Myasthenia gravis (MG) is a type of neuromuscular disease that causes certain muscles to fatigue and weaken. The disease is considered to affect voluntarily controlled muscles such as those involved in chewing, facial expression, speaking, eye and eyelid movements and swallowing. The disease occurs in all sexes and age groups. However, it commonly affects women under 40 years and people aged between 50 and 70 years in both sexes, though it is known to affect older people at large (Sieb, 2014). Within the UK, it is estimated that in 100,000 people, there are 15 cases of the disease. In the United States, it is estimated that about 0.5-20.4 per 100,000 people are infected by MG (Sathasivam, 2014).
Myasthenia gravis is described as an autoimmune condition affecting muscles and nerves. As an autoimmune condition, the disease is caused when healthy tissues are mistakenly attacked by the body’s immune system. It is thus evident that it is the production of antibodies by the immune system that blocks or damages muscle receptor cells to cause myasthenia gravis (MG). Although MG is one of the most common disorders of the neuromuscular transmission, it is one of the most common treatable neurological disorders. Commonly, two major tests have been used in diagnosing the disease: single-fiber electromyography (SFEMG) and anti-AChR antibody tests. Although the anti-MuSK antibody test can be used, it is yet to be validated in the UK industry (Sathasivam, 2014). Sieb (2014) has specifically indicated that since the Anti-AChR antibody positive type of MG is predominant in patients with eye muscle problems, it was important the anti-AChR antibody testing is carried out among such patients. The anti-MuSK antibody test will be much relevant in middle aged women since the Anti-body MuSk- positive type of MG is much prevalent among them. SFEMG and Repetitive Nerve Stimulation (RNS) are the commonly used neurophysiological tests. However, results obtained can be misleading especially in patients on chronic high dose acetylcholinesterase inhibitors. Since the disease is also prevalently noted in the thorax, the patient has to undergo magnetic resonance (MRI) or computed tomography (CT) imaging. Other two important tests have included ice pack test and edrophonium test. Ice pack test is important in distinguishing whether the ptosis screened is caused by MG or other causes. Edrophonium test is carried out to demonstrate if the muscle weaknesses can be reversed (Sathasivam, 2014).
In the UK, there has been no specific guideline for prognosis and treatment of the disease. Physicians have been relying on their own experiences and practices to choose prognosis and treatment options (Sathasivam, 2014). According to Sieb (2014), treatment has involved four basic options: neuromuscular improvement, acute exacerbation treatment, immunosuppression and immunomodulation. However, one should note that prognosis and treatment options have to be individualized, as not all MG cases will be the same (Sathasivam, 2014). Prognosis basically begins with symptomatic treatments by improving neuromuscular transmissions using acetylcholine esterase inhibitors such as pyridostigmine bromide. The next phase of the prognosis will involve treating present acute exacerbations by Plasmapheresis, immunoadsorption and the intravenous administration of immunoglobulins (Sieb, 2014). The next phase can involve the administration of immunosuppressant (Sathasivam, 2014; Sieb, 2014). Short term immunosuppression will need the patient being involved in oral prenisolone to act as an interim suppressant as long-term suppressants of maximum effects are sought. Several long-term immunosupressants have been developed, but Azathloprine is the most widely used. It is important in suppressing the production of the antibodies that blocks or damages muscle receptor cells to cause MG (Sathasivam, 2014; Sieb, 2014). Immunomodulation will also be done on both short term and long term bases. In acute cases of MG that require short-term immunomodulation, plasma exchange (PE) or intravenous immunoglobin (IVIG) is used to optimize muscle strength after surgery (Sathasivam, 2014). Long-term immunomodulation is done in thymomatous patients; if the MG patients have thymoma, they will be required to undergo long-term immunomodulation in form of thymectomy because of likely malignant cases in the affected muscles (Sathasivam, 2014; Sieb, 2014).
References
Sathasivam, S. (2014).Diagnosis and management of myasthenia gravis. Progress in Neurology and Psychiatry, 18(1). Retrieved on 6 May 2016 from http://onlinelibrary.wiley.com/doi/10.1002/pnp.315/pdf
Sieb, J.P. (2014).Myasthenia gravis: an update for the clinician. Clinical & Experimental Immunology, 175(3), pp. 408-418. Retrieved on 6 May 2016 from http://onlinelibrary.wiley.com/doi/10.1111/cei.12217/full
