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.