Definition and causes
Myasthenia gravis is a rare auto immune disease with only one new case per year in around 200.000 citizens. Auto Immune means that the immune system attacks the body's own cells. In myasthenia gravis the link between nerves and muscles is adversely affected with anti bodies piling up compromising the connection between nerves and muscles.
As a reslut the muscles become weak and tire easily. Particularly the muscles of the eyes, throat, face and limps are mostly affected. It is very rarely hereditary and affects young or middle aged people, mostly women between 20 and 40 years.
The exact cause of myasthenia gravis is not known, but three out of four cases have an enlarged thymus gland (thymus is a gland in the chest, which contribute to the formation of immune defense cells) and in some cases Thymoma (tumour in the thymus gland) is present. Other autoimmune diseases are often concomitant with myasthenia gravis, for example increased activity in the thyroid.
Symptoms of Myasthenia Gravis
Decreased muscle force is the main symptom. It usually start in the face with double vision, hanging eyelids, speech trouble, problems with swallowing and fatigue. To begin with symptoms are most pronounced in the evening, and muscle weakening disappears after a short rest. Later the muscle weakness spreads to the arms and legs, and the patient experience difficulty in walking, combing the hair, carrying objects and so forth.
Diagnosis and treatment of Myasthenia Gravis
The diagnosis of myasthenia gravis involve meassuring antibodies in the blood, and also examination of the muscle response to electrical stimulation. The latter is called Electromyography (EMG). Also a thorough examination of all the body's muscles and their force is made.
Another important is the injection of the drug adrohonium into a vein which increases the connection between nerves and muscles (an acetylcholine-esterase inhibitor). If this results in a temporary improvement of the symptoms there is strong indication of of myasthenia gravis.
Treatment depends on the cause of the illness and its severity, and may consist of:
Acetylcholine esterase-inhibitor: Drugs that increase the connection between nerves and muscles. This is the first treatment provided.
Removal of the thymus: Performed by those who have an enlarged thymus. This improves symptoms in some individuals.
Adrenal cortical hormones (steroids): Used in addition to acetylcholine esterase-inhibitor.
Chemotherapy: Used in very severe cases.
Filtering the blood (apheresis): Removes the excess anti bodies and improves the symptoms considerably for a few months.
Outlook and complications
Some have only symptoms with eyes, but in most people the disease is progressive in character. As a general rule the deterioration stops after a few years, but the disease can be very volatile and there can be rapid deterioration (myastene crises). The disease is rarely fatal and better treatment has improved the outlook considerably, although it does not lead to genuine recovery.