Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune, inflammatory disorder of the CNS affecting both adults and children.  About 4% of NMOSD cases are seen in the pediatric population, disease onset between 10-12 years, with female predominance 3:1. The choice of disease modifying treatments for pediatric NMOSD is limited. Satralizumab is approved for NMOSD for ages 12 years and older. We report a pediatric case successfully treated with rituximab later transitioned to s.c. tocilizumab, which is FDA approved for juvenile arthritis age >=2.  

A 6-year-old male of Hispanic decent presented with ptosis, diplopia, and left leg weakness.  MRI brain showed T2 signal abnormality in the upper pons, midbrain, and right middle cerebellar peduncle with subtle contrast enhancement.  Treatment IV methylprednisolone 30mg/kg; discharged on a 3-week prednisone taper. About 7 weeks later, he presented with left CN IV palsy.  MRI showed progressive expansile T2/FLAIR hyperintensity within bilateral inferior colliculi, bilateral cerebral peduncles, pons, midbrain, with contrast enhancement.  He was again treated with IV methylprednisolone and IVIG.  Prior to treatment, testing for anti-AQP4 antibodies resulted positive and anti-MOG was negative.  He was started on rituximab 375 mg/m2 two weeks apart and then Q 6 months. He was stable on this regimen.  However, 14 months after the initiation of rituximab, his IgG and IgM started to trend low.  About 3.5 years later, his IgG levels were 50% of the lower limit of normal range.  No protracted infections, including COVID.  Due to his low IgG levels, he was transitioned to s.c tocilizumab 62mg subcutaneously (12mg/kg) every 14 days.  The patient remains stable on tocilizumab.

This case highlights the effectiveness and safety of two DMTs for NMOSD in children < 12 years of age. Given the need for immunizations in children, s.c. tocilizumab may be a more suitable choice in this age group.