Clinical Utility of Acetylcholine Receptor Antibody Testing in Ocular Myasthenia Gravis. Crandall E. Peeler, MD; Lindsey B. De Lott, MD; Lina Nagia, DO; Joao Lemos, MD; Eric R. Eggenberger, DO, MSEpi; Wayne T. Cornblath, MD JAMA Neurol. 2015;72(10):1170-1174.
Submitted by Niranjan N. Singh, MD, News Science Editorial Board
A retrospective review of 223 patients diagnosed with ocular myasthenia gravis at two academic medical centers between 1986 and 2013 was conducted. All patients underwent serum testing for the acetylcholine receptor (AChR) binding antibody using alpha-bungarotoxin; values greater than 0.02 nmol/L were considered positive. AchR antibody testing was positive in 70.9%. Generalized myasthenia gravis developed in 20.2% of patients during the follow-up interval of 60 months. The mean antibody level in patients who developed generalized symptoms (12.7 nmol/L) was significantly higher than in those who did not develop generalized symptoms (4.2 nmol/L) (P = .002).
Comment: Myasthenia gravis causes weakness of the eyelids and extraocular muscles in 90% of patients, and approximately half of such patients will present with isolated ocular symptoms. The AChR antibody test is highly specific but historically has shown a sensitivity of less than 50%. The antibody was elevated in 70% of patients in this study. Possible explanations for the higher sensitivity identified in this study include improved testing methods, longstanding disease, careful exclusion of mimics of ocular myasthenia gravis, and lengthy follow-up periods.
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