Myasthenia gravis

Myasthenia gravis (MG) is a rare autoimmune disorder which involves skeletal muscle weakness. It is a progressive disorder which becomes worse with repeated use of the affected muscle. The muscles which are most commonly affected include those involved in speaking, chewing, swallowing, eye and eyelid movement and facial expressions. Myasthenia gravis can spread to the other body parts within one or two years. In severe cases, MG can become life-threatening.

Symptoms

The primary symptom of myasthenia gravis is the weakness of the skeletal muscles which are under one’s control. This weakness worsens with an increased use of the muscle. The symptoms of MG may vary from person to person and may include:

• Difficulty to climb the stairs or lift weights
• Slurring of speech
• Hoarseness in voice
• Trouble chewing and swallowing
• Difficulty with breathing
• Facial paralysis
• Fatigue
• Double vision
• Drooping of eyelids

Usually the symptoms get worse when the person is tired. Consult the doctor if the above symptoms are long-lasting or if they become bothersome.

Causes

Myasthenia gravis occurs when the immune system attack the body’s own healthy cells. The antibodies attack the receptors on the muscles, thereby, reducing their number. Due to this reduction in the available receptors, the signals from the nerves are not properly received by the muscles, leading to their weakness. However, the exact cause of such autoimmune reaction is not clear so far.

Risk factors

Although myasthenia gravis can affect people of any age group, it is more common from the age of 40 years in women, while in men it occurs usually after 60 years of age.

Diagnosis

The doctor checks the signs and symptoms and performs a physical examination of the patient. Additionally, the medical and medication history of the patient is collected. Following this, a neurological examination may be performed which includes:

• Checking for reflexes, muscle tone, eye movements and certain motor functions
• Looking for muscle weakness
• Testing the sensations in different areas

Further tests as mentioned below may help in a critical diagnosis of myasthenia gravis:

• Blood tests are performed to check for the presence of specific antibodies.
• Imaging tests such as a CT scan or an MRI give a detailed view of the chest region and help to exclude tumors.
• Repetitive nerve stimulation test is carried out by sending small electrical impulses to the muscles and the ability of the nerves to send signals to these muscles is measured.
• Tensilon test is done by giving the drug tensilon into the vein and the muscle movements are observed.

Treatment

In very rare cases, MG gets better even without treatment. Treatment aims at improving the symptoms and the quality of life of the patient. Treatment options as detailed below may be used either alone or in combinations:

Medications

• Cholinesterase inhibitors are the medicines which improve the communication between the nerves and the muscles. Therefore, these drugs improve the muscle strength and contraction. Side effects of these drugs include gastrointestinal (GI) upset, profuse salivation and sweating.
• Immunosuppressant drugs are given to prevent the immune cells from attacking the healthy body cells. However, they can cause serious side effects such as GI discomfort, kidney or liver damage.

Plasmapharesis

Plasmapharesis is the method in which harmful antibodies are removed from the blood to improve the muscle strength. However, it is a short-term treatment and is usually performed prior to surgery.

Surgery

Nearly 15% of the patients with MG are found to have a tumor in the thymus gland. This gland is located under the breastbone and is associated with the immune system. Therefore, treatment in such patients includes surgical removal of the thymus gland.

Hospitalization may be required if the symptoms such as breathing or swallowing difficulties worsen.

Lifestyle changes

Following measures can help to reduce the symptoms of myasthenia gravis:

• Taking plenty of rest to reduce the muscle weakness
• Avoiding stress and exposure to heat
• Eating in small quantities for several times which is easy for the associated muscles to handle
• Regularly visiting the doctor to talk  about problems such as double vision