Adolf Bingel, the second inventor of lumbar pneumencephalography.

More than 20 years had to pass until the x-rays discovered in 1895 by Röntgen in Würzburg made visible the interior of the skull by outlining the inner and outer surfaces of the brain. A pioneer in this field was the American Walter Dandy, who in 1918 was the first to inject air into the lateral ventricles through a burr hole. Although in 1919 he reported eight pneumencephalographies after lumbar air insufflation, he stayed with direct ventriculography because he was afraid of possible complications (1, 2). Stimulated by Dandy’s paper of 1919, the Norwegian Sofus Wideröe stepped into the field of encephalography shortly thereafter. In 1921 Wideröe published 11 cases of patients with spinal diseases in whom he used the spinal pain caused by lumbar air injection as a means of segmental identification of spinal tumors. He succeeded in demonstrating several intracranial air bubbles but failed to show the ventricular system or the spinal subarachnoid spaces (3). At the same time as Wideröe, the German internist Adolf Bingel (Fig 1) in Braunschweig transferred his experiences from air insufflation into joints and the peritoneum to the central nervous system. It was an accidental observation that led Bingel to encephalography when he saw an air bubble in the lateral ventricles of a patient who had undergone lumbar puncture on the preceding day (4). Contrary to Dandy and Wideröe, Adolf Bingel learned from this observation. He proceeded to ventricular imaging, improved the technique of lumbar puncture, and did a scientific evaluation of the results. Bingel started with cadaver experiments in which he could see air penetrating into the cra-