Computed tomography combined with gas cisternography for the diagnosis of expanding lesions in the cerebellopontine angle.

A new method combining selective gas cisternography and computed tomography for the examination of expanding lesions in the cerebellopontine angle cistern is described. Small amounts of gas injected by lumbar puncture can, with proper technique, easily be trapped in the cerebellopontine cistern. Acoustic neuromas protruding into the cistern are visualized as filling defects in the gas. Filling of the internal auditory canal with gas may be demonstrated in normal cases. The possibility of diagnosing intracanalicular tumors is uncertain.