So much anger

Hello. My son is almost 20 years old. He was diagnosed with epilepsy when he was 9. He had a left temporal lobectomy/amygdilalohippocampectomy when he was 12. He takes Tegretol XR 400mg twice a day. His seizures are under control since surgery and while taking the medication. His EEG is still abnormal hence still being on Tegretol. The issue is his constant underlying anger. The smallest, most trivial things set him off. He has punched holes in our walls, one time breaking his hand because there happened to be a stud behind the drywall. Right after he blows up he feels regret but his dad and I are really getting fed up. When we give him an ultimatum, stop tearing up our house, clean up after yourself, be respectful or you'll need to leave, it just makes things worse. We have done everything under the sun to help him. Psychologist (specializing in pediatric Epilepsy) counseling, tried an antidepressant, researched adult psychologists which he wants no part of now that he's an adult. He is our life but we just are getting toward the end of our rope. Is this an issue that is relatively common with epilepsy? I don't want to make his diagnosis an excuse but we need help understanding and, perhaps, some ideas on how to help him. We love him so much.