Primary progression in NMOSD. Does it really exist?

Acute myelitis, in conjunction with a longitudinally extensive MRI pattern, is a core feature of aquaporin 4 IgG-associated neuromyelitis optica spectrum disorders (NMOSD). According to current diagnostic criteria for transverse myelitis and NMOSD, clinical worsening should not exceed 3-4 weeks from attack onset. Recently, we were able to document, through frequent clinical examination and radiological follow-up, the unusual case of an ab initio progressive myelopathy, ultimately attributed to aquaporin-4 autoimmunity. Although this case might merely represent an overlooked cluster of individual clinical attacks, it could, however, draw attention to the controversial concept of disease progression in the context of NMOSD.