Adult-onset Opsoclonus-Myoclonus Syndrome Associated With Ganglionic Acetylcholine Receptor Autoantibody

Introduction: Opsoclonus-myoclonus syndrome (OMS) may have a toxin induced, parainfectious, or paraneoplastic etiology. Several autoantibodies have been associated with adult-onset OMS, most commonly antineuronal nuclear antibody 2 (Ri), and it is most frequently associated with breast or small cell lung cancer. The nicotinic ganglionic acetylcholine receptor autoantibody (α3-AChR Ab) has not been described in association. Case Report: A 46-year-old woman was evaluated for symptoms of oscillopsia, tremor, gait imbalance, and mild cognitive deficits that began 6 weeks prior. Neurological examination demonstrated opsoclonus, myoclonus, and mild gait ataxia. Laboratory evaluation revealed an elevated α3-AChR Ab at 0.27 nmol/L (normal ≤0.02 nmol/L) with no other autoantibodies or infectious etiology detected. Thorough screening revealed no evidence of associated malignancy. Immunotherapy with weekly methylprednisolone led to significant improvement. Conclusions: This first reported case of α3-AChR Ab positivity in the setting of adult-onset OMS expands the spectrum of associated autoantibodies. The mechanism of disease may be linked to cholinergic nuclei within the brainstem. This case suggests including α3-AChR Ab in the evaluation of adult-onset OMS, and highlights the importance of further understanding α3-AChR within the brain.