Table 1.

Characteristics of the included studies

References	N	Stroke duration	Mean age (years)	Intervention	Outcomes	Findings	Adverse events
Alon et al. [51]	N=19; experimental (n=10, females=no information); control (n=9, females=no information)	(experimental = 4.05±2.9; control =4.3±3.3) years	67 ± 6.8years; (experimental = 62.7±11.3; control =62.6±8.2)	FES Experimental= received self-administered stimulation using multi-segment hybrid orthosis-stimulation system . Upper limb- electrodes were placed to ensure accurate stimulation of extensor digitorum, extensor pollicis brevis, flexor digitorum superficialis, flexor pollicis longus, and thenar muscles groups . Lower limb -3 electrodes were positioned over the peroneus longus and tibialis anterior; while 2 electrodes were placed over the 2 heads of gastrocnemius muscle. An alternating current (AC) was delivered at a carrier frequency of 11 KHz for 60 mins two times per day. Control= performed exercise for the distal and upper limb, and foot-leg starting with 10 mins and progressing to 60 mins. Both groups received functional exercises for 60 mins two times per day Interventions in both groups lasted for 3 months in both groups	Gross motor function (BBT), manual dexterity (JHFT), walking speed (10MWT), cadence (10MWT) and number of steps (10MWT)	All outcomes improved better in the experimental group post intervention.	Two participants in the experimental group experienced a temporary and minor skin irritation that resolved after 2 to 3 days
Kimberly et al. [53]	N=16; experimental (n=8, females=3); control (n=8, females=2)	35.5±25.1 months; (experimental = 68.13±39.62; control =22.00±16.06)	60.1±14.5 years years; (experimental = 62.75±7.36; control =53.75±8.53)	NMES Experimental=subjects were instructed to use the electrical stimulator, which delivers 200 μs rectangular biphasic, constant current at 50 Hz, 6 hours per day, for 10 days over the course of 3 weeks. Control= Sham electrical stimulation for the same period	Gross motor function (BBT), quality and quantity of use of the limb, manual dexterity (JHFT), muscle strength (load cell), finger movement control (tracking), and changes in cortical activation (fMRI).	All functional performance outcomes improved in the experimental group. On the other hand, in the control group, only muscle strength improved. However, there was no significant improvement in finger tracking performance and cortical activation in either group.	Fatigue in one patient
Gabr et al. [64]	N=12; experimental (n=8, females=4); control (n=4, females=1)	52.75 ± 39.82 months; (experimental = 68.13±39.62; control =22.00±16.06)	59.7 ± 8.53 years; (experimental = 62.75±7.36; control =53.75±8.53)	NMES Experiment: Participants used electromyography-triggered neuromuscular stimulation (ETMS) at a pulse width, between 100 and 400 μs to stimulate forearm muscles in addition to home exercise, twice every weekday in 35-min increments during an eight-week period Control: performed home exercises comprising of supination/pronation exercises; flexion and extension of the individual fingers; wrist extension and flexion exercises; elbow flexion and extension exercises; and shoulder adduction and abduction exercises. Participants switched groups after 8 weeks.	Compliance (home-use diary), range of motion (goniometry) level of motor impairment (UEFMA), motor function (ARAT)	Range of motion improved in both groups. However, only stimulation used in the experimental group improved level of motor impairment	Not reported
Ng et al. [54]	N=80; Control (n=20, females=3); TENS (n=19, females=2); Placebo+TRT (n=20, females=3); TENS+TRT (n=21, females=5);	Control (5.2±2.9 years); TENS 6.2±4.1); Placebo+TRT (4.7±4.1); TENS+TRT (5.0±3.0);	Control (57.3±8.6 years); TENS 56.4±9.1); Placebo+TRT (57.1±7.8); TENS+TRT (58.4±7.1);	TENS There are 4 groups in this study. Two of the groups are considered as experimental groups (TENS and TENS+TRT), and they received 60 minutes of TENS (100 Hz, 0.2-ms square pulses, 2 to 3 times sensory threshold) alone, or followed by 60 minutes of TRT comprising of 4 weightbearing and stepping exercises using wooden blocks of 2.5 or 5 cm in height respectively, 5 days a week for 4 weeks. The other two groups are considered as control (placebo+ TENS and control), which received sham TENS and TRT or no treatment at all respectively for the same period as in the experimental group	Ankle flexor spasticity (composite spasticity scale), peak torques of maximum isometric voluntary contraction of ankle dorsiflexors and plantar flexors (load cell) and gait velocity (GAITRite) Compliance- phone call and logbook	Significant increase in gait velocity, functional mobility and walking endurance in the TENS and TENS+TRT group compared to the other groups	Not reported
