"Pseudonystagmus" due to bilateral vestibular loss and head tremor
Abnormal VOR HIT
Daniel R. Gold, DO, Departments of Neurology, Ophthalmology, Neurosurgery, Otolaryngology - Head & Neck Surgery, Emergency Medicine, and Medicine, The Johns Hopkins School of Medicine
This is a 65-yo-woman with complaints of imbalance, dizziness, and horizontal oscillopsia. On exam, she had a high frequency, low amplitude (mainly horizontal) head tremor, and with ophthalmoscopy, the optic nerve was clearly oscillating back and forth at the same frequency as her head tremor, which was responsible for her horizontal oscillopsia. In her case, she also had bilateral vestibular loss demonstrated by + head impulse testing in the planes of right and left horizontal canals (also in anterior and posterior canals, not seen in this video). If a patient with a head tremor has an impaired or absent vestibulo-ocular reflex (VOR), the eyes will move with the head with each head oscillation, and oscillopsia will result. The term "pseudonystagmus" has been used to indicate oscillopsia (not due to nystagmus) that results from bilateral vestibular loss and head tremor.
Spencer S. Eccles Health Sciences Library, University of Utah