LETTER TO THE EDITORS Isolated recurrent myelitis in a 7-year-old child with serum aquaporin-4 IgG antibodies Andrea Bianchi 1 • Emanuele Bartolini 2 • Federico Melani 2 • Renzo Guerrini 2 • Mario Mascalchi 1,3 Received: 18 October 2016 / Revised: 1 November 2016 / Accepted: 2 November 2016 Ó Springer-Verlag Berlin Heidelberg 2016 Dear Sirs, The diagnosis of Devic neuromyelitis optica (NMO) is classically based on the combination of bilateral optic neu- ritis and extensive myelitis in young adults and, rarely, in children [1]. The presence of aquaporin-4 immunoglobulin G antibodies (AQP4IgG) in serum is highly specific for NMO and allows definition of neuromyelitis optica spectrum disorder (NMOSD) in cases with isolated optic nerve, spinal cord or brain involvement [2]. Moreover, AQP4IgG seropositivity predicts a severe relapsing inflammatory course with multifocal distribution [3]. Finally, the discovery of AQP4IgG has opened the way to immunological treat- ment with the anti-CD20 monoclonal antibody rituximab, which appears to be effective in prevention of relapses in pediatric NMOSD with individualized therapeutic dosing [4–7]. Isolated recurrent spinal cord involvement has been reported in only four children with AQP4IgG [4], but data on long-term neurological outcome and the possible effects of rituximab are still lacking. We report on a 12-year-old girl with AQP4IgG-positive NMOSD presenting with three episodes of isolated recurrent myelitis between age 7 and 9 years who had no further relapses after rituximab introduction. At 7 years of age she presented with cervical back pain followed by paraparesis. Blood test showed a high platelet count (472.000 cells/mcl) and CSF analysis demonstrated mild lymphocytic pleocytosis (10 cells/mm 3 ) and protein increase (79 mg/dl). Serum and CSF infectious serology was negative. Brain MRI was unremarkable. Spinal MRI showed swelling and T2W hyperintense lesions from C2 to D5 and from D8 to D10 with faint, diffuse and inhomo- geneous contrast enhancement (Fig. 1). Tumor or myelitis was hypothesized. An indirect immunofluorescence assay revealed positive serum AQP4IgG antibodies. Pattern reversal visual evoked potentials were normal. After 5 days of intravenous steroid administration (methylprednisolone 500 mg daily), symptoms and signs completely remitted. MRI, performed 8 weeks later, revealed decreased swelling and extension of T2 hyperintensities with some punctate contrast enhancement in the lower lesion (Fig. 1). In spite of chronic oral steroid and azathioprine (50 mg t.i.d.) administration, acute paraparesis relapsed at 8 years of age. Brain MRI was unremarkable. Spinal MRI showed swel- ling and T2 W heterogeneous hyperintensity from C6 to D5 and from D7 to D9, with marked patchy contrast enhancement in both locations (Fig. 1). Spinal MRI per- formed 11 months later showed normal size of the spinal cord, mild T2 W hyperintensities at D3–D4 and D8–D9 levels and no contrast enhancement (Fig. 1). One year later, a further episode of paraparesis occurred. MRI & Mario Mascalchi mario.mascalchi@unifi.it Andrea Bianchi dott.abianchi@gmail.com Emanuele Bartolini emanuele.bartolini@meyer.it Federico Melani f.melani@meyer.it Renzo Guerrini r.guerrini@meyer.it 1 Neuroradiology Unit, Meyer Children’s Hospital Florence, Florence, Italy 2 Neurology Unit and Laboratories, Meyer Children’s Hospital, University of Florence, Florence, Italy 3 ‘‘Mario Serio’’ Department of Experimental and Clinical Biomedical Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy 123 J Neurol DOI 10.1007/s00415-016-8332-8