The long-term clinical response of patients with myasthenia gravis (MG) after thymectomy is significantly lower than the initial response, according to a new study published in the European Journal of Neurology.

None of the clinical factors that were evaluated were associated with the outcome, which included age of disease onset, thymus histology, time to surgery after disease onset, type of surgery, whether corticosteroid therapy, and clinical severity before surgery. This, the researchers said “supports the current clinical practice of patient selection for thymectomy.”

To investigate the short- and long-term outcomes in patients with MG who are positive for acetylcholine-receptor-antibody after thymectomy, a team of researchers led by Fritz Zimprich, MD, PhD, from the Medical University of Vienna in Austria retrospectively analyzed rates of clinical response that lasted at least 1 year after thymectomy in 94 patients with MG, aged 22 to 51 years. Clinical response was defined as minimal disease manifestation and pharmacological or complete stable remission.

Read more about the prognosis of MG

Of the 94 patients who were analyzed 68% had nonthymomatous MG while 32% had thymoma-associated disease. The majority of patients (72%) reached an initial clinical response following thymectomy. However, during follow-up, which ranged between 46 and 189.5 months only half of those who had an initial response showed sustained response with no disease relapse.

“The long-term disease course must be evaluated separately from the initial clinical response,” the researchers wrote. They also found that in patients who did not receive immunosuppressive therapy before surgery a high rate of reduction in the levels of acetylcholine receptor antibody after thymectomy was associated with a higher likelihood of achieving an initial response.

They concluded that the relative decline of acetylcholine receptor antibody following surgery could be a promising prognostic marker in patients with acetylcholine receptor antibody-positive MG.

Reference

Rath J, Taborsky M, Moser B, et al. Short-term and sustained clinical response following thymectomy in patients with myasthenia gravis. Eur J Neurol. Published online April 18, 2022. doi:10.1111/ene.15362