It would be wise for you to collect your son's medical records and any information available about his guardians and seek the opinion of a personal injury attorney in your area. These are not simple cases and can be very time consuming and expensive to work up. An important question is whether the guardians have adequate insurance and/or assets to make the pursuit of damages on your son's behalf worthwhile. An attorney can help you answer these questions and I would encourage you to seek counsel.
It is hard to tell from limited facts, but seems to me to warrant a consultation with a personal injury or medical malpractice lawyer. There are many firms, mine included, that offer a free consultation and I would encourage you to take advantage of that option. Best wishes and good luck.
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