Holmes振戦を来した第三脳室内成熟奇形腫の1例

A Case of Mature Teratoma in the Third Ventricle with Holmes Tremor

Ⅰ．はじめに

　頭蓋内奇形腫は小児期に好発する胚細胞腫瘍であり，原発性脳腫瘍のうち約0.1%と稀である．また，好発部位として松果体部や第三脳室内が知られている²⁾．その初発症状は，頭痛，痙攣，運動・感覚障害などであり，振戦を来すことは少ない．Holmes振戦は安静時や企図時に上肢でみられる低振幅の振戦で，中脳や小脳における変性疾患，血管障害，外傷などで起こることが多く，脳腫瘍での報告は極めて稀である¹³⁾．

　今回われわれは，Holmes振戦を主訴とした5歳男児の第三脳室内巨大成熟奇形腫の1例を経験したので，若干の文献的考察を加えて報告する．

　Intracranial teratoma is a rare disease that frequently occurs in children and young adults. It comprises of approximately 0.1% of the brain tumors. We report a case of a large mature teratoma in the third ventricle with Holmes tremor. A 5-year-old boy presented with tremors 2 years ago. CT showed a 56×48 mm tumor in the third ventricle and hydrocephalus. The tumor was well demarcated from the surrounding brain tissue and contained calcification. MRI indicated a partially high-intensity signal on T1-weighted and T2-weighted images. The preoperative diagnosis was teratoma. Initially, the tumor was biopsied using neuroendoscopy and the Ommaya reservoir was set. The pathological results showed fat-like tissues and fibroblasts. Subsequently, the tumor was completely removed using the interhemispheric transcallosal transchoroidal approach. The tumor included fat and hair tissues. It also included calcification similar to that observed in a tooth. It was strongly adhered near the pineal gland. Pathologically, the diagnosis was a mature teratoma. Postoperatively, the tremor disappeared and the patient was discharged from the hospital without neurological deficits. We believe that compression of the Guillain-Mollaret triangle was relieved by removal of the tumor. Hence, the tremor disappeared after the operation.