The cascade sign in aquaporin-4-IgG positive (AQP4-IgG+) NMOSD

Background: The cascade sign was reported in 2003 as pathognomonic of the parenchymal form of neuro-Behçet’s. At the time, diencephalo-mesencephalic lesions in neuromyelitis optica (NMO) were largely ignored. Only with the 2015 revision of NMO spectrum disorders diagnostic criteria, were localizations in these areas fully acknowledged. Case report: Here we report a case of AQP4-IgG+ NMOSD presenting with acute transverse myelitis, bilateral optic neuritis, with early brain magnetic resonance imaging (MRI) showing confluent diencephalo-mesencephalic lesions evoking the cascade sign (Figure 1, a-b). Conclusion: MRI presentation evoking the cascade sign might hinder the correct differential diagnosis and delay appropriate treatment in AQP4-IgG+ NMOSD.