Action observation therapy impact on mirror neurons combined with acupuncture for upper limb motor impairment rehabilitation in stroke patients

Stroke affects approximately 15 million people annually worldwide, with 5 million left permanently disabled. Upper limb (UL) motor impairment affects 55%–75% of stroke survivors and severely limits activities of daily living. Mirror neurons (MNs), first identified in nonhuman primates and subsequently supported in humans, activate during both action execution and observation and are implicated in motor learning and rehabilitation. Clinical techniques based on MNs include mirror therapy and action observation therapy (AOT), which may stimulate residual or suppressed MNs to enhance motor recovery. Acupuncture is widely used to modulate peripheral and central neural function and promote neuroplasticity. The present study investigated whether combining central stimulation via AOT with peripheral stimulation via acupuncture improves UL motor recovery after stroke compared with either modality alone.

The paper reviews evidence that MNs in premotor and parietal regions support action understanding and motor facilitation through observation and imagery, forming the basis for mirror therapy and AOT in stroke rehabilitation. Prior studies indicate AOT activates bilateral motor-related cortices and can aid UL recovery. Acupuncture, recommended as complementary therapy for stroke by the WHO, is reported to stimulate neurogenesis, modulate cortical lateralization, enhance functional connectivity, and regulate whole-brain networks. Common acupoints for motor recovery include GV20, GB20, LI4, ST36, SP6, LI11, GB39, and motor scalp areas. The authors selected Baihui (GV20), Sishencong (EX-HN1), Hegu (LI4), Binao (LI14), Shousanli (LI10), Quchi (LI11), Jianyu (LI15), and Neiguan (PC6) based on traditional meridian theory and prior evidence linking these points to motor function and cognition. The rationale is that AOT may promote central neuroplasticity via the MN system while acupuncture may enhance peripheral afferent input and neuroplasticity, potentially yielding synergistic effects.

Design: Randomized, three-arm clinical study conducted January–December 2022 in the Jing'an Northern Medical Consortium of Shanghai. Ethics approval YL-2021422-01; informed consent obtained; trial registered ChiCTR2300077010. Participants: 82 adults within 6 months post first-ever stroke with UL dysfunction; right-handed; age 30–80; MMSE >17; Brunnstrom stage II–IV for distal joint; adequate vision/hearing/comprehension and educational level (above primary school). Exclusions included acute cardiopulmonary or hypertensive conditions, severe joint pain, major sensory/comprehension deficits, UL deformities, bilateral or cerebellar/brainstem lesions, progressive stroke or SAH, severe cognitive impairment/depression/aphasia, TBI/tumor, or noncooperation. Groups: Random assignment to (1) Acupuncture (AC) group; (2) AOT + AC group; (3) AOT group. Common conventional therapy for all: Standard UL rehabilitation including positioning, 60 min/day exercise therapy (5 days/week, 8 weeks), and 30 min/day occupational therapy (5 days/week, 8 weeks). Interventions: - AOT: MNST V1.0 device delivering UL action videos; patients observed then imitated/practiced with affected limb; 20 min/session, daily, 6 days/week, for 8 weeks. - Acupuncture: Disposable sterile needles at Baihui (GV20, flat 15–20 mm), Sishencong (EX-HN1, flat 13–20 mm), Quchi (LI11, perpendicular 25–40 mm), Shousanli (LI10, perpendicular 25–40 mm), Neiguan (PC6, perpendicular 13–25 mm), Jianyu (LI15, toward Jiquan, 50–75 mm), Binao (LI14, perpendicular/oblique 20–40 mm), Hegu (LI4, perpendicular 13–20 mm). Sought local deqi sensations (soreness/numbness/bloating/meridian conduction). 20 min/session, daily, 5 days/week, 8 weeks. - Combined group: AOT followed by acupuncture in each session. Outcomes and assessment: UL motor function via Fugl-Meyer Assessment–Upper Extremity (FMA-UE; 33 items, max 66), activities of daily living via modified Barthel Index (BI; max 100), and hand/arm function via Action Research Arm Test (ARAT). Assessed at baseline (0 weeks), 4 weeks, and 8 weeks by a single-blinded evaluator unaware of group allocation. Statistical analysis: SPSS 25.0. Continuous data as mean±SD or median (IQR); categorical as n (%). Repeated-measures ANOVA tested time (0, 4, 8 weeks), group, and time×group effects with partial eta-squared (ηp²) effect sizes. Bonferroni-corrected post hoc tests for pairwise comparisons; simple-effect analyses for between-group at each time point and within-group over time. Chi-square or Fisher’s exact tests for categorical variables. Two-tailed P≤0.05 considered significant.

