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

    loading  Checking for direct PDF access through Ovid

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.

Related Topics

    loading  Loading Related Articles