A Pediatric Patient with ANNA-1 Associated Opsoclonus Myoclonus and Epilepsia Partialis Continua (P5.137)

Objective : To report a pediatric patient with epilepsia partialis continua, opsoclonus myoclonus (OMS), seropositivity for ANNA-1 and a paraspinal neuroblastoma. Background : OMS consists of involuntary, chaotic eye movements, myoclonus of the limbs, and ataxia. Neuroblastoma is found in about half of children with OMS and most cases occur in children less than 2 years of age. There are few reported cases of the presence of ANNA-1 (anti-Hu) in children with neuroblastoma and OMS, all occurring in children less than 3 years old. Concurrent OMS and epilepsia partialis continua has not been reported in children. Design/Methods/Results: An 11-year-old female presented with new onset focal seizures without alteration of consciousness, opsoclonus and ataxic limb movements. Initial brain MRI demonstrated an area of increased T2/FLAIR signal in the right mesial temporal lobe and left subinsular region. Despite escalating anti-epileptic treatments, her seizures continued. CSF analysis demonstrated 20 OCBs and IgG index 1.58, with other indices normal. Serum and CSF paraneoplastic panel (Mayo Medical Laboratories) returned positive with ANNA-1 titers of 1:7680 (serum) and 1:1024 (CSF). She was treated with IV methylprednisolone, plasmapheresis and IVIG without clear benefit. Spinal MRI revealed a paraspinal mass at the L2-L4 level. Biopsy and partial resection were performed and showed a ganglioneuroblastoma (nodular subtype). Relevant features include non-amplification of N-MYC, low MKI, no increased uptake on MIBG, and negative urine HVA and VMA. She was started on chemotherapy per protocol ANBL0532. After 3 rounds, she continues to have frequent focal seizures with fluctuating frequency and intensity. She continues to have subtle opsoclonus and mild ataxia. Conclussions : Though rare, the presence of anti-neuronal antibodies should be considered in childrenpresenting with limbic encephalitis or OMS. Disclosure: Dr. Sweeney has nothing to disclose. Dr. Paz Soldan has nothing to disclose. Dr. Lowichik has nothing to disclose. Dr. Sweney has nothing to disclose. Dr. Clardy has received personal compensation for activities with the DAVICK Group and Trinity Partners. Dr. Clardy9s spouse holds stock and/or stock options in Quadex. Dr. Clardy has received research support from Western Institue for Biomedical Research