Clinical differences between early-and late-onset myasthenia / 中华老年医学杂志

ABSTRACT

Objective To explore the clinical differences between patients with early-onset myasthenia gravis (EOMG)and those with late-onset myasthenia gravis(LOMG).Methods This was a retrospective study enrolling 157 MG patients.Based on the age of onset,patients were divided into the EOMG group(n=85)and the LOMG group(n =72).The groups were compared on clinical characteristics,including clinical manifestations,MG classification,electrophysiological findings on repetitive nerve stimulation(RNS),single fiber electromyography(SFEMG),levels of antibody against acetylcholine receptors(Ach-R Ab),antibody to muscle-specific kinase(MuSK Ab),titin antibody(Titin Ab),ryanodine receptor antibody(RyR Ab),thyroid function,thymectomy,thymus pathology and responses to treatment.Results The mean ages of onset were markedly different [(40.9 ± 9.7) years vs.(62.0 ± 12.2) years,P＜ 0.05] between the EOMG and LOMG groups.The LOMG group was associated with a significantly higher rate of the ocular form(50.0 ％,n=36 vs.32.9％,n=28,P＜0.05),a lower rate of the general form(50.0％,n=36 vs.67.1％,n=57,P＜0.05),and an increased risk of bulbar involvement(41.7％ n=30 vs.23.5％,n=20,P＜0.05)than those in the EOMG group.There was no significant difference in positive rates of RNAS and SFEMG,and levels of AChR Ab,MuSK Ab and double serum negative(DSN)MG between the groups (P＞0.05).Moreover,patients in the EOMG group were more likely to have abnormal thyroid function and higher percentages of receiving steroids,tacrolimus,plasma exchange therapy,and thymectomy (P＜ 0.05).Conclusions The clinical profiles of LOMG are different from those of EOMG in clinical manifestations,thyroid function,thymectomy frequency,striational antibody levels and disease-modifying drug options.