Provided the nice radiological and clinical recovery, which anti MOG Abs became negative, in the context of an initial and unique neurological event, it was decided to keep the patient without specific treatment. Open in a separate window Figure 1 (A, B) First brain MRI showing optic nerves, superior cerebral peduncles and periaqueductal FLAIR hyperintensities (arrows). the acute phase treatment, and that anti MOG Abs became negative, it was decided to keep the patient without specific treatment. However, during follow-up, while the patient was asymptomatic, a control brain MRI showed the appearance of new lesions with morphology and topography suggestive of multiple sclerosis (MS). This, added to the presence of OB, made the diagnosis of pediatric-onset MS (POMS) likely. Immunosuppressive treatment was restarted with a good response since then. Unlike adult-onset MS, children with POMS may usually not have entirely typical clinical and radiological features at presentation. In many cases, the time factor and close clinical and radiological monitoring could be critical to make an accurate diagnosis. Keywords: acquired demyelinating syndrome (ADS), myelin oligodendrocyte glycoprotein (MOG), MOG antibody-associated disease (MOGAD), neuromyelitis optica spectrum disorder (NMOSD), multiple sclerosis (MS), pediatric onset multiple sclerosis (POMS) Introduction Acquired demyelinating syndrome (ADS) is defined as the first event of neurological dysfunction, acute or subacute onset, associated with evidence of inflammatory demyelination of the central nervous system (CNS), including the optic nerves (Absoud et al., 2013). The first demyelinating event or ADS in children 18 years can have a very varied clinical and radiological expression. The main diagnoses that encompass an ADS in the pediatric age are acute disseminated encephalomyelitis (ADEM), multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody disease (MOGAD) (Luchesa Smith et al., 2022). Although important advances have occurred in recent A-419259 years in terms of establishment of refined diagnostic criteria, A-419259 identification of anti MOG and aquaporin-4 (AQP4) antibodies (Abs), as well as progress in therapeutic management, the clinical-radiological and biological overlap of the spectrum of pediatric demyelinating disorders, makes the diagnostic process of a child with ADS truly challenging (Krupp et al., 2013; Chitnis, 2019). In this context, we A-419259 will describe an illustrative case report. Case report We present a 9-year-old girl, from Morocco, with no medical history except for type 1 diabetes mellitus in her father. In December 2019, the patient was referred to the Emergency Department of our hospital due to decreased visual acuity in both eyes for 3 days, associating ocular pain with eyes mobilization. In the last 24 h she added gait disturbance and vomiting. The week before symptoms onset, the patient had presented an upper respiratory infection with fever. The first ophthalmological assessment revealed a visual acuity (VA) of 0.05 in the right eye (RE) and 0.08 in the left eye (LE) with raised and poorly defined papillae, predominantly in the LE. The neurological examination showed dysarthria, nystagmus, ataxic gait, generalized hyperreflexia and bilateral Babinski. Ambulation without support was Rabbit Polyclonal to MEKKK 4 not possible. The physical disability measured by the Expanded Disability Status Scale (EDSS) was 6.0. An urgent brain and spinal cord MRI was performed, which identified subtle lesions affecting the posterior fossa, specifically the superior cerebral peduncles, periaqueductal gray matter, right middle cerebellar peduncle, both cerebellar hemispheres, and the area postrema. A subtle involvement of the right thalamic nucleus and subcortical white matter of right frontal and temporal lobes was observed, with hypersignal of both optic nerves and chiasm, as well as the diencephalon. After gadolinium administration, multiple lesions involving the brainstem and cerebellum showed poorly defined cotton-wool enhancement, with very striking uptake along both optic nerves. Likewise, multisegmental involvement of the spinal cord was found, specifically at the cervical (C2 and C6) and dorsal levels (D8-D9 and D11-D12). Lesions were short and peripheral, with ill-defined uptake after.