Welcome grandparent, to the CWE forum,
I do feel very sorry and sad for you and your family about the diagnosis Early Infantile Epileptic Encephalopathy. I can imagine your worries about having to loose this grandchild at an early age because this diagnosis doesn't have a good prognosis. This condition is a very rare epilepsy syndrome also known as the 'Othahara syndrome'.
Sometimes Othahara syndrome is an early onset of symptomatic Infantile Spams, (IS) the burst suppresion pattern on the EEG can change into a for IS typical hypsarythmia EEG pattern. This may develop in the Lennox Gastaut syndrome (the epilepsy syndrome my 9-year old son has.)
The course of Ohtahara syndrome is severely progressive. Seizures become more frequent, accompanied by physical and mental retardation. Some children will die in infancy; others will survive but be profoundly handicapped. As they grow, some children will progress into other epileptic disorders such as West syndrome and Lennox-Gestaut syndrome.
http://www.ninds.nih.gov/disorders/ohtahara/ohtahara.htm
I welcome you here because I think I might be the only one or perhaps one of a few members here who knows parents & their children with the same diagnosis as your grandchild. I don't think we've other members on CWE who have (grand)children with this epilepsy syndrome.
I'm hosting a Dutch support group and forum for parents to children with several maligne epilepsy syndromes. Among our many members Early Infantile Epileptic Encephalopathy is very rare. These Dutch moms also do write on this support forum, I think you'll get a warm welcome there and lots of information:
http://www.ohtaharasyndrome.org/
On our Dutch parent support forum we've had only six members/parents to children with the Othahara syndrome; I really do regret to say that, in 6 years, we've lost 4 of them; 3 of these kids died at an early age (3 months - 2 years.) But one of them has ignored all bad prognosises and has lived to be 16; he died last december. At this moment in our group we've a 3-year old boy and a 3-year old girl with Othahara syndrome. For now, they both do well, I'm happy to say so, no severe health problems. But their development is very slow, they're both 100% dependent, can't walk, sit, crawl, talk. Children with Othahara's have severe complex handicaps and several health problems and they're very 'floppy' in their muscles. Many are G-tube fed. The kids with OS I know all are beautiful children with big eyes and long eye lashes.
The only reference on CWE is in this recent thread
http://www.coping-with-epilepsy.com/forums/f31/ohtahara-syndrome-god-bless-ivan-cameron-5954/ Not a joyfull one, I'm afraid.

You can find a few links in this thread to more information on Othahara's.
My heart goes out to you and your son & daughter (in law); this diagnosis will have an enormous influence on your lives. I do hope you'll find your way in dealing with this sad reality and hope you do get the chance to enjoy the very special gift this special needs child can bring to your lives.