Myasthenia Gravis
Myasthenia gravis is an acquired organ specific autoimmune disorder of neuromuscular transmission resulting from antibodies directed against the Acetylcholine receptor (AChR), Muscle specific tyrosine kinase (MuSK) and Lipoprotein related protein 4 (LRP4).
The incidence of myasthenia is slightly greater in women than in men (3:2) and the estimated prevalence is around 20 per 100000 population.
The clinical hallmark of myasthenia gravis is fluctuating weakness and abnormal fatigability of voluntary skeletal muscles that improve with rest. Drooping of eyelid, double vision, difficulty swallowing, slurring of speech or change of voice, and proximal limb weakness are the commonest symptoms. Occasionally, patients may present with difficulty breathing due to respiratory muscle weakness known as myasthenic crisis. Stressful life events, viral infections, pregnancy and delivery may precipitate the development of myasthenic crisis.
Diagnosis is mainly clinical supported by electrophysiologic (RNST,SFEMG) and lab tests (AChR ab). MG is associated with other autoimmune diseases in about 30% of cases, eg. thyroid diseases, RA, SLE etc.
Acetylcholine esterase inhibitors, immunosuppressive/immunomodulating drugs, plasma exchange (PLEX) and thymectomy are various treatment modalities in the selected set of patients with fairly good results.
Although the number of patients with MG continues to rise, it is still a rare disease. Further epidemiological research with a view to establish population registries and to estimate economic impact of disease on population as well as quality of life of patients with MG is needed.