# Reversible Isolated Opsoclonus in a Patient With Gastric Cancer and Antibodies to Glutamic Acid Decarboxylase and Myelin Oligodendrocyte Glycoprotein

## TL;DR

A patient with gastric cancer showed reversible isolated opsoclonus linked to antibodies against GAD and MOG, and improved with immunoglobulin treatment.

## Contribution

Reports of GAD and MOG antibodies together in gastric cancer with isolated reversible opsoclonus are rare.

## Key findings

- The patient exhibited isolated opsoclonus without significant myoclonus.
- Symptoms improved after intravenous immunoglobulin administration.
- GAD and MOG antibodies were both present in the patient.

## Abstract

Opsoclonus and myoclonus are known paraneoplastic manifestations of malignancy. The most common antibodies found are anti-neuronal antibodies (Hu, Ri, and Ma). The most common affiliated malignancies are small-cell lung cancers, breast cancers, or gynecological malignancies. Gastric cancer is uncommon. Other antibodies have been cited, but are rare. Isolated opsoclonus without significant myoclonus is also rare. While both glutamic acid decarboxylase (GAD) and myelin oligodendrocyte glycoprotein (MOG) antibodies have individually been reported to be associated with opsoclonus, reports of a combination of these two in a patient with gastric cancer with isolated reversible opsoclonus are scarce. In this case, we follow a patient who presented as such and demonstrated significant symptomatic improvement after the administration of intravenous immunoglobulin.