Stroke threatens human health, and approximately 70% of survivors experience varying levels of limb paralysis [1]. Among them, foot drop accounts for 20–25% of lower extremity motor dysfunction in stroke survivors [2]. It is a very common stroke sequela, in which ankle dorsiflexion is impossible [3]. This impairment, in combination with the low selectivity of the hip and knee in this patient group, results in an abnormal gait, consisting of hip hitching, circumduction, and toe catch, which is also called equine gait [4]. It causes motor dysfunction and seriously affects patients’ quality of life; thus, effective treatment is necessary [3].

Splinting, usually using a custom-fitted ankle–foot orthosis, is the conventional treatment of foot drop; however, this treatment has limitations, being both uncomfortable and awkward to use [5]. Other treatments for post-stroke foot drop mainly include rehabilitation training; however, existing interventions are often poorly effective with unsatisfactory outcomes [6]. Meanwhile, several clinical studies have found that applying acupuncture based on rehabilitation training to treat post-stroke foot drop can improve the patient’s lower limb function and quality of life [7]. In particular, electroacupuncture (EA) has outstanding advantages, such as parameterized stimulation, good stability, and strong controllability, and can promote blood circulation and regulate muscle tension [8]. Several studies have shown that EA can reflexively inhibit spastic muscles by stimulating nerves and muscle spindles, thereby balancing the lower extremity muscle groups, restoring walking ability, accelerating foot drop recovery, and improving the patient’s quality of life [9-11].

In the domestic databases, no study has used EA for post-stroke foot drop. In international databases, several studies including randomized controlled trials (RCTs) have been conducted; however, to the best of our knowledge, no review studies have been conducted on this topic. Therefore, this review aimed to confirm the efficacy and safety of EA for the treatment of post-stroke foot drop and offer basic data for related clinical trials in the future.

1. Selection and exclusion criteria

The inclusion criteria were as follows: (1) studies on patients diagnosed with post-stroke foot drop (cerebral hemorrhage or cerebral infarction) based on clinical symptoms; (2) RCTs of EA regardless of the number of treatments, waveform, needle size, insertion depth, stimulation points, treatment periods, and frequency; and (3) studies using EA exclusively in the treatment group. The exclusion criteria were as follows: (1) duplicate studies, (2) non-RCTs, (3) studies without full text, (4) studies published in nonacademic journals, (5) studies not related to EA or post-stroke foot drop, (6) not the latest paper of the same author, (7) studies using EA as an intervention in both the treatment and control groups (e.g., a study comparing the effects of EA by frequency), and (8) studies that did not commonly use treatments other than EA in the treatment and control groups (e.g., a study that employed functional electric stimulation as “other treatments” exclusively in the treatment group). No restrictions were set on the publication language, date, study location, and the age, sex, or ethnicity of the patients.

2. Database and search methods

The Cochrane Library, Excerpta Medica Database (Embase), PubMed, China National Knowledge Infrastructure (CNKI), Korean Studies Information Service System (KISS), Research Information Sharing Service (RISS), and Oriental Medicine Advanced Searching Integrated System (OASIS) were searched for the latest studies published from January 1, 2014, to December 31, 2023. The terms ([“foot drop” OR “foot-drop”] AND [“electroacupuncture” OR “electrical acupuncture” OR “electro-acupuncture” OR “electric acupuncture”]) were used in the database search.

3. Risk of bias assessment

Three independent investigators used 7 questions from the Cochrane risk of bias (RoB) tool to evaluate the RoB in the included studies. RoB assessment covered various aspects, namely, random sequence generation (selection bias), allocation concealment (selection bias), blinding of participants and personnel (performance bias), blinding of outcome assessment (detection bias), incomplete outcome data (attrition bias), selective reporting data (attrition bias), and other potential biases. Each category was rated high, low, or unclear. Any discrepancies were resolved through consultation with the corresponding author or third party.

1. Study selection

The search retrieved 17 studies from the Cochrane Library, 12 from Embase, 10 from PubMed, 132 from CNKI, 2 from KISS, 4 from RISS, and 6 from OASIS. A total of 183 studies were retrieved. Of these, 14 were duplicates. Of the 169 remaining studies, 64 were not related to EA or post-stroke foot drop, 57 were not RCTs, 1 had no full text, 22 were published in nonacademic journals, and 1 were not the latest paper of the same author. Of the remaining 24 studies, 8 used EA in both the treatment and control groups. Moreover, 4 studies were excluded because they used an intervention other than EA exclusively in the treatment group. After consideration of the abstract and patient groups, 12 studies were included in the analysis (Fig. 1).

Figure 1. Flow chart of the screening process. RCT, randomized controlled trial.

2. Risk of bias

The Cochrane RoB tool was used to assess the RoB in 12 RCTs. Results were graphed and summarized using RevMan 5.4.1 (Figs. 2, 3).

