Abstract Details

Title A Case Report of Primary Position Downbeating Nystagmus in Association with a Unilateral Internuclear Ophthalmoplegia (INO) Secondary to a Dorsal Midbrain Infarction.

Topic Neuro-ophthalmology/Neuro-otology

Presentation(s) Neuro-ophthalmology/Neuro-otology Posters (7:00 AM-5:00 PM)

Poster/Presentation
Number 027

Objective We report a case with primary position downbeating nystagmus (DBN) that is atypical in its location and associated findings.

Background Downbeating nystagmus is classically associated with lesions in the cranio-cervical junction or cerebellum. secondary to a midbrain stroke. Vertical nystagmus is well reported in patients with INOs but almost all have been upbeating.

Design/Methods We describe a patient with an INO and DBN secondary to a midbrain lesion.

Results A 49 year old female presented with dizziness and blurred vision. Her neurological examination was initially intact, but a few hours later she started to complain of intermittent binocular vertical diplopia worse on right gaze. Exam showed a left INO with skew deviation, a primary position downbeating nystagmus, and an impaired vestibulo-ocular Reflex (VOR) to downward head thrusts. MRI showed an acute infarct in the left paramedian midbrain. Symptoms had nearly totally resolved by day 3.

Conclusions Downbeating nystagmus is a common finding in patients with inferior cerebellar disease and other abnormalities involving the craniocervical junction. It has been only rarely reported in midbrain lesions. Our case is also unusual in that vertical nystagmus with INOs is almost always upbeat, while our patient showed downbeating nystagmus. The association in our case with poor VOR to anterior canal stimulation suggests the DBN may be secondary to an imbalance between the anterior canal pathways which can initiate upward eye movements and posterior canal pathways involved in downward VOR movements.

Authors/Disclosures
Gayane Avagyan, MD (UHS) PRESENTER	Dr. Avagyan has nothing to disclose.
Mahsa Mohajery, MD (Tisch MS Research Center of New York)	Dr. Mohajery has nothing to disclose.
Danisette Torres, MD (Florida Atlantic University)	Dr. Torres has nothing to disclose.
Michael L. Rosenberg, MD (New Jersey Neuroscience Institute)	Dr. Rosenberg has nothing to disclose.
Siddhart K. Mehta, MD	Dr. Mehta has nothing to disclose.

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