As this is a colon cancer forum, most of us have very limited knowledge of other cancers. You will likely have better luck if you can find a forum with people who have your type of cancer.
My mother had leptomeningeal disease from leukemia. She had a port inserted into her brain to deliver chemo directly into her brain. It was called an ommaya port. I do not if they are using this to treat leptomeningeal disease from other cancers but it may be something to look into.
Good luck. Hope you find others who can better help you.