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

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

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      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.


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