I use one occasionally to ease pain, fasciculations and spasticity associated with neuro issues. It does help, maybe just placebo effect, but I will take that gladly.
. It can also cause overheating and worsening of symptoms, so it should be used for a short period of time.
The biggest risk I see in using it with children would be limiting chest wall movement risking respiratory compromise. I would have the parents talk to his pediatrician first.