Current Abstracts

DIAGNOSIS

Michael Beenstock. Predicting the stability and growth of acoustic neuromas. Otol Neurotol 2002; 23:542-549

Hypothesis: Acoustic neuroma (AN) growth can be predicted using information gathered at the time the AN is initially diagnosed. Background: Knowledge of AN growth is essential for treatment planning. Previous studies have not been able to identify predictors of AN growth.

Methods: A multivariate statistical analysis was carried out using two independent sets of secondary data from the natural histories of ANs. Logit, probit, and censored regression techniques were used to test alternative hypotheses of AN growth between the initial and second measurements, as well as between subsequent measurements.

Results: In one data set, AN growth between the first and second measurements varied significantly and inversely with age. It was much greater if the AN was on the left side and if there were more symptoms. It did not depend on initial tumor size or the measurement interval. In the other data set, AN growth was also greater for left-sided tumors and depended on symptoms. However, it varied inversely with tumor size and directly with the measurement interval. There was also some evidence that tumors that were more stable between the initial two measurements were more likely to remain stable between the second and third measurements. However, this did not apply to AN growth between the third and fourth measurements.

Conclusions: AN growth is predictable but the prediction model is not apparently independent of the policy for selecting ANs for conservative management.

Fred F. Telischi, Orlando Gomez-Marin, Barden Stagner, Glen Martin. Effect of acoustic tumor extension into the internal auditory canal on distortion-product otoacoustic emissions. Ann Otol Rhinol Laryngol 2002;111:912

We studied the effects on distortion-product otoacoustic emissions (DPOAEs) of internal auditory canal (IAC) extension of acoustic neuromas (ANs) with the hypothesis that cochlear patterns of DPOAEs would be more commonly observed when the IAC was completely filled with tumor because of direct tumor involvement of either the inner ear or its blood supply. In a retrospective analysis of 86 patients with surgically proven ANs, DPOAEs were classified as having cochlear or noncochlear patterns on the basis of comparisons with the behavioral pure tone thresholds. The results of behavioral audiometry and DPOAEs were compared with the extension of the tumor into the IAC, which was categorized as full or partial. Of the 86 patients, 58 had tumors with full IAC extension, and 28 had tumors with partial IAC involvement. Cochlear patterns of DPOAEs were found in 55.2% of the tumors in the full IAC group and in 71.4% of those in the partial IAC group (not statistically different). It was concluded that the extent of IAC involvement by ANs was not significantly related to the negative effects of the tumor on cochlear function as represented by DPOAEs.