[Functional outcomes of radiosurgical treatment of vestibular schwannomas: 1000 successive cases and review of the literature].

RATIONALE: To evaluate the functional results of Gamma Knife surgery of vestibular schwannomas relying on a large and prospective series of consecutive cases.

MATERIAL AND METHOD: The first 1000 patients with cerebello-pontine angle schwannomas were consecutively treated by Gamma Knife in Marseille Timone University Hospital between July 1992 and March 2001. Patients without NF2 and or clinico-radiological arguments in favor of a facial origin accounted for a population of 927 patients (414 males, for 513 females) including 843 treated in first intention. In this series the Koos classification was: stage I 77 patients, stage II 520 patients, stage III 287 patients and stage IV 42 patients. The average Volume was 12.7mm3. Haring was usefull (Gardner and Robertson) before radiosurgery in 47% of the patients (subnormal in 20.3%).

RESULTS

Tumor control at last follow-up was 97%. Globally, a clinical trigeminal injury was observed in 0.6% of the patients and a facial palsy in 1.3%. There was clearly a decrease of the incidence of neuropathies with time; no facial palsy being reported among the last 258 patients. The rate of functional hearing preservation (Gardner) for patients initially in class I was 77.8% (47.6% for class II) at 3 Years. This rate of functional preservation reached 95% among patients with tinnitus as a first symptom.

CONCLUSION

Today, strong evidence surports the superiority of Gamma Knife surgery in term of functional perservation and equal efficacy compared with microsurgical removal. Consequently, radiosurgery must be preferred as a first intention choice for young patients with few symptoms presenting with a small to middle size vestibular schwannomas (Koos I-III).