Tumor Control And Clinical Outcome Of Vestibular Schwannomas After Gamma Knife Radiosurgery

A Jose Aguilar1, Banzali Michael H2, Vesagas Theodor S1, Gimenez Michael Louis1

1Philippine Gamma Knife Center 2Armed Forces of the Philippines Medical Center

Keywords: eating disorder, Decompression, cadaver dissection, back pain, acromegaly

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Abstract

      This retrospective study investigates effect of Gamma Knife on rates of tumor control, hearing preservation, facial and trigeminal function after acoustic schwannoma radiosurgery.
      We performed a database and chart review of all patients from the Cardinal Santos Medical Center with a unilateral Vestibular Schwannoma treated at the Philippine Gamma Knife Center from 1998 to 2007. Patients with multiple schwannomas, neurofibromatosis type 1 or 2, and patients with unilateral vestibular schwannomas who were lost to follow-up were excluded. Out of 79 patients, 58 were evaluable.
      There were 23 males and 35 females with a mean ff-up of 3.36 years (range 0.45-8.45 years). The average tumor size was 6.37 cm3 (range 0.0443 cm3 to 21.9 cm3). A 96.5% tumor control rate was achieved with a mean dose of 12.2 Gy (range 10-15 Gy) delivered to the 50% isodose line. In patients with normal  pre-operative auditory, facial and trigeminal nerve function no complications were observed post-operatively. Of the patients who presented with hearing loss, facial palsy and trigeminal neuropathy,  6%, 27% and 45% respectively, improved post-operatively. Only 1 patient (4.55%) presented with worsening of trigeminal neuropathy.
      Gamma Knife Radiosurgery is a safe and effective treatment for vestibular schwannoma.  A radiation dose of 12 Gy can achieve a high tumor control rate with a low rate of cranial nerve complications. Gamma Knife radiosurgery is comparable to microsurgery for tumor control rates and lower morbidity and mortality for tumors less than 22 cm3.


Acknowledgements

Project Roles:

A. Aguilar (), B. H (), V. S (), G. Louis ()