In PD, Non-Invasive Trans-Spinal Magnetic Stimulation Enhances the Effect of Transcranial Magnetic Stimulation on Axial Motor Symptoms: A Double-Blind Randomized Clinical Trial

Background: Axial symptoms in Parkinson's disease (PD) often respond poorly to pharmacological treatment. We evaluated whether combining repetitive transcranial magnetic stimulation (rTMS) and repetitive spinal magnetic stimulation (rSMS) is more effective than rTMS alone in improving axial and other motor disabilities in PD.

Methods: A total of 42 PD patients with axial symptoms were randomly allocated to 2 experimental intervention groups: Group I received active rTMS + active rSMS (2000 pulses; 20 Hz; 80% resting motor threshold for each motor area "M1" + 1500 pulses rSMS 10 Hz, at 50% of maximal stimulator output). Group II received active rTMS + sham rSMS with the same number of pulses. Both groups received 10 sessions (5 consecutive days/week for 2 weeks). Assessments using Freezing of Gait Questionnaire, walking speed, Movement Disorder Society-Sponsored Revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) parts II and III, and Parkinson's Disease Questionaire-39 (PDQ-39) were performed at baseline (T0), end of sessions (T1), and 1 month later (T2).

Results: At T0, Group II showed higher walking speed. At T1 and T2, Group I demonstrated significantly greater improvements in MDS-UPDRS parts II, III, and sub-items of part III. Group I showed stronger improvement in TUG-T and average fast velocity immediately post-intervention, but this effect diminished after 1 month. PDQ-39 scores for leisure activity and walking problems were significantly higher in group I.

Conclusions: These findings indicate that combining rTMS and rSMS for 10 sessions is more effective than rTMS alone in managing PD's motor and axial symptoms. The effect size of the outcome is large enough to be of significance in clinical practice.

Trial registration: The study was registered prospectively on 26/12/2021 at the clinicaltrial.gov website with the registration ID: NCT05271513, https://clinicaltrials.gov/study/NCT05271513.