Dancing Eyes A 25-month-old boy presented with abnormal eye movements, a history of myoclonic jerks progressing to near-continuous tremulousness, and unsteadiness of gait for the last month. He also had irritability, reduced sleep, and feeding difficulties. He was born to nonconsangui- neous parents, had a smooth perinatal transition, and was developmentally normal before this presentation. Examina- tion revealed normal head size, extreme irritability, truncal ataxia, peculiar eye movements, and tremulousness (Video; available at www.jpeds.com), which led to a syndromic diagnosis of opsoclonus myoclonus ataxia syndrome. Neuroimaging was normal. Abdominal ultrasound examination ruled out an abdominal mass. Screening magnetic resonance imaging of the neck, chest, abdomen, and pelvis revealed a posterior mediastinal mass (Figure,A and B), which was further confirmed on positron-emission tomography scan (Figure, C and D). The child was diagnosed with paraneoplastic opsoclonus myoclonus ataxia syndrome secondary to neuroblastoma. Opsoclonus myoclonus ataxia syndrome is a neurologic syndrome characterized by opsoclonus, myoclonus, ataxia, and behavioral abnormalities. 1 It may be paraneoplastic or parainfectious. The exact pathophysiology of opsoclonus myoclonus ataxia syndrome is unclear. A proposed mecha- nism for opsoclonus includes Purkinje cell dysfunction and disinhibition of oculomotor neurons of the caudal fastigial nucleus of the cerebellum. 1 Another proposed mechanism is disinhibition of burst neurons (responsible for generation of saccades) secondary to disruption of omnipause cells. 2 This clinical syndrome needs to be identified because it is associated with neuroblastoma in approximately one-half of the children. Neuroblastoma associated with opsoclonus myoclonus ataxia syndrome usually has a favorable prog- nosis, because opsoclonus myoclonus ataxia syndrome un- veils any occult neuroblastoma. n Amrit Kaur, MBBS Department of Pediatrics Chandana Bhagwat, MD Priyanka Madaan, DM Lokesh Saini, DM Pediatric Neurology Unit Department of Pediatrics Anmol Bhatia, MD Department of Radiodiagnosis Harmandeep Singh, MD Department of Nuclear Medicine Naveen Sankhyan, DM Pediatric Neurology Unit Department of Pediatrics Postgraduate Institute of Medical Education and Research (PGIMER) Chandigarh, India References 1. Sahu JK, Prasad K. The opsoclonus-myoclonus syndrome. Pract Neurol 2011;11:160-6. 2. Zee DS, Robinson DA. A hypothetical explanation of saccadic oscillations. Ann Neurol 1979;5:405-14. Figure. Magnetic resonance imaging and gallium-68 DOTA- NOC positron-emission tomography/CT scan of chest and abdomen reveal a mass in left posterior mediastinum (likely neuroblastoma). A, Coronal T1-weighted postcontrast image and B, axial T2-weighted image reveal a well-defined isointense lesion (42 Â 26 Â 27 mm) in the left posterior medi- astinum extending from D7 to D11 vertebrae. C, Positron- emission tomography/CT Maximum intensity projection image shows increased uptake in left lower thoracic paraspinal re- gion. D, Axial fused positron-emission tomography-CT image shows somatostatin-receptor expressing mass (maximum standardized uptake value, 21; arrow) in the same location. The authors declare no conflicts of interest. J Pediatr 2019;214:231. 0022-3476/$ - see front matter. ª 2019 Elsevier Inc. All rights reserved. https://doi.org/10.1016/j.jpeds.2019.06.035 231 REDISCOVERING THE PHYSICAL EXAM