直腸癌の脳転移により発症した外転神経麻痺の1例

A case of abducens palsy due to metastasis of rectal cancer to the brain

要約　目的：直腸癌の海綿静脈洞への遠隔転移により外転神経麻痺を生じ，短期間で急速に進展した症例報告。

症例：複視で受診した41歳女性。右外転神経麻痺を認め，約3か月後には両側の外転神経麻痺をきたし10か月後には死への転帰をたどった。大腸癌の既往歴があり，当初より脳への遠隔転移を疑ったが，単純MRIで明らかな異常が検出されず，他の眼球運動神経麻痺もきたさなかったため，海綿状静脈洞に転移した腫瘍が拡大進展するまで遠隔転移が診断できなかった。

結論：癌の遠隔転移が疑われる場合の診断にMRIを造影で行うことが大切である。

Abstract　Objective: Report of a rapidly progressing case of distant metastasis of rectal cancer to the cavernous sinus causing abducens nerve palsy.

Case: The patient was a 41-year-old woman who presented to our department with diplopia. She was found to have right abducens nerve palsy, which progressed to bilateral abduces nerve paralysis over a period of about 3 months, resulting in fatal outcome in 10 months. She had a history of colorectal cancer, and we suspected distant metastases to the brain from the initial consultation. However, initial non-contrast MRI revealed no obvious abnormalities, and she did not develop paralysis involving other eye-movement nerves. Therefore, we could not diagnose distant metastasis of the tumor to the cavernous sinus until its expansion and progression.

Conclusion: It is diagnostically imperative to perform contrast-enhanced MRI when distant metastasis is suspected.