Opsoclonus myoclonus syndrome (OMS) is a rare movement disorder in children often associated with an underlying neuroblastoma. In other cases, it is believed that the tumor is occult or there is another immune-stimulating precipitating event. Diagnosis can be difficult, requiring 3 of 4 criteria: opsoclonus or ocular flutter, myoclonus or ataxia, behavioral or sleep disturbances, and neuroblastoma. Prompt treatment of OMS is crucial to preventing permanent neurologic sequelae. In order to better characterize the clinical profile of this syndrome and its associated conditions, we present a case report of a 9 month old male with OMAS without an associated neuroblastoma and with new onset supraventricular tachycardia (SVT) and review the associated literature.

A 9-month-old male with a past medical history of macrocephaly, hypotonia, and developmental delay presented with abnormal eye and body movements starting one month prior. Due to concern for OMS, the patient underwent an extensive initial workup including CT neck, chest, abdomen, and pelvis and VHA/HMA levels, which were all within normal limits. The patient’s spinal fluid revealed no evidence of paraneoplastic, autoimmune, or infectious processes. Per neurology recommendations, the patient was started on IVIG and dexamethasone. After his first IVIG infusion, the patient’s abnormal movements worsened, and his heart rate increased into the 300s. The IVIG was discontinued. However, the patient continued to have recurring bouts of SVT, which was eventually controlled with digoxin. After resuming treatment with IVIG and dexamethasone, the patient’s opsoclonus myoclonus symptoms began to improve. All additional metabolic labs resulted normal and the patient was discharged.

Because OMS can cause permanent developmental delay, prompt recognition and treatment of this syndrome is necessary. This is a unique case of OMAS without neuroblastoma, associated with recurrent bouts of SVT. Recognizing rare complications of OMS is crucial to improving medical management of its sequelae.