It hard to find any info on adults who have DW and was not DX as a child here is a few links I have found. If anyone has any more please let me know.
http://www.answers.com/topic/dandy-walker-syndrome?cat=health
http://www.hydroassoc.org/default.htm
http://www.spinejournal.com/pt/re/spine/abstract.01.htm;jsessionid=Hp2QhlNyRyR0STQJ1WYvPRQGpP9WLnQT2q0mnjk352QhBDQhFWYN!!181195629!8091!-1
http://www.emedicine.com/radio/topic206.htm
http://www.ccm.ucsd.edu/DW.htm