Figure 2. Risk of bias (RoB) graph: judgments of the review authors about each RoB item presented as percentages across all the included studies.

Figure 3. Risk of bias (RoB) summary: judgments of the review authors about each RoB item for each included study.

1) Random sequence generation

All studies [12-23] randomized patients and used double crossover RCTs; thus, the RoB was rated “low.”

2) Allocation concealment

All studies [12-23] were rated as having an “unclear” RoB because they did not mention the concealment of assignment to reduce selection bias.

3) Blinding of participants and personnel

Of the 12 studies, 10 were rated as having a “high” RoB [12,13,15-20,22,23] because they did not describe the use of blinding. The other 2 studies [14,21] were rated as having an “unclear” RoB because whether they used blinding or not was unclear.

4) Blinding of outcome assessment

Six studies [12,15,17,19,20,22] that did not describe the use of blinding were rated as having a “high” RoB. The other studies [13,14,16,18,21,23] did not properly describe the method, so they were rated “unclear.”

5) Incomplete outcome data

All 12 studies [12-23] reported all expected outcomes; therefore, the RoB was assessed as “low.”

6) Selective reporting data

All studies [12-23] have reported all outcomes expected from their study design and were rated as having a “low” RoB.

7) Other bias

All 12 studies [12-23] were rated “low” because no additional potential biases were identified.

3. Overview of the selected studies

The 12 RCTs were retrieved only from CNKI, which were published between 2014 and 2023 and were reported in Chinese and English. All 12 RCTs were conducted in China.

Overall, 890 participants with post-stroke foot drop were included in the 12 RCTs. The study with the largest sample comprised 134 participants, and most studies included > 60 participants. The study with the smallest sample included 20 participants. The inclusion and exclusion criteria were applied in all 12 studies. In all studies, patients were diagnosed with stroke by brain computed tomography or magnetic resonance imaging and subsequently developed clinical symptoms of foot drop, i.e., ankle dorsiflexion is impossible.

Sun et al. [12] included patients who had foot drop symptoms for at least 15 days and up to 4 months. Luo [13] included patients aged 25–75 years in the acute phase within 2 weeks of the onset with tibialis anterior muscle strength grade of < 3. Wang et al. [14] included only patients diagnosed with ischemic stroke among patients aged 30–75 years. Li et al. [15] included patients within 6 months of symptom onset; Wang [17] and Ke et al. [23], within 1–6 months; Wang et al. [18], within 1 month; and Gu et al. [19], within 1–3 months. Wu [20] included patients with modified Ashworth scale (MAS) grades 2–4, and Ke et al. [23] included individuals with Brunnstrom recovery stage > 2, which evaluates the recovery stage of patients with hemiplegia.

In all studies, the general characteristics of the treatment and control groups were comparable, and no significant differences were observed (Table 1).

Table 1 . Overview of the selected studies.

Author (y)	Type	Country	Sample size	Criteria	Age (y)	Course of disease
Sun (2014) [12]	RCT	China	TG 30 CG 30	40–76 y Symptoms (15 d to 4 mo)	-	-
Luo (2014) [13]	RCT	China	TG 30 CG 26	25–75 y Symptoms (< 2 wk) Tibialis anterior muscle strength (grade < 3)	TG 60.8 ± 9.58 CG 62.47 ± 8.72	-
Wang (2017) [14]	RCT	China	TG 39 CG 39	38–74 y Symptoms (2–6 mo)	55.33 ±15.49	3.44 ± 1.59 mo
Li (2017) [15]	RCT	China	TG 10 CG 10	Symptoms (< 6 mo)	TG 53 ± 9 CG 58 ± 6	TG 3.17 ± 1.34 mo CG 3.81 ± 1.21 mo
Zeng (2018) [16]	RCT	China	TG 38 CG 38	-	TG 59.3 ± 9.7 CG 58.1 ± 7.5	TG 55.6 ± 22.8 d CG 58.9 ± 20.1 d
Wang (2019) [17]	RCT	China	TG 40 CG 40	32–76 y Symptoms (1–6 mo)	TG 54.23 ± 5.66 CG 54.25 ± 5.64	TG 2.05 ± 0.11 mo CG 2.11 ± 0.24 mo
Wang (2019) [18]	RCT	China	TG 30 CG 30	Symptoms (< 1 mo)	TG 59 ± 7 CG 60 ± 7	TG 11.5 ± 4.6 d CG 12.3 ± 5.1 d
Gu (2020) [19]	RCT	China	TG 45 CG 45	40-74 y Symptoms (1–3 mo)	TG 63.7 ± 8.8 CG 63.1 ± 8.9	TG 57.8 ± 9.6 d CG 58.1 ± 9.3 d
Wu (2021) [20]	RCT	China	TG 67 CG 67	42–78 y MAS (grades 2–4)	TG 57.63 ± 7.51 CG 58.43 ± 7.29	TG 73.25 ± 14.98 d CG 69.03 ± 15.17 d
Wang (2021) [21]	RCT	China	TG 30 CG 30	-	TG 65.27 ± 7.12 CG 36.01 ± 7.43	TG 37.78 ± 10.28 d CG 37.05 ± 10.37 d
Xie (2022) [22]	RCT	China	TG 28 CG 28	45-76 y	TG 61.2 ± 1.5 CG 60.9 ± 1.3	-
Ke (2023) [23]	RCT	China	TG 60 CG 60	45–80 y Symptoms (1–6 mo) Brunnstrom stage (> 2)	TG 65 CG 64	TG 32.5 ± 4.3 d CG 33.9 ± 4.7 d

