Neuromyelitis optica (NMO) is an immune-mediated inflammatory disorder of the central nervous system. It is characterized by concurrent inflammation and demyelination of the optic nerve (optic neuritis [ON]) and the spinal cord (myelitis). Multiple studies show variations in prevalence, clinical, and demographic features of NMO among different populations. In addition, ethnicity and race are known as important factors on disease phenotype and clinical outcomes. There are little data on information about NMO patients in underserved groups, including Puerto Rico (PR). In this research, we will provide a comprehensive overview of all aspects of NMO, including epidemiology, environmental risk factors, genetic factors, molecular mechanism, symptoms, comorbidities and clinical differentiation, diagnosis, treatment, its management, and prognosis. We will also evaluate the demographic features and clinical phenotype of NMO patients in PR. This will provide a better understanding of NMO and establish a basis of knowledge that can be used to improve care. Furthermore, this type of population-based study can distinguish the clinical features variation among NMO patients and will provide insight into the potential mechanisms that cause these variations.

Background: There are limited data on multiple sclerosis (MS) patients in underserved groups, including Puerto Rico. In this study, we analyzed the characteristic of MS symptoms and number of relapses in Puerto Rican patients. We then compare these characteristics with MS patients from the US. The number of MS relapses is highly correlated with the treatment onset and adherence. Patients in Puerto Rico have been experiencing lengthy treatment delay. We will discuss the possible causes of such delay and its impact on MS prognosis. Methods: This retrospective cohort study consisted of the evaluation of 325 medical records from MS patients attending the Caribbean Neurological Center from 2014 to 2019. We gathered symptoms and comorbidities data as binary objects. The treatment delay was calculated based on the mean value of days between diagnosis and treatment onset for these groups of patients. Results: We found that on average, the treatment delay for MS patients in Puerto Rico (PR) to receive their medication was 120 days. The most common MS subtype was relapsing-remitting 72.8%, with a mean of 1.684 relapses per year. Initial symptoms were sensory 54%, visual 33.1%, motor 28.8%, coordination 23.2%, fatigue 9.7%, memory 7.3%, depression 6.5%, urinary 4.9%, gastrointestinal 2.4%, and sexual dysfunction 1.6%. The most common comorbidities were hypertension 18.4%, asthma 13.6%, and thyroid disease 12.8%. When we compared the comorbidities between the two populations, immune thrombocytopenia had the highest percent change with the value of almost 200% (0.001% of US patient vs. 0.8% of Puerto Rican MS patients). Conclusion: Patients from Puerto Rico had a 33% higher relapse rate compared to the one reported for MS patients in the US. This higher rate may be related to the long delay in receiving their medications. They also had a higher rate of complex comorbidities such as immune thrombocytopenia or thyroid disease. Our findings provide a proof of concept that delay in receiving medications can increase the number of relapses and complex comorbidities among MS patients.