Functional electrical stimulation for unilateral spatial neglect after stroke: A retrospective cohort study

Abstract

Objective

Functional electrical stimulation is a well-established rehabilitation therapy for post-stroke motor dysfunction; however, its clinical value in treating post-stroke unilateral spatial neglect remains unclear.

Methods

We conducted a retrospective cohort analysis of 58 patients with post-stroke unilateral spatial neglect who received either conventional rehabilitation therapy alone (n = 28) or a combination of functional electrical stimulation and conventional rehabilitation (n = 30). Treatment outcomes were assessed using the Catherine Bergego Scale, the Behavioral Inattention Test, the Fugl-Meyer Assessment for Upper Extremity, and the Modified Barthel Index.

Results

No significant differences were detected in baseline characteristics between the two groups. Following treatment, both groups demonstrated significant improvements across all outcome measures (p < 0.05). However, the functional electrical stimulation group demonstrated superior improvements in Behavioral Inattention Test (23.70 ± 19.10 vs. 14.93 ± 9.66, p = 0.031), Catherine Bergego Scale (7.07 ± 6.13 vs. 4.11 ± 3.46, p = 0.039), Modified Barthel Index (21.43 ±19.45 vs. 12.43 ± 8.60, p = 0.024), and Fugl-Meyer Assessment for Upper Extremity (13.40 ±10.10 vs. 7.64 ± 5.02, p = 0.045) compared with the conventional rehabilitation group. In addition, functional electrical stimulation demonstrated a favorable safety profile.

Conclusions

This study provides real-world evidence supporting that functional electrical stimulation may be an effective intervention for post-stroke unilateral spatial neglect.

Introduction

Unilateral spatial neglect (USN) is a common attentional disorder following stroke, characterized by a diminished or absent response to stimuli arising from the contralesional side of the body or space. It occurs in approximately 50% of patients during the acute phase of stroke, particularly after right hemisphere damage. ¹ As an important impediment to the recovery of functional independence after stroke, USN impairs not only sensory, motor, and cognitive functions but also significantly limits independent mobility of the patient, thereby placing a considerable burden on both families and society. ² The pathogenesis of USN is believed to involve dysfunction in distributed cortical networks responsible for attentional control. ³ Despite increasing awareness, current therapeutic strategies for USN remain limited in both scope and efficacy. Developing effective interventions to alleviate USN symptoms, restore patients’ perceptual and motor abilities, and enhance performance in daily activities remains a pressing challenge in neurorehabilitation.

Functional electrical stimulation (FES) is a rehabilitative technique that applies electrical currents to stimulate peripheral nerves. It is widely used in stroke rehabilitation to promote motor recovery in paralyzed limbs, improve muscle strength and coordination, and prevent muscle atrophy. ⁴ In addition, FES has been shown to reduce perceived effort, increase cerebral perfusion, and improve certain cognitive performance in patients with post-stroke conditions. ⁵ However, the application of FES in treating cognitive–perceptual deficits such as USN has received limited attention. This study aimed to investigate the clinical efficacy of FES in alleviating USN after stroke, thereby expanding its potential utility in comprehensive stroke rehabilitation.

Materials and methods

Trial design and data source

This retrospective study included patients with post-stroke USN who were hospitalized in the Department of Rehabilitation at Hunan Provincial People’s Hospital between January 2021 and December 2024. Patients received either conventional rehabilitation therapy alone or in combination with FES. The inclusion criteria were as follows: (a) right-handedness, with right hemispheric stroke confirmed by imaging and physical examination; (b) disease duration ≥1 week and ≤3 months; (c) presence of USN as determined by the Behavioral Inattention Test (BIT); ⁶ and (d) age ≥18 years. Exclusion criteria included the following: (a) non-first stroke and (b) incomplete clinical score data before or after treatment. Owing to the retrospective design of this study, a formal sample size calculation was not performed in advance. Instead, the study size was determined by all eligible patients available during the study period. To minimize selection bias and improve statistical precision, all cases meeting the predefined eligibility criteria were included in the analysis. The clinical data collected encompassed patients’ baseline characteristics and pre- and post-intervention outcome measures. All data were independently extracted from the electronic medical records by two investigators, and any discrepancies were reviewed and adjudicated to minimize potential bias.

This study does not include any identifiable patient information. It was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2024, and the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines for reporting cohort studies. ⁷

Intervention

The conventional treatment group received conventional rehabilitation therapy comprising bridge exercise, passive joint movement, cognitive dysfunction training, and activities of daily living (ADL) training in 30-min sessions once daily, 5 days per week for 4 weeks.

