Observations on the presence of subdural gas after pneumoencephalography.

The present study was undertaken to investigate the significance and mechanism of filling of the subdural space with gas following pneumoencephalography. Several articles concerning this subject have appeared in the literature and are well reviewed by Von Storch and Buermann (10). No systematic study of roentgenograms made twenty-four hours after encephalography has appeared, however, except for a reference by Penfield and Nor-cross (8). They found that 18 of 22 patients with post-traumatic headaches, on whom second day roentgenograms were obtained following spinal insufflation, showed gas in the subdural space, while only 2 out of 18 controls showed subdural gas. These findings suggested that the demonstration of subdural gas on twenty-four-hour roentgenograms was almost pathognomonic of post-traumatic headache. It should be pointed out, however, that the technic employed in the two groups differed. Our experience with subdural gas was at variance with this conclusion and we felt it necessary to make mor...