Trying to figure out the child::item[position()=1] syn

I use XSL sporadically and, as such, haven't quite figured out all the
syntax yet.

Here's a snippet of my XML:

<menuItems>
  <menuItem>
     <pageID>1</pageID>
  </menuItem>
  <menuItem>
     <pageID>2</pageID>
  </menuItem>
</menuItems>

In my XSL, I want to determine if the 'pageID' value of the first
menuItem (and ONLY the first menuItem) matches a particular value that I
am passing into the XSL file.