Myasthenia gravis is a chronic neuromuscular condition. If you
have myasthenia gravis, you experience weakness from using the
same muscles over and over. A simple chore like brushing your
teeth, for example, can become exhausting. With myasthenia
gravis, muscles return to normal after a short rest. But then
with repeated use, they become weak again. This occurs because
your body is making antibodies that block nerve impulses to
muscle cells. It can be dangerous when muscles involved with
swallowing or breathing are affected. The cause of myasthenia
gravis is unknown. But scientists believe the thymus gland plays
a role in its development. The thymus is a butterfly-shaped
gland located in front of the heart, just behind the breastbone.
Its entire function is to produce immunities to disease and
infection. That's why the thymus is very large in infants and
small in children. It shrinks over time, getting smaller after
most of its job is done. Myasthenia gravis can be very difficult
to diagnose. Someone using mu