Acoustic Neuroma Growth: A Systematic Review of the Evidence

Aim: To undertake a systematic review of the literature on acoustic neuroma growth. Predictors of growth were also explored. Materials and Methods: A comprehensive search was conducted to identify the relevant literature. The search yielded 2,455 papers. All titles were reviewed by 2 of the authors, and finally, 41 papers were found reporting data pertinent to growth. Results: The percentage of acoustic neuromas exhibiting growth ranges widely from 18 to 73%. The percentage of tumors reported not to grow for some years after diagnosis ranges from 9 to 75%. Some ( usually less than 10%, but up to 22%) may get smaller. No reliable predictors of growth have been identified. The mean growth rate for all tumors varies between 1 and 2 mm/yr, and for only those that grow, between 2 and 4 mm/yr. However, there are cases with significant regression or exceptional growth ( exceeding 18 mm/yr). There are various patterns of growth, and a tumor that shows growth may stop doing so and vice versa. Finally, some tumors that have been stable for many years can exhibit tumor growth. Conclusion: The growth pattern of acoustic neuromas is variable and incompletely understood. As much as 75% of tumors have been reported to show no growth, supporting a Bwait and rescan policy in many patients, although there are no reliable predictors of tumor behavior, and some tumors may grow rapidly. Primary longitudinal studies are needed to better define the natural history and limit unnecessary interventions.