ガンマナイフ治療10年後に微小血管減圧術を行った三叉神経痛の1例

A Case of Trigeminal Neuralgia Treated with Microvascular Decompression 10 years after Gamma Knife Radiosurgery

Ⅰ．はじめに

　ガンマナイフは1968年，Sweden Karolinska大学のLeksell教授によって開発された定位的放射線治療装置である．日本では既に脳腫瘍や脳動脈奇形での使用が保険適用となっていたが，2015年7月1日より三叉神経痛にも保険が適用されるようになった．しかしながら，ガンマナイフ治療を施行した患者において，長期間経った後に三叉神経にどのような変化が起こっているのか，詳細が知られていないのが現状である．今回われわれは，ガンマナイフ治療10年後に痛みの再燃を来し，微小血管減圧術を行った症例を経験したので，文献的考察を含めて報告する．

　We report a case of trigeminal neuralgia treated with microvascular decompression 10 years after We report a case of trigeminal neuralgia treated with microvascular decompression 10 years after Gamma Knife radiosurgery was performed. The patient was a 65-year-old female. The root entry zone of the trigeminal nerve received irradiation:a 4-mm shot, with a maximum dose of 80 Gy. The symptoms improved following treatment, however pain recurred five and a half years later. The pain gradually increased over time, to the point where the patient was unable to eat solid food. Carbamazepine was prescribed and the dosage increased. However, side effects such as dizziness and drowsiness manifested. Microvascular decompression was performed, revealing that the trigeminal nerve was markedly atrophied and being pressed upon by the superior cerebellar artery. The superior cerebellar artery was transpositioned with Teflon braided tape to the cerebellar tent. There were no abnormal findings such as arachnoid thickening, adhesions between vessels and nerves, or atherosclerotic plaque in the affected vessels. Pain completely abated following surgery, and side effects such as numbness of the face have not been observed at the time of writing this report.