Re: pneumocephalus
This is peripheral to what you're discussing, but years ago, pneumoencephalograms were sometimes done: CSF was removed and oxygen introduced in order to provide contrast for x-rays. I remember that from school but never actually saw one done. They were pretty much abandoned when CT scans and MRIs were developed. I actually did a short Google search of the term to see if there was any information that addressed labman's question, but I didn't find anything.
I did take care of quite a few patients who had myelograms done, "back in the day" and know how bad the headache can be from losing just a small amount of CSF; I can't imagine how hideous a pneumoencephalogram must have been. We kept our myelogram patients flat and pushed fluids for 24 hours but occasionally one would think it was cute to "cheat" and sneak up to the bathroom; they very often lived to regret it.
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