Long-Term Results of LINAC-Based Stereotactic Radiosurgery for Acoustic Neuroma: The Greek Experience

Purpose: To estimate the value of LINAC-based stereotactic radiosurgery (SRS) for the long-term local control of unilateral acoustic neuromas.
Materials and Methods: Twenty patients (median age 66; range 57-80 years) with unilateral acoustic neuroma underwent LINAC-based SRS from May 2000 through June 2004 with a dose of 11-12 Gy. The follow-up period ranged from 36 to 84 months (median follow-up period: 55 months).
Before SRS none of the patients had useful hearing. The follow-up consisted of repeat imaging studies and clinical examination for assessment of facial and trigeminal nerve function at 6-month intervals for the first year and yearly thereafter.
Results: Eleven tumors (58%) decreased in size and eight (42%) remained stable. One tumor showed a minor increase in size on the MRI done 6 months after SRS in comparison with the pretreatment MRI; however, a subsequent decrease was noticed on the next radiographic assessment and the tumor remained stable from then on. None of the tumors increased in size in the long-term follow-up, thus giving an overall growth control of 100% for the patients in this study.
None of the patients had useful hearing before SRS, so hearing level was not assessed during follow-up. No patient developed new, permanent facial or trigeminal neuropathy.
Conclusion: LINAC-based SRS with 11-12 Gy provides excellent tumor control in acoustic neuroma and has low toxicity even after long-term follow-up.

Keywords
Acoustic neuroma, linear accelerator, local control, stereotactic radiosurgery