Thanks for using the forum. I am happy to address your questions, and my answer will be based on the information you provided here. Please make sure you recognize that this forum is for educational purposes only, and it does not substitute for a formal office visit with a doctor.
Without the ability to examine and obtain a history, I can not tell you what the prognosis for your child is. However I will try to provide you with some useful information. This must be a very difficult time for you.
When cardiac arrest occurs, blood flow to the brain (and other organs) is significantly reduced, and sometimes the brain doesn't receive oxygen or nutrients for several minutes. The longer the cardiac arrest, obviously the more injury occurs. This is compounded by other medical complications. After a cardiac arrest, certain features on examination help predict outcome. However, in children, these physical examination features are less accurate than adults, and children are particularly resistant. Early on, sometimes little can be predicted, but after a few days, more becomes apparent regarding what the prognosis will be. Eye opening and some spontaneous movements do not necessarily imply significant recover, so caution should be taking in interpreting such things. Purposeful movement, interaction (following commands, communicating specifically) and tracking with the eyes (rather than just roving eye movements) are all good signs. There are certain ancillary tests that can be helpful but not definitive, such as an MRI (though even with a normal MRI, significant damage could have occurred), EEG (though as you mention, EEG can be influenced by drugs), and some other tests. A CT scan showing global injury implies just that: that the brain received a significant insult.
Again, I can not make any predictions about your son, but I encourage you to discuss in detail with your son's physicians to better understand what to expect.
Thank you for this opportunity to answer your questions, I hope you find the information I have provided useful, good luck.
Thank you for your comments, the purposeful movements he is doing, watching and following and moving his head from side to side on command. so i guess its all good signs.
his muscle spasims have increased slightly but we are increasing baclophyn at presnt