Myasthenia gravis: Symptoms, diagnosis and treatment
What is myasthenia gravis?
Myasthenia gravis is a chronic condition involving a problem with the immune system that causes muscles to tire and weaken easily. For example, if you have myasthenia gravis you may notice that during a meal your jaw muscles become tired and weak. This will interfere with your ability to chew food. After you have rested for a little while, the muscles may become strong again allowing you to resume eating.
This waxing-and-waning weakness of muscles, worsening with use and improving with rest, is a hallmark of this particular disease. There typically are periods when you may notice more symptoms (called an exacerbation) interspersed with periods when your symptoms decrease or disappear (called remission).
The disease most commonly affects muscles that control eye and eyelid movement, so the first symptoms you notice may be eyelid drooping and/or blurred or doubled vision. Many myasthenia gravis patients start out with this "ocular myasthenia". The majority will go on to develop weakness in other muscle groups within one or two years.
Myasthenia gravis which affects several muscle groups throughout the body is called generalised myasthenia gravis. Other common muscle groups that are affected may make it difficult for you to chew, swallow, smile, shrug, lift your arm up, grip, rise to stand or walk up stairs. When the muscles necessary for breathing are affected, a patient is said to be in myasthenic crisis. This is a life-threatening situation.
Myasthenia gravis affects about one person in every 10,000 in the UK. It can develop at any age, but is most common in women under 40 and men over the age of 60.
If a woman with myasthenia gravis gives birth, the baby may have some temporary but potentially life-threatening muscle weakness (neonatal myasthenia) because of antibodies that have transferred from the mother's bloodstream. Typically, during the baby's first weeks of life, the antibodies are cleared from the baby's circulation and the baby develops normal muscle tone and strength.