Hara et al. [62]	N=20; experimental (n=10, females=2); control (n=10, females=4)	(experimental = 13 months±; control =13 months±)	(experimental = 56.0 years; control =60.5 years)	FES Experimental=received a train of biphasic rectangular electric impulses with a pulse width of 50 ms of functional electrical stimulation (FES) to finger and wrist extensors in addition to standard therapy for 1 hour (starting from 30 ins in the first 5 days) per day for 5 months to finger and wrist extensors. Control= received standard therapy alone for the same period.	Motor impairment (SIAS), ROM (goniometer), spasticity (MAS), gross motor function (10-CMT)), manual dexterity (9-HPT)) and muscle activity (EMG)	Significant improvement in active wrist and finger extension and shoulder flexion in the experimental group compared to the control Spasticity decreased in wrist and finger flexors in the experimental group Significant improvement in level of motor impairment, muscle activity, gross motor function and manual dexterity in the experimental group	Not reported
Ng et al. [55]	N=109; Control (n=29, females=no information); TENS (n=28, females==no information); Placebo+TRT (n=27, females==no information); TENS+TRT (n=25, females==no information);	4.7±3.4 years	56.6±7.9 years	TENS There are 4 groups in this study. Two of the groups are considered as experimental groups (TENS and TENS+TRT), and they received 60 minutes of TENS (100 Hz, 0.2ms square pulses, at 4 lower limb acupuncture sites recommended in Chinses Medicine Literature alone, or followed by 60 minutes of TRT, respectively, 5 days a week for 4 weeks. The other two groups are considered as control (placebo+ TENS and control), which received sham TENS and TRT or no treatment at all respectively for the same period as in the experimental group	Ankle flexor spasticity (Composite Spasticity Scale), peak torques of maximum isometric voluntary contraction of ankle dorsiflexors and plantarflexors (load cell), gait velocity (GAITRite), walking endurance (6MWT)) and functional mobility (TUG) compliance- phone call and logbook	Significant iincrease in gait velocity, functional mobility and walking endurance in the TENS and TENS+TRT group compared to the other groups.	Not reported
Sullivan et al. [58]	N=38; experimental (n=18, females=13); control (n=20, females=4)	7.2 ± SD (1–29) (experimental = 7.7 ± SD (1–29) years±; control =6.6 ± SD (3–14) years	60.6 ± SD (37–88) (experimental = 61.6 ± SD (37–88); control =59.5 ± SD (41–85)	NMES All subjects were instructed to exercise twice daily for 30 minutes, 5 days/week for four weeks. During practice, subjects in the experimental group received electrical stimulation with the following current parameters: symmetrical biphasic waveform, pulse duration 250 microseconds, amplitude at sensory threshold, frequency 35 Hz, and a duty cycle of 10 seconds ON: 10 seconds OFF The control group received sham electrical stimulation.	Level of motor impairment (UEFMA), motor function (AMAT), real world arm use (MAL), tolerance for Eeectrical stimulation (PTTES), stereognosis (Nottingham stereognosis assessment), quality of life (SIS) and spasticity (Tardieu scale)	There was no significant difference between groups in the outcomes of interest.	Not reported
dos Santos-Fontes et al [61]	N=20; experimental (n=10, females=5); control (n=10, females=4)	(experimental = 3.8 ± 4.5; control =3.3 ± 2.1) years	(experimental = 52.2 ± 11.1; control =59.1 ± 11.1)	NMES Experimental=2 hours, daily biphasic square-wave electrical nerve stimulation at a frequency of 31 Hz, immediately before motor training for 4 weeks Control= sham stimulation, 2 hours daily before motor training for 4 weeks. Both groups performed two blocks of the following tasks: writing, turning cards, picking small objects, picking beans with a spoon, and stacking checkers daily for four weeks	Feasibility-compliance (weekly phone call) and safety (presence of adverse events), and manual dexterity (JHFT)	Participants in both groups reported good compliance with the stimulation. However, the participants in the experimental had significantly better compliance. Only 1 participant in the control group reported nocebo effect In addition, manual dexterity improved more significantly in the experimental than the control group	Only 1 participant in the control group reported nocebo effect
Chan [60]	N=37; TENS+TRTT (n=12, females=4); Placebo + TRTT (n=13, females=3); control (n=12, females=2)	44.2 ± 28.3 months TENS+TRT (43.9 ± 28.4); Placebo + TRT (41.8 ± 28.7); control (47.3 ± 29.8)	57.8 ± 9.4 years TENS+TRT (58.2 ± 10.7); Placebo + TRT (56.3 ± 7.4); control (59.3 ± 10.4)	TENS The experimental group is the TENS+TRTT; while the control groups are two (Placebo + TRTT and control). The experimental group received high-frequency TENS (frequency 100 Hz; pulse width 0.2 ms) to the abdominal muscles simultaneously with the TRTT at home for 60 mins per day, 5 times a week for 6 weeks. under the instruction of a physical therapist. For the two control groups, the placebo-TENS + TRTT received sham TENS+ TRTT; while the control group did receive any active treatment except health education.	The isometric peak trunk flexion torque and extension torque was measured using a Cybex NORM isokinetic dynamometer, dynamic balance (functional reach test), trunk control (trunk impairment scale)	The experimental groups improved significantly better the control in all outcomes of interest at all periods post intervention and at follow-up. However, TENS+TRT group demonstrated greater and earlier improvement than placebo TENS+TRTT group.	Not reported
