Myasthenia gravis in mothers and their newborns

Abstract

Myasthenia gravis is a complex autoimmune disorder. Anti-AChR antibodies destroy elements of the postsynaptic membrane of the myoneural junction in affected muscle groups. This results in decreased nerve-impulse transmission. Myasthenic patients have diminished skeletal muscle strength and tire rapidly with exercise. Pregnancy threatens maternal myasthenic exacerbation and crisis, particularly early in the puerperium. The medication requires frequent adjustment during pregnancy due to changing requirements and physiologic changes in absorption and excretion. Myasthenia results in an increase in maternal mortality, morbidity, pregnancy wastage, and premature labor. Anticholinesterase medications and corticosteroids are the mainstays of medical therapy of maternal MG. Thymectomy, plasmapheresis, immunosuppressant drugs, gamma globulin, and ACTH are adjuvants of varying usefulness. Enforced rest periods, a tranquil environment, and prompt treatment of intercurrent infections are important for myasthenic mothers. The management of myasthenic crisis requires hospital intensive care with mechanical respiratory support and careful monitoring of blood gases. Plasmapheresis is an effective means of controlling crises. It is usually combined with intensive steroid and or immunosuppressant therapy. The myasthenic mother undertakes pregnancy with increased risk to herself and her infant. There is a 40% chance of exacerbation of her MG during pregnancy and an additional 30% risk in the puerperium. Maternal mortality risk is approximately 40 per 1,000 live births. Perinatal mortality approximates 68 per 1,000 births, five times that of uncomplicated pregnancies. Modern management minimizes these risks to the extent that pregnancy is not precluded in myasthenic women. A good outcome depends on meticulous maternal and fetal prenatal surveillance and early detection and management of exacerbations. Facilities and trained personnel must be available to support labor and manage vaginal or operative delivery. Intensive care of myasthenic crises is critical to the prevention of maternal complications and death.