Try this. It assumes you have an id column in the category table. If the field is called something else, substitute it.
Code:
<tr><td class="thead">
<a href="#top" style="float:$stylevar[right]"
onclick="return toggle_collapse('categ$cat[id]')"><img
id="collapseimg_categ$cat[id]"
src="$stylevar[imgdir_button]/collapse_tcat$vbcollapse[collapseimg_categ$cat[id]].gif"
alt="" border="0" /></a>
<a href="$cat[caturl]">$cat[title]</a></td></tr>
<tbody id="collapseobj_categ$cat[id]" style="$vbcollapse[collapseobj_categ$cat[id]]">
<tr><td>$cat[description]</td></tr>
</tbody>