The FES treatment group received FES in addition to the conventional rehabilitation described above. FES was administered using the WOND2000F multifunctional neurorehabilitation instrument (Sanjia Medical Company; Guangzhou, China), which primarily stimulated muscles of the affected upper limb, including the supraspinatus, deltoid, and wrist dorsiflexor muscles. The default treatment program, positive biofeedback (PBF) mode, was selected. Prior to treatment, patients were positioned either lying down or sitting and were instructed to exercise to generate electromyographic signals. When the detected surface electromyographic value reached or exceeded the preset threshold, the instrument delivered electrical stimulation according to the intensity and duration of the active contraction of the muscle. Each electrical stimulation session lasted 8 s, followed by a 15-s interval before the next cycle. The stimulation intensity was generally 20–32 mA, with a pulse frequency of 35 Hz. The current strength and duration of the output electrical stimulation pulses were adjusted in real time based on the patient’s training condition, ensuring that the patients could complete the movement and tolerate the stimulation. During treatment, the patient were instructed to follow the image prompts of the therapeutic instrument and the voice prompts, such as “force, stimulation, maintenance, and rest,” practicing and controlling movements according to the feedback signal of the instrument to help the patient complete the maximum degree of joint movement. FES was administered for 20 min per session, once daily, 5 times per week, for 4 weeks. A schematic diagram of FES treatment is shown in Figure 1.

Figure 1.

Schematic diagram of FES applied in USN treatment. FES: functional electrical stimulation; USN: unilateral spatial neglect.

Efficacy evaluation

The BIT, Catherine Bergego Scale (CBS), Modified Barthel Index (MBI), and Fugl-Meyer Assessment for Upper Extremity (FMA-UE) were used to assess efficacy at pre-intervention and at 4 weeks post-intervention. The selection of these measures was intended to provide a multidimensional assessment, capturing perceptual deficits associated with USN and reflecting their impact on ADL and motor function. Furthermore, these indicators are well-established and have been extensively validated in previous studies investigating USN.^8–10

The BIT is a widely recognized and reliable tool comprising both behavioral and conventional sections for evaluating spatial neglect. This study used the conventional section (BIT-C), including six items: representational drawing, letter cancellation, star cancellation, figure and shape copying, line bisection, and line crossing. The maximum score is 146, and a score below 129 was considered indicative of USN. ⁶

The CBS is a validated and reliable 10-item scale used to assess daily life performance in areas such as grooming, dressing, and wheelchair driving in patients with USN. Items are rated on a scale from 0 to 3, representing no neglect, mild, moderate, and severe neglect, respectively. The total score ranges from 0 to 30, with higher scores indicating greater severity. ¹¹

The FMA-UE is a reliable, valid, and responsive tool used to assess motor impairments in patients with stroke. It evaluates arm movement, coordination, and reflexes using a three-point ordinal scale. Scores range from 0 to 66, with higher scores indicating less severe impairment. ¹²

The MBI is designed to measure independence in basic ADL across 10 domains: feeding, personal hygiene, toilet use, bladder control, bowel control, bathing, dressing, chair/bed transfer, ambulation, and stair climbing. Scores range from 0 to 100, with higher scores reflecting greater functional independence. ¹³

Statistical analysis

Statistical analysis was conducted using Statistical Package for Social Sciences (SPSS) version 26.0 (IBM; USA). Qualitative variables were presented as counts and percentages, whereas quantitative variables were reported as mean ± SD. Paired Student’s t-test or Wilcoxon signed-rank test was used to compare scores before and after intervention. Between-group comparisons of continuous variables were conducted using the two-sample t-test or Mann–Whitney U test. Categorical data were analyzed using the chi-square test or Fisher’s exact test. All p-values were two-tailed, with p < 0.05 considered statistically significant.

Results

Patients’ baseline features

The initial study cohort included 95 patients with post-stroke USN. After excluding 4 patients with left hemispheric stroke, 9 patients with a disease duration of >3 months, 7 patients with a history of previous stroke, and 17 patients with incomplete clinical data, a total of 58 patients were included in the final analysis. Among these, 28 were assigned to the conventional rehabilitation group and 30 to the FES treatment group. The mean age of participants was 47.31 ± 6.93 years in the conventional treatment group and 49.50 ± 8.87 years in the FES treatment group. Both groups were predominantly male, with males representing 71.4% and 76.7% of the conventional and FES groups, respectively. Ischemic stroke was the most prevalent type in both groups, comprising 82.1% of the conventional group and 73.3% of the FES group. Figure 2 outlines the study workflow.

Figure 2.

Workflow of the study.

At baseline, the conventional treatment group had mean scores of 82.79 ± 20.99 on the BIT, 13.82 ± 7.09 on the CBS, 51.75 ±13.09 on the MBI, and 25.71 ± 13.41 on the FMA-UE. The FES treatment group had mean baseline scores of 79.50 ± 20.85 on the BIT, 15.80 ± 6.48 on the CBS, 47.77 ±15.63 on the MBI, and 21.30 ± 8.93 on the FMA-UE. No significant differences were observed between groups in baseline characteristics (Table 1).