Values are presented as mean ± standard deviation..

RCT, randomized controlled trial; TG, treatment group; CG, control group; MAS, modified Ashworth scale; -, not applicable..

4. Interventions of the selected studies

All 12 studies used EA as the intervention of choice for treatment groups (Table 2). In all 12 studies [12-23], rehabilitation was commonly used in the treatment and control groups, and no study had used EA exclusively in the treatment group. In the control group of these studies, 8 [12,13,15-18,22,23] used rehabilitation alone, and the other 4 studies [14,19-21] used it in combination with acupuncture. Zeng et al. [16] used exercise therapy and physiotherapy, and Wang et al. [18] used neurodevelopmental treatment as rehabilitation for patients with central nervous system damage; thus, we considered it a rehabilitation treatment. Treatment was usually performed 6 times a week [15,16,19-23] for 4–6 weeks, with the shortest of 24 days and the longest of 6 months (Table 3). Ten studies used stainless steel and sterile acupuncture needles, whereas 2 [12,22] used 30- and 32-gauge needles. The needle remaining time was usually 20–40 minutes, and 3 studies [17,22,23] did not mention this parameter. The needle depth varied between studies, ranging from 0.3 to 1.5 cun. The waveforms also varied; however, 3 studies [12,13,22] used continuous waves. The frequency of EA also varied, with most studies using low frequency. Six studies used low frequencies of 1 or 2 or 10–20 Hz [14,17-20,22], and 2 used high frequencies of 20–100 or 50 Hz [15,21]. Two studies also appropriately combined a high frequency of 50 Hz and a low frequency of 10 Hz [16,23]. Overall, 37 acupuncture points (acupoints) were used in the 8 studies, wherein the gallbladder meridian (GB) 34 [12-14,16,17,21,22], GB 39 [12,13,16-18,23], and stomach (ST) 36 (Table 4) [13,14,16,18,21,23] were most commonly used acupoints. The remaining 4 studies [15,19,20,22] used motor points of antagonist muscles rather than acupoints for EA. Furthermore, the GB was the most commonly used meridian (Table 5).

Table 2 . Interventions and results of the selected studies.

