Hierarchical Custom Posts – Highlighting Current Post in Sub-Menu

I have created a hierarchical custom post type called events and have used wp_list_pages to list the sub-posts for each event post (See below). This navigation works great, but I cannot figure out how to highlight the menu items based on the post being viewed. I normally use .current_menu_item, but this class is not generated for CPT.

Is there any way I can add this class to the link for the current post? Thank you for your help!

//If the post has a parent, get the parent id
if($post->post_parent) {
    $args = array(
      'title_li'  => '',
      'child_of'  => $post->post_parent,
      'post_type' => 'events',
      'echo'      => 0
    );
    //Create a variable for the parent post id
     $top_page = $post->post_parent;
}
//If the post is a parent, get the post id
else {
    $args = array(
      'title_li'  => '',
      'child_of'  => $post->ID,
      'post_type' => 'events',
      'echo'      => 0
    );
    //Create a variable for the post id
    $top_page = $post->ID;  
}
//List child pages
$post_children = wp_list_pages( $args );
//Get the title of the the parent page
$top_title = get_the_title($top_page); 
//Get the of permalink the parent page
$top_link = get_permalink($top_page);

    //If there are children, list them in a side nav
    if ( $post_children ) {
    ?>
    <!--Sub-page side nav-->
    <div id="inline-side-nav">
        <a href="<?php echo $top_link; ?>"><h3><?php echo $top_title; ?></h3></a>
        <ul>
            <?php echo $post_children ?>
        </ul>
    </div>