Myasthenia Gravis- Origins, Causes, and Recognizing Symptoms

Facts on Myasthenia gravis

1. In Myasthenia gravis, the immune system mistakenly attacks the cells or proteins needed for normal muscle function.
2. The most common symptoms of myasthenia gravis are drooping eyelids, double vision, difficulty speaking, swallowing, chewing, and breathing. These symptoms can vary in severity and frequency depending on the person and the activity level.
3. There is no cure for myasthenia gravis, but treatments can help manage the symptoms and improve the quality of life.
4. Myasthenia Gravis may result in fatal respiratory issues. Patients are more likely to develop autoimmune diseases such as systemic lupus erythematosus (lupus), rheumatoid arthritis, and thyrotoxicosis.
5. Anticholinesterase medications like Neostigmine or Pyridostigmine can enhance nerve-muscle communication, helping to improve muscle strength and reduce weakness in some people with myasthenia gravis.

Symptoms of Myasthenia Gravis

The voluntary muscles become weak as a result of myasthenia gravis. Usually, the autonomic muscles of the heart and digestive system remain unaffected. MG causes muscular weakness that worsens with exercise and improves with rest. Different muscles in the body may be affected by the symptoms of MG, which may vary in severity. Some of the symptoms of myasthenia gravis are discussed below:

1. Muscle Weakness: The main sign of this condition is skeletal muscle weakness. It frequently begins in the eye muscles and results in Ptosis. (Ptosis is when one or both eyelids droop. You have droopy eyelids, which may affect your vision and make it hard to keep your eyes open).
2. Blurring vision: Double vision, or diplopia, occurs when a single object appears as two different images.
3. Facial weakness: Problems like smiling and controlling facial expressions might result from facial muscular weakness.
4. Limb Weakness: MG can cause weakness in the muscles of the arms and legs, making it challenging to lift items or even difficult to stand, walk, climb stairs, or even brush your hair.
5. Neck and Throat Weakness: Neck muscular weakness can make it challenging to hold up the head, and control of the head posture can get complicated. Throat muscle weakness can cause difficulty chewing and swallowing, which might cause choking while eating or drinking.
6. Respiratory muscle weakness: In severe cases, MG can weaken the respiratory muscles, which might result in shortness of breath, breathing problems, and even respiratory failure.

Causes of Myasthenia Gravis

Although the specific cause of MG is not entirely understood, it is thought to involve a combination of genetic, environmental, and immunological factors.

1. Autoimmune response: When the body’s immune system recognizes potentially hazardous compounds, it produces proteins called antibodies. Antibodies may be developed when the immune system mistakenly views healthy tissue as a harmful substance, as in myasthenia gravis. When a person has myasthenia gravis, their bodies create antibodies (antibodies to the acetylcholine receptor, antibodies to other proteins, such as MuSK (Muscle-Specific Kinase) protein) that block or destroy the receptor site, preventing the muscle cells from receiving neurotransmitters, which are signals from the brain’s nerve cells.
2. Genetic predisposition: Genetic investigations have primarily identified particular HLA alleles linked to susceptibility to MG. However, in a recent genome-wide association study (GWAS), both TNFAIP3-interacting protein 1 (TNIP1) and tyrosine phosphatase non-receptor 22 (PTPN22) were highlighted as being connected to MG. A few genetic components contribute to the development of MG. Some people can be more susceptible to this condition due to a genetic predisposition.
3. Environmental triggers: The autoimmune response is thought to be triggered by environmental factors. Viral infections, stress, and other environmental variables that might upset the immune system’s balance may be among these triggers.
4. Medications: Some common medications you take can induce or exacerbate the symptoms of MG, like- antibiotics, beta-blockers, verapamil, quinidine, lithium, and prednisone.

Diagnosis of Myasthenia Gravis

The diagnosis of myasthenia gravis can be challenging because it can mimic other conditions that cause similar symptoms. Your primary care physician must consider clinical features, laboratory tests, and imaging studies. Therefore, it is essential to consult a neurologist with experience managing this disorder and follow their treatment recommendations.

