forgetParameter not working with Resources

I'm working with Laravel 5.1.

Let's say that I have a route group defined like this:

Route::group(array('prefix' => 'item/{itemId?}', 'middleware' => ['itemStrip']), function(){

And within the Middleware itemStrip, I want to work with the item passed, then remove it from the URI before moving onto a resource within the group. The Resource would be defined like this, for example:

Route::resource('itemA.itemB',
    'ItemController',
    ['only'=>['index']]);

So, this resource has one variable that it needs to access, which is held between itemA and itemB.

I find that, even if I use

$request->route()->forgetParameter('itemId');

within the itemStrip middleware, the parameter still ends up making it to the actual resource. Which is to say, when we finally hit:

public function index($itemAId)

within the resource controller, it is grabbing the parameter itemId as opposed to the parameter between itemA and itemB. Why is this, after I stripped the Parameter from the route in the Middleware? Is there anyway to fully remove itemId, in order to keep it from hitting the resource?

A little more information, I'm finishing the Middleware with this:

return $next($request);

via Chebli Mohamed