Author (y)	Intervention	Control	Outcome measurement	Result	Adverse events
Sun (2014) [12]	EA (+ rehabilitation)	Rehabilitation	1. Reduction in MAS 2. Increase in the Barthel index 3. Increase in the Kendall percentage method	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05)	Not mentioned
Luo (2014) [13]	EA (+ rehabilitation)	Rehabilitation	1. Increase in FMA-L 2. Increase in the AROM of ankle dorsiflexion	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05)	Not mentioned
Wang (2017) [14]	EA (+ rehabilitation)	Acupuncture (+ rehabilitation)	1. Increase in the AROM of ankle dorsiflexion 2. Reduction in MAS 3. Increase in FMA-L 4. Increase in the Holden scale score 5. Increase in the Tinetti scale score	1. TG > CG (p < 0.05) 2. No difference 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05) 5. TG > CG (p < 0.05)	Not mentioned
Li (2017) [15]	EA (+ rehabilitation)	Rehabilitation	1. Increase in the AROM of ankle dorsiflexion 2. Increase in the iEMG of the tibialis anterior 3. Increase in FMA-L	1. No difference 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05)	Not mentioned
Zeng (2018) [16]	EA (+ exercise therapy and physiotherapy)	Exercise therapy and physiotherapy	1. Increase in the AROM of ankle dorsiflexion 2. Reduction in MAS 3. Increase in MWS 4. Increase in BBS	1. TG > CG (p < 0.05) 2. No difference 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05)	No
Wang (2019) [17]	EA (+ rehabilitation)	Rehabilitation	1. Increase in the total efficacy 2. Increase in FMA-L 3. Increase in the Tinetti scale score	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05)	Not mentioned
Wang (2019) [18]	EA (+ neurodevelopmental therapy)	Neurodevelopmental therapy	1. Increase in FMA-L 2. Increase in the AROM of ankle dorsiflexion 3. Increase in the sEMG of the tibialis anterior muscle 4. Increase in MWS	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05)	Not mentioned
Gu (2020) [19]	EA (+ rehabilitation)	Acupuncture (+ rehabilitation)	1. Increase in FMA-L 2. Increase in BBS 3. Increase in the iEMG of the tibialis anterior 4. Reduction in the iEMG of the gastrocnemius muscle and CR	1. TG > CG (p < 0.01) 2. TG > CG (p < 0.01) 3. TG > CG (p < 0.01) 4. TG > CG (p < 0.01)	Not mentioned
Wu (2021) [20]	EA (+ acupuncture, rehabilitation)	Acupuncture (+ rehabilitation)	1. Increase in the total efficacy 2. Increase in FMA-L 3. Increase in BBS 4. Reduction in CR	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05)	Not mentioned
Wang (2021) [21]	EA (+ rehabilitation, ankle joint trainer)	Acupuncture (+ rehabilitation, ankle joint trainer)	1. Increase in the total efficacy 2. Increase in the sEMG of the tibialis anterior 3. Increase in the sEMG of the gastrocnemius	1. TG > CG (p < 0.01) 2. TG > CG (p < 0.01) 3. TG > CG (p < 0.05)	Not mentioned
Xie (2022) [22]	EA (+ rehabilitation)	Rehabilitation	1. Increase in the total efficacy 2. Increase in foot inversion angle 3. Increase in FMA-L 4. Increase in the Tinetti scale score 5. Increase in the RMS of ankle dorsiflexion AROM	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05) 5. TG > CG (p < 0.05)	Not mentioned
Ke (2023) [23]	EA (+ rehabilitation)	Rehabilitation	1. Increase in the iEMG of the tibialis anterior 2. Reduction in the iEMG of the gastrocnemius and CR 3. Increase in the AROM of ankle dorsiflexion 4. Increase in the percentage of MAS grades 0–2 5. Increase in MWS 6. Increase in BBS 7. Increase in the total efficacy	1. TG > CG (p < 0.05) 2. TG > CG (p < 0.05) 3. TG > CG (p < 0.05) 4. TG > CG (p < 0.05) 5. TG > CG (p < 0.05) 6. TG > CG (p < 0.05) 7. TG > CG (p < 0.05)	Not mentioned

CR = antagonist muscle iEMG / (agonist muscle + antagonist muscle) iEMG × 100%..

EA, electroacupuncture; MAS, modified Ashworth scale; TG, treatment group; CG, control group; FMA-L, Fugl–Meyer motor scale of lower limbs; AROM, active range of motion; iEMG, integrated surface electromyography; MWS, maximum walking speed; BBS, Berg balance scale; sEMG, surface electromyography; CR, cocontraction rate; RMS, root mean square..

Table 3 . Implementation of acupuncture intervention.

Author (y)	Periods	Electroacupuncture frequency	Acupoints	Needle size	Insertion depth	Waveform
Sun (2014) [12]	30 d	7 trials/wk for 40 min	GB 34, GB 39, GB 40, ST 41	1.5 cun 30-gauge	0.5–1 cun	Continuous wave
Luo (2014) [13]	4 wk	5 trials/wk for 30 min	GB 34, ST 36, ST 40, GB 39	Not mentioned	Not mentioned	Continuous wave
Wang (2017) [14]	24 d	6 trials/wk for 30 min	SP 10, ST 34, ST 36, GB 34, GB 40, ST 41	0.30 × 40 mm	Not mentioned	1 Hz
Li (2017) [15]	4 wk	5 trials/wk for 20 min	Tibialis anterior muscle motor point	Not mentioned	Not mentioned	20–100 Hz 0.1–1 mA
Zeng (2018) [16]	4 wk	6 trials/wk for 20 min	ST 36, GB 34, GB 39, GB 40, LR 3, BL 62, KI 6	0.20 × 40 mm	0.3–1.5 cun	50/10 Hz 1–3 mA
Wang (2019) [17]	4 wk	Not mentioned	GB 34, GB 39, ST 41	Not mentioned	Not mentioned	1 Hz
Wang (2019) [18]	6 wk	5 trials/wk for 30 min	GB 39, ST 36	Not mentioned	Not mentioned	10–20 Hz
Gu (2020) [19]	4 wk	6 trials/wk for 20 min	Antagonist muscle motor point	Not mentioned	Not mentioned	2 Hz 0.5–1.0 mA
Wu (2021) [20]	6 mo	6 trials/wk for 30 min	Antagonist muscle motor point	Not mentioned	Not mentioned	2 Hz 0.5–1.0 mA
Wang (2021) [21]	6 wk	6 trials/wk for 20 min	GB 34, ST 36	0.30 × 40 mm	1–1.5 cun	Discontinuous wave, 50 Hz
Xie (2022) [22]	12 wk	6 trials/wk	Antagonist muscle motor point	1.5 cun 32-gauge	Continuously adjust	Continuous wave, 1 Hz
Ke (2023) [23]	4 wk	6 trials/wk	GB 34, ST 41, LR 3, LR 4, ST 36, GB 37, GB 39, SP 6, KI 6	0.20 × 40 mm	15–30 mm	50/10 Hz 1–3 mA

GB, gallbladder meridian; ST, stomach meridian; SP, spleen meridian; LR, liver meridian; BL, bladder meridian; KI, kidney meridian..

