I don't think it's been explored by the researchers yet.
I remember this statement by hwebb:
Apparently (according to wikipedia at least) research has indicated an enlarged blood vessel can compress or throb against the trigeminal nerve/s causing pain in the ear, eye, lips, nose, scalp, forehead, teeth or jaw on the side of the face.
If it's caused by an enlarged blood vessel pressing on the trigeminal nerve, then having CCSVI treated might decrease the size of the enlarged blood vessel, if it is a collateral vein, because the flow would instead travel through the jugulars. So there could be some logic to it.