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MYASTHENIA GRAVIS (DISORDER OF THE NEUROMUSCULAR SYSTEM)

OVERVIEW OF MYASTHENIA GRAVIS

Myasthenia gravis is a chronic autoimmune neuromuscular disorder that occurs suddenly in which the immune system attacks the joint between the nerves and muscle called the neuromuscular joint of the body, in this disorder the antibodies attacks the acetylcholine receptor which are the protein on the muscle cell used for muscle contraction. Overtime because of the attack of the antibodies, the skeletal muscles become tired and stressed.

The name Myasthenia gravis is coined from the Latin and Greek origin meaning “grave or serious muscle weakness”, research has showed that myasthenia gravis is not contagious nor hereditary, it has to do with the immune system attacking the body although, genetic susceptibility plays a role about 3-5% in the occurrence of the disease since it can occur with different people in a family.

In Myasthenia gravis, the muscles attacked are the muscles responsible for breathing and moving parts of the body (voluntary muscles).

WHAT CAUSES MYASTHENIA GRAVIS?

The causes of myasthenia gravis are listed below:

  1. Antibodies: it is known that myasthenia gravis is an autoimmune disorder, in which the immune system attack its own body and cells, the antibodies block, attack and alter the acetylcholine receptor of the muscles which prevents the muscle from contracting and performing its normal function. Overtime the skeletal muscles break down and don’t function anymore they become weak and stressed.
  2. Thymus gland: the thymus gland is the main gland needed in the development of the immune system, which grows gradually during puberty then replaced by fat and grows smaller overtime. It is the gland that helps in production of the T-lymphocytes cells that helps to fight against any infection and viruses. Normally the thymus gland decreases in size and becomes less active during puberty into early adulthood but in people that have myasthenia gravis, the thymus gland remains large and there is cluster of T-lymphocytes cells gathered leading to thymomas (tumor of the thymus gland). Research has shown because of the clusters of the immune cells instructions are misinterpreted causing the autoimmune attack.

SYMPTOMS OF MYASTHENIA GRAVIS

Myasthenia gravis affects the whole muscular system especially the voluntary muscles in the body. People with myasthenia gravis experience the following symptoms which are listed below:

  1. Impaired speech of an individual (dysarthria)
  2. Shortness of breath
  3. Difficulty in swallowing (causing an individual to easily choke, making the liquids for swallowing easily come out from the nose)
  4. A change in facial expression, smile looking like a snarl
  5. Drooping of one or both eyelids (ptosis)
  6. Weakness of the eye muscles (called ocular myasthenis)
  7. Blurred or double vision (diplopia)
  8. Difficulty in breathing
  9. Weakness and fatigue in the neck and jaw

DIAGNOSIS OF MYASTHENIA GRAVIS

The diagnosis of myasthenia gravis can be done in the following ways

  1. Physical and neurological examination: The medical personnel perform an assessment to check for the muscle tone, coordination and sense of touch. In this the examiner asks the patient to smile, raise and object and walk to check the muscle tone.
  2. Blood Test: laboratory test is requested to see if there is presence of acetylcholine receptors antibodies, MuSK antibodies and the seronegative (negative antibody) myasthenia to know if it is abnormally high which can cause myasthenia gravis.
  3. Pulmonary function testing
  4. CT scan: Direct imaging is done to detect the presence of thymomas in an individual.
  5. An edrophonium test: it is a test that uses edrophonium chloride injection to test for ocular muscle weakness.

HOW IS MYASTHENIA GRAVIS TREATED?

Treatments of myasthenia gravis are listed below:

  1. Medications: the medications used for treating myasthenia gravis mainly used for suppressing the immune system and allowing the communication between the nerves and the muscle. Immunosuppressant: used for suppressing the immune system e.g. azathioprine (Azasan), mofetil (Cellcept) and cyclosporine (Sandimmun). Cholinesterase inhibitors: used to enhance communication between muscle and nerves e.g. pyridostigmine (Mestinon, Regonal).
  2. Surgical Treatment: the surgical therapy used for myasthenia gravis is known as thymectomy, in which the surgeon removes the thymus gland of the individual.

COMPLICATIONS OF MYASTHENIA GRAVIS

The complications of myasthenia gravis are listed below:

  1. Mental disorders (panic disorders, anxiety disorder and depression. This occurs mainly because of the stress that people with myasthenia gravis go through)
  2. Cataracts (occurs because of the long term use of corticosteroids)
  3. Osteoporosis(weak bones)
  4. Hip problems
  5. Stomach ulcers
  6. Diabetes
  7. High blood pressure
  8. Heart disease
  9. Myasthenic crisis (e.g. double vision, falling, weakness and problem with swallowing)
  10. Thyroiditis (infection of the thyroid gland)
  11. Scleroderma
  12. Lupus
  13. Multiple sclerosis

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