Suggest Remedy For Problem In Using Right Hand

I am researching a condition of a student of mine. He is about 8 years old, was bitten by a deadly rattlesnake when he was about 4. He needed extremely high doses of medication and is lucky to be alive, let alone have his hand. He refuses to use his right hand, the one bitten and is struggling academically. Could his struggles now have been caused by either the poison of the bite or the high doses of medications?