Chen [59]	N=54; experimental (n=27, females=9); control (n=27, females=12)	Days; (experimental = 24.96 ± 5.62; control =26.85 ± 4.68)	(experimental = 66.52 ± 12.08; control =66.15 ± 12.33)	NMES Experimental (at home- tele-supervised) and control (conventional in the clinic) Both groups received electromyography-triggered neuromuscular stimulation of ECRL and tibialis anterior muscle of hemiplegic side limbs the for 20 minutes, twice in a working day for 12 weeks, a total of 60 sessions. The stimulation parameters used were: stimulus duration for 5 seconds, intermittent time for 2 seconds, pulse width of 0.2 seconds, frequency of 50 Hz, stimulus intensity of between 8 to 45 mA. Both groups also performed physical exercises comprising of Bobath and Neuromuscular facilitation concepts for 1 hour, twice in a working day for 12 weeks, a total of 60 sessions	Disability and ADL (MBI), balance (BBS), caregiver stress (CSI), muscle contraction condition (EMG),	There was no significant difference between groups in all outcomes of interest post intervention and at follow-up.	Not reported
Minami  [56]	N=8; experimental (n=5, females=2); control (n=3, females=1)	8.8±5.6 years	63.1±10.9 years (experimental = 64.0± 13.4; control = 61.7± 10.4)	FES All participants received occupational therapy consisting of 40-min sessions that include range of motion training, strength training, and exercise involving occupational activities with the aim of maintaining and recovering daily life Experimental=10–20 min per session, twice per day, at least 3 time a week of purposeful activity-based electrical stimulation therapy (PA-EST) at 36 Hz for 3 months. Control= stretching/ exercise for the same period Cross over took place after the intervention period	Level of motor impairment (UEFMA), real world arm use (MAL), goal attainment (GAS-light), and muscle thickness of the upper limb and abdominal muscles.	Level of motor impairment, motor function, real world arm use and goal attainment improved significantly in the experimental group compared to the control.	None
Choudhury [52]	N=95; experimental paired (n=32, females=8); ; experimental random (n=32, females=7); control (n=31, females=13)	months; (experimental paired= 55 (142); experimental random= 43 (94); control =30 (29))	(experimental paired= 51 (12.1); experimental random= 53 (9.9); control =53 (10.6))	TENS There are to experimental groups (paired and random stimulation groups). In the paired stimulation group, each shock was given 12 ms before the click. For the random stimulation group, the click and shock occurred independently at random, with the same interval distribution as in the paired stimulation group. For the experimental groups, electrodes were placed over the forearm extensor muscles for the transcutaneous electrical stimulation using a single 0.15-ms pulse, over 4 weeks for at least 4 h/d at home from the first day of assessment. Control= received standard care	Motor function (ARAT), ROM (goniometer), muscle torque/ strength, spasticity (MAS), grip strength (dynamometer), maximum muscle contraction (a custom device)	Only experimental paired improved motor function post intervention	Not reported
Prathum et al. [57]	N=24; experimental (n=12, females=4); control (n=12, females=4)	15.92 ± 2.06 months (experimental = 16.33 ± 3.30; control = 15.50 ± 2.60)	57.75 ± 2.45 years; (experimental = 56.83 ± 3.58; control = 58.67 ± 3.70)	tDCs Experimental= 1-h home-based exercise after 20-min dual-tDCS at 2-mA, thrice a week for 4 weeks Control= sham 1-h home-based exercise after 20-min dual-tDCS at 2-mA, thrice a week for 4 weeks The exercise comprises of (1) stretching of the elbow flexor, wrist flexor, and shoulder flexor muscles (hold for 2 min/muscle group); (2) active exercise involving elbow extension, shoulder flexion, forearm pronation, and supination (10 times/ set/ direction, 3 sets/direction/session); (3) reach-to-grasp exercise in different directions (50 times/direction, 3 directions/session)	Level of motor impairment (UEFMA & LEFMA), motor function (WMFT), functional mobility (TUG), walking speed (6MWT), lower-limb functional muscle strength (five times sit to stand test), muscle strength (handheld dynamometer), and grip strength (handgrip dynamometer)	Experimental group had significantly better improvement in level of motor impairment and motor function than the control.	Mild tingling, itching, headache and burning sensation in the experimental group.
