Trigeminal schwannomas: results of Gamma Knife surgery in 37 cases

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Information on outcomes of Gamma Knife surgery (GKS) for patients harboring trigeminal schwannomas is limited because these tumors are rare. The authors evaluated tumor control and functional outcomes in patients who underwent GKS for trigeminal schwannomas to clarify the efficacy of this treatment.


Forty-two patients with trigeminal schwannomas but no evidence of neurofibromatosis Type 2 were treated with GKS at Komaki City Hospital between November 1991 and December 2003. Of these, 37 patients were assessed. The mean tumor volume in these patients was 10 cm3. The mean maximum radiation dose directed to the tumor was 27.9 Gy and the mean dose directed to the tumor margin was 14.2 Gy. The mean follow-up period was 54 months. In four patients (11%) there was complete tumor remission; in 20 (54%) there was partial tumor remission; in eight (22%) the disease remained stable; and in five (14%) the tumor enlarged or uncontrollable facial pain developed with radiation-induced edema requiring resection. The actuarial 5- and 10-year tumor control rates were both 84%. With respect to functional outcomes, 40% of patients noted an improvement in their symptoms, and one patient experienced new symptoms despite good tumor control.


Gamma Knife surgery was a safe and effective treatment for a select group of patients harboring trigeminal schwannomas. Large tumors that compress the brainstem and cause deviation of the fourth ventricle should first be removed surgically and any remnant should be treated by GKS.

Abbreviations used in this paper:GKS = Gamma Knife surgery; MR = magnetic resonance; SRS = stereotactic radiosurgery.

Article Information

Address reprint requests to: Toshinori Hasegawa, M.D., Department of Neurosurgery, Komaki City Hospital, Gamma Knife Center, 1-20 Jobushi, Komaki, Aichi Prefecture, 485-8520, Japan. email:

© AANS, except where prohibited by US copyright law.



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    Graph demonstrating a Kaplan–Meier curve of the tumor control rate in 37 patients harboring trigeminal schwannoma who were treated by GKS.

  • View in gallery

    Graphs showing Kaplan–Meier curves of tumor control rates according to tumor type (upper) and group (lower).

  • View in gallery

    Bar graph showing post-GKS changes in symptoms in patients who had facial numbness or pain. Notched bars represent improvement in symptoms; white bars stable symptoms; and black bars worsened symptoms.


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