Myasthenia gravis

A disorder of neuromuscular transmission leading to fluctuating weakness and fatigue. A myasthenic crisis may give rise to a generalized paralysis and assisted ventilation may be required. It is one of the best known autoimmune diseases and the antigens and disease mechanisms have well been identified. Weakness is caused by circulating antibodies that block acetylcholine receptors at the neuromuscular junction. Acetylcholine is a chemical substance that sustains muscle contraction by stimulating the muscle fibers by binding to its receptors. The immunologic reaction against these receptors and consecutive damage of the neuromuscular endplate give rise to deficient stimulation of muscle fibers. Patients frequently present with restricted movements of eye muscles and eyelids, difficulty swallowing and speaking, generalized weakness and fatigue. Myasthenia gravis is usually treated by cholinesterase inhibitors, immunosuppressive drugs, thymectomy and plasma exchange. Although the term gravis means grave, recent developments in disease treatment have made the prognosis more favourable. However a considerable portion of patients still find it necessary to seek admission to the intensive care units for assisted ventilation.