Until two weeks ago, I had never heard of this condition, much less needed to research what it was and try to pronounce it in discussions with hospitals all over the country. You can find plenty of information about the condition on the internet (which is mostly what I have done), along with pictures of extreme cases that will scare you silly. Rest assured, Addy's case is not that frightening to look at. (I plan to post a few pictures soon.) But for those who don't want to spend hours on the internet researching the condition, I will try to provide some basic information here. I just might be stealing some things verbatim from the Wikipedia article on it (among others), but let's just keep that to ourselves. Fortunately there is no penalty for plagiarism here.
What is craniosynostosis?
Craniosynostosis is a condition in which one or more of the sutures (gaps between skull plates which are held together with strong, fibrous tissues) closes prematurely in an infant's head. Normally the sutures remain flexible throughout childhood, allowing the brain to expand as needed. When the sutures close prematurely, it can cause the head to grow abnormally as the brain tries to find other directions in which to expand, and it can cause brain damage if not corrected.
Normal infant head
An example of craniosynostosis which looks almost exactly like Addy's case
(note the closed suture and asymmetric head shape)
Upon initial diagnosis, Addy apparently has a closure of the right coronal suture, as pictured above.
What causes craniosynostosis?
The cause of the majority of craniosynostosis cases is unknown. It is estimated that it occurs in 1 out of every 2000 births, so it is fairly common. It can be the result of an inherited syndrome (about 20% of cases), or it can occur sporadically, without any known link or cause. Addy's case seems to be the latter, as she is physically and developmentally normal in all other areas as far as we know.
Other important questions to be answered in the following post...