Purpose: To examine the lesion associated with external ophthalmoplegia in Fisher syndrome using three-dimensional magnetic resonance imaging (3-D MRI).
Method: Case report. A 65-year-old woman with Fisher syndrome was investigated by gadolinium-enhanced 3-D MRI.
Result: The extramedullary portion of the left trochlear nerve was enhanced.
Conclusion: Contrast-enhanced 3-D MRI revealed that the lesion responsible for the external ophthalmoplegia in Fisher syndrome is located in the extramedullary portion of the trochlear nerve.