Introduction

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune demyelinating disorder characterized by extensive transverse myelitis, optic neuritis, and area postrema syndrome (APS), a clinical entity defined by intractable nausea, vomiting, or hiccups (singultus) lasting for at least 48 hours. Its prevalence ranges from 0.3 to 4.4 cases per 100,000 adults, with an incidence of 0.05-0.4 per 100,000 per year and a marked female predominance (9:1 ratio), typically presenting in the third decade of life [1-3]. This condition belongs to the spectrum of antibody-mediated central nervous system disorders, alongside myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and multiple sclerosis (MS). Although clinical overlap led to the historical consideration of NMOSD and MOGAD as MS variants, distinct clinical, serologic, imaging, and prognostic features established them as independent entities by 2023, with MOGAD being more frequent and carrying a better prognosis [2-5].

In Colombia, NMOSD onset occurs between the ages of 40 and 60 years, with a prevalence of 5.3 per 100,000 inhabitants - among the highest in Latin America - and a 3:1 female-to-male ratio [6,7]. While susceptibility genes remain unidentified, human leukocyte antigen (HLA)-DPB1*0501 associations have been reported in Asian populations. Both infections and vaccines (yellow fever, influenza, hepatitis B, HPV, and COVID-19) have been implicated as triggers [8].

NMOSD pathogenesis involves immunoglobulin G antibodies against aquaporin-4 (AQP4) water channels on astrocytes in the spinal cord, optic nerves, pia mater, and ependymal surfaces. Complement activation triggers neutrophil and eosinophil degranulation, immune complex deposition, axonal injury, and neuronal death, facilitated by blood-brain barrier-deficient regions such as the area postrema [1,5]. Conversely, MOGAD features predominantly extrathecal autoantibody production (though intrathecal synthesis may occur). Interleukin-6 drives MOG-IgG-secreting plasmablasts, which cross the blood-brain barrier, target oligodendrocytes, and trigger complement-mediated damage alongside CD4+ T-cell activation (whereas CD8+ T cells predominate in MS) [5].

The 2015 International Consensus Diagnostic Criteria for NMOSD require optic nerve involvement (unilateral or bilateral acuity/motility impairment) plus spinal cord involvement, intractable nausea/vomiting, headache, or sensory loss. Cerebrospinal fluid typically lacks oligoclonal bands (<20% of cases), though hyperproteinorrhachia (>40 mg/dL) or pleocytosis (>50 cells/field) may occur. Magnetic resonance imaging (MRI) demonstrates spinal cord edema with contrast enhancement in the optic nerves, brainstem, diencephalon, hypothalamus, and periventricular regions [2]. Since 2023, live-cell assays for AQP4 and MOG antibodies have been mandatory [3,5].

Pediatric cases (5% to 10%) mirror adult presentations, radiology, and laboratory findings, permitting use of identical diagnostic criteria [1,9]. Since 2020, increasing reports have documented an association between NMOSD and SARS-CoV-2 infection [10,11] and COVID-19 vaccination [11,12], with AQP4+ mechanistic links established by 2023 [13]. Vaccine- and infection-related cases share similar clinical courses [11], though pediatric cases remain scarce [10,14]. Post-COVID-19 or post-vaccination MOGAD exceeds NMOSD (2:1 ratio), although both constitute <1:1,000,000 events, predominantly affecting adults with encephalitis. MOGAD maintains a superior prognosis, whereas pediatric NMOSD appears more treatment-refractory [14,15].

We present a pediatric post-COVID-19 NMOSD case, underscoring its inclusion within SARS-CoV-2 immunologic complications - a highly morbid yet fully treatable entity when recognized early.