Thymectomy in nonthymoma early-onset myasthenia gravis in correlation with disease severity and muscle autoantibodies.
OBJECTIVE
To study the clinical effect of thymectomy in a well-defined early-onset MG subgroup and to correlate it to MG severity, the presence of circulating muscle autoantibodies, and the need for pharmacological treatment in a long-term setting.


METHODS
Fifty-two consecutive AChR antibody-positive early-onset MG patients (34 thymectomized and 18 nonthymectomized) were included. Severity was assessed and the pharmacological treatment monitored on a yearly basis, starting from the year of MG onset, for 5, 10, 15, and 20 consecutive years; AChR, titin, and RyR antibodies were assayed.


RESULTS
In the four follow-up groups, MG severity was significantly higher in nonthymectomized compared to thymectomized MG patients. The postthymectomy MG improvement was significant and persistent. There were 21/34 remissions in thymectomized patients and only 4/18 in the nonthymectomized group. Patients with initially high or low AChR antibody concentration had a similar thymectomy outcome. Only 6 patients had titin antibodies, and none had RyR antibodies.


CONCLUSIONS
The present study indicates a benefit of thymectomy in early-onset MG. The muscle autoantibody concentration does not influence the outcome of thymectomy in early-onset MG.
Romi
F
F
Department of Neurology, Haukeland University Hospital, Bergen, Norway. fredrik.romi@haukeland.no
Gilhus
N E
NE
Varhaug
J E
JE
Myking
A
A
Aarli
J A
JA
D000109:Acetylcholine / Q000097:blood / Q000276:immunology; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D017668:Age of Onset; D001323:Autoantibodies / Q000097:blood*; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use; D064211:Connectin; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009124:Muscle Proteins / Q000097:blood / Q000276:immunology; D018908:Muscle Weakness / Q000209:etiology / Q000503:physiopathology*; D009132:Muscles / Q000276:immunology; D009157:Myasthenia Gravis / Q000097:blood / Q000628:therapy*; D010956:Plasmapheresis; D011494:Protein Kinases / Q000097:blood / Q000276:immunology; D011729:Pyridostigmine Bromide / Q000627:therapeutic use; D012074:Remission Induction; D012189:Retrospective Studies; D019837:Ryanodine Receptor Calcium Release Channel / Q000097:blood / Q000276:immunology; D012720:Severity of Illness Index; D013934:Thymectomy; D013950:Thymus Gland / Q000473:pathology / Q000601:surgery; D016896:Treatment Outcome
D000305:Adrenal Cortex Hormones; D001323:Autoantibodies; D002800:Cholinesterase Inhibitors; D064211:Connectin; D009124:Muscle Proteins; D019837:Ryanodine Receptor Calcium Release Channel; C577285:TTN protein, human; D011494:Protein Kinases; D011729:Pyridostigmine Bromide; D000109:Acetylcholine