Clinical and radiological profile of neuromyelitis optica spectrum disorders in an Ecuadorian cohort

Background: Neuromyelitis optica spectrum disorder (NMOSD) is a complex disease characterized by a severe inflammation of the central nervous system (CNS). This disease typically manifests with recurrent optic neuritis (ON) and acute transverse myelitis (ATM). The clinical and radiological spectrum of NMOSD is little known in Latin America (LATAM) and few reports have been published in the literature so far. In Ecuador, no reports on NMOSD have been published. For this reason we aimed to assess the demographic, clinical and imaging characteristics of patients with NMOSD from third level hospitals from Ecuador.

Methods: This is a descriptive study in which we assessed medical reports of patients with inflammatory demyelinating diseases who were attended in third level hospitals from Ecuador in 2017. Then we applied the 2015 diagnostic criteria, those patients who met the new NMOSD diagnostic criteria were selected and analyzed. Additionally, exploratory sub-analyses were subsequently carried out.

Results: We identified 59 patients with NMOSD, the relative frequency of NMOSD was 15.9%. The multiple sclerosis (MS) /NMOSD ratio was 5.2:1. Twenty four percent of patients were newly defined as having NMOSD when 2015 criteria was applied. The median time to diagnoses was shorter by the 2015 criteria than 2006 criteria (p<0.001). NMOSD was more prevalent in women (female/male ratio 4.4:1). The disease onset was more frequent at the fourth decade of life. The most common symptoms at the disease onset were ON and the association of ON with ATM. The mean of expanded disability status scale (EDSS) was 4.8 (SD±1.8). Concomitant autoimmune diseases were infrequent in this population (11.9%). The brain magnetic resonance imaging (MRI) abnormalities were present in 25.7% of patients at disease onset. Spinal cord MRI showed longitudinally extensive transverse myelitis (LETM) in 91.5% of cases. Recurrent NMOSD was frequent in this cohort (88%). Positivity for antibodies against aquaporin-4 (AQP4-IgG) which was measured through indirect immunofluorescence assay (IIF) was identified in 81% of the patients tested. Patients with seronegative AQP4-IgG had higher grade of disability than seropositive patients (p<0.05). Ninety eight percent of patients received treatment with immunosuppressive drugs. Three patients died due to gastric cancer (1 patient) and infectious diseases (2 patients).

Conclusions: This is the first descriptive study in an Ecuadorian cohort of patients with NMOSD. We show a wide epidemiological, clinical and radiological spectrum of NMOSD.