Myasthenia gravis: discover the symptoms and treatments for this neuromuscular condition

Myasthenia gravis is an autoimmune neuromuscular disease characterized by muscle weakness that increases during activity and decreases with rest. It is caused by a defect or blockage in the transmission of nerve impulses to the muscles at the neuromuscular junction because the autoimmune response destroys the receptors for acetylcholine, a neurotransmitter substance. The thymus gland is believed to be involved in this destructive immune response since adults affected by myasthenia gravis have an abnormal thymus gland.

This disease most often affects young women under 40 and men over 60, but there are also cases of infantile and juvenile myasthenia gravis. It is not considered hereditary and is not contagious. The first noticeable symptom is usually the drooping of one or both eyelids (ptosis).

Causes of myasthenia gravis There is no normal communication between nerve and muscle

The immune system sends antibodies that cause a defect in the transmission of nerve impulses to the muscles, specifically, at the neuromuscular junction. The neurotransmitter acetylcholine, a substance that travels through the neuromuscular junction, adhering to its receptors and activating muscle contraction, is blocked, altered or destroyed by the antibodies.

It is suggested that the thymus gland, located under the sternum and which plays an important role in the development of the immune system in the first years of life, is related to the incorrect response of the immune system by generating incorrect instructions on the production of antibodies to acetylcholine receptors. Those affected by myasthenia gravis, which is large in children and grows until adolescence before shrinking and being replaced by fatty tissue over the years, have an abnormal thymus.

Types of myasthenia gravis:

- Ocular myasthenia gravis. It is limited to the eye muscles.

- Seronegative myasthenia gravis. It is related to antibodies against lipoprotein receptor-binding protein 4.

- Neonatal myasthenia gravis. Myasthenia transmitted by a seronegative mother during pregnancy. It is treatable in the newborn.

- Congenital myasthenic syndrome. It is a rare form of inherited myasthenia caused by defective genes that control proteins in the acetylcholine or acetylcholinesterase receptors (cholinesterase enzyme inhibitor that prevents the destruction of released acetylcholine).

Symptoms of myasthenia gravis Weakness and fatigue among others

Myasthenia gravis can affect any muscle, but symptoms most commonly occur in the muscles of the eyes, face and throat, and in the neck and limbs. The most common symptoms are:

- Drooping of one or both eyelids (ptosis).

- Changes in facial expression.

- Double vision (diplopia).

- Changes in speech and voice.

- Difficulty chewing and swallowing.

- Drooling ( thialism ).

- Respiratory problems.

- Weakness in the neck, arms and legs.

- Waddling.

- Difficulty climbing stairs.

Myasthenic crises can occur, which involve the weakening of the muscles that control breathing. This is a cause for medical emergency and requires the use of an artificial respirator. They can be triggered by stress, infections, fever or an adverse reaction to a medication.

People with myasthenia gravis are also more likely to develop:

- Hypothyroidism or hyperthyroidism.

- Rheumatoid arthritis .

- Lupus.

Diagnosis of myasthenia gravis Physical examination, neurological examination and various tests

The physical examination at the doctor's office may include, in addition to reviewing the medical history, the examination of reflexes, muscle strength, muscle tone, senses of touch and sight, coordination and balance.

- The edrophonium test, an injection of edrophonium chloride, temporarily improves muscle strength.

- The blood test looks for the presence of abnormal antibodies that alter the neuromuscular junction.

- In repetitive nerve stimulation, electrodes are placed on the skin of the muscles to measure the nerve's ability to send a signal to the muscle.

- Electromyography (EMG) measures electrical activity between the brain and muscles.

- Computed tomography (CT) or magnetic resonance imaging (MRI) can confirm whether there is an abnormality in the thymus or a tumor in this gland.

- Pulmonary function tests assess how the disease affects breathing.

Treatment and medication for myasthenia gravis Focusing on symptoms

Treatment is based on drugs, intravenous therapy, and surgery if there is a tumor in the thymus. Each case will require a different approach. The drugs of choice are cholinesterase inhibitors to improve communication between nerves and muscles; corticosteroids to limit antibody production; and immunosuppressants to reduce the activity of the immune system.

Plasmapheresis, filtering the blood to remove antibodies; intravenous immunoglobulin, which provides normal antibodies; and monoclonal antibody to alter the immune system are the intravenous therapies that may be considered.

In cases of a tumor in the thymus or thymoma, surgery, a thymectomy, may be considered.

Prevention of myasthenia gravis Without prevention

Myasthenia gravis cannot be prevented, but there are some precautions that can be taken to reduce its impact on quality of life. Those affected must rest a lot and avoid exposure to heat. They cannot carry out daily tasks normally, so they must know when they have the most energy to be able to deal with the matters that require more effort. Work or school performance is reduced, so it is important to have support and avoid overexertion at work or school.

They should avoid stressful situations, limits and unpleasantness, and it is very positive to follow a psychological support therapy to accept the disease and its limitations.