Below is a recursive version of this function.

<?php
    /**
     * A recursive array_change_key_case function.
     * @param array $input
     * @param integer $case
     */
    function array_change_key_case_recursive($input, $case = null){
        if(!is_array($input)){
            trigger_error("Invalid input array '{$array}'",E_USER_NOTICE); exit;
        }
        // CASE_UPPER|CASE_LOWER
        if(null === $case){
            $case = CASE_LOWER;
        }
        if(!in_array($case, array(CASE_UPPER, CASE_LOWER))){
            trigger_error("Case parameter '{$case}' is invalid.", E_USER_NOTICE); exit;
        }
        $input = array_change_key_case($input, $case);
        foreach($input as $key=>$array){
            if(is_array($array)){
                $input[$key] = array_change_key_case_recursive($array, $case);
            }
        }
        return $input;
    }
?>