Case Report: Multiple Sclerosis Presenting as Unilateral Gaze-evoked Nystagmus

Unilateral gaze-evoked nystagmus is a rare neurologic finding that is largely diagnosed in connection with ischemic stroke. Gazed-evoked nystagmus is also a rare initial presentation of multiple sclerosis.

This study aimed to report a rare presentation of gaze-evoked nystagmus in a patient with multiple sclerosis and review the mechanism underlying the gaze-evoked nystagmus.

A 32-year-old man presented with a 1-week history of diplopia. Neurologic examination revealed right-sided gaze-evoked nystagmus and right-sided ataxia. Laboratory test revealed a positive result for oligoclonal bands. Contrast brain MRI revealed multiple hyperintense T2 lesions including a hyperintense patch at the right inferior cerebellar peduncle. A diagnosis of multiple sclerosis was made. The patient received methylprednisolone 500 mg intravenously for 14 days. The diplopia and gaze-evoked nystagmus resolved and remained stable 2 months later.

Our case demonstrates that damage to the inferior cerebellar peduncle may result in ipsilesional gaze-evoked nystagmus and ipsilesional ataxia, in contrast to ipsilesional gaze-evoked nystagmus and contralesional ataxia.