E-Pearl of the Week: Anti-MuSK Antibody Myasthenia Gravis
July 29, 2013
Anti-MuSK (muscle-specific tyrosine kinase) myasthenia gravis (MG) was first described in 2001, with the associated antibody isolated a couple of years later. MuSK-Ab MG is more commonly seen in woman, with a diagnosis frequently made in the fourth decade, as compared to the second or third decade in typical AChR+ Ab MG.  It has a preference to affect bulbar and respiratory muscles. Although it can present with a generalized picture, the presence of bulbar symptoms at onset suggests a worse prognosis. A rapid progression to respiratory crisis is not uncommon after symptom onset. In comparison to AChR+ Ab MG, response to acetyl-cholinesterase inhibitors (AChE-I) is not as common in patients with MuSK-Ab MG. 
1. Guptill JT, Sanders DB and Evoli A. Anti-MuSK antibody myasthenia gravis: Clinical findings and response to treatment in two large cohorts. Muscle and Nerve 2011; 44: 36-40.
2. Zebardast N, Patwa HS, Novella SP, Goldstein JM. Rituximab in the management of refractory myasthenia gravis. Muscle and Nerve 2010; 41: 375-380.
Submitted by James Addington, MD Resident Physician, University of Virginia
Dr. Addington reports no disclosures.