Geochick, yes, have someone at home with you for the lumbar puncture. Only a very few people have problems but if you do you want someone to be there for a bit just so you don't have to keep standing up and definitely to drive you home. I was one of the lucky tiny minority and got a spinal headache for almost a week, but I have a migraine/headache history which probably gave me more sensitivity to the drop in pressure. I then drank 6 liters of water a day trying to push liquids which meant I had to stand up extra times -- the doc's office didn't quite get the fact that cyclists push liquids a bit more than normal folk.
The neuro finally figured out that I was extra miserable because I wasn't getting my normal endorphin fix. As long as I stayed lying down there was no head pain. The puncture itself wasn't that big a deal and wasn't that uncomfortable. Probably lots of people on this forum can relate their own lumbar puncture experiences.
Keep in touch.
SK
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.