Pneumoencephalography (sometimes abbreviated PEG) was a medical procedure in which most of the cerebrospinal fluid is drained from around the brain and replaced with air, oxygen, or helium to allow the structure of the brain to show up more clearly on an X-ray image. It was derived from ventriculography, an earlier and more primitive method where the air is injected through holes drilled in the skull.
Pneumoencephalography was performed extensively throughout the early 20th century, but it was extremely painful. The test was generally not well tolerated by patients. Headaches and severe vomiting were common side effects. Replacement of the drained spinal fluid is by slow natural production, and therefore required recovery for as long as 2–3 months before normal fluid volumes were restored. Video of the procedure is documented in a BBC documentary of an early EMI installation. .
Modern imaging techniques such as MRI and Computed tomography have rendered pneumoencephalography obsolete. Today, pneumoencephalography is limited to the research field and is used under rare circumstances. A related procedure is pneumomyelography, where gas is used similarly to investigate the spinal canal.
Pneumoencephalography appears in popular culture in the movie The Exorcist (1973), when Linda Blair's Regan MacNeil character undergoes the procedure. It is also referred to in Episode 7, Season 7 of House M.D. as an example of a dangerous procedure.
See also 
- "Walter Dandy". Walter Dandy. Society of Neurological Surgeons. Retrieved 2011-04-28.
- Greenberg, Mark (2010). Handbook of Neurosurgery. Thieme.