Dara, I've read all the responses. I'm on board with the parent who thinks the behavior could be/is likely Pervasive Developmental Disorder (PDD) related, although it's hard to get a doctor to commit to that diagnosis. at a young age. I would stick with the Dev. Pediatrician and maybe try another neuropsychologist. Neuropsychs who are good are fantastic diagnosticians. Sounds like you had a lemon. My son is Pervasive Developmental Disorder (PDD)-not otherwise specified. As a toddler, he had a speech delay, social delays, and was so frustrated he had the tantrums from hello. They were not psychiatric reasons. He didn't understand our world, was greatly frustrated, and lashed out when frustrated or when his ordered world was disturbed even in a mild way. He has always had interventions consistent with Autism Spectrum Disorders (ASD), because we forced them to give him those interventions, even without a diagnosis, so he is now going to turn fourteen and a sweeter, more easygoing child doesn't exist. This is my tantrummer!!! He had so much speech intervention. When he hit about 4 1/2 he broke into speech, seemingly overnight (he always grew in spurts) and his tantrums fizzled out as soon as he could communicate. He still had some weird delays and seemed hyper-out-of-control. He had two wrong diagnoses: ADHD/ODD first (stimulants were not fun here) and then bipolar disorder, which was weird since he no longer raged. However, he is "quirky" and would talk to himself in an empty room (he still talks to his television and videogames), so the psychiatrist mistakenly thought he was hallucinating. He's not, and never talks to himself when he thinks anyone can hear him. He is very grounded in reality. It was a horrible diagnosis--he never even had moodswings (not since he learned to talk). In all, he was placed on a total of over ten medications that he didn't need and that didn't really work. He is doing great three years after his Pervasive Developmental Disorder (PDD)-not otherwise specified diagnosis and is medication free (although some Autism Spectrum Disorders (ASD) kids do need medications). My advice is to look around and keep an open mind about what could be wrong. Each diagnosis sort of mimics the others, but the treatments for each one are very different. For ADHD, it's stimulants. For bipolar, mood stabilizers and antipsychotics. For Autism Spectrum Disorders (ASD), the best you can do for your child is intensive interventions: Occupational Therapist (OT), PT, social skills, sometimes an aide or Learning Disability (LD) class helps with focus. Also, as parents we need to learn what triggers our children and work around that. in my opinion a PET test won't help...to date, there is no test that the medical community believes can find a disorder with brain pictures. I just had a CAT scan of the brain and it was normal, in spite of having bipolar and neurological issues. I would save the money for the Dev. Pediatrician and the neuropsychologist and work with the school district to get him in interventions. In spite of your liking for the private school, in my opinion public schools know more about childhood disorders and are far more helpful. My son started out in private school, and he didn't learn much until public school placement, where he not only leaped to his potential; he made friends and really, for lack of a better word, "Normalized." He can "pass" as a child who maybe just has ADHD, but he is still on The Spectrum. I hope you are thoughtful and careful in your journey and get many opinions. WHen something starts working for Sammy, then you've hit paydirt. in my opinion I'd back off behavioral therapy right now. Until you know why he is unable to control himself, the behavioral therapist will probably cost a lot and do very little to help you. Although he could be having seizures, in my opinion, I don't feel that's the whole story. Certainly, if he is having some, maybe treating them will help his behavior--it's worth a shot. Everything diagnostic is worth looking into. I hope you get something out of this LONG post. Big hugs to you and little Sam.