# Repetitive transcranial magnetic stimulation promotes the recovery of upper limb motor dysfunction in ischemic stroke patients: a DTI-based glymphatic system imaging prospective study

## TL;DR

This study shows that rTMS can help stroke patients recover upper limb motor function, with different effects on the glymphatic system depending on the stimulation frequency.

## Contribution

The study introduces DTI-ALPS as a method to assess how rTMS affects the glymphatic system in stroke recovery.

## Key findings

- HF-rTMS led to a significant decrease in the DTI-ALPS index in the non-stimulated hemisphere.
- Changes in the DTI-ALPS index were negatively correlated with upper limb motor recovery in the HF-rTMS group.
- LF-rTMS improved motor function without significant changes in the DTI-ALPS index.

## Abstract

Repetitive transcranial magnetic stimulation (rTMS) is an effective tool for motor function recovery in patients with ischemic stroke (IS). Dysfunction of the glymphatic system is implicated in the pathological process of IS. However, it is still unclear whether the recovery of upper limb motor function in IS is affected by rTMS-driven modulation of glymphatic system function. This study aimed to investigate the potential utility of diffusion tensor imaging analysis along the perivascular space (DTI-ALPS) in assessing the impact of rTMS on IS recovery.

This prospective study recruited IS participants with upper limb motor disorders. A total of 35 participants were randomly assigned to receive either low-frequency rTMS (LF-rTMS) or high-frequency rTMS (HF-rTMS) for two weeks. HF-rTMS was conducted on the infarcted hemisphere M1 and the LF-rTMS was conducted on the non-infarcted hemisphere M1. The information collected from each patient included clinical characteristics, upper limb motor function score, and bilateral hemisphere DTI-ALPS index. Paired t-tests were used to evaluate longitudinal changes of the DTI-ALPS index in LF-rTMS and HF-rTMS groups. The DTI-ALPS index change rates were calculated, and their differences were compared between groups. Spearman’s correlation analyses were performed to assess the relationships between DTI-ALPS index changes and changes in upper limb motor function score.

At baseline, no significant differences were observed in the DTI-ALPS index between the HF-rTMS and LF-rTMS groups. After two weeks of rTMS treatment, the DTI-ALPS index of the non-stimulated hemisphere in the HF-rTMS group significantly decreased (t = 2.42, P = 0.028), and the change rate of the DTI-ALPS index was negatively correlated with the recovery of upper limb motor function (r =  − 0.42, P = 0.011). In the LF-rTMS group, longitudinal analysis showed improvement in upper limb motor function scores, but there was no significant change in the DTI-ALPS index.

Both HF-rTMS and LF-rTMS are beneficial for the rehabilitation of upper limb motor function in patients with IS, but the different changes in DTI-ALPS index may indicate differential effects of HF-rTMS and LF-rTMS on the glymphatic system. However, more research is needed to confirm the underlying mechanisms of this interaction.