Myasthenia is a chronic autoimmune disease in which antibodies destroy the communication between nerves and muscles, resulting in weakness of the skeletal muscles.
Being an autoimmune disease, it can often accompany vitiligo.
Myasthenia gravis affects the voluntary muscles of the body, particularly those that control the eyes, mouth, throat, and limbs.
The disease can affect anyone at any age, but is more common in young women (between the ages of 20 and 30) and in men aged 50 and over. A temporary form of myasthenia gravis can develop in the fetus when a woman with the condition passes antibodies to the fetus. It typically resolves in 2 to 3 months.
A crisis of myasthenia gravis can result in difficulty swallowing or breathing.
The cause of myasthenia gravis is unknown and there is no cure, but early diagnosis and prompt medical management can help people live longer and better.
What is myasthenia
Myasthenia is a chronic autoimmune neuromuscular disease that causes weakness in the skeletal muscles. Worsens after periods of activity and improves after periods of rest.
These muscles are responsible for functions involving breathing and moving parts of the body, including the arms and legs.
There is no known cure, but with current therapies, most cases of myasthenia are not severe. Available treatments are able to control symptoms and often allow people to have a relatively high quality of life. Most people with this condition have a normal life expectancy.
Myasthenia is neither hereditary nor contagious.
Myasthenia gravis symptoms
The hallmark of myasthenia gravis is muscle weakness. Some muscles such as those that control the movement of the eyes and eyelids, facial expression, chewing, speaking and swallowing are often involved in the disorder.
The onset of the disorder can be sudden and the symptoms are often not immediately recognized as myasthenia gravis. The degree of muscle weakness involved in myasthenia gravis varies greatly between individuals.
People with myasthenia gravis may experience the following symptoms:
- weakness of the eye muscles (ocular myasthenia gravis)
- drooping of one or both eyelids (ptosis)
- blurred or double vision (diplopia)
- change in facial expression
- difficulty swallowing
- shortness of breath
- speech disorders (dysarthria)
- weakness in the arms, hands, fingers, legs and neck
Sometimes the severe weakness of myasthenia gravis can cause respiratory failure, which requires immediate emergency medical attention.
Myasthenia symptoms: These can often resemble other conditions. Always consult your doctor for a diagnosis.
Myasthenia gravis Diagnosis
Your doctor can diagnose myasthenia based on symptoms and some tests. During the physical exam, the doctor will ask about your medical history and symptoms.
A common way to diagnose disease is to test how you respond to certain medications. Muscle weakness often improves dramatically for a short time when an anticholinesterase medicine is given. If the patient responds to the drug, the diagnosis of myasthenia is confirmed.
Other tests that can be done include:
- blood analysis. They look for antibodies that may be present in people with myasthenia gravis
- genetic tests. They are performed to check for any familiarity
- nerve conduction studies. A test called repetitive nerve stimulation is used to diagnose myasthenia gravis
- electromyogram (EMG). It is a test that measures the electrical activity of a muscle. An EMG can detect abnormal electrical muscle activity due to neuromuscular diseases and conditions
Myasthenia gravis causes
Causes of the disease may concern antibodies or the thymus gland.
Myasthenia gravis is an autoimmune disease. This means that the immune system, which normally protects the body from foreign organisms, mistakenly attacks.
Chronic myasthenia is caused by an error in the transmission of nerve impulses to the muscles. It occurs when normal communication between the nerve and the muscle is disrupted at the neuromuscular junction. A place where nerve cells connect to the muscles they control.
Neurotransmitters are chemicals that neurons use to communicate information.
Normally, when electrical signals or impulses travel along a motor nerve, the nerve endings release a neurotransmitter. This is called acetylcholine and binds to sites, the acetylcholine receptors, on the muscle. The binding of acetylcholine to its receptor activates the muscle and causes a muscle contraction.
In the disease, antibodies block, alter or destroy acetylcholine receptors at the muscle junction, preventing muscle contraction.
Antibodies to other proteins can also impair transmission at the neuromuscular junction.
The thymus gland controls immune function and may be associated with myasthenia gravis.
It gradually grows until puberty. After, its involution begins. During childhood, the thymus plays an important role in the development of the immune system because it is responsible for the production of lymphocytes or T cells (a specific type of white blood cell that protects the body from viruses and infections).
In many adults with the condition, the thymus remains large.
People with the disease typically have clusters of immune cells in their thymus and can develop thymomas (tumors of the thymus). Thymomas are often harmless, but they can become cancerous.
Researchers believe that the thymus gland may give incorrect instructions for the development of immune cells. In this way, the immune system would attack its own cells and tissues and produce antibodies to the acetylcholine receptor. Thus, the foundations are laid for the attack on neuromuscular transmission.
Myasthenia gravis therapy
There is no cure for myasthenia gravis. Often, however, the symptoms can be controlled.
Pathology is a lifelong medical condition. Early diagnosis is the key to managing the condition.
The goal of the treatment is to increase muscle function and prevent swallowing and breathing problems.
Most people with this condition can improve their muscle strength and lead normal or near normal lives. In severe cases, help with breathing and eating may be needed.
Treatment can include:
- medicines. Anticholinesterase drugs, steroids, or drugs that suppress the immune system response (immunosuppressants) can be used
- thymectomy. It involves the surgical removal of the thymus. The role of the thymus in myasthenia gravis is not fully understood, and thymectomy may or may not improve symptoms
- plasmapheresis. A procedure that removes abnormal antibodies from the blood and replaces them with normal antibodies from donated blood
- immunoglobulins. Administered intravenously. They help reduce the immune system’s attack on the nervous system
Myasthenia and Vitiligo
Myasthenia gravis is a neuroimmunological disease. The anti-acetylcholine receptor autoantibodies produced by the thymus and neoplastic thymus disturb the myonal junctions. This leads to the manifestation of myasthenic symptoms.
On the other hand, vulgar vitiligo is the most common pigmentation disorder. For vitiligo, caused by the destruction of melanocytes, numerous etiological hypotheses are suggested. One of these assumes that environmental, genetic and immunological factors influence the destruction of melanocytes induced by an autoimmune mechanism. Vitiligo definitely has a genetic side. In fact, 20% of patients with the disease have a family history.
Although there are various cases of autoimmune myasthenia accompanied by vitiligo vulgaris, the immunological relationship between the two conditions is not yet known. There is still no report that provides a detailed description of the clinical course of vitiligo vulgaris after the treatment of myasthenia.