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