alykitcat
Contributor
alkitycat, I'm not sure where your information comes from about cerebrospinal fluid. Although I have to confess not to have tasted it, I would be quite surprised if it has a metallic flavor, as it is clear, colorless, and contains no metalloproteins. In addition, CSF does not leak under any normal circumstances. CSF leaking into the nose or mouth is an indicator of a fracture of the cribriform plate, which is the thin area of the skull above the nose. It's not a trivial injury, and I would be extremely surprised if it would occur in any normal diving-related activity. It usually takes a major blow to the face to do it.
By far and away the easiest way to get a metallic taste in your mouth as a new diver is to get some minor barotrauma and get some blood in your mouth. Blood is very metallic-tasting, because of the iron in the hemoglobin.
It is metallic tasting, almost like chewing aluminum foil, my reference is someone who had a spinal fluid leak from an ear surgery. There have been medically documented cases of spinal fluid leaking. Usually however this can also be caused by either birth defect or past surgery etc. The patches used to take care of these holes are pressure sensative and often any activity that would change ambient pressure is usually forbidden..ie flying, diving. I have done my research. However i didn't think about blood which is MUCH more likely.