Pneumoencephalography is an obsolete imaging technique that allowed evaluation of the contours of the brain and ventricles by the deliberate introduction of air into the subarachnoid space.
This was achieved initially by a needle passed directly into the ventricles (via the fontanelles or a burr hole). Small amounts of CSF were withdrawn and replaced with room air. The process was repeated over and over until no more CSF could be obtained 1,2.
Later, it was realized that air inserted into the lumbar theca (via puncture) could be maneuvered into the desired subarachnoid spaces by careful position and tilting of the head.
In the 1950s and 60s, as air was often to be found rather lacking as a negative contrast agent, there was a switch to using positive agents, known as contrast encephalography. Iofendylate (Pantopaque/Myodil), a contrast agent similar to Lipiodol, was a popular choice 4.
Complications
Pneumoencephalography was said to be an extremely unpleasant undertaking for patients who commonly experienced severe headaches, nausea, diaphoresis, lassitude, and hypotension 4.
Early mortality rates of pneumoencephalography, quoted in one source as 1-3% were high, considering it was a diagnostic, and not a therapeutic technique 4.
History and etymology
The procedure was developed by Walter E Dandy (1886–1946) an American pediatric neurosurgeon who practised at Johns Hopkins Hospital in Baltimore, Maryland in the United States 3.
Pneumoencephalography rapidly became obsolete as CT entered clinical practice in the mid 1970s 4.