Table 1.

Baseline characteristics of patients.

Characteristics	Conventional treatment group (n = 28)	FES treatment group (n = 30)	p-value
Age (years)	47.31 ± 6.93	49.50 ± 8.87	0.30
Sex (n, %)			0.65
Male	20 (71.4%)	23 (76.7%)
Female	8 (28.6%)	7 (23.3%)
Course of disease (days)	86.70 ± 62.91	74.20 ± 51.34	0.41
Stroke type (n, %)			0.42
Ischemic	23 (82.1%)	22 (73.3%)
Hemorrhagic	5 (17.9%)	8 (26.7%)
BIT	82.79 ± 20.99	79.50 ± 20.85	0.28
CBS	13.82 ± 7.09	15.80 ± 6.48	0.14
MBI	51.75 ± 13.09	47.77 ± 15.63	0.15
FMA-UE	25.71 ± 13.41	21.30 ± 8.93	0.072

BIT: Behavioral Inattention Test; CBS: Catherine Bergego Scale; FES: functional electrical stimulation; FMA-UE: Fugl-Meyer Assessment for Upper Extremity; MBI: Modified Barthel Index.

FES promoted improvement in symptoms of USN

In the conventional treatment group, the BIT score increased from 82.79 ± 20.99 at baseline to 97.71 ± 15.12 after treatment, representing a mean improvement of 14.93 ± 9.66 points (p < 0.001). In the FES treatment group, the BIT score increased from 79.50 ± 20.85 to 103.20 ± 15.46, corresponding to a mean gain of 23.70 ± 19.10 points (p < 0.001). The improvement in BIT score was significantly greater in the FES group than in the conventional treatment group (23.70 ± 19.10 vs. 14.93 ± 9.66, p = 0.031, Figure 3).

Figure 3.

Changes in scores before and after treatment. BIT: Behavioral Inattention Test; CBS: Catherine Bergego Scale; FES: functional electrical stimulation; FMA-UE: Fugl-Meyer Assessment for Upper Extremity; MBI: Modified Barthel Index.

In the conventional treatment group, the CBS score improved from 13.82 ± 7.09 before treatment to 9.71 ± 3.99 post-treatment, corresponding to a reduction of 4.11 ± 3.46 points (p = 0.002). In the FES treatment group, the CBS scores decreased from 15.80 ± 6.48 before treatment to 8.73 ± 3.86 after treatment, corresponding to a reduction of 7.07 ± 6.13 points (p < 0.001). The FES group showed a greater improvement in CBS score than the conventional treatment group (7.07 ± 6.13 vs. 4.11 ± 3.46, p = 0.039, Figure 3). These findings indicate that FES is effective in enhancing recovery in patients with USN.

FES facilitated functional recovery

The MBI score in the conventional treatment group increased from 51.75 ± 13.09 at baseline to 64.18 ± 12.34 post-treatment, reflecting an improvement of 12.43 ± 8.60 points (p < 0.001). In the FES treatment group, the MBI score increased from 47.77 ± 15.63 to 69.20 ± 14.17, with an improvement of 21.43 ± 19.45 points (p < 0.001). The FES group achieved a significantly greater improvement in MBI score than the conventional treatment group (21.43 ± 19.45 vs. 12.43 ± 8.60, p = 0.024, Figure 3).

Regarding the FMA-UE score, the conventional treatment group showed an increase of 7.64 ± 5.02 points (p = 0.012), from 25.71 ± 13.41 before treatment to 33.36 ± 6.77 after treatment. The FES treatment group showed an increase of 13.40 ± 10.10 points (p < 0.001), from 21.30 ± 8.93 to 34.70 ± 7.35. The improvement was significantly greater in the FES group than in the conventional treatment group (13.40 ± 10.10 vs. 7.64 ± 5.02, p = 0.045, Figure 3). These findings suggest that FES substantially enhances the recovery of both ADL and motor function in patients.

Safety of FES therapy

Throughout the intervention period, FES was well tolerated by all patients. No serious adverse events were observed. A small number of patients experienced mild, transient reactions, including localized skin redness or mild discomfort at the electrode sites, which resolved spontaneously or after minor adjustments to stimulation parameters or electrode placement. No cases of muscle injury, exacerbation of neurological symptoms, or cardiovascular complications were reported.

