+A A-

Thymectomy & Myasthenia Gravis

Image title


Thymectomy – Thymoma and Myasthenia Gravis


The thymus is an organ located in your rib cage in front of the trachea (the windpipe). The thymus, an endocrine gland, begins to downsize, starting at adolescence. This organ, which plays a very significant role in the maturity of the immune system after birth, weighs about 20 g. The organ continuously enlarges, resulting in two times the weight at birth (approximately 40 g).


The thymus plays significant roles in the immunity system of the body up to adolescence. This gland takes role not only in the production of antibody, but also in cellular defense.


Thymectomy implies the surgical removal of the thymus.


Thymectomy is absolutely indicated for the tumor of thymus (thymoma). Thymoma causes cough due to close proximity of the gland to the windpipe and also shortness of breath in case of pulmonary metastasis.


On the other hand, thymoma is associated by a neuromuscular disease, namely Myasthenia Gravis, in one third of cases with thymoma.


Myasthenia Gravis is principally a neurological disorder and the underlying cause is an abnormality of the immune system. Although the condition is common in young women and elderly men, it can be seen at all ages.


Our muscles are signaled by the nervous system in order to contract or relax. When the immune system functions abnormally, antibodies are produced that attack the junction of nerves and muscles. Receptor implies the structure that is located on the muscle and senses the signals transmitted by nerves. Chemical substances play a role in this transmission between muscles and nerves. Acetyl choline is chemical substance that is commonly cited in Myasthenia Gravis. The ultimate result is the attack of the body to own tissues, referred to as autoimmune disorder in medical terminology. This disorder causes inability of muscles receive contraction and relaxation muscles carried by nerves. In conclusion, various symptoms emerge depending on the muscle involved, including but not limited to droopy eyelids, double vision and weakness of arm(s) and leg(s). If muscles of neck and throat are involved, it may cause inability to keep the head upright, difficulty swallowing and changes in the voice tone.


However, Myasthenia Gravis can occur in the absence of antibodies that compromise the communication between muscles and nerves. Therefore, there is no consensus on the factor that causes the autoimmune reaction – the underlying factor of Myastheania Gravis.


Thymectomy is the absolute indication for concomitant presence of Myasthenia Gravis and thymoma. However, thymectomy may help relieving symptoms of thymectomy if symptoms of thymoma are absent.


Diagnosis:

The first step of diagnosis in Myasthenia Gravis involves review of all symptoms and the health history. A physical examination is made that reviews all systems. As Myashthenia Gravis is a neuro-muscular disease, the physical examination principally focuses on the nervous system and muscles.


Vision, coordination of movements, reflexes, muscle strength and tone as well as tactile sensation and postural balance are assessed in detail.


Blood analyses are required to investigate autoantibodies that cause Myasthenia Gravis.


Electromyography (EMG) can be ordered by your doctor to determine the extent your muscles are involved.


Pulmonary function tests are ordered to check findings of your respiratory system.


CT or MRI is scanned to rule out or reveal association of Myasthenia Gravis and thymoma.


Treatment:

Treatment of Myasthenia Gravis starts with accurate diagnosis.


The principal problem is that the thymus produces auto-antibodies that attack the native cells of the body, resulting in the compromised neural conduction at the neuromuscular junction.


Therefore, medical treatment includes medications that improve the neural conduction or medications that suppress the immune system (corticosteroids and other immunosuppressive agents).


Another non-surgical treatment option is plasmapheresis. Plasmapheresis is used to remove auto-antibodies that damage the receptors, which regulate transmission of relaxation or contraction signals to the muscles, from the blood. Your blood is filtered by a special machine in this procedure. This treatment option enables regression of complaints for several weeks, as the production of auto-antibody will continue.


The last non-surgical option is intravenous immunoglobulins. Antibodies with normal function are administered into blood vessels in order to treat the condition. Although the risk of side effect is lower comparing to the immunosupression and the plasmapheresis, therapeutic effects are temporary and short lasting, as the case for other two options.


Surgical removal of the thymus:

Thymectomy is the absolute indication for concomitant presence of Myasthenia Gravis and thymoma. However, thymectomy may help relieving symptoms of thymectomy if symptoms of thymoma are absent.


The thymus gland can be removed with open surgery or minimally invasive surgery or videothoracoscopic technique.


Minimally invasive surgery is the ideal option due to particular advantages, including but not limited to less bleeding, mild postoperative pain and shorter stay at hospitals, but the best option will be determined by the thoracic surgeon.


Supportive treatment and life style changes

Your doctor may recommend medications to manage weakness of muscle and fatigue.


Particular symptoms, such as weakness of muscles and double vision, will bring safety risks in your social and work life, such as fall and fall-related injuries. Therefore, those risks can be minimized by assembling handles and handrails to corridors, stairs and bathroom.


You will required to use your muscle strength and energy efficiently in Myasthenia Gravis. You may even need help for activities of daily living when symptoms exacerbate.


There are some evidences that stress aggravate symptoms of Myasthenia Gravis. Therefore, stress management is a factor that should not be ignored in the management of this condition.