Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis

Authors

• Katherine M. Clifford, Larner College of Medicine, University of Vermont, 1 South Prospect Street, Burlington, Vermont 05401, USA.
• Lisa D. Hobson-Webb, Department of Neurology, Duke University School of Medicine, Durham, North Carolina, USA.
• Michael Benatar, Department of Neurology, University of Miami Health System, Miami, Florida, USA.
• Ted M. Burns, Department of Neurology, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
• Carolina Barnett, Department of Neurology, University of Toronto School of Medicine, Toronto, Ontario, Canada.
• Nicholas J. Silvestri, Department of Neurology, University at Buffalo Jacobs School of Medicine & Biomedical Sciences, Buffalo, New York, USA.
• James F. Howard, Department of Neurology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.
• Amy Visser, Department of Neurology, Oregon Health & Science University, Portland, Oregon, USA.
• Brian A. Crum, Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA.
• Richard Nowak, Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA.
• Rachel Beekman, Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA.
• Aditya Kumar, Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA.
• Katherine Ruzhansky, Department of Neurology, Medical University of South Carolina, Charleston, South Carolina, USA.
• I-Hweii Amy Chen, Department of Neurology, Medical University of South Carolina, Charleston, South Carolina, USA.
• Michael T. Pulley, Department of Neurology, University of Florida, Jacksonville, Florida, USA.
• Shannon M. Laboy, Department of Neurology, University of Florida, Jacksonville, Florida, USA.
• Melissa A. Fellman, Department of Neurology, University of Miami Health System, Miami, Florida, USA.
• Diantha B. Howard, Larner College of Medicine, University of Vermont, 1 South Prospect Street, Burlington, Vermont 05401, USA.
• Noah A. Kolb, Larner College of Medicine, University of Vermont, 1 South Prospect Street, Burlington, Vermont 05401, USA.
• Shane M. Greene, Larner College of Medicine, University of Vermont, 1 South Prospect Street, Burlington, Vermont 05401, USA.
• Mamatha Pasnoor, Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA.
• Mazen M. Dimachkie, Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA.
• Richard J. Barohn, Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas, USA.
• Michael K. Hehir, Larner College of Medicine, University of Vermont, 1 South Prospect Street, Burlington, Vermont 05401, USA.

Document Type

Article

Abstract

INTRODUCTION: A randomized trial demonstrated benefit from thymectomy in nonthymomatous acetylcholine receptor (AChR)-antibody positive myasthenia gravis (MG). Uncontrolled observational and histologic studies suggest thymectomy may not be efficacious in anti-muscle-specific kinase (MuSK)-MG. METHODS: The therapeutic impact of thymectomy was evaluated from data collected for a multicenter, retrospective blinded review of rituximab in MuSK-MG. RESULTS: Baseline characteristics were similar between thymectomy (n = 26) and nonthymectomy (n = 29) groups, including treatment with rituximab (42% vs. 45%). At last visit, 35% of thymectomy subjects reached the primary endpoint, a Myasthenia Gravis Foundation of America (MGFA) post-intervention status (PIS) score of minimal manifestations (MM) or better, compared with 55% of controls (P = 0.17). After controlling for age at onset of MG, rituximab, prednisone, and intravenous immunoglobulin/plasma exchange treatment, thymectomy was not associated with greater likelihood of favorable clinical outcome (odds ratio = 0.43, 95% confidence interval 0.12-1.53, P = 0.19). DISCUSSION: Thymectomy was not associated with additional clinical improvement in this multicenter cohort of MuSK-MG patients. Muscle Nerve 59:404-410, 2019.

Medical Subject Headings

Adolescent; Adult; Age of Onset; Aged; Child; Cohort Studies; Female; Humans; Immunoglobulins, Intravenous (therapeutic use); Male; Middle Aged; Myasthenia Gravis (genetics, therapy); Prednisone (therapeutic use); Receptor Protein-Tyrosine Kinases (genetics); Receptors, Cholinergic (genetics); Retrospective Studies; Rituximab (therapeutic use); Thymectomy; Treatment Outcome; Young Adult

Publication Date

4-1-2019

Publication Title

Muscle & nerve

E-ISSN

1097-4598

Volume

59

Issue

4

First Page

404

Last Page

410

PubMed ID

30575980

Digital Object Identifier (DOI)

10.1002/mus.26404

Recommended Citation

Clifford, Katherine M.; Hobson-Webb, Lisa D.; Benatar, Michael; Burns, Ted M.; Barnett, Carolina; Silvestri, Nicholas J.; Howard, James F.; Visser, Amy; Crum, Brian A.; Nowak, Richard; Beekman, Rachel; Kumar, Aditya; Ruzhansky, Katherine; Chen, I-Hweii Amy; Pulley, Michael T.; Laboy, Shannon M.; Fellman, Melissa A.; Howard, Diantha B.; Kolb, Noah A.; Greene, Shane M.; Pasnoor, Mamatha; Dimachkie, Mazen M.; Barohn, Richard J.; and Hehir, Michael K., "Thymectomy may not be associated with clinical improvement in MuSK myasthenia gravis" (2019). Neurology. 1675.
https://scholar.barrowneuro.org/neurology/1675