My child still has seizures. what are risks of hemispherectomy?

Talk to neurosurgeon: The fact that a hemispherectomy is a consideration indicates your child has intractable seizures. Hopefully the best outcome from a hemispherectomy would be stopping seizures. I would talk to the surgeon about the risks. Removing a large part of the brain would result in weakness even paralysis. Surgeon would know that most as he is the one doing the procedure.

Hard to say: Many kids eventually grow out of having seizures or at least attain control under the guidance of a pediatric neurologist. You give no specifics about your case, so risk of such a procedure in the future is unknown. If you are concerned about the direction your kids management is taking, seek out a second opinion with a pediatric neurologist.