An epidemiological study recently published in Neurología shows that almost all patients in a region of Mexico who have neuromyelitis optica spectrum disorder (NMOSD) have experienced disease recurrence.

This retrospective study included 58 patients, discovering an incidence of 0.71/100,000. This cipher is unexpectedly above that reported in the literature, almost 3 times the incidence in most Caucasian populations. 

Regardless, the prevalence was relatively low, at 1.09/100,000. Other non-Caucasian regions such as Iran, Malaysia, India, and Japan exhibit a prevalence of 1.9/100,000, 1.00/100,000, 2.6/100,000, and 4.1/100,000, respectively.


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Moreover, among the patients with NMOSD, mostly were females. Although the mean age at which symptoms appeared was 36 years, the final diagnosis was usually made in the fifth decade of life, at a mean age of 41 years.

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The most common symptom was transverse myelitis, present in 62% of the cases, although the most frequent first symptom was neuromyelitis optica in 58.6%. All patients had positive immunoglobulin G (IgG) against aquaporin-4 (AQP4), while nearly two-thirds of them (65.5%) showcased pathological findings on magnetic resonance imaging (MRI).

Almost all participants (94.8%) experienced disease recurrence, and the most frequently used treatment was rituximab, in 82.7% of the cases. This result is comparatively high, as in previous reports from other communities, the drug is often used by approximately 50% of patients. 

“However, it also raises questions about the response we have obtained when using rituximab more frequently than other populations, or whether the response to azathioprine, or mycophenolate mofetil, is similar to that of other populations reported,” the study concluded.

Reference

Mireles-Ramírez M, Velázquez-Brizuela I, Sánchez-Rosales N, Márquez-Pedroza Y, Hernandez-Preciado M, Gabriel Ortiz G. The prevalence, incidence, and clinical assessment of neuromyelitis optica spectrum disorder in patients with demyelinating diseases. Neurología (English Edition). Published online July 23, 2022. doi:10.1016/j.nrleng.2022.06.002