Myasthenia gravis and thymus: long-term follow-up screening of thymectomized and non-thymectomized patients

Abstract

Thymoma is strongly associated with myasthenia gravis (MG), particularly at the onset of the disease 1 . Thymus investigation in MG patients is typically recommended at the onset of MG or when patients present with clinical deterioration or a progressive increase of anti-acetylcholine receptor (AChR) antibody 2,3 . However, it is unknown if repeated screenings for thymoma at fixed intervals, even in the absence of MG deterioration, are necessary when the initial screening is negative. In addition, therapeutic guidelines do not mention the importance of thymus follow-up if the initial screening is negative 1,4 .The main objective of this study was to determine the recurrence rate and incidence of new thymoma in a series of MG patients without clinical deterioration who underwent long-term follow-up. METHODSWe included MG patients who fulfilled the following criteria: (1) diagnosis based on abnormal repetitive nerve ABSTRACTThymoma screening is recommended at the onset of myasthenia gravis (MG) or when patients with MG present with clinical deterioration or a progressive increase of anti-acetylcholine receptor antibody. However, it is unknown if it is necessary to repeat the screening of thymoma at fixed intervals, even in the absence of MG deterioration, when the initial screening is negative. We analyzed the recurrence rate and incidence of new thymoma in a series of patients with well-controlled MG. The sample consisted of 53 patients, aged 17 to 72 years, and the follow-up varied between 75 and 472 months. The chest computerized tomography detected thymus abnormalities in eight patients at the initial screening and no abnormalities in all patients at a second screening after five years. The findings of this study support the classical opinion that screening for thymoma should be recommended only if there is clinical deterioration due to the disease.Keywords: myasthenia gravis, thymus gland, thymoma, tomography. RESUMOA investigação de timoma é recomendada em pacientes com miastenia gravis (MG) no início da doença, em caso de haver piora clínica ou aumento dos níveis do anticorpo antirreceptor de acetilcolina. Contudo, não foi estabelecido se é necessário repetir a investigação de timoma em intervalos fixos, na ausência de piora clínica, quando a investigação inicial foi negativa. A taxa de recorrência e a incidência de novo timoma foram analisadas em uma série de pacientes com MG bem controlada. A amostra consiste de 53 pacientes, idade entre 17 e 72 anos, com tempo de acompanhamento variando entre 75 e 472 meses. A primeira tomografia computadorizada de tórax detectou anormalidades no timo em oito pacientes durante a investigação inicial da doença e nenhuma anormalidade no segundo exame, após cinco anos de doença, em todos os pacientes. Os achados desse estudo corroboram a clássica opinião de que a investigação de timoma deveria ser recomendada somente se houver piora clínica da doença.

Clinical profile of patients with myasthenia gravis followed at the University Hospital, Federal University of Minas Gerais

“…Only the latest studies detailed the therapeutic strategies used, 29,30 and they are concordant with the clinical practice in our clinic. In contrast, even recent Brazilian case series 18,19,22,23,25,27,29 used the clinical classification of Osserman-Gerkins, while the recommended standards of clinical research on MG and the international literature have adopted MGFA since the early 2000s.…”

“…In contrast, even recent Brazilian case series 18,19,22,23,25,27,29 used the clinical classification of Osserman-Gerkins, while the recommended standards of clinical research on MG and the international literature have adopted MGFA since the early 2000s. 21,30 conclusion Despite the clinical heterogeneity of MG, the clinical and demographic profiles and therapeutic strategies reported in Brazilian case series are quite similar. Further studies in different settings (i.e.…”

“…[17][18][19][20][21][22][23][24][25][26][27][28][29][30] Ocular symptoms were the first symptoms described by most MG patients; however, they were not considered the main problem with the disease progression. Bulbar symptoms were considered the most disabling, which is in agreement with some studies.…”

“…There was no significant difference between thymectomized and non-thymectomized patients in clinical parameters which is concordant with other Brazilian reports. 20,29,30 Indeed, several cross-sectional studies failed to find any significant difference between patients who underwent thymectomy and those under conservative treatment. 5,9,12,20,21,24,29 In this scenario and taking into account the risks associated with the surgical procedure, the indication of thymectomy is frequently withheld.…”

“…Conversely, a few Brazilian case series have been reported, describing clinical and sociodemographic features of patients followed at specialized clinics. [17][18][19][20][21][22][23][24][25][26][27][28][29][30] The aim of the current study was to determine the clinical profile of patients with MG under treatment at the Neuromuscular Diseases Clinic of the University Hospital, Federal University of Minas Gerais (UFMG), com-paring it with other series to draw a picture of the MG in Brazil.…”