Good Vibrations: A Novel Method of Damping Acquired Pendular Nystagmus with Vibration (S19.001)

OBJECTIVE: To report the novel, heretofore unreported, nystagmus-damping effects of applying vibration to the skull in three patients with acquired pendular nystagmus (APN). BACKGROUND: APN may be monocular or binocular, vary in trajectory (horizontal, vertical, elliptical, or circular), and consist of pseudo-sinusoidal oscillations at a single frequency (3-5 Hz) that are transiently-stopped ("reset") by saccades and blinks. APN results in highly-disabling oscillopsia that interferes with visual acuity and postural stability, and also impacts cosmetic appearance and social interactions. DESIGN/METHODS: Patient 1 is a 32-year-old woman with multiple sclerosis who developed a left monocular pendular horizontal nystagmus. Patient 2 is a 41-year-old woman who developed an unusual oculopalatal tremor syndrome (with a hemi-seesaw pendular nystagmus) following surgery on a fourth ventricle cavernoma. Patient 3 is a 62-year-old man who developed oculopalatal tremor (with a right monocular vertical pendular nystagmus) after a pontine hemorrhage. We applied vibration using a Brookstone™ Mini Muscle Massager® over the vertex, both mastoids, and dorsal neck muscles. RESULTS: In all our patients, the nystagmus amplitude (and associated oscillopsia) was markedly attenuated with vibration over the vertex, and both mastoids; it was reduced less consistently by dorsal neck muscle vibration. Cessation of vibration resulted in immediate return of the nystagmus. The nystagmus was unaffected by vibrating the elbow, or by exposure to only the noise or pressure of the vibrator. CONCLUSIONS: Our patients showed a striking damping effect of vibration on nystagmus. Possible mechanisms include indirect stimulation of the vestibular system; such a mechanism has been posited for the nystagmus-dampening effects of head-shaking in spasmus nutans. Alternatively, vibration may provide a exteroceptive input that diminishes instability in the gaze-holding circuits, similar to how neck vibration and acupuncture attenuates congenital nystagmus. If our novel observation can be replicated in a larger cohort, a plan to develop an inconspicuous, effective, user-friendly, vibration-delivery device that can help improve visual function, may be justified. Disclosure: Dr. Beh has received research support from Biogen Idec. Dr. Kheradmand has nothing to disclose. Dr. Frohman has received personal compensation for activities with Biogen Idec, Novartis, Acorda Therapeutics, and Questcor. Dr. Conger has nothing to disclose. Dr. Conger has nothing to disclose. Dr. Calabresi has received personal compensation for activities with Abbott and Vertex. Dr. Calabresi has received research support from Bayer, Abbott, Novartis, Biogen Idec, and Vertex. Dr. Balcer has received personal compensation for activities with Biogen Idec, Questcor, Novartis, and Vaccinex. Dr. Frohman has received personal compensation for activities with Biogen Idec, Teva Neuroscience, Acorda, Novartis, Astellas, and Abbott. Dr. Zee has received personal compensation for activities with Sun Pharma and Abbott. Dr. Zee has received royalty payments from Oxford University Press.