Co-occurrence of myasthenia gravis and neuromyelitis optica spectrum disorder: A case series and literature review.

BACKGROUND

Patients with myasthenia gravis develop other autoimmune diseases in 5-30% of cases and have a higher incidence of demyelinating disorders than the general population. An increased risk of neuromyelitis optica spectrum disorder following thymectomy has also been reported.

OBJECTIVE

To describe two adult patients from Bogotá, Colombia, with concurrent myasthenia gravis and neuromyelitis optica spectrum disorder after thymectomy, and to provide a literature review.

METHODS

A retrospective literature review of articles published up to October 2024 was performed using PubMed and Embase with the terms "Neuromyelitis," "Thymectomy," "Myasthenia Gravis," and "Aquaporin 4." Studies in English or Spanish reporting myasthenia gravis and neuromyelitis optica spectrum disorder were included. Additionally, two adult patients from Bogotá who developed neuromyelitis optica spectrum disorder after thymectomy for myasthenia gravis were analyzed.

RESULTS

60 patients were included, comprising 58 cases identified in the literature and 2 additional cases from our center. Two adult patients (one male, one female) previously diagnosed with myasthenia gravis developed neuromyelitis optica spectrum disorder symptoms following thymectomy. The literature search yielded 24 articles describing 58 patients, 94.8% were women. Myasthenia gravis preceded neuromyelitis optica spectrum disorder in most cases (85.7%). Thymectomy was reported in 39 of 58 patients (67.2%). Among patients in whom thymectomy preceded neuromyelitis optica spectrum disorder, the mean interval between thymectomy and NMOSD onset was 12.8 ± 9.3 years.

CONCLUSIONS

Myasthenia gravis and neuromyelitis optica spectrum disorder coexistence follow a consistent pattern, supporting shared autoimmune susceptibility. Further studies are needed to clarify its clinical implications.