We report four patients in whom gas was seen in the head on CT shortly
after cardiopulmonary resuscitation. The gas was in the posterior cra
nial fossa, presumably within veins, or in the cavernous sinus. The ca
use of the cardiac arrest was myocardial infarction in three patients
and hanging in one. All had peripheral or central venous lines. The me
chanism by which gas appeared in the intracranial veins is discussed.