Yes regexp is definitely case sensitive although i have checked with below example
Result '0' when Surname and '1' when SurName
sColname = "this,SurName,test,where"
Set oreg = new Regexp
oreg.pattern = ".*Surname.*"
Set Matches = oreg.execute(sColname)
Check for the existence of "Surname" column anywhere in the page as suggested by previous post