Gas computed tomographic cisternography: evaluation of small and intracanalicular acoustic neuromas

With improvements in microsurgical techniques, early evaluation of small and intracanalicular acoustic neuromas has taken on added importance. Since its introduction in 1979 by Sortland, several authors have demonstrated the accuracy and safety of computed tomography combined with gas cerebellopontine angle cisternography in the early diagnosis of acoustic neuromas. We present our experience with 32 patients referred for gas computed tomographic cisternography yielding five surgically proved acoustic neuromas, three of which were less than 1 cm in size. This procedure can be performed on an outpatient basis, has a low morbidity, and is highly accurate in diagnosing even purely intracanalicular tumors. Gas computed tomography cisternography offers several advantages over positive contrast cisternography, and is the procedure of choice in the radiologic diagnosis of acoustic neuromas after contrast-enhanced computed tomography has excluded the presence of a large tumor.