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Disabling Central Paroxysmal Positioning Upbeat Nystagmus and Vertigo Associated With the Presence of Anti–Glutamic Acid Decarboxylase Antibodies

Martins Ana I. MD; Carvalho, João N. MD; Amorim, Ana M. MD; Geraldo, Argemiro MD; Eggenberger, Eric DO, MSEpi; Lemos, João MD
Journal of Neuro-Ophthalmology: Post Author Corrections: August 01, 2017
doi: 10.1097/WNO.0000000000000547
Original Contribution: PDF Only

Abstract:

An immune attack by anti–glutamic acid decarboxylase (GAD) antibodies is believed to cause a deficiency in gamma-aminobutyric acid–mediated neurotransmission in the cerebellum. This, in turn, leads to several eye movement disorders, including spontaneous downbeat (DBN) and periodic alternating nystagmus. We describe a 68-year-old diabetic woman with disabling paroxysmal positioning upbeat nystagmus (UBN) exclusively in the supine position, associated with asymptomatic spontaneous DBN, alternating skew deviation and hyperactive vestibulo-ocular reflex responses on head impulse testing, in whom high titers of anti-GAD antibodies were detected. After treatment with intravenous immunoglobulin, a complete resolution of positioning UBN and spontaneous DBN occurred, along with a decrease in anti-GAD antibody titers. Positioning UBN in this case may reflect a transient disinhibition of the central vestibular pathways carrying posterior semicircular canal signals, due to lack of normal inhibitory input from the cerebellar nodulus/uvula. Immunoglobulin restored cerebellar inhibitory output, possibly by improving gamma-aminobutyric acid neurotransmission.

Address correspondence to João Lemos, MD, Department of Neurology, Coimbra University Hospital Centre, Praceta Professor Mota Pinto, 3000-075 Coimbra, Portugal; E-mail: merrin72@hotmail.com

The authors report no conflicts of interest.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the full text and PDF versions of this article on the journal's Web site (www.jneuro-ophthalmology.com).

A. I. Martins and J. Lemos contributed equally to this article.

© 2018 by North American Neuro-Ophthalmology Society