Myasthenia gravis: A study from India

Background: We present the findings from the largest hospital-based studies on myasthenia gravis from India, using data collected over a period of 43 years from the Neurology Department in a tertiary referral center in India. Objectives: To study the clinical presentation, age at onset, gender distribution, serological status and thymic pathology in patients with myasthenia gravis. Materials and Methods: A retrospective study was carried out using records of patients with myasthenia gravis from the years 1965 to 2008. Results: Of 841 patients, 836 (611 males and 225 females) had acquired myasthenia (myasthenia gravis) and five congenital myasthenia. The median age at onset was 48 years (males 53 years and females 34 years). The peak age at onset for males was in the sixth and seventh decade and in females, in the third decade. Two hundred and twenty-two (26.31%) patients had ocular and 616 (73.68%) generalized myasthenia. Serological studies were done in 281 patients with myasthenia gravis for Acetylcholine receptor (AchR) antibodies of which 238 (84.70%) were seropositive. The most common histopathology was thymoma and the second most common was thymic hyperplasia. Conclusion: Myasthenia gravis in our study was more common in males (M:F of 2.70:1). There was a single peak of age at onset (males sixth to seventh decade; females third decade). The higher prevalence of thymomas in this series is in all probability related to selection bias as patients with thymic enlargement or more severe disease underwent thymectomy. Thymoma was more common in males; hyperplasia in females.

Keywords
Acetylcholine receptor antibodies, congenital myasthenia, myasthenia gravis, thymoma