Baseline: Groups comparable on general characteristics and outcome measures (P>0.05). FMA-UE: Significant time×group interaction (F=7.213, P<0.001, ηp²=0.154) and main effect of time (F=383.794, P<0.001, ηp²=0.829); no main effect of group (F=1.912, P=0.154, ηp²=0.046). All groups improved over time (P<0.05). At 8 weeks, combined AOT+acupuncture > acupuncture alone (P=0.003). Group means (mean±SD): 0w—AC 36.37±6.11, AOT+AC 34.93±8.55, AOT 32.92±6.59; 4w—AC 46.97±8.93, AOT+AC 51.71±8.40, AOT 49.46±7.45; 8w—AC 51.33±8.47, AOT+AC 58.07±7.47, AOT 55.83±5.97. Barthel Index (BI): Significant time×group interaction (F=4.411, P=0.005, ηp²=0.100), main effect of time (F=261.034, P<0.001, ηp²=0.768), and main effect of group (F=5.204, P=0.008, ηp²=0.116). All groups improved over time (P<0.05). At 4 weeks, AOT > acupuncture (P=0.043). At 8 weeks, both AOT+acupuncture and AOT > acupuncture (P<0.05). Means (mean±SD): 0w—AC 52.80±9.88, AOT+AC 58.79±14.05, AOT 57.83±11.65; 4w—AC 62.87±11.24, AOT+AC 70.18±12.56, AOT 70.88±11.13; 8w—AC 64.60±10.89, AOT+AC 76.61±11.36, AOT 75.21±12.04. ARAT: Significant time×group interaction (F=6.285, P=0.001, ηp²=0.137) and main effect of time (F=315.437, P<0.001, ηp²=0.800); no main effect of group (F=0.941, P=0.395, ηp²=0.023). All groups improved over time (P<0.05). No significant between-group differences at any time point. Means (mean±SD): 0w—AC 27.93±9.78, AOT+AC 23.50±12.40, AOT 20.88±10.69; 4w—AC 35.27±10.55, AOT+AC 35.18±11.73, AOT 31.58±10.48; 8w—AC 40.40±8.90, AOT+AC 43.00±10.61, AOT 40.38±10.24. Overall: AOT accelerated ADL gains at 4 weeks versus acupuncture; by 8 weeks, AOT and AOT+acupuncture showed superior ADL (BI) to acupuncture, and combined therapy yielded the highest motor recovery on FMA-UE versus acupuncture alone.

The study addressed whether combining central neural stimulation via AOT (leveraging the mirror neuron system) with peripheral afferent stimulation via acupuncture enhances UL recovery post-stroke beyond either modality alone. All modalities improved motor function and ADLs over 8 weeks, supporting their rehabilitative value. Early ADL benefits at 4 weeks in the AOT group suggest that MN-based visual-motor engagement may rapidly facilitate functional task performance. By 8 weeks, the combined AOT+acupuncture group outperformed acupuncture alone on FMA-UE and matched or exceeded AOT on BI, indicating a synergistic effect over time. This synergy likely reflects complementary mechanisms: AOT primes and activates motor-related cortical networks and motor representations, while acupuncture modulates neuroplasticity, potentially rebalancing interhemispheric activity and enhancing functional connectivity. The absence of between-group differences on ARAT may reflect the test’s sensitivity, sample size, or the timescale needed for fine motor and grasp functions to differentiate among interventions. These findings support integrating MN-based therapies with acupuncture to maximize multi-pathway neuromodulation for UL recovery after stroke.

AOT and acupuncture each improved upper limb dexterity and daily function after stroke, with combined AOT+acupuncture demonstrating superior motor recovery over acupuncture alone at 8 weeks and AOT showing earlier ADL gains at 4 weeks. AOT is a simple, economical MN-based technique that can benefit stroke rehabilitation, and manual acupuncture activates afferent fibers influencing central plasticity. Further research is needed to elucidate the neuronal mechanisms and to define optimal protocols and combinations of AOT and acupuncture across different stroke stages.

The study acknowledges that the underlying neuroregulatory mechanisms of AOT and acupuncture for upper limb recovery at different post-stroke stages were not clarified. The optimal strategy and neuromodulation mechanisms for AOT, and the best way to combine AOT with acupuncture, require further investigation.