Test Your Knowledge!

Goal: This multiple choice question will test students' knowledge and understanding of anti-GAD antibody syndrome, including the definition and neuro-ophthalmic findings that are associated with this condition. Learning Point: Anti-GAD antibody syndrome occurs due to the presence of antibodies against the glutamic acid decarboxylase (GAD) enzyme. GAD, which removes the carboxyl group from glutamic acid, is responsible for converting glutamic acid to gamma-aminobutyric acid (GABA). When there are antibodies against the GAD enzyme, glutamic acid can no longer be adequately converted to GABA, thus leading to a notable reduction in GABA. The reduction in GABA (inhibitory neurotransmitter) yields a hyperexcitability syndrome. Neuro-ophthalmic findings in this hyperexcitability condition includes oscillopsia, nystagmus (such as downbeat nystagmus), cerebellar ataxia, ophthalmoplegia, and diplopia. However, bitemporal hemianopsia, which may be seen in patients with a tumor pressing against the optic chiasm, is not characteristic of patients with anti-GAD antibody syndrome. Additionally, cranial nerve III palsy and transient monocular vision loss are not characteristic of anti-GAD antibody syndrome.