroke survivors were recruited and screened. Of these, four participants aged over 80 years and two participants whose BRS was over III were excluded, and the remaining nine stroke survivors participated in this trial and were randomly assigned to group A (n = 5) and group B (n = 4). One participant from group B withdrew due to private reasons after phase 1. Therefore, a total of eight participants (five men, three women) who completed the phase 1 and 2 were analyzed. No participants experienced any adverse events during either intervention period. The mean age of the participants was 63.1±10.9 years, the mean time since stroke onset was 8.8±5.6 years, and the BRS was 2.8±0.5. At baseline, there were no significant differences in age and motor function between groups A and B (Table 1).

Fig. 1

Flow chart of the study.

3.2Difference in the effects of PA-EST and stretching/exercise training

The mean frequency of PA-EST was 4.25±1.83 days per week, and that of stretching and exercises was 4.00±1.69 days per week (P = 0.501).

FMA, MAL AOU and QOM, GAS-light, and muscle thickness before and after PA-EST and stretching/exercise are shown in Table 2. There was a significant interaction between the type of intervention and time for FMA-U (F = 16.303, P = 0.005), MAL AOU (F = 7.966, P = 0.026) and QOM (F =6.408, P = 0.039), and GAS-light (F = 6.905, P =0.034), with significantly improved motor function and goal achievement after PA-EST.

Regarding muscle thickness, none of the measured muscles showed significant interaction between the type of intervention and time (brachioradialis: F = 0.925, P = 0.368; biceps brachii: F = 0.844, P = 0.389; rectus abdominis: F = 0.007, P = 0.937; external oblique: F = 1.453, P = 0.267; internal oblique: F = 0.048, P = 0.833; transverse abdominis: F = 0.034, P = 0.858).