1/2 Over 2 decades have already passed since non-invasive brain stimulation (NIBS) was
first applied to patients with various neurological disorders [1]. Building on advances in engineering and our understanding of clinical neurophysiology, we now have effective tools that can non-invasively strengthen or weaken the activities of specific areas or networks of the human brain. These tools include repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), and more recently, transcranial focused ultrasound (tFUS). These tools are often collectively referred to as NIBS.
Many reports have described positive effects of rTMS on various conditions, including pain;
psychiatric disorders such as substance abuse, schizophrenia, and depression; motor deficit and language disorders after stroke; and tinnitus [2]. Although it is uncommon for NIBS to be the mainstay treatment for various diseases, it has been thought that NIBS can play an adjuvant treatment role. However, this idea was challenged after a large-scale clinical trial of rTMS on upper limb motor deficits after stroke showed negative results [3]. Active discussion continues on how to apply NIBS more effectively in various conditions [2]. In order to enhance the effectiveness of NIBS, it may be necessary to consider increasing stimulation intensity, stimulation duration, or the number of treatment sessions. In this regard, having a safety guideline for the use of NIBS on the human brain becomes even more important.
In this issue, 3 excellent review articles are published on the safety of NIBS techniques.
Kim and Paik [4] reviewed the safety of rTMS in neurological disorders such as stroke or traumatic brain injury. They suggest that rTMS can be used relatively safely in clinical settings and for research if the current guideline for rTMS parameters is followed. However, the use of a checklist beforehand is highly recommended to ensure the absence of contraindications.
Brain Neurorehabil. 2021 Mar;14(1):e10 https://doi.org/10.12786/bn.2021.14.e10 pISSN 1976-8753·eISSN 2383-9910
Editorial
Received: Mar 9, 2021 Revised: Mar 15, 2021 Accepted: Mar 20, 2021 Correspondence to Byung-Mo Oh
Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul; National Traffic Injury Rehabilitation Hospital, 260, Jungang-ro, Yangpyeong, Korea.
E-mail: [email protected]
Copyright © 2021. Korean Society for Neurorehabilitation
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (https://
creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
ORCID iDs Byung-Mo Oh
https://orcid.org/0000-0001-9353-7541 Conflict of Interest
The author is the principal investigator of 2 ongoing clinical trials on the effect of transcranial focused ultrasound and transcranial direct current stimulation, which are supported by Neurosona co. LTD, and National Rehabilitation Center in Korea (NRCRSP-EX21001), respectively.
Byung-Mo Oh ,1,2 Editor-in-Chief, Brain & Neurorehabilitation
1 Department of Rehabilitation Medicine, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, Korea
2National Traffic Injury Rehabilitation Hospital, Yangpyeong, Korea
Non-Invasive Brain Stimulation:
Back to the Basics of Safety for More Effective Use
Brain & NeuroRehabilitation
02
https://e-bnr.org
► See the article “Safety Review and Perspectives of Transcranial Focused Ultrasound Brain Stimulation” in volume 14, number 1, e4.
► See the article “Safety Review for Clinical Application of Repetitive Transcranial Magnetic Stimulation” in volume 14, number 1, e6.
► See the article “Safety of Transcranial Direct Current Stimulation in Neurorehabilitation” in volume 14, number 1, e9.
Ko [5] reviewed the safety of tDCS in clinical practice and research. In this review, he proposes that tDCS, which is currently used in clinical practice, is safe because it uses a weak intensity of less than 5% of the current threshold that can cause irreversible brain changes.
Future research seems to be required on how to increase stimulation intensity to achieve sufficient clinical effects without increasing significant adverse effects.
As a newly emerging NIBS technique, tFUS is attracting considerable attention in the field of neurorehabilitation. In particular, it is considered highly advantageous that tFUS can stimulate much deeper brain structures (such as the thalamus) than rTMS or tDCS can, while maintaining excellent spatial resolution [6]. However, since the action potential of a nerve is essentially an electrical phenomenon, more studies on the neurobiological mechanism of tFUS would appear to be necessary than is the case for rTMS or tDCS. Lee et al. [7] present a broader perspective and an extensive review on the state-of-the-art evidence for the safety of tFUS. I expect that their excellent review will serve as a landmark article on the safety of this emerging neuromodulation technique.
The applications of NIBS in the field of neurorehabilitation continue to expand. For further development, it is essential to show solid evidence of the effects of NIBS on specific diseases, which may require higher stimulation intensity. Therefore, re-examining the basics of safety would be the first step towards using NIBS more effectively. I hope the articles published in this issue will spark future clinical and preclinical studies.
REFERENCES
1. George MS, Nahas Z, Molloy M, Speer AM, Oliver NC, Li XB, Arana GW, Risch SC, Ballenger JC. A controlled trial of daily left prefrontal cortex TMS for treating depression. Biol Psychiatry 2000;48:962-970.
PUBMED | CROSSREF
2. Lefaucheur JP, Aleman A, Baeken C, Benninger DH, Brunelin J, Di Lazzaro V, Filipović SR, Grefkes C, Hasan A, Hummel FC, Jääskeläinen SK, Langguth B, Leocani L, Londero A, Nardone R, Nguyen JP, Nyffeler T, Oliveira-Maia AJ, Oliviero A, Padberg F, Palm U, Paulus W, Poulet E, Quartarone A, Rachid F, Rektorová I, Rossi S, Sahlsten H, Schecklmann M, Szekely D, Ziemann U. Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): an update (2014-2018). Clin Neurophysiol 2020;131:474-528.
PUBMED | CROSSREF
3. Harvey RL, Edwards D, Dunning K, Fregni F, Stein J, Laine J, Rogers LM, Vox F, Durand-Sanchez A, Bockbrader M, Goldstein LB, Francisco GE, Kinney CL, Liu CYNICHE Trial Investigators. Randomized sham-controlled trial of navigated repetitive transcranial magnetic stimulation for motor recovery in stroke. Stroke 2018;49:2138-2146.
PUBMED | CROSSREF
4. Kim WS, Paik NJ. Safety review for clinical application of repetitive transcranial magnetic stimulation.
Brain Neurorehabil 2021;14:e6.
CROSSREF
5. Ko MH. Safety of transcranial direct current stimulation in neurorehabilitation. Brain Neurorehabil 2021;14:e9.
CROSSREF
6. Yoo SS. Technical review and perspectives of transcranial focused ultrasound brain stimulation for neurorehabilitation. Brain Neurorehabil 2018;11:e16.
CROSSREF
7. Lee W, Weisholtz DS, Strangman GE, Yoo SS. Safety review and perspectives of transcranial focused ultrasound brain stimulation. Brain Neurorehabil 2021;14:e4.
CROSSREF
2/2 https://doi.org/10.12786/bn.2021.14.e10
Safety of Brain Stimulation Brain & NeuroRehabilitation
02
https://e-bnr.org
