Air cisternography of the cerebellopontine angle using high-resolution computed tomography.

While high-resolution CT/air cisternography is considered the preferred method of investigating non-enhancing or small acoustic neuromas, it is not without pitfalls. Eighty such studies were reviewed, emphasizing procedural problems and sources of interpretive error. Two patients presented difficulty in transporting the air bolus due to a spinal cord tumor coexisting with bilateral acoustic neuromas; spinal cord decompression was required in one case. Three potential false positives were avoided by persistent efforts to fill the internal auditory canal. Of 4 patients thought to have a tiny acoustic neuroma, elective vestibular nerve section in 2 revealed no evidence of tumor. One unilateral Mondini malformation was diagnosed. Four patients required a blood patch for persistent headaches.