donsdatter,
I did lumbar puncture and understand your concern. Thought a lot before I did it. Luckily no adverse affects and didn't show any abnormalities. orthostatic headaches are tough (took many months to diagnose even for George Clooney and after surgery he is all fine ofcourse

)
If there is a leak I think the only way is surgery and you will be completely relieved of symptoms. If there is no leak......well......there is no leak
I posted in the following link about my experience.
http://neurotalk.psychcentral.com/thread177848.html
Cheers!