Ko et al. [63]	N=26; experimental (n=12, females=8); control (n=14, females=6)	(≥6 months after onset)	59.42±11.32 years; (experimental = 61.25±12.85; control = 57.86±10.04)	tDCs Experimental=tDCS (constant current of 2 mA) self -application, 5 d/wk for 4 weeks for 30 minutes per session. Control= sham tDCS (constant current of 2 mA) self-application, 5 d/wk for 4 weeks for 30 minutes per session. Both groups received 30 mins cognitive therapy comprising of various tasks based on memory and attention areas.	Cognitive function (K-MoCA) Dementia (Korean version of the Dementia Rating Scale-2), lexical retrieval abilities and aphasia (Korean-Boston Naming Test), visual attention and task switching (Trail Making Test), determining the ability of an individual to inhibit a response deemed inappropriate (Go/No Go), and verbal fluency (Controlled Oral Word Association Test) Feasibility (completion rate and protocol adherence)	No significant difference between groups in any of the outcomes post intervention and at follow-up. Feasibility: Adherence rate was 98.4%.	No serious adverse effects were detected

Key: BBT=box and block test, JHFT=Jebsen Taylor hand function test, 10MWT= ten-meter walk test, fMRI =function magnetic resonance imaging, NMES=Neuromuscular electrical stimulation, FES=Functional electrical stimulation, Key: UEFMA=upper extremity Fugl Meyer motor assessment, ARAT=Action research arm test, SIAS= stroke impairment assessment set, ROM=range of motion, MAS =modified Ashworth scale, 10-CMT = Ten-Cup-Moving Test, 9-HPT= Nine-Hole-Peg Test, EMG=Electromyography, TRT=tasks-related training, NMES=Neuromuscular electrical stimulation, TENS=Transcutaneus electrical stimulation, Key: TENS=transcutaneous electrical nerve stimulation, TRT=tasks-related training, 6MWT =six-minute walk test, TUG = timed-up and go test, UEFMA = upper extremity Fugl Meyer motor assessment, AMAT = arm mobility test, MAL=motor activity log, PTTES= Perceptual Threshold Test – Electrical Stimulation, ARAT=Action research arm test, SIS= stroke impact scale, JHFT= Jebsen Taylor hand function test, NMES=Neuromuscular electrical stimulation, TENS=Transcutaneus electrical stimulation. Key: TRTT =task-related trunk training, ECRL= extensor carpi radialis longus, MBI=modified Barthel index, BBS=Berg balance scale, MRS= modified Rankin scale, CSI=caregiver strain index, EMG=electromyography, UEFMA = upper extremity Fugl Meyer motor assessment, MAL=motor activity log, GAS-light=goal attainment scale-light, NMES=Neuromuscular electrical stimulation, TENS=Transcutaneus electrical stimulation, FES=functional electrical stimulation. Key: ARAT=Action research arm test, ROM=range of motion, MAS =modified Ashworth scale tDCss=transcortical direct current stimulation, UEFMA= upper extremity Fugl Meyer motor assessment, LEFMA= lower extremity Fugl Meyer motor assessment, WMFT=Wolf motor function test, TUG = timed-up and go test, 6MWT =six-minute walk test, TUG = timed-up and go test, K-MoCA=Korean-Montreal cognitive assessment, TENS=Transcutaneus electrical stimulation