Positive angle myelograms without acoustic neuroma

The early diagnosis of acoustic neuroma has become largely dependent on positive angle myelograms combined with audiometric and neurological tests; however, one can discover instances of false positive myelograms as mentioned in the literature by Valvassori, Hanafee, Scanlon, Penfield, Rydell and others. We feel it is important to review this topic and are reporting four cases of false positives. In our cases, three were explored with the findings of a normal anatomical variation in the size of the internal auditory canal, an adhesive arachnoid band, and a possible viral neuronitis, resulting in nonfilling of the internal canal. The fourth patient was found to have multiple sclerosis as the etiology of her symptoms, but no explanation for her abnormal angle myelogram has been found. Our incidence of false positive myelograms was 7.8 percent of myelograms done by the Emory University Medical Center since 1969. We feel it is important for all neuro‐otologic surgeons to realize that this can occur and why.