As with many subjects, when I am in need of answers I turn to Totse. Currently I am putting together a video for a DJ for a Halloween party. The theme is Stuck in an Asylum. In short I need disturbing video dealing with medical staff, crazy doctors, scary/unnerving images. Some of the footage I have so far comes from Clockwork Orange, Silence of the Lambs, Saw, ect.

If you know of other films I should look into let me know.

Jacob's Ladder is the first thing that comes to mind. Maybe some scenes from The Brood and In the Mouth of Madness.

Though the film isn't that good; Mirrors has a few scenes that might fit into your theme.