add parent cat to drop down cat list?

Hi guys, I am using this code to generate a list of 2nd-level categories so it output a <option>/<select> list of category links, but I want to include the parent category’s name at the top of the <option> list without making it selectable – just as a header/default value. How would I grab the parent category’s name and put it in at the top of the dropdown list? (Cat ID 33).

<form id="cities" method="post">
	<?php
	function replace_id_for_slug($option){
		$categories = get_categories("hierarchical=1&echo=0&child_of=33");
		preg_match('/value="(\d*)"/', $option[0], $matches);
		$id = $matches[1];
		$slug = "";
		foreach($categories as $category){
			if($category->cat_ID == $id){
				$slug = $category->slug;
			}
		}
		return preg_replace("/value=\"(\d*)\"/", "value=\"$slug\"", $option[0]);
	}
	$select = wp_dropdown_categories("hierarchical=1&echo=0&child_of=33&depth=1");
	$select = preg_replace_callback("#<option[^>]*>[^<]*</option>#", "replace_id_for_slug", $select);
	echo $select;
	?>

	<script type="text/javascript"><!--
	    var dropdown = document.getElementById("cat");
	    function onCatChange() {
			if ( dropdown.options[dropdown.selectedIndex].value != -1 ) {
				location.href = "<?php echo get_option('home');?>/uk/"+dropdown.options[dropdown.selectedIndex].value;
			}
	    }
	    dropdown.onchange = onCatChange;
	--></script>
</form>