Radiological techniques for small acoustic tumors--a re-evaluation.

Small acoustic neuromas are not detected on conventional, computed tomography (CT) brain scans. Eighteen patients with proven acoustic tumors and negative CT brain scans were studied retrospectively to re-evaluate current radiological techniques. We found that the conventional mastoid plain film or thin section tomography is an accurate, cost effective, screening test for acoustic tumors. When these screening studies are positive and agree with the clinical and audiometric examinations, a CT brain scan should then be performed. If the latter is negative, Pantopaque myelography or air-CT should follow. The decision to proceed to invasive studies has been helped by such tests as brain stem audiometry. Since no single, noninvasive X-ray test currently exists to diagnose the small acoustic tumor, screening X-ray studies are indicated before the use of invasive, expensive studies. A protocol for the radiological work-up of small acoustic tumors is suggested.