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

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 noncontrast MRI revealed no obvious abnormalities, and she did not develop paralysis involving other eyemovement 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.