About a year or so ago I also had a myleogram. It sure was intimidating! I was fortunate that my headache lasted only a few days.
A few weeks later though I was back for a nerve block, in essence, much the same procedure wrt needle placement etc. Unfortunately, this time, because of minimal disc space, scar tissue and fusion hardware (that was his excuse anyway) the needle slipped and punctured the thecal sac. There were some immediate concerns with possible loss of bowel and bladder function, stop breathing and scary stuff like that but all was well. Except...
after the treatment was finally completed they went to raise the head of my bed and I literally screamed with the pain that hit my head. I had to spend the day in the hospital to ensure there were no lasting effects before being released.
While the headache intensity improved gradually, I was plagued with a wicked "spinal tap headache" for 3 weeks! What was worse than that was that the nerve block was only mildly effective and lasted only about 2 weeks... one week less than my headache.
When doing these procedures, I am now aware that in the event of SF leakage from a thecal sac puncture they can seal the leak using what's called a blood patch. A simple procedure apparently. I'm at a loss as to why they wouldn't do it as a precautionary measure. These headaches are a lot more common than they lead you to believe. Since they're already there with everything necessary in place it would be a fairly simple thing to so.
Because of this last experience, I am sworn off any more of these minimally invasive procedures.
The headache will eventually pass... a few days, a few weeks, whatever. They can be pretty nasty though in the mean time. All you can do in recline in a 45 degree angle or less. MeRAB just don't seem to work for this at least they didn't for me.
Sorry to scare you all out there considering these types of procedures but I sure wish someone had given me a truer picture of the possibilities.
Eva