Table 4 . Frequency of acupoints used in the studies.

Frequency	Acupoints
7	GB 34
6	GB 39, ST36
4	ST41
3	GB 40
2	LR 3, KI 6
1	GB 37, ST 34, ST 40, SP 6, SP 10, LR 4, BL 60

GB, gallbladder meridian; ST, stomach meridian; LR, liver meridian; KI, kidney meridian; SP, spleen meridian; BL, bladder meridian..

Table 5 . Frequency of meridians used in the studies.

Frequency	Meridians	Acupoints
4	Gallbladder meridian (GB)	GB 34, GB 37, GB 39, GB 40
4	Stomach meridian (ST)	ST 34, ST 36, ST 40, ST 41
2	Liver meridian (LR)	LR 3, LR 4
2	Spleen meridian (SP)	SP 6, SP 10
1	Kidney meridian (KI)	KI 6
1	Bladder meridian (BL)	BL 62

5. Assessment indicators

Various evaluation indicators were used in each study. Among them, the Fugl–Meyer motor scale of the lower limbs (FMA-L), which evaluates mobility recovery of the upper or lower limbs after stroke (Table 6), was the most frequently used indicator [13-15,17-20,22]. For the lower extremities, the perfect score is 34 points, and a higher score means higher motor function. In all 8 studies using this indicator, the difference in FMA-L score increases before and after treatment was significantly higher in the treatment group (p < 0.05). This means the presence of a significant treatment effect in the treatment group compared with the control group.

Table 6 . FMA-L and MAS reported in the studies.

Author (y)	Assess indicators	Treatment (before → after)	Control (before → after)	p-value
Luo (2014) [13]	FMA-L	12.95 ± 3.22 → 22.17 ± 8.23	13.16 ± 3.96 → 17.32 ± 5.94	< 0.05
Wang (2017) [14]	FMA-L	20.30 ± 4.25 → 28.44 ± 3.23	21.71 ± 5.02 → 24.06 ± 4.26	< 0.05
Li (2017) [15]	FMA-L	23.31 ± 4.13 → 31.17 ± 5.22	20.25 ± 3.84 → 26.15 ± 5.13	< 0.05
Wang (2019) [17]	FMA-L	12.07 ± 2.12 → 36.72 ± 4.45	11.75 ± 2.24 → 25.86 ± 5.67	< 0.05
Wang (2019) [18]	FMA-L	12.71 ± 2.63 → 23.82 ± 5.85	13.12 ± 2.74 → 21.54 ± 6.17	< 0.05
Gu (2020) [19]	FMA-L	14.9 ± 3.8 → 24.1 ± 4.0	15.2 ± 3.7 → 20.2 ± 4.3	< 0.01
Wu (2021) [20]	FMA-L	15.63 ± 3.95 → 25.26 ± 5.56	15.89 ± 4.07 → 21.45 ± 4.88	< 0.05
Xie (2022) [22]	FMA-L	14.42 ± 1.56 → 26.62 ± 3.41	14.33 ± 1.51 → 20.11 ± 3.05	< 0.05
Sun (2014) [12]	MAS	3.44 ± 0.61 → 2.13 ± 0.76	3.37 ± 0.60 → 2.63 ± 0.76	< 0.05
Wang (2017) [14]	MAS	3.12 ± 0.71 → 2.01 ± 0.15	2.99 ± 0.32 → 1.92 ± 0.28	0.08
Zeng (2018) [16]	MAS	2.69 ± 0.59 → 1.18 ± 0.87	2.62 ± 0.50 → 1.41 ± 0.56	0.17
Ke (2023) [23]	MAS	Grade 0–2 (%) 31.7 → 88.3	Grade 0–2 (%) 26.7 → 68.3	< 0.05

Values are presented as mean ± standard deviation..

FMA-L, Fugl–Meyer motor scale of the lower limbs; MAS, modified Ashworth scale..

Four studies used the MAS (Table 6) [12,14,16,23]. The MAS evaluates the stiffness of the tibialis anterior from level 0 to 4. The higher the resistance during passive exercise, the higher the level. Ke et al. [23] used the proportion of patients in grades 0–2 before and after treatment as an evaluation index. Sun et al. [12] and Ke et al. [23] reported a significant difference between the change in the scores of the treatment and control groups (p < 0.05). However, Wang et al. [14] and Zeng et al. [16] did not find a significant difference in the MAS between the 2 groups (p = 0.08, p = 0.17, respectively).