Here are some of the steps involved in the diagnosis process:

1. Your primary care physician will ask about your medical history and symptoms, such as droopy eyelids, double vision, difficulty speaking, swallowing, chewing, and breathing. You need a physical examination to check your muscle strength, reflexes, sensation, coordination, and balance.
2. Blood tests to look for acetylcholine receptor antibodies and anti-Musk antibodies.
3. Imaging studies such as CT or MRI scans to check for abnormalities in your thymus gland or other organs related to myasthenia gravis.
4. Nerve conduction measures the speed at which electrical signals pass through a nerve.
   Single fiber electromyography (EMG) to assess the electrical activity traveling between your brain and muscles. This test involves inserting a fine wire electrode through your skin and into a muscle to record its response.
5. The repetitive nerve stimulation (RNS) test measures how well your nerves can signal your muscles. This test involves attaching electrodes to your skin over the muscles to be tested and applying small pulses of electricity. The results show whether the nerve function improves or worsens with fatigue.
6. Pulmonary function tests (PFTs) to check if MG is affecting your breathing.
7. A drug called edrophonium (Tensilon) may also be used as an adjunctive test to diagnose myasthenia gravis. This drug is given intravenously through a vein and causes temporary weakness in some muscles. If you have myasthenia gravis, you should experience more weakness than average after receiving this drug.

Complications of Myasthenia Gravis

1. Myasthenia Gravis may result in fatal respiratory issues. Patients are more likely to develop autoimmune diseases such as systemic lupus erythematosus (lupus), rheumatoid arthritis, and thyrotoxicosis.
2. Respiratory muscle weakness attacks are called crises (myasthenic crises). These episodes may happen suddenly when using too much or too little medicine. These outbursts often only last a few weeks. You may need hospital admission, where ventilator support may be required to help you breathe.
3. Long-term use of medications used to treat MG could cause side effects like osteoporosis, weight gain, and an increased susceptibility to infections.

Treatment of Myasthenia Gravis

Myasthenia gravis treatment: Common medications like anticholinesterase drugs and immunosuppressants are often prescribed to manage myasthenia gravis symptoms. However, these medications come with limitations and potential side effects, prompting a search for alternative approaches.

• Non-Pharmacological treatment

Non-pharmacological treatments offer a holistic approach to managing myasthenia gravis. The shift towards holistic health has led individuals to explore complementary therapies that focus on overall well-being rather than solely targeting symptoms.

• Pharmacological treatment:

1. Anticholinesterase medications like Neostigmine or Pyridostigmine for symptomatic treatment, such as to enhance nerve-muscle communication. These medications can help improve muscle strength and reduce weakness in some people with myasthenia gravis
2. Immunosuppressive agents, such as corticosteroids and non-steroid immunosuppressants like azathioprine, mycophenolate mofetil, methotrexate, cyclosporine, tacrolimus, sirolimus, rituximab, cyclophosphamide to suppress the immune system response if you have severe symptoms and previous medications have not been successful.
3. Immunomodulatory therapies like plasmapheresis and IVIg: IVIg treatments appear to modify the immune system temporarily and are used to treat your rapidly worsening MG. Plasmapheresis, or “plasma exchange,” is a procedure that removes antibodies from the blood and is done for patients experiencing pronounced symptoms of MG or those requiring enhanced strength before a surgical procedure. Both of these treatments offer short-term relief.

• Surgical Treatment:

Surgical treatment of MG involves removing part or all of the thymus gland located behind the breastbone and producing antibodies that attack the neuromuscular junction. Thymectomy can help reduce or eliminate some of the antibodies and improve symptoms in some people with myasthenia gravis. Thymectomy may provide a durable remission or lessen the need for medication.

Management of Myasthenia Gravis

Myasthenia gravis has no recognized treatment options. After receiving treatment, you could experience remissions—a time of no symptoms. You may frequently carry on with your everyday tasks by making lifestyle modifications. The following might be suggested:

• Avoid stressors, tiredness, and excess heat, which may aggravate symptoms.
• Use of an eye patch if uncomfortable double vision
• Your muscle strength can be preserved with physical therapy. This is particularly significant for the respiratory muscles.

References

1. Myasthenia gravis: Medlineplus medical encyclopedia (no date) MedlinePlus. Available at:https://medlineplus.gov/ency/article/000712.htm
2. https://www.medscape.com/viewarticle/991453?form=fpf
3. https://pubmed.ncbi.nlm.nih.gov/24361103/
4. https://www.myastheniagravis.org/about-mg/treatments/