Wall-eyed Bilateral Internuclear Ophthalmoplegia (WEBINO) in MS

This is a young woman with a years-long history of multiple sclerosis who presented 2 years prior to this examination with complaints of oscillopsia (which was due to spontaneous upbeat nystagmus), as well as diplopia (which was due to bilateral internuclear ophthalmoplegia, INO). ; ; At the time of this exam, although she still had spontaneous upbeat nystagmus, she was not experiencing oscillopsia. She had dorsal medullary lesions that were bilateral and midline in the vicinity of the nucleus intercalatus and nucleus of Roller to explain her upbeat nystagmus. She had bilateral adduction deficits that were more significant than what was seen previously, in addition to abducting nystagmus bilaterally. She had a very large angle exotropia, which was also larger than what had been seen several years prior. She was not experiencing diplopia, presumably due to the magnitude of her strabismus - e.g., when fixating with one eye, the visual target falls so far peripherally on the retina of the other eye that this very blurry image is likely being ignored by the brain. This large angle exotropia in the setting of bilateral INOs is also referred to as a wall-eyed bilateral INO, or WEBINO.