“Myasthenia gravis” came from the Greek words “mus” which means “muscle”, and “asthenes” which means “weak”; and from the Latin word “gravis”, which means “serious”. This is characterized by the deterioration of the nerves and muscles. The symptoms include muscle fatigue and weakness, difficulty in walking, swallowing, and talking, enlarged thymus, double vision, ocular weakness, difficulty in holding the head upright, and a snarling expression when trying to smile. The weakness may improve with rest and worsen when the affected muscles are used. Moreover, the symptoms may be aggravated by illness, stress, menstruation and certain medications like beta blockers, quinine, and antibiotics. The onset of this long-term neuromuscular disease can be sudden and the usual age of onset for females is under 40 while that of males is over 60.
Myasthenia is generally caused by the immune system’s production of antibodies which block muscles’ receptor sites for acetylcholine (hyperlink), a neurotransmitter responsible for the contraction of muscles. The antibodies also block the protein, muscles-specific receptor tyrosine kinase which helps in forming the nerve and muscle junction. This condition has no cure but treatments can help relieve symptoms such as increasing the amount of acetylcholine and therapeutic plasma exchange.