In foot drop, in which ankle dorsiflexion is impossible, the active range of motion (AROM) of the ankle was often used as an evaluation index (Table 7). Seven studies used dorsiflexion AROM [13-16,18,22,23], and Xie [22] also evaluated ankle-inversion AROM. Ankle AROM was significantly improved in the treatment group compared with that in the control group (p < 0.05); however, 1 study [15] reported no significant difference (p > 0.05).

Table 7 . Active range of motion of the ankle reported in the studies.

Author (y)	Motion	Treatment (before → after)	Control (before → after)	p-value
Luo (2014) [13]	Dorsiflexion	5.97 ± 1.86 → 20.65 ± 4.97	6.36 ± 1.52 → 13.69 ± 4.58	< 0.05
Wang (2017) [14]	Dorsiflexion	5.12 ± 0.92 → 14.22 ± 5.32	5.24 ± 0.77 → 9.01 ± 4.62	< 0.05
Li (2017) [15]	Dorsiflexion	5.45 ± 1.35 → 6.21 ± 1.20	6.51 ± 1.12 → 7.02 ± 1.03	> 0.05
Zeng (2018) [16]	Dorsiflexion	2.04 ± 1.03 → 9.48 ± 4.56	1.84 ± 0.86 → 5.64 ± 3.34	< 0.05
Wang (2019) [18]	Dorsiflexion	1.34 ± 0.1 → 14.97 ± 6.54	1.41 ± 0.09 → 12.58 ± 5.76	< 0.05
Xie (2022) [22]	1. Inversion 2. RMS of dorsiflexion	1. 10.15 ± 1.52 → 20.24 ± 2.41 2. 1.12 ± 0.31 → 2.71 ± 0.23	1. 10.24 ± 1.53 → 17.51 ± 2.12 2. 1.14 ± 0.32 → 2.33 ± 0.28	< 0.05 < 0.05
Ke (2023) [23]	Dorsiflexion	8.2 ± 1.7 → 22.3 ± 2.0	7.9 ± 1.2 → 15.6 ± 2.5	< 0.05

Values are presented as mean ± standard deviation..

RMS, root mean square..

Electromyography (EMG) assesses the electrical activity of muscles and can mainly detect the condition of atrophied muscles. EMG was used in 6 studies [15,18-21,23], of which Wang et al. [18] and Wang et al. [21] used surface EMG (sEMG), which measures EMG with the relaxed ankle. Meanwhile, Li et al. [15], Gu et al. [19], Wu [20], and Ke et al. [23] used integrated sEMG (iEMG) to measure EMG with the ankle in dorsiflexion (Table 8). In sEMG with the ankle relaxed, as muscle strength increases, the activities of both the agonist tibialis anterior and antagonist gastrocnemius muscles increase; however, in iEMG measured during ankle dorsiflexion, as muscle strength increases, the activity of the antagonist gastrocnemius and cocontraction rate (CR) decreases. The changes, increase or decrease, in EMG and CR values of the tibialis anterior and gastrocnemius were significant in the treatment group compared with that in the control group. As a result of comparing the change in EMG and CR between the treatment and control groups, the p-value was < 0.05 or < 0.01 in all studies.

Table 8 . iEMG and sEMG reported in the studies.

Author (y)	Assess indicators	Muscle	Treatment (before → after)	Control (before → after)	p-value
Li (2017) [15]	iEMG	Tibialis anterior m.	30.19 ± 9.531 → 48.14 ± 10.612	32.84 ± 8.841 → 41.21 ± 11.297	< 0.05
Wang (2019) [18]	sEMG	Tibialis anterior m.	29.57 ± 9.43 → 0.10 ± 0.09	31.34 ± 8.76 → 142.58 ± 49.81	< 0.05
Gu (2020) [19]	iEMG	Tibialis anterior m. Gastrocnemius m. Ankle dorsiflexion state CR (%)	33.2 ± 3.0 → 39.7 ± 3.3 38.8 ± 2.8 → 34.0 ± 2.5 52.4 ± 3.7 → 42.9 ± 3.1	33.7 ± 3.1 → 36.8 ± 3.2 38.6 ± 2.9 → 36.2 ± 2.7 51.9 ± 3.6 → 46.5 ± 3.0	< 0.01 < 0.01 < 0.01
Wu (2021) [20]	iEMG	Ankle dorsiflexion state CR (%)	51.58 ± 3.59 → 42.49 ± 3.41	51.13 ± 3.87 → 46.56 ± 4.95	< 0.05
Wang (2021) [21]	sEMG	Tibialis anterior m. Gastrocnemius m.	20.3 ± 5.16 → 33.3 ± 9.56 19.31 ± 9.37 → 34.2 ± 8.87	21.3 ± 6.27 → 29.1 ± 6.27 20.18 ± 7.32 → 28.6 ± 5.19	< 0.01 < 0.01
Ke (2023) [23]	iEMG	Tibialis anterior m. Gastrocnemius m. Ankle dorsiflexion state CR (%)	32.8 ± 2.6 → 39.5 ± 2.1 38.6 ± 2.2 → 33.8 ± 1.9 52.0 ± 3.1 → 44.1 ± 3.5	33.1 ± 2.4 → 36.4 ± 1.8 39.1 ± 2.3 → 36.6 ± 1.7 53.4 ± 2.8 → 48.5 ± 3.0	< 0.05 < 0.05 < 0.05

Values are presented as mean ± standard deviation..

