CONDITIONS
Myasthenia gravis
Myasthenia gravis is a disease that causes loss muscles under the voluntary control to weaken and fatigue quickly due to faulty communication between nerves and muscles that are damaged. Myasthenia gravis is a rare autoimmune neuromuscular disease (where the body’s own immune system attacks itself) and has an estimated prevalence of 10 – 20 in 1,00,000 (approaching 0.02%) people in general population.
Although a disease affecting people of any age, myasthenia gravis is more common in women younger than 40 and in men older than 60.
What are the symptoms of Myasthenia gravis?
Symptoms or weakness of the muscle weakness worsens upon using the affected muscles and improve with rest. Muscle weakness in myasthenia gravis is irregular and comes and goes at regular intervals with symptoms progressing with time.
In general, MG may affect some muscle groups than others as follows:
Eye muscles:
Visual symptoms occur in 50% of the people with myasthenia gravis and these are:
- Droopy eyelids (ptosis)
- Double vision (diplopia) that resolves after closing one eye
Some people with MG have problems only with their eye muscles (ocular myasthenia), but most people develop weakness in other muscles.
Face, mouth, and throat:
- Slurred speech
- A weak or hoarse-sounding voice
- Trouble chewing or swallowing
- A change in facial expressions
Neck, arms, and legs:
- Holding the head up
- Difficulty using arms or hands
- Affect the gait of a person
Breathing muscles:
A person must immediately consult the doctor in case shortness of breath is experienced as myasthenia gravis may cause respiratory failure if the muscles that help in breathing become weak.
Some percent of the people may get sudden weakness in the jaw, throat, or breathing muscles. This is called myasthenia crisis and may require emergency treatment.
What are the causes of Myasthenia gravis?
In myasthenia gravis, a person’s immune system attacks the neuromuscular junction (the point of meeting between the nerve cells and muscle fibers). This neuromuscular junction is a communication point between the muscles and nerves by releasing certain chemicals.
In myasthenia gravis, a person’s own immune system starts producing antibodies that block or destroy many of the chemical receptors (acetylcholine) at the neuromuscular junction. With fewer receptor sites available, the muscles receive fewer nerve signals resulting in muscle weakness.
Why these antibodies are generated by a person may be attributed to certain factors like genetics or enlarged thymus gland. Factors that worsen myasthenia gravis include:
- Fatigue.
- Illness or infection.
- Surgery.
- Stress.
- Some medicines — such as beta blockers, quinidine gluconate, certain anesthetics and some antibiotics.
- Pregnancy.
- Menstrual periods.
How is Myasthenia gravis diagnosed?
Although, a regular or doctor or even an ophthalmologist (eye specialist) may be able to spot signs of myasthenia gravis, a person would be referred to a neurologist who may suggest the following tests:
Neurological examination
The following parameters are checked and testes by the doctor:
- Reflexes.
- Muscle strength.
- Muscle tone.
- Senses of touch and sight.
- Coordination.
- Balance.
Confirmatory diagnostic tests of myasthenia gravis might include:
Ice pack test – Bag filled with ice is placed on eyelid for a couple of minutes to see if it helps lift droopy eyelids.
Blood analysis – To check for nontypical antibodies that interrupt the receptor sites
Repetitive nerve stimulation – A needle is inserted into muscle the muscle to detect nerve problems. This is done by attaching electrodes to the skin over the muscles to be tested and small pulses of electricity is run through the electrodes. These pulses measure whether the nerve can send a signal to the muscle and the test is repeated several times to see if its ability to send signals worsens with fatigue.
Single-fiber electromyography (EMG) – Electrical activity between brain and muscle is measured and this is done by inserting a fine wire electrode through skin and into a muscle to test a single muscle fiber.
Imaging – A CT scan or an MRI may be ordered to check if for a tumor or other problem with the thymus.
Pulmonary function tests – To check the lung function and see if the muscle weakness is affecting the breathing.
What are the treatment options for Myasthenia gravis?
Treatments focus on symptom improvement, and this depends on the age, severity of disease and the speed of progression. Treatments are usually as follows:
Medications
- Drugs to increase muscle strength – In mild to moderate myasthenia gravis, anticholinesterase drugs are given to boost acetylcholine in the muscles
- Drugs to suppress your immune system – To slow the immune system, medications such as steroids, nonsteroidal immunotherapy, or long-term immunosuppressive drugs may be given
Intravenous therapy
A special treatment through a vein in neck, chest, or arm is given in case the symptoms get worse fast (myasthenia crisis), if other drugs are not enough to ease the symptoms.
IV therapy for MG include:
- Plasmapheresis
- Intravenous immunoglobulin (IVIG).
- Monoclonal antibodies.
Surgery
People with myasthenia gravis who may have a tumor in the thymus gland require surgery to remove the thymus gland (thymectomy).
What should a person with myasthenia gravis regularly do?
Get good nutrition – Weakness makes it hard to follow a healthy diet, and in that case partake smaller meals throughout the day or eat at a time of day with highest energy.
Exercise the right way: In MG, the muscles tire easily but regular movement may boost energy in the long run. Ask the doctor or a physical therapist for a safe workout routine.
Rest when tired: Active lifestyle with MG is possible but notice the early signs of fatigue and rest.
Know your triggers: Ask the doctors what to watch out for in MS as may incidences such as when a person is sick, or very active, on period, or post delivering a baby may result in increased fatigue.
Wear an eye patch: In case a person has double vision, wearing an eye patch can help.
References
- Rare Diseases Reviews (RDR) at Rare Diseases India (RDI), of Foundation for Research on Rare Diseases and Disorders. May 2024. https://www.rarediseasesindia.org/learnraredis/musculardystrophy
- Myasthenia gravis. Mayo Clinic. May 2024. https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/diagnosis-treatment/drc-20352040
- Myasthenia gravis. WebMD. May 2024. https://www.webmd.com/brain/myasthenia-gravis