Gamma Knife surgery for epidermoid tumors: Possibility of nerve decompression or neuromodulation

Takenori Kato1, Toshinori Hasegawa2, Yoshihisa Kida3

1Aichi, Japan 2Komaki, Japan 3Komaki City Hospital

Keywords: outcome, hemifacial spasm, epidermoid tumor, trigeminal neuralgia, gamma knife

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     Epidermoid tumors can cause cranial nerve symptoms. Radiosurgery may be of value for the treatment of epidermoid tumors.
The management of a series of 12 patients treated using Gamma Knife surgery (GKS) is evaluated, emphasizing the long-term follow-up of hyperactive nerve dysfunction.
A total of 12 patients (7women, 5men) who underwent GKS for epidermoid tumors between 1991 and 2011 were reviewed. 7 patients suffered from trigeminal neuralgia (TN) and one patient had hemifacial spasm (HFS). Our radiosurgical targets were either entire tumor or partial one around the hyperactive nerve for the large epidermoid, so the mean target volume was 3.5 cc. The mean maximum and marginal dose were 25.6 Gy and 14.6 Gy respectively.
     We reviewed clinical outcomes in our radiosurgery series of epidermoid tumors.
     In the mean follow-up of 55.4 months, all the tumors showed a good tumor control without any progression, and tumor shrinkage is confirmed in 2 out of 12 cases. Symptomatic TN improved or disappeared in all 7 cases, and HFS disappeared in one. No neurological deterioration was found in any case after the treatment.
     This was a retrospective series.
     Hyperactive nerve dysfunctions associated with epidermoid tumors are significantly improved by GKS either with entire or partial tumor coverage. 
     Therefore the radiosurgical nerve decompression or neuromodulation for epidermoid tumor is seemingly achieved by GKS.


Project Roles:

T. Kato (), T. Hasegawa (), Y. Kida ()