Case Report: Opsoclonus-Myoclonus Syndrome Associated With Contactin-Associated Protein-Like 2 and Acetylcholine Receptor Autoantibodies in the Setting of Non-Small Cell Lung Carcinoma

Abstract

Opsoclonus myoclonus syndrome (OMS) is a rare immune-mediated paraneoplastic or para/-post-infectious syndrome characterized by “dancing” eye movements, myoclonus, and ataxia. Neuropsychiatric symptoms have also been reported. Without treatment, OMS may progress to further neurological impairment and even death. Autoimmune attack of CNS structures in OMS is most commonly mediated by anti-Ri (also known as ANNA2) IgG antibodies, with additional findings implicating antibodies targeting various neurotransmitter receptors. Prompt immunotherapy and neoplasm treatment may result in improvement. We report a novel association of Contactin-Associated Protein-Like 2 (Caspr2) antibodies occurring in association with paraneoplastic OMS. While breast cancer and small cell lung cancer (SCLC) are more commonly associated with OMS among adults, we characterize a novel association between Caspr2 antibody in a patient with mixed non-small cell and small cell lung carcinoma.

Myoclonus in CASPR2 Autoimmune Encephalitis: A Distinctive Association

“…Since the first description of orthostatic myoclonus (OM) in association with CASPR2 Autoimmune Encephalitis (AE), 2 there have been multiple reports of spinal myoclonus involving the lower limbs and the abdominal muscles 3,4 . Most frequently observed as a paraneoplastic manifestation or a post infectious phenomenon, Opsoclonus Myoclonus Syndrome (OMS) has recently been described in an adult with lung carcinoma demonstrating CASPR2 and Acetylcholine Receptor Autoantibodies 5 . I aim to describe two patients with non‐neoplastic CASPR2 AE, presenting solely with two novel combination of movement disorders: OMS in a young girl and parkinsonism‐OM in an elderly lady.…”