Modulation of cerebral cortex activity by acupuncture combined with continuous theta-burst stimulation in post-stroke upper limb spasticity: an fNIRS study

Abstract

Objective: To observe the modulation and clinical efficacy of acupuncture combined with continuous theta-burst stimulation (cTBS) on cerebral cortical activity in post-stroke upper limb spasticity.

Methods: Patients with upper limb spasticity after stroke were randomly divided into two groups. The control group (n = 15) received acupuncture treatment, and the experimental group (n = 15) received cTBS treatment of the premotor cortex of the healthy side in addition to acupuncture. The efficacy was evaluated before and after the first treatment and 2 weeks after treatment. MAS, FMA, MBI, fNIRS and F wave evaluation were observed in the two groups.

Results: After treatment, there were significant differences between the two groups in MAS, FMA-UE, MBI, F-wave amplitude, and the F/M amplitude ratio index of the experimental group (p < 0.05). Comparison between groups, the MAS-elbow flexor in the experimental group decreased significantly after the first treatment and 2 weeks after treatment. After 2 weeks of treatment, the HbO₂ concentration in the CH4 channel exercise phase in the experimental group increased compared with the control group (p _FDR <0.05). The strength of functional connection in the left primary motor area (M1)-the left primary somatosensory cortex (S1), the left S1-the right premotor cortex and supplementary motor area (PMC & SMA), and the left S1-the left PMC&SMA showed an increasing trend (0.05 < p _FDR < 0.1). The F wave amplitude was significantly lower than before intervention, and the difference was significant (p < 0.05).

Conclusion: Acupuncture combined with cTBS can relieve upper limb spasticity, enhance motor function, improve daily living ability, and reduce excessive spinal cord excitability. It can also increase HbO₂ concentration in the cerebral cortex. However, large-sample studies are still needed to prove the effect of this therapy on brain networks.

Significance: This study provides evidence for the potential of combined cTBS and acupuncture in stroke rehabilitation.

Clinical trial registration: identifier ChiCTR2400083631.

Keywords: F-wave; acupuncture; continuous theta burst stimulation; fNIRS; spasticity; stroke.

Figure 1

Schematic diagram of the trial process. MAS, Modified Ashworth Scale; FMA-UE, Fugl-Meyer Assessment-Upper Extremity; MBI, Modified Barthel Index; fNIRS, functional near-infrared spectroscopy.

Figure 2

Continuous theta burst stimulation (cTBS) paradigm and neurophysiological effects. The fundamental element of cTBS comprises a burst of 3 stimuli delivered at 50 Hz (each lasting 60 ms), repeated every 200 ms, resulting in an uninterrupted 40-s TBS sequence (totaling 600 pulses). Following a 10-min rest period, the stimulation is repeated with an additional 600 pulses.

Figure 3

Distribution of light sources, detectors, and channels.

Figure 4

fNIRS task-state design paradigm.

Figure 5

Schematic diagram of F-wave detection. (a) Detection position schematic. Stimulation electrode: 1 cm proximal to wrist crease. Recording electrode: On abductor pollicis brevis belly. Reference electrode: On corresponding tendon. Grounding electrode: Attached to dorsal hand. (b) F-wave waveform diagram. (c) F-wave waveform after 20 superimposed stimulations. (d) Relevant parameters for F-wave assessment.

Figure 6

Graph of outcome indicators. MAS, Modified Ashworth Scale; FMA-UE, Fugl-Meyer Assessment-Upper Extremity; MBI, Modified Barthel Index. Significance levels between-group comparisons: **P < 0.01, *P < 0.05.

Figure 7

The difference in brain activation between the experimental group and the control group.

Figure 8

The FC map of experimental group ROI.

Figure 9

FC of the experimental group (a) and the control group (b) before treatment.

Figure 10

FC of the experimental group (a) and the control group (b) after treatment.