Thymectomy eases symptoms for children, teens with juvenile MG

Surgical removal of the thymus, or thymectomy, significantly improves nerve-muscle communication and eases symptoms and their impact on daily activities in children and adolescents with juvenile myasthenia gravis (JMG), a small U.S. study showed.

After thymectomy, young patients not only showed measurable improvements in how efficiently their nerves activated an eye muscle commonly affected in JMG, but also reported meaningful relief in everyday tasks.

The findings suggest that “thymectomy is well-tolerated and leads to both objective and subjective improvement in JMG patients,” the researchers wrote.

The study, “Improved Neuromuscular Transmission Following Thymectomy in Juvenile Myasthenia Gravis: A Case Series,” was published in Muscle & Nerve.

Myasthenia gravis (MG) is an autoimmune disease typically caused by self-reactive antibodies that target proteins involved in nerve-muscle communication, usually acetylcholine receptors (AChRs). This leads to MG symptoms such as muscle weakness and fatigue. JMG, marked by a disease onset before age 18, “is a rare but disabling condition and can be [resistant] to medical management,” the researchers wrote.

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Because abnormalities in the thymus gland, a part of the immune system, are thought to contribute to the production of self-reactive antibodies that drive MG, thymectomy is commonly performed to help ease MG symptoms.

While improvements after thymectomy have been reported in children and adolescents with JMG, “the benefits are not well-quantified in the literature as results are measured using clinical symptom severity scales designed for adult patients, which may be inaccurate in pediatric patients,” the researchers wrote.

The team retrospectively analyzed data from 12 JMG patients, six boys and six girls, who underwent thymectomy at Children’s Healthcare of Atlanta between 2014 and 2024. They had a mean age of 12.9 at diagnosis and 15.2 years at thymectomy, and all had anti-AChR antibodies.

Their most common presenting symptoms included upper eyelid droopiness (91.7%), double vision (91.7%), facial muscle paralysis (75%), weakness in the muscles closer to the trunk (66.7%), swallowing difficulties (50%), and abnormal voice (33.3%).

Before and after surgery, seven patients underwent single-fiber electromyography to measure electrical activity in the orbicularis oculi, a muscle that primarily controls eyelid closure and blinking and is commonly affected in MG. The test uses a specialized needle electrode to measure jitter, or the time it takes for the muscle fiber to respond to a nervous signal.

Results demonstrated that the mean jitter was abnormally high (88.2 microseconds) before surgery, reflecting poor nerve-muscle communication, and that it significantly decreased to 55 microseconds at a median of 7.3 months after the procedure. However, it remained above normal values, which should be below 24 microseconds.

A total of 11 participants had available pre- and post-surgery data on the Myasthenia Gravis Activities of Daily Living (MG-ADL) scale, a patient-reported tool used to assess MG severity based on the disease’s impact on daily functions.

The mean MG-ADL score dropped significantly, from 4.4 before thymectomy to 2.2 after thymectomy, indicating a less severe disease impact on daily life. A 2-point reduction in score is considered clinically meaningful. When considering only the participants with available jitter results, the decrease in MG-ADL score was even more pronounced, declining from 6.3 to 2.9.

Further statistical analyses showed no significant link between mean jitter changes and MGADL score changes. The timing of thymectomy after diagnosis was not significantly associated with changes in mean jitter or MG-ADL scores, and “no major post-surgical complications were observed,” the team wrote.

The mean number of MG medications used remained generally unchanged at 2.5 years after the surgery (3.3 vs. 2.8 after the procedure).

“This study showed a significant improvement in jitter values and MG-ADL scores post-thymectomy in JMG patients,” the researchers wrote. “We plan to continue to follow this [group] of thymectomy patients, as the long-term benefits of thymectomy and its durability with regard to sustained improvement in patient symptoms, need for immunotherapies, and outcomes such as MG-ADL and jitter remain to be seen.”