I have no internal monologue, but I certainly have intrusive thoughts. They just aren't in words.

I think every verbal person has the ability to “speak” phrases in their mind; people without an internal monologue (as is, I suppose, the case for me) just don’t need / tend to do that with every thought they have.

Of course someone without an internal monologue can have intrusive thoughts! Do you think intrusive thoughts have to come in the form of a monologue? You don't have intrusive 'scenes' in your everyday experience?