Myasthenia gravis

"The prognosis is positive and in most cases tends to stabilize with treatment".


Myasthenia gravis is a disease of the neuromuscular junction, of autoimmune etiology and characterized by variable muscle weakness, which appears after physical activity and recovers with rest.

Only striated or voluntary muscles are affected, and not involuntary muscles such as the heart or intestines.

Although myasthenia gravis can be fatal if a respiratory crisis is not treated immediately, with proper care, patients usually have a normal life expectancy.

The disease tends to stabilize within a few years of its onset, and tends not to be progressive, although the severity of the disease can vary rapidly.

The typical patient who is not under treatment may feel strong after a night's sleep or a nap, but as the day progresses the weakness increases.

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What are the symptoms of myasthenia gravis?

Although myasthenia gravis can manifest itself differently in each patient, the clinical picture is characterized by variable muscle weakness and fatigue, always in relation to physical activity, although a worsening throughout the day is common and reversible in whole or in part with rest.

Usually its first symptoms are the fall of the eyelids (palpebral ptosis) and the double vision or diplopia, since the clinical manifestations are located mainly in the extrinsic musculature of the eye. It appears in up to 90% of patients in an asymmetric and changing form.

Weakness of the bulbar muscles can produce difficulty in speaking, chewing and swallowing.

The most common symptoms are:

  • Muscle weakness and fatigue.
  • Drooping of the eyelids.
  • Double vision.

These symptoms can extend to the extremities with lack of strength in the arms and legs. Unlike other neuromuscular diseases, weakness in the extremities caused by myasthenia gravis is not symmetrical, that is, one side of the body is often weaker than the other.

The severe part of myasthenia is especially evident when the weakness involves the respiratory muscles. In these cases, dyspnea and acute respiratory insufficiency may occur, and hospital admission may be required. This situation is called myasthenic crisis.

Do you have any of these symptoms?

You may have myasthenia gravis

What causes myasthenia gravis?

The cause of this disease is not known today, although the finding of anti-receptor antibodies to acetylcholine presupposes an autoimmune basis.

This means that our own immune defense system, by mistake, is able to recognize as foreign, attack and destroy some component of the tissues of our own body.

The relative frequency with which the thymus is affected (thymoma in 10% of cases and thymic hyperplasia in 70%), with which other autoimmune diseases and other autoantibodies are associated, also supports the autoimmune pathogenesis of this disease.

Who can get myasthenia gravis?

It is a rare disease and although it can appear at any age, it usually begins to manifest itself between the second or third decade of life.

Sometimes, children born to non-myasthenic mothers present symptoms due to genetic defects that affect neuromuscular transmission. This is known as congenital myasthenia.

It affects predominantly women, especially when it starts below the age of 40 and there is no racial predominance.

How is myasthenia gravis diagnosed?

<p>Imagen Laboratorio de Bioquimica&nbsp;</p>

If myasthenia gravis is suspected due to the clinical picture and the physical examination, the diagnosis should be confirmed by performing complementary explorations such as:

  • Administration of anticholinesterase drugs. The edrophonium test (Tensilon®) consists of achieving a rapid antimyasthenic effect.
  • Electrophysiological studies. There are two tests that are the test of repetitive stimulation (sensitivity of 77%) and the isolated fiber electromyograph (sensitivity 92%).
  • Determination of anti-receptor antibodies to acetylcholine.

They are positive in up to 50% of patients with ocular myasthenia and in 75% of the cases of generalized myasthenia.

A tumour of the thymus (thymoma) should always be ruled out by CT or MRI, the thyroid function should be studied and the presence of other autoimmune diseases should be ruled out.

How is myasthenia gravis treated?

Anticholinesterases are the first choice group of drugs and their action is to block the degradation of acetylcholine by the enzyme cholinesterase. This type of drug helps make more acetylcholine available for the muscle to work better.

Based on the immune mechanism by which the disease occurs, corticosteroids or other immunosuppressants such as methotrexate, azathioprine or cyclosporine A can be used alone or in association with corticosteroids.

With this same idea, plasmapheresis has also been used. This technique achieves rapid clinical improvement.

Intravenous administration of immunoglobulins is a procedure contrary to plasmapheresis, attempting a general suppressive effect on the immune system. As with plasmapheresis, the improvement is rapid and transitory.

The surgical treatment consists of the removal of the thymus (thymectomy). It constitutes the second therapeutic option, after anticholinesterases and before using other previously indicated treatments, achieving improvements in approximately 85% of patients.

Where do we treat it?


The Department of Neurology
of the Clínica Universidad de Navarra

The Neurology Department has extensive experience in the diagnosis and multidisciplinary treatment of neurological diseases.

We offer a diagnosis in less than 72 hours, along with a proposal for personalized treatment and post-consultation follow-up of the patient by our specialized nursing team.

We have the most advanced technology for an accurate diagnosis with cutting-edge equipment such as HIFU, deep brain stimulation devices, video EEG, PET and epilepsy surgery, among others.

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Why at the Clinica?

  • State-of-the-art diagnostic assistance with great work in research and teaching.
  • Specialized nursing team.
  • We work together with the Sleep Unit.

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