Thymus involvement in myasthenia gravis: Epidemiological and clinical impacts of different self-tolerance breakdown mechanisms.
The reasons for the abrogation of self-immunological tolerance in patients with myasthenia gravis (MG) may be different between those with concomitant thymic hyperplasia or thymoma, and those with no evidence of thymic involvement. We conducted a retrospective observational case series study to investigate the epidemiology as well as the clinical, serologic, and electromyographic (EMG) characteristics of individuals diagnosed as having MG. We found that the average age at MG onset of patients with either thymic hyperplasia or thymoma was much younger (by ~20years) than that of MG patients without thymic involvement. Thymic hyperplasia was more common in females than males. There were no differences in the rates of ocular MG vs. generalized MG among those three study groups. There were also no group differences in the rates of neuromuscular junction disfunction, as observed on EMG or by the results of serology tests for acetyl choline receptor antibody. Interestingly, only patients without thymic involvement had other autoimmune diseases, and most of them were females. The patients with other coexisting autoimmune disease had a similar age at MG onset as the other patients with no thymic involvement. These results shed light on the impact of epidemiological and clinical factors that result from different mechanisms of self-immunological tolerance breakdown that occurs in MG.
Neuroimmunology Clinic, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: arnonk@tlvmc.gov.il.
Arnon
A
Karni
Neuroimmunology Clinic, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: asmail.ali12@gmail.com.
Ali
A
Asmail
Neuromuscular Service of the Department of Neurology, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: vdrory@post.tau.ac.il.
Vivian E
VE
Drory
Neuroimmunology Clinic, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: hadar.kolb@gmail.com.
Hadar
H
Kolb
Neuro-ophtalmology Unit of the Department of Ophthalmology, Tel Aviv Sourasky Medical Center, affiliated to the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel. Electronic address: anatk@tlvmc.gov.i.
Anat
A
Kesler
D000328:Adult; D017668:Age of Onset; D000368:Aged; D001323:Autoantibodies / Q000097:blood; D004576:Electromyography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009157:Myasthenia Gravis / Q000453:epidemiology / Q000276:immunology / Q000503:physiopathology; D011950:Receptors, Cholinergic / Q000276:immunology; D012189:Retrospective Studies; D017634:Self Tolerance / Q000502:physiology*; D012737:Sex Factors; D013945:Thymoma / Q000453:epidemiology; D013950:Thymus Gland / Q000473:pathology*; D013952:Thymus Hyperplasia / Q000453:epidemiology
D001323:Autoantibodies; D011950:Receptors, Cholinergic
Myasthenia gravis; Thymic hyperplasia; Thymoma