Myasthenia gravis (MG)
Myasthenia gravis pseudoparalytica
In myasthenia gravis there is formation of autoantibodies to acetylcholine receptors for the biotransmitters the muscular side of the motor end plate, the place where the nerve signal is transmitted to the muscle. The reduction of these receptors leads to a load-muscular weakness.
The exact cause of this disease is still unclear, but it is likely that there is a connection with diseases of the thymus, as is observed in 85% of patients a change in this institution.
Furthermore, can be in about two thirds of the cases discuss specific psychological distress situations that precede the disease directly (eg death of a relative)
Frequency
Per 100,000 inhabitants myasthenia gravis occurs about five to ten times, with the female sex predominates.
Symptoms
- abnormal muscle fatigue during exercise. In the early stages of the disease, the muscular obtained after long breaks (eg, nap) return to normal proportions.
- Infestation especially the small muscles in the early stages
- Ptosis: drooping of the upper lid
- Dysarthria and Dysphagia: voice and swallowing disorders
Diagnosis
- typical image in the electromyography (EMG): reduction of the amplitudes of muscle potentials ("decrement") for the rapid succession of the following ("of repetitive") stimulation.
- Antibody detection in blood
- Tensilon ® test: administration of an inhibitor of the enzyme acetylcholinesterase. This breaks down acetylcholine, so that inhibition of this enzyme occurs through a short-term improvement of symptoms.
Complications
- Myasthene crisis: at 10% of those affected symptoms occurring in advanced stages of the disease. Here, there is a life-limiting breathing and swallowing muscles, which necessitates an intensive care.
- Cholinergic crisis: an overdose of acetylcholinesterase leads to muscle spasms
Therapy
- Removal of the thymus gland (thymectomy) leads in about 75% to a good result
- immunosuppressive long-term therapy (especially Aszathioprin and Korstikosteroide)
- With the drug pyridostigmine (Mestinon ®), an acetylcholinesterase inhibitor, can achieve rapid improvement in symptoms. However, the effect wears with time and the degradation of the receptors is not stopped.
- When failure of treatment with immunoglobulins or when a crisis myasthenen plasmapheresis is performed. Here, the part of the blood is exchanged in which are the antibodies.