(DRG) Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine, Baltimore, Maryland
This is a 30-yo-woman with the relatively acute onset of diplopia. There was a large angle exotropia, very subtle lag of the adducting saccades OD>OS, suggestive of bilateral INOs. This was best seen with rapid horizontal saccades, and a lesion involving bilateral MLFs in the caudal midbrain was demonstrated on MRI. There was also upbeat nystagmus in upgaze which is a typical finding in bilateral MLF lesions as some of the fibers responsible for vertical gaze holding travel through the MLF.
