Myasthenia Gravis

Myasthenia Gravis

Wilma J. Koopman

Joanne V. Hickey

Acquired myasthenia gravis (MG) is an uncommon chronic disease of the neuromuscular junction (NMJ) in which an autoimmune process in most cases attacks the acetylcholine (ACh) receptors at the postsynaptic muscle membrane. In other cases, nonACh components of the NMJ, such as muscle-specific receptor kinase (MuSK) may be the target of the attack. There are two clinical forms of the disease; ocular and generalized. In ocular MG, the weakness is restricted to the eyelids and extraocular muscles and about 50% will have detectable acetylcholine receptor (AChR) antibodies. In contrast, generalized MG affects to a variable degree the eyes, face, bulbar, limb, and respiratory muscles with 80% having detectable AChR antibodies.1 In 15% to 20% of AChR antibody negative MG, the anti-MuSK antibodies have been implicated and this form is often considered to have a distinct generalized form.2

The hallmark of MG is fluctuating muscle weakness that worsens with effort or exercise and improves with rest. MG used to have a fatal outcome for many people, but treatment now available is highly effective, although there is no cure. MG is classified as an autoimmune disease, and persons with MG may have other autoimmune conditions. The thymus gland in anti-AChR positive generalized MG cases will have abnormalities; thymic hyperplasia in greater than 50% or a thymoma in 10% to 15%. The prevalence of MG is about 20 per 1,00,000 in the US population.3 It affects people of all ages, and women are affected more frequently than men by a 3:2 ratio. The highest incidence noted is in women in their 20s and 30s and men after the age of 60. The estimated annual health plan paid costs for treating MG were $15,675. Home health services represent 23% of MG patient costs, largely driven by IVIg administration.4

Jul 14, 2016 | Posted by in NURSING | Comments Off on Myasthenia Gravis

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