Safety of noninvasive brain stimulation in children and adolescents

Abstract

Background: Noninvasive brain stimulation (NIBS) techniques such as transcranial magnetic stimulation (TMS) and transcranial current stimulation (tCS) have the potential to mitigate a variety of symptoms associated with neurological and psychiatric conditions, including stroke, cerebral palsy, autism, depression, and Tourette syndrome. While the safety of these modalities has been established in adults, there is a paucity of research assessing the safety of NIBS among children.

Objective: To examine the existing literature regarding the safety of NIBS techniques in children and adolescents with neurologic and neuropsychiatric disorders.

Methods: An electronic search was performed on online databases for studies using NIBS in individuals less than 18 years of age. Non-English publications, diagnostic studies, electroconvulsive therapy, single/dual pulse TMS studies, and reviews were excluded. Adverse events reported in the studies were carefully examined and synthesized to understand the safety and tolerability of NIBS among children and adolescents.

Results: The data from 48 studies involving more than 513 children/adolescents (2.5-17.8 years of age) indicate that the side effects of NIBS were, in general, mild and transient [TMS: headache (11.5%), scalp discomfort (2.5%), twitching (1.2%), mood changes (1.2%), fatigue (0.9%), tinnitus (0.6%); tCS: tingling (11.5%), itching (5.8%), redness (4.7%), scalp discomfort (3.1%)] with relatively few serious adverse events.

Conclusion: Our findings indicate that both repetitive TMS and tCS are safe modalities in children and adolescents with various neurological conditions, especially when safety guidelines are followed. The incidence of adverse events appears to be similar to that observed in adults; however, further studies with longer treatment and follow-up periods are needed to better understand the benefits and tolerance of long-term use of NIBS in children.

Keywords: Guidelines; Safety; TMS; Theta burst; Tolerability; tDCS.

Copyright © 2015 Elsevier Inc. All rights reserved.

Figures

Figure 1

Radial plot depicting the reported adverse effects of repetitive transcranial magnetic stimulation (rTMS) and transcranial current stimulation (tCS) in children and adolescents from 51 studies (35 rTMS and 16 tCS). The angular data represent the reported adverse effects and the circular data represent the total number of studies reporting a particular adverse effect. 23 studies (14 rTMS and 9 tCS) reported no adverse effects. Scalp discomfort and minor headaches were the most commonly reported adverse effect of rTMS. Tingling, redness, and scalp discomfort were the most commonly reported adverse effect of tCS. Note that a study was counted for an adverse effect even if one subject was reported to have an adverse effect.

Figure 2

Bar graphs representing the incidence (i.e., frequency) of various adverse effects reported for (A) rTMS and (B) tCS in children/adolescents. The gray bars indicate the percentage of each adverse event calculated based on the total number of subjects (N = 322 for rTMS, N= 191 for tCS) and the black bars indicate a conservative estimate of the percentage of each adverse event calculated based on the total number of subjects on the studies that reported an adverse event (N = 243 for rTMS and N = 95 for tCS). The conservative estimate assumed that only those studies that reported an adverse event attempted to capture the incidence of adverse effects using appropriate follow-up or questionnaires.

Figure 3

Bar charts representing number of published papers per year on tDCS (left panel) and rTMS (right panel) until 2013. The search was conducted on the PubMed database using the search terms “transcranial direct current stimulation” and “repetitive transcranial magnetic stimulation”.

Figure 4

Reporting guidelines for noninvasive brain stimulation (NIBS) research. We suggest that authors consider including detailed information regarding various factors that could influence safety and efficacy when constructing manuscripts for publication. A checklist for reporting standards is also included in the supplementary material, which could serve as a guideline for writing NIBS manuscripts.