Neuromodulation in Gamma Knife Surgery for Functional Disorders: Current and Future

Motohiro Hayashi1, Noriko Tamura1, Shoji Yomo2, Manabu Tamura1

1Tokyo, Japan 2Saitama, Japan

Keywords: gamma knife, trigeminal neuralgia, functional, headache, tremor

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     Gamma knife surgery (GKS) has been applied as a treatment for functional disorders, and the clinical results are preferable and acceptable to be evaluated. However, the critical action mechanism is not known yet. Among of them, we suspected it should be destructive change due to GKS for tremor and epilepsy caused by hypothalamic hamartoma. On the other hand, we also suspected that intractable pain and mesial temporal lobe epilepsy(MTLE) might not be triggered by the destructive change according to postoperative clinical course. 
     We will report our clinical results to demonstrate neuromodulative change which might provide the patients cure.
     130 patients with essential trigeminal neuralgia(TGN), 21 patients with cancer pain(CP), 24 patients with thalamic pain syndrome(TPS), and 4 patients with MTLE were registered in our retrospective study.
      All patients could be followed up at least 3 years excluding the cases with cancer pain. In TGN, the target should be the trigeminal nerve at retrogasserian region with 90Gy at maximum dose using single shot of 4 mm collimator. In CP and TPS, the target should be the anterior lobe of the pituitary gland with 140-180Gy at maximum dose using single shot of 8 mm collimator. In MTLE, the target should be the archeocortex and entrhinal cortex, whose target volume should be ranged between 7 and 8cc, with 22-24Gy at marginal dose using 4 and 8 mm collimators.
     In TGN, 98% of initial electric discharge free, 66% of complete pain free at the last follow up, and 24% of significant complication (facial numbness). In CP, 90.5% of significant pain reduction without significant complication. In TPS, 71% of significant pain reduction without significant complication excluding 30% of endocrinological impairment. In MTLE, 75% of significant seizure cessation without significant complication excluding MR morphological changes were seen.
     This was a retrospective study.
     The true action mechanism of these presenting disease could not be elucidated yet without some hypothesis that GKS might provide something of neuromodulative effect to the patients, according to postoperative clinical phenomena. 
     We would like to have much more experience and perform basic research to prove our hypothesis.


Project Roles:

M. Hayashi (), N. Tamura (), S. Yomo (), M. Tamura ()