Effectiveness of immunotherapy in myasthenia gravis: Epidemiological evidence from Sri Lanka

Background and objectives: Myasthenia gravis (MG) has been treated with immunosuppressive agents over the last three decades. This study aimed to determine the change in disease pattern that coincides with the advent of immunomodulatory therapy in the Sri Lankan patients. Methods: 112 Subjects diagnosed with myasthenia gravis in the Neurology Unit of the Teaching Hospital in Kandy, Sri Lanka were followed prospectively for 10 years from 1993 to 2003. The clinical features at initial presentation, course of illness, associated autoimmune diseases, MG-related complications, and treatment were documented. Results: The ratio of males to females was 2 to 1.2. The distributions of age of onset were not significantly different between males and females. Ptosis and extra ocular muscle palsies were the most common clinical features at presentation; 51 % had ocular myasthenia, and 9 % had other associated autoimmune disorders. Thymectomy was performed in 13 subjects, and eight subjects developed 23 MG-related crises over 10 years. At the time of analysis, 40 % did not require medications for treatment of their MG or needed only anticholinesterase agents to control their symptoms. Symptoms of MG were well controlled with prednisolone (26%) or a combination of prednisolone and azathioprine (28%). Another 5 % were resistant to treatment. The mortality rate was 2%. Conclusion: Myasthenia gravis predominantly affects males in Sri Lanka. No bimodal age distribution is found in the Sri Lankan population. Recent use of immunotherapy has changed the epidemiology of the disease and has increased the percentage of ocular MG and has thereby reduced disability and respiratory failure