Table 2.

Main characteristics of studies which encountered adverse effects

Author (year)	Population	Safety criteria	Intervention	Sessions	Intensity	Duration	Current density (mA/cm2)	Adverse effects
Mortensen (2015)	Intracerebral hemorrhage mean age:62.60 years ± 10.28 (SD)	Traumatic ICH, epilepsy, metal implants in the head, other neurological diseases/cognitive disabilities	(i)A-tDCS+occupational therapy; (ii)sham tDCS+occupational therapy	5	1.5mA	20 min	0.04	Itching, tingling, burning sensation, headache and sleepiness
Gillick (2015)	Children with congenital hemiparesis+mean age:14 years ± 3.5 (SD)	Epilepsy, pregnancy, indwelling metal or medical devices incompatible with NIBS, evidence of skin disease or skin abnormalities and botulinum toxin or phenol intramuscular block within 6 months preceding tDCS	Bi-tDCS alone	1	0.7mA	10 min	0.02	Itchining, burning, sleepiness and difficulty of concentration
Kim (2014)	Subacute poststroke +mean age:55.4 years ± 17.6 (SD)	Contraindications for TMS or tDCS, previous seizure history, concurrent use of Na+ channel blocking agent or N-methyl-D-aspartate receptor antagonist	(i)active wrist exercise alone; (ii)VR wrist exercise alone; (iii)active wrist exercise + atDCS; (iv)VR wrist exercise + atDCS	4	1mA	20 min	0.028	Mild headache and itching
Wang (2014)	Subacute poststroke +mean age:52.9 years ± 11.9 (SD)	Contraindications for TMS, history of alcohol/drug abuse, use of certain neuropsychotropic drugs, epilepsy, having already received methylphenidate and/or tDCS treatment, being pregnant, coexisten of advanced or terminal disease and use of certain neuropsychotropic drugs	(i)Drug alone; (ii)tDCS alone; (iii)drug + tDCS	1	1mA	20 min	0.028	Mild tingling and mild fatigue
Rosso (2014)	Chronic poststroke +mean age:57 years ± 18 (SD)	No contraindication for tDCS	(i)atDCS alone; (ii)ctDCS alone	2	1mA	15 min	0.028	Itching
Wu (2013)	Chronic poststroke +mean age:45.9 years ± 11.2 (SD)	Unstable, progressive, or severe neurologic disease and heart conditions	(i)ctDCS+physical therapy; (ii)sham tDCS+physical therapy	20	Not Specified	20 min	Not Specified	Slight, itching and tingling
Cherney (2013)	Chronic poststroke+age not specified	Not specified	ctDCS+speech therapy	30	1mA	13 min	0.015	Itching, burning sensation increasing over days
Kim (2010)	Subacute poststroke +mean age:55.3 years ± 16.4 (SD)	Presence of a metallic foreign body implant, history of seizure or another unstable medical condition, depression history of severe alcohol or drug abuse; Patients who were taking Na+ or Ca2+ channel blockers or N-methyl-D-aspartate (NMDA) receptor antagonists were also excluded	(i)atDCS+occupational therapy; (ii)ctDCS+occuptional therapy; (iii) sham tDCS+occupational therapy	10	2mA	20 min	0.08	Headache and dizziness
Jo (2009)	Subacute poststroke +mean age: 44 years ± 16.43 (SD)	Seizure disorder, intracranial metal insertion, cardiac pacemaker or history of other neuropsychiatric diseases	(i)atDCS+working memory task; (ii) sham tDCS+working memory task	2	2mA	30 min	0.08	Aching or burning and transient skin redness
Hesse (2007)	Subacute/ Chronic poststroke +mean age:63.3 years	Preceding epileptic fits, an EEG suspect of elevated cortical excitability, a sensitive scalp skin, severe cognitive impairment, metallic implants within the brain, previous brain neurosurgery, medications altering the level of cortical excitability or with a presumed positive/negative effect on brain plasticity	atDCS+robot assisted arm training	30	1.5mA	7 min	0.042	Slight itching and bearable headache

Abbreviations: ICH, Intracranial Hemorrhage; a-tDCS, anodal transcranial Direct Current Stimulation; c-tDCS, cathodal transcranial Direct Current Stimulation; bi-tDCS, bihemispheric transcranial Direct Current Stimulation; mA, miliampère, min, minutes; NIBS, Non Invasive Brain Stimulation; TMS, Transcranial Magnetic Stimulation; VR, Virtual Reality; EEG, electroencephalogram.