The air bubble sign is seen on CT of the brain and represents multiple small foci of air within the subarachnoid space, especially the Sylvian fissure.1
Although described as a sign of tension pneumocephalus it is also seen in pneumocephalus without elevated pressures.2
It should not be confused with the similarly named sign of complicated pulmonary hydatid disease: see air bubble sign (pulmonary hydatid).
- 1. Ishiwata Y, Fujitsu K, Sekino T, et al. Subdural tension pneumocephalus following surgery for chronic subdural hematoma. J Neurosurg 1988; 68:58–61
- 2. Sebastian B, Moideen J. Mount Fuji is Not as “Active” as We Think. (2018) Indian Journal of Neurosurgery. 77 (11): 880.