CR = antagonist muscle iEMG / (agonist muscle + antagonist muscle) iEMG × 100%..

iEMG, integrated surface electromyography; sEMG, surface electromyography; CR, cocontraction rate..

Several studies have also used gait-related parameters (Table 9). Sun et al. [12] confirmed significant effectiveness in the treatment group using the Barthel index, which evaluates the activities of daily living, and the Kendall percentage, which evaluates the strength of the tibialis anterior (p < 0.05). Wang et al. [14], Wang [17], and Xie [22] demonstrated the significant effect of EA using the Holden and Tinetti scores, which are gait-related indices. The maximum walking speed measures the maximum speed of walking 10 m and was used by Zeng et al. [16], Wang et al. [18], and Ke et al. [23]. In addition, 4 studies used the Berg balance scale, which evaluates balance function during activities of daily living, in the evaluation before and after treatment and confirmed that the treatment effect was significantly better in the treatment group than in the control group (p < 0.05 or p < 0.01) [16,19,20,23].

Table 9 . Gait-related parameters reported in the studies.

Author (y)	Assess indicators	Treatment (before → after)	Control (before → after)	p-value
Sun (2014) [12]	1. Barthel index 2. Kendall percentage	44.33 ± 7.93 → 69.67 ± 6.05 17.83 ± 10.46 → 45.33 ± 14.08	43.50 ± 9.50 → 55.17 ± 8.41 17.67 ± 11.23 → 33.67 ± 13.53	< 0.05 < 0.05
Wang (2017) [14]	1. Holden score 2. Tinetti score	2.97 ± 0.33 → 4.58 ± 0.92 4.87 ± 1.24 → 8.01 ± 2.93	3.01 ± 0.52 → 3.93 ± 1.01 4.53 ± 0.98 → 6.58 ± 2.10	< 0.05 < 0.05
Zeng (2018) [16]	1. MWS 2. BBS	10.9 ± 7.9 → 53.6 ± 10.5 35.72 ± 7.15 → 48.34 ± 5.87	11.2 ± 7.6 → 34.6 ± 12.6 34.91 ± 4.34 → 42.56 ± 7.12	< 0.05 < 0.05
Wang (2019) [17]	Tinetti score	5.36 ± 2.15 → 42.65 ± 8.44	5.25 ± 2.22 → 30.21 ± 7.95	< 0.05
Wang (2019) [18]	MWS	0.10 ± 0.09 → 3.14 ± 1.35	0.13 ± 0.09 → 2.87 ± 1.23	< 0.05
Gu (2020) [19]	BBS	34.2 ± 5.9 → 47.5 ± 6.4	34.8 ± 5.6 → 41.7 ± 6.0	< 0.01
Wu (2021) [20]	BBS	34.78 ± 5.69 → 47.81 ± 6.70	35.12 ± 6.02 → 42.25 ± 6.57	< 0.05
Xie (2022) [22]	Tinetti score	6.25 ± 1.15 → 40.12 ± 4.36	6.21 ± 1.12 → 31.12 ± 4.15	< 0.05
Ke (2023) [23]	1. BBS 2. MWS	32.3 ± 4.1 → 48.2 ± 6.8 11.4 ± 5.1 → 43.1 ± 9.5	33.1 ± 4.8 → 41.5 ± 7.2 10.6 ± 4.6 → 32.6 ± 8.4	< 0.05 < 0.05

Values are presented as mean ± standard deviation..

MWS, maximum walking speed; BBS, Berg balance scale..

Five studies used total efficacy, which evaluates the overall effectiveness of treatment, as an indicator (Table 10) [17,20-23]. Treatment effectiveness was evaluated in percentage, and in all 5 studies, the effect was significantly higher in the treatment group than in the control group (p < 0.05).

Table 10 . Total efficacy reported in the studies.

Author (y)	Treatment (%)	Control (%)	p-value
Wang (2019) [17]	95.00	75.00	< 0.05
Wu (2021) [20]	82.09	65.67	< 0.05
Wang (2021) [21]	90.00	83.30	< 0.05
Xie (2022) [22]	96.43	78.57	< 0.05
Ke (2023) [23]	96.67	83.33	< 0.05

6. Adverse events

Of the 12 studies, 11 did not mention any adverse events [12-15,17-23], and 1 reported a lack of adverse events (Table 2) [16]. In the study by Zeng et al. [16], the treatment group received EA, exercise therapy, and physiotherapy, whereas the control group received exercise therapy and physiotherapy, and no obvious adverse events occurred in both groups.

