Combined gas cisternography and edge-enhanced computed tomography of the internal auditory canal

Gas cisternography was combined with edge-enhanced computed tomography (CT) in 6 patients and demonstrated the seventh and eighth cranial nerves thorugh both the cerebellopontine angle cistern and the internal auditory canal in the normal patients. The normal nerve outline was lost when a tumor was contained within the canal. This technique is a more reliable means of identifying small tumors than relying on non-filling of the canal by positive contrast media or gas.