Because of the resurgence of COVID19 you are still practicing telemedicine.
You are presented a case of a previously healthy 35-year-old woman who presents with
acute onset nystagmus (see video below). You are given no other information.
What is your diagnosis, what test(s) would you order to confirm your suspicions,
and what treatment, if any, do you recommend?
DIAGNOSIS: Acquired pendular nystagmus (APN) in a patient with multiple sclerosis
(MS). APN is characterized by sinusoidal oscillations at a frequency of 2-6 Hertz. Theories
to explain APN in patients with MS include delayed transmission of visual information
secondary to demyelinization of the optic nerve and/or instability of neural integrator
cells distributed across the brainstem and cerebellum. Treatment includes gabapentin
(a N-2-delta calcium channel blocker) or memantine (a glutamine receptor blocker).
Eye movement disorders occur in 40-76% of MS patients. In addition to APS these
may include interocular ophthalmoplegia (IOP) and abnormalities in saccades, vestibulo-ocular
reflexes, smooth persuit, and gaze holding.
Other causes of APS include inherited genetic defects (ERCCU, PLP1, GFAP genes),
paroxisomal disorders, toluene and fosphenyltoin toxicity, sarcoidosis, oculopalatal
tremor, Whipples disease, and, disputedly, Parkinsons disease.
Sinusoidal oscillations characteristic of APS in a patient with multiple scerosis. Note the frequency (in Herz) of the oscillations.