Article
Reducing the risk of surgically inflicted motor deficits by accelerated low-frequency repetitive navigated transcranial magnetic stimulation (rnTMS) – a feasibility study
Reduktion des Risikos für chirurgisch induzierte motorische Defizite durch intensive niedrig-frequente repetitive navigierte transkranielle Magnetstimulation (rnTMS) – eine Machbarkeitsstudie
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Published: | June 4, 2021 |
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Objective: Low frequency repetitive transcranial magnetic stimulation (rTMS) can induce changes in the functional organization of underlying brain areas, thus being a promising tool to reduce the risk of surgically inflicted motor deficits preoperatively. However, current rTMS protocols are often time-consuming and hence difficult to implement in clinical settings where patients are only seen for limited times. The aim of the present study was to show the feasibility and safety of an accelerated low-frequency rTMS protocol applying multiple sessions daily, thus offering a new treatment approach for patients.
Methods: Nine healthy subjects (age: mean 25.4 years, range = 22-31 years; 1 female) were recruited for this feasibility study. All subjects received 14 sessions of rTMS (1 Hz, 30 minutes, 110% RMT) to the hand motor hotspot. Subjects were divided to receive stimulation for either 14 days once daily (classical low-frequency rTMS; c-rTMS), 7 days twice-daily (accelerated rTMS; a-rTMS) or sham stimulation for 14 days once-daily (s-rTMS). Daily stimulation sessions in the a-rTMS group were delivered with a 90-minute break in between. Directly after the stimulation, a motor training of 10 minutes targeted to the stimulated hand muscles was performed to support reorganization of motor function via recruitment of other brain areas.
Results: In total, 74% of rTMS sessions in the c-rTMS group, 89% in the a-rTMS group and 98% in the s-rTMS group were free of any side effects. Subjects reported occurrence of brief headaches in 14% of sessions in the c-rTMS group, 2% in the a-rTMS group and 0% in the s-rTMS group. Headaches were always reported to be at maximum mild and of short duration. Dizziness during stimulation was reported in 5% of sessions in the c-rTMS group, 2% in the a-rTMS group and 0% in the s-rTMS. Subjects reported a feeling of fatigue in the stimulated hand muscles in 2% of all sessions in the c-rTMS group, 7% in the a-rTMS group and 0% in the s-rTMS group. This feeling was noticeable specifically during the consecutive motor training and vanished quickly afterwards.
Conclusion: Accelerated low-frequency rTMS of the motor cortex is a safe and feasible method, previously shown to induce a functional reorganisation of the motor system. This offers a promising new treatment approach also for preoperative patients by shortening treatment duration and thus, potentially making rTMS protocols more accessible to a wider range of patients.