Discussion

This study demonstrated the enhanced efficacy of FES in the treatment of USN. Compared with conventional rehabilitation, FES showed greater improvements across multiple outcome measures, including BIT, CBS, FMA-UE, and MBI, highlighting its advantages in promoting neurorehabilitation. The more pronounced gains in BIT and CBS scores in the FES group indicate superior recovery of attention and spatial awareness, which are crucial for reducing neglect symptoms and improving overall interaction with the environment.^14,15 Furthermore, the greater increase in FMA-UE score suggests enhanced motor recovery, whereas the larger improvement in MBI score reflects greater independence in ADL. The significant improvements observed in BIT and CBS scores within the FES group represent a marked reduction in spatial neglect, which translates into enhanced functional independence in daily life. Particularly, the reduction in CBS score indicates that patients in the FES group exhibited fewer neglect-related behaviors during essential ADL, such as eating, dressing, and navigating their immediate environment. This cognitive–perceptual recovery may be a prerequisite for the broader improvements observed in MBI score. By decreasing the severity of USN, FES enables patients to utilize their motor gains more effectively, thereby decreasing dependence on caregivers and improving overall quality of life. This synergy between the alleviation of neglect symptoms and the enhancement of functional autonomy underscores the comprehensive rehabilitative value of FES in this patient population. In addition, FES exhibited a favorable safety profile in this cohort. Collectively, these findings support the role of FES as a neuromodulatory intervention that can facilitate functional recovery in patients with USN.

The observed clinical benefits are likely underpinned by several neurophysiological mechanisms. First, FES may facilitate recovery by addressing interhemispheric competition in USN. According to the interhemispheric rivalry model, damage to one hemisphere caused by brain injury results in pathological overactivation of the contralateral hemisphere, further inhibiting the lesioned side.^16,17 The afferent input provided by FES to paretic limbs may act as a bottom-up stimulus, increasing arousal in the damaged cortex. This increased neural activity could potentially rebalance reciprocal inhibition between the cerebral hemispheres, thereby restoring spatial attention.^16,18

Second, FES promotes neuroplasticity by stimulating the motor cortex and associated neural pathways, thereby encouraging reorganization of cortical networks. This reorganization is essential for improving attention and perceptual processing in USN, as it activates dormant neural circuits and strengthens synaptic connections to support recovery. ¹⁹ FES enhances sensorimotor integration by delivering continuous afferent feedback to the brain during motor tasks, helping retrain sensory processing, improve motor coordination, and increase proprioceptive awareness, which are key elements for performing daily activities. ²⁰ Additionally, direct stimulation of muscles through FES facilitates neuromuscular re-education, restoring voluntary movement and reinforcing motor pathways, ²¹ which is consistent with the greater FMA-UE gains observed in this study.

Furthermore, the clinical efficacy of FES in treating USN may also be attributed to its unique capacity to integrate top-down intentionality with bottom-up sensory feedback. Unlike passive sensory stimulation, FES is often synchronized with patients’ voluntary attempts to engage in functional tasks, thereby creating a closed-loop reinforcement of motor pathways. This synchronized activation of central motor commands and peripheral sensory input drives Hebbian plasticity.^22,23 By bridging the gap between proprioceptive feedback and exploration of the neglected hemispace, FES facilitates more effective sensorimotor integration. This mechanism likely explains the concurrent improvements in motor control (FMA-UE) and spatial perception (BIT) observed in this cohort, as FES reinforces the functional connectivity required for both movement execution and environmental awareness.

FES has been recognized as a well-established intervention in the field of motor rehabilitation. However, clinical understanding of its application in the treatment of USN remains limited. Existing evidence in this area is largely confined to case reports or small case series,^24,25 which lack the statistical power from controlled trials. Moreover, prior studies have employed passive, open-loop stimulation paradigms, in which electrical stimulation is delivered at preset time intervals irrespective of patients’ motor intention. In contrast, this study adopts a retrospective controlled design and implements a feedback-based (closed-loop) paradigm, thereby addressing a gap in the current literature.

Despite the promising results, this study has several limitations. First, the retrospective design inherently carries a risk of selection bias and limits causal inference. Second, as a single-center study, the findings may be influenced by institutional practices, which may limit the generalizability of the results. Third, the relatively small sample size and absence of long-term follow-up data may limit the robustness of the conclusions. Finally, the proposed mechanisms, such as cortical plasticity and sensorimotor integration, are primarily theoretical and were not directly verified by neurophysiological or neuroimaging measurements in this study. Future studies should address these limitations by recruiting larger and more diverse cohorts across multiple centers to validate the present findings and assess long-term outcomes. More rigorous prospective randomized controlled trials are warranted to minimize bias and provide higher-level evidence. Additionally, incorporating tools such as electroencephalography, transcranial magnetic stimulation, functional near-infrared spectroscopy, and functional magnetic resonance imaging into mechanistic assessments would help validate the hypothesized pathways and elucidate how FES modulates attention circuits specific to USN. Overall, although the current study provides meaningful preliminary evidence, further rigorous investigation is required.

Conclusions

FES may confer notable therapeutic benefits for USN and may serve as a valuable adjunct within a comprehensive rehabilitation program to facilitate functional recovery.