Effects of segmental muscle vibration on flexor and extensor groups of the upper limb in enhancing functional recovery after stroke: A randomized trial

Background

Upper limb motor impairment is a common sequela of stroke, often leading to long-term functional limitations. Segmental vibration therapy (SVT) has been proposed to facilitate sensorimotor recovery by enhancing proprioceptive input and cortical excitability. However, its differential effects on upper limb flexor and extensor muscle groups remain underexplored.

Objective

The objective of this study was to determine the effects of segmental vibration on flexors and extensor muscle groups for upper limb functional ability, recovery, and spasticity in post-stroke patients.

Methodology

This two-arm, parallel-design, double-blinded randomized clinical trial was conducted at Zohra Institute of Health Sciences. A total of 62 patients were recruited using a non-probability convenience sampling technique and randomized into two groups through an online randomization tool. Group A received low-frequency segmental muscle vibration (41 Hz) applied over the flexor muscles of the upper limb, along with routine physical therapy. Group B received the same vibration frequency applied to the extensor muscles of the upper limb, in addition to routine physical therapy. Stroke patients with spasticity graded 1–3 on the Modified Ashworth Scale and who were 3–6 months post-stroke were included in the study. The intervention lasted for six weeks, comprising 18 sessions (three sessions per week). The Wolf Motor Function Test (WMFT) was used to assess upper extremity functional ability, while the Fugl-Meyer Assessment (FMA) evaluated motor function. Muscle spasticity was measured using the Modified Ashworth Scale (MAS), and motor recovery stages were assessed via the Brunnstrom scale. Data analysis was performed using SPSS version 26. An independent t-test was used for between-group comparisons, and a paired t-test was applied for within-group analysis.

Results

Post-intervention, WMFT scores improved in Group A (60.93 ± 6.12) compared to Group B (58.45 ± 7.66), though the difference was not statistically significant (p = 0.207). MAS scores decreased in Group A (0.56 ± 0.58) versus Group B (0.72 ± 0.74; p = 0.151). BSMR scores improved in both Group A (4.94 ± 1.19) and Group B (5.25 ± 1.23; p = 0.148). FMA scores increased in Group A (57.41 ± 3.97) compared to Group B (53.61 ± 4.89; p = 0.151). However, none of the between-group differences reached statistical significance.

Conclusion

The findings of this study suggest that segmental vibration therapy applied to both flexor and extensor muscles effectively improves upper limb function in post-stroke patients. However, no statistically significant difference was observed between the effects of vibration therapy on the two muscle groups.

Trial registration

The trial registration number for this study is NCT05356481. The trial started on May 2, 2022, and was completed on June 30, 2023.