Predicting the efficacy of early non-invasive neuromuscular electrical stimulation in post-stroke upper extremity motor recovery and their correlation with blood biomarkers

Objectives: Non-invasive neuromuscular electrical stimulation (NMES) enhances cortical excitability and muscle protein synthesis. Serum neurofilament light chain (NFL) and matrix metalloproteinase-9 (MMP-9) levels are negatively correlated with the modified rankin score (mRS) and predict poor outcomes 3 months following a stroke. This study aimed to assess the effect of non-invasive early NMES on upper limb paresis and serum NFL and MMP-9 levels at 3-month follow-up. Materials and Methods: This quasi-experimental trial was conducted in the inpatient department from February 2021 to January 2023, included 54 first-ever ischemic stroke patients with stroke severity 2–4 on mRS, divided into intervention and control groups. The intervention group received non-invasive early NMES plus standard rehabilitation, and the control group received standard rehabilitation only. Primary outcomes included upper extremity Fugl–Meyer assessment (FMA) sub-sections A, A-D, and mRS. Secondary outcomes were serum NFL and MMP-9 levels, which were assessed at baseline and a 3-month follow-up. Results: Significant differences were observed between intervention and control groups at 3 months follow-up in mRS, 1 (1–2) and 3 (2–3) P < 0.01, Fugl-Meyer assessment-upper extremity (FMA-UE)- A 29 (19–32) and 15 (11–19), P < 0.01, FMA-upper extremity sub-scale A-D-FU 53 (33–60) and 34 (25–49) P = 0.02. There was no significant difference in biomarker levels between groups at follow-up. Conclusion: Early non-invasive NMES demonstrated superior efficacy in improving motor outcomes compared to standard rehabilitation, but its association with blood biomarkers needs further exploration.