Mystery Case: Superior oblique myokymia:An uncommon cause of intermittent diplopia

A 31-year-old man presented with intermittent vertical diplopia, lasting for seconds to hours. He described a sensation of movement of his right eye, comparable to that of involuntary eyelid contractions. Fatigue induced the symptoms. Self-recorded videos (videos 1 and 2, links.lww.com/WNL/A195 and links.lww.com/WNL/A196; video legends, links.lww.com/WNL/A269) showed involuntary paroxysmal, intorsional movements of the right eye, consistent with superior oblique myokymia.(1,2) This condition can be caused by trochlear neuropathy, for example due to microvascular compression, tumor in the tectal region, or trauma.(1,2) Brain MRI did not reveal any abnormalities. Carbamazepine, which is recommended as first-line treatment,(1,2) only slightly reduced the symptoms, making this essentially benign condition quite disabling