WASHINGTON, DC — New research shows that transcranial direct-current stimulation (tDCS) is safe and well tolerated and that it enhances motor learning in healthy children.
A similar preliminary study found that this treatment is possibly efficacious in children who have experienced a perinatal stroke and hemiparesis.
Adam Kirton, MD, associate professor, pediatrics and clinical. neurosciences, University of Calgary, and director, Calgary Pediatric Stroke Program, Alberta, Canada, presented the results at the 44th Child Neurology Society (CNS) Annual Meeting 2015.
Transcranial DCS is a relatively new form of noninvasive brain stimulation that uses a weak but consistent electrical current. In these studies, the target of the current, delivered through electrodes placed strategically over the scalp, was the motor cortex.
In the first study, 19 healthy right-handed children aged 8 to 17 years were trained to learn a variety of dexterity-based motor tasks with their left hand over 3 consecutive days. They were randomly assigned to four groups — one sham and three receiving different types of tDCS:
1 mA (milli-amp of strength) contralateral anodal
1 mA ipsilateral cathodal
2 mA ipsilateral cathodal
On the primary outcome of change on the Purdue Pegboard test (PPT), which measures gross movements of arms, hands, and fingers and fine motor skills, all three tDCS groups improved the score two- to three-fold more than did sham (P = .01).
This represents a "very robust effect" on motor learning, Dr Kirton told Medscape Medical News. "We were able to show that different kinds of stimulation could enhance the learning. The children would learn these complex motor tasks with their hands faster if they were getting the tDCS stimulation."
The difference between stimulation groups was "subtle," he added. "But overall the net effect was quite comparable between the three forms."
The effects were sustained to 6 weeks, he noted.
More than half of the healthy kids in this study (52%) experienced irritation or itchiness at the site where the electrodes were placed, but none of them ranked it as more than mild and none had to stop treatment or drop out of the trial because of it, Dr Kirton reported.
Stroke Patients
The second study tested the effect of tDCS on children who had sustained a perinatal stroke. Such a stroke can cause hemiparetic cerebral palsy.
The phase 2 double-blind study included children aged 6 to 18 years, all of whom had experienced a stroke at birth with resulting weakness on one side but who had varying disabilities. They were enrolled in an after-school program that included intensive goal-directed therapy with the assistance of occupational therapists.
For 20 minutes at the beginning of every session and continuing for 2 weeks, patients received the tDCS stimulation or a sham.
"tDCS is easy to sham because you can turn on the system and people feel the same sensation on their skin, but they're not actually getting any stimulation," commented Dr Kirton.
In this case, the target of the weak electrical current was the opposite side of the where the stroke occurred.
The primary safety outcome was decrease in motor function of either upper extremity (using the Melbourne Assessment Box and Blocks Grip and Pinch Strength test) at 1 week and 2 months.
"We tested both the affected and unaffected side," explained Dr Kirton. "We wanted to see if the weak hand is getting better, but we also have to make sure the good hand doesn't change."
A pediatric brain stimulation tolerability measure — a standard test that asks subjects to rank their experience — was applied daily.
These tests showed that the procedure was safe and well tolerated, said Dr Kirton.
Efficacy outcomes included the Assisting Hand Assessment (AHA) and the Canadian Occupational Performance Measure (COPM).
In the first 12 participants completing the study (median age, 11 years), there was no decrease in paretic or unaffected upper-extremity function at 1 week or 2 months.
The mean change in AHA was positive and possibly larger in those receiving tDCS than those receiving sham (P = .09). Change in COPM at 2 months was greater than in those receiving tDCS (P = .01).
Meaningful Change
These kinds of changes meant that some kids could tie their shoelaces for the first time or finally do a two-handed chest pass when playing basketball. "They can't do it perfectly or normally, but they can actually do it where they couldn't do it before," said Dr Kirton.
He stressed, however, that this intervention isn't a cure. "It's not like they couldn't do anything before with their hand and then they could do everything with that hand," he said. "But although it was a mild improvement, they were able to do functions that matter to them."
These data represent the interim analysis, but the full study of 24 patients is now complete. "We did see a change; we did see higher COPM scores, in the treatment group, which is encouraging, but not a definitive efficacy result yet," reported Dr Kirton.
Although tDCS has been used in adult stroke patients, this is a new approach in kids. The Calgary center is one of only a few that does brain stimulation on children. It has one of the largest perinatal stroke cohorts, with some 700 families from across Alberta.
Dr Kirton and his colleagues are now planning a multicenter trial of tDCS that will probably enroll over 100 children with some form of paralysis.
Dr Kirton has disclosed no relevant financial relationships.
44th Child Neurology Society (CNS) Annual Meeting 2015. Platform Session 2-1 and 2-3.
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Cite this: Electrical Stimulation Promising for Motor Function in Kids - Medscape - Nov 02, 2015.
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