Advances in the Treatment of Myasthenia Gravis

Nils Erik Gilhus

Disclosures

Future Neurology. 2012;7(6):701-708. 

In This Article

Abstract and Introduction

Abstract

Myasthenia gravis (MG) should be classified according to antibody status (acetylcholine, MuSK, LRP4, titin), thymus (hyperplasia, neoplasia, atrophy), age at debut (< or >50 years), symptom localization (generalized, ocular) and severity. With optimal treatment, the prognosis is good in terms of daily functions, quality of life and survival. Symptomatic treatment with acetylcholine esterase is usually combined with immunosuppression. A combination of prednisolone and azathioprine remains the first choice alternative, whereas rituximab is a promising second choice drug for severe generalized MG. Thymectomy is recommended for early-onset, generalized MG and for thymoma MG. In acute exacerbations including MG crisis, intravenous immunoglobulin and plasma exchange have good and similar effects. MG in young females needs therapeutic considerations regarding potential pregnancy.

Introduction

Myasthenia gravis (MG) is an autoimmune and antibody-mediated neuromuscular disease that leads to muscle weakness and fatigue. The weakness can be focal or generalized. Symptoms and signs are restricted to striated skeletal muscles, and all such muscles can be affected. MG has a total prevalence of 140 per million in Caucasian populations, with an annual incidence of 15 per million.[1,2] Whereas prevalence and incidence have remained stable and with a constant female preponderance in those experiencing symptom onset before 50 years of age, there has been an increase of MG in the elderly population, and especially in males.[3]

MG without any treatment has a 10-year mortality, which is thought to be around 50%,[4] and is thus a truly severe disease (gravis). However, with today's optimal treatment including a combination of immunosuppression, symptomatic and supportive therapy, there should be no increased mortality for MG patients.[5] Quality of life with MG is generally very good, although most patients experience moderate restrictions regarding selected tasks involving muscular strength and repetitive movements.[4]

MG diagnosis is in most cases straightforward for specialists, with typical symptoms and signs and detection of autoantibodies with very high MG specificity, i.e., against acetylcholine receptors (AChR) or MuSK.[6] The diagnosis can be supported by neurophysiology, imaging of the mediastinum and response to acetylcholine esterase inhibitors. In antibody-negative cases, the diagnostic process needs more consideration. Extensive neurophysiological testing is crucial. In elderly patients, cerebrovascular disease or amyotrophic lateral sclerosis can be suspected initially, and even more so as the temporal variation with weakeness and fatigue is not always prominent.

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