In this review, the effectiveness of EA was evaluated by reviewing existing RCTs that used EA for post-stroke foot drop. Foot drop is a common symptom in patients with stroke and is mainly caused by the loss of balance between ankle dorsiflexion and plantar flexion because of the weakness of the tibialis anterior and spasms in the gastrocnemius [24]. Post-stroke foot and ankle dysfunction affects the patient’s sense of balance and walking ability, and if not treated promptly or treated inappropriately, severe greater ankle joint damage may occur [10]. Therefore, actively seeking effective methods to treat post-stroke foot drop is significant in correcting patients’ abnormal gait patterns and improving walking ability [25].

Post-stroke foot drop mainly focuses on adjusting the tension of the agonist and antagonist muscles [19]. Exercise training, low-frequency electrical stimulation, ankle and foot orthoses, rehabilitation, botulinum toxin type A injection, and kinesio taping are commonly used treatment methods [26-29]. Among them, exercise therapy and neuromuscular electrical stimulation therapy are being used as basic treatments with proven efficacy [30]. Compared with the above treatments, EA has a simpler procedure and fewer adverse events; thus, it may be suitable for the treatment of post-stroke foot drop [16].

In Oriental Medicine, patients in the recovery stage of post-stroke hemiplegia often suffer from qi and blood deficiency [31], and the yangmyeong meridian has a lot of qi and blood, which can be utilized to control qi and blood through acupuncture [32]. Therefore, the acupoints used for patients with post-stroke foot drop are mainly located in the 3 yang meridians of the lower extremities and are mainly distributed in the calf and foot acupoints [18]. All 14 acupoints used in the 12 studies analyzed in this review [12-23] were also located on the lower extremities or feet: 6 on the foot, 5 on the lower leg, and 3 on the thigh. In addition, the GB and ST meridians, which correspond to the 3 yang meridians, were widely used. A study reported that stimulating ST 36, ST 41, and GB 34 locally excites the tibialis anterior, extensor digitorum longus, and common peroneal nerves, thereby improving active ankle dorsiflexion [19]. Meanwhile, 4 studies [15,19,20,22] treated foot drop using antagonist muscle motor points rather than acupoints. Because muscle motor points are rich in nerve endings and have a high excitability threshold, EA stimulation can relieve lower limb muscle spasms, reduce muscle tension in antagonist muscles, and improve coordination [19].

Most studies have analyzed targeted patients who developed foot drop symptoms after a stroke, within 6 months of symptom onset. Luo [13] and Wang et al. [18] also selected patients in the acute phase within 2 weeks and 1 month, respectively. In all studies, the treatment group received EA along with rehabilitation or physical therapy, and the control group received rehabilitation alone or a combination of acupuncture and rehabilitation. EA of post-stroke foot drop demonstrated a statistically significant effect. This could be proven by significantly increasing FMA-L, ankle AROM, EMG of related muscles, and gait-related parameters in the treatment group compared with the control group. These results indicate that EA improves not only foot drop symptoms but also the patient’s walking ability and quality of life.

Out of the 12 studies, only one [16] confirmed that no adverse events occurred. Most studies do not mention this; thus, additional clinical studies are needed to investigate potential adverse events.

However, this study has several limitations. First, although we attempted to include studies conducted in various countries, all current RCTs were conducted only in China. Second, the number of studies included was small. Third, no studies have used EA alone in the treatment group. Fourth, EA-related methods varied in frequency, waveform, needle size, depth of needle insertion, etc. Thus, more studies are needed to supplement these points. This study confirmed that EA had a positive and significant effect on post-stroke foot drop; however, assert its effectiveness is still difficult. Therefore, additional domestic and international studies are needed to supplement the above limitations and confirm our research results.

In the 12 studies on EA for post-stroke foot drop, we can draw some conclusions: First, all 12 RCTs revealed that EA has statistically significant effects on post-stroke foot drop. Second, EA can improve the symptoms and overall quality of life of patients with foot drop. Third, GB and ST meridians are the most frequently used, and GB 34 was the most used acupoint. The acupoints used in all studies were located in the lower extremities. Fourth, EA is a safe treatment method for foot drop because no significant adverse events were noted in this study. Fifth, further research is needed to confirm the effectiveness of EA treatment on post-stroke foot drop.

Conceptualization: HJJ. Data curation: HJJ, HWK, AK, JEC. Formal analysis: HJJ, YJL, GEC. Investigation: HJJ, AK, YJL, GEC. Methodology: HJJ, HWK, SJK. Project administration: HJJ. Supervision: WYK. Writing – original draft: HJJ. Writing – review & editing: HJJ, JEC, SJK.

The authors have no conflicts of interest to declare.

None.

This research did not involve any human or animal experiments.