Robot-assisted thymectomy ‘safe and feasible’ in MG: Study
At five-year follow-up, 4 of 5 patients saw easing of symptoms
Robot-assisted surgery to remove the thymus is generally safe for people with myasthenia gravis (MG), with most patients who undergo the procedure seeing a reduction in symptom severity afterward, a study reports.
“This retrospective follow-up study showed that robotic thymectomy [thymus removal surgery] is safe and feasible in patients with [MG],” the researchers wrote in “Outcomes after robotic thymectomy in nonthymomatous versus thymomatous patients with acetylcholine-receptor-antibody-associated myasthenia gravis,” which was published in Neuromuscular Disorders.
The thymus is a small gland in the upper chest. It plays an important role in the developing immune system in children, but its function declines after puberty. Many MG patients have an enlarged thymus and up to 20% have thymus tumors, or thymomas.
Surgical removal of the thymus, called a thymectomy, is sometimes performed for people with MG. Advances in surgical techniques are allowing it to be done less invasively.
Robotic-assisted thoracoscopic surgery, or RATS, uses a robot attached to specially designed surgical instruments that are threaded through small openings to reach the thymus. The technique was first reported in 2003 and has since become increasingly common.
Outcomes of thymectomy for MG patients
Researchers at a center in the Netherlands reviewed the outcomes of 230 MG patients who underwent RATS at their center between April 2004 and December 2018. All were positive for antibodies against the acetylcholine receptor (AChR), the most common type of MG-driving antibody.
Patients were a mean age of 40.9 and around a third (33%) had a thymoma. Patients with a thymoma tended to have a shorter wait for a thymectomy referral after diagnosis than those without a thymoma (mean, 16.4 vs. 28.7 months).
The patients were hospitalized for about three days around the time of surgery and the procedure took slightly less than two hours. Complications related to the surgery were reported in 23 patients and were more common in those with a thymoma. In particular, thymoma patients commonly had atrial fibrillation — a type of heart rhythm abnormality — which was likely due to surgical instruments irritating the tissue around the heart, the researchers said.
Follow-up data with a mean time of more than five years were available for 165 patients. At the end of follow-up, more than four out of every five (82.4%) patients saw an easing of MG symptoms, as indicated by improved scores on the MG Foundation of America (MGFA) scale.
More than one in three (39.4%) patients were in pharmacological remission after thymectomy, meaning they had no noteworthy MG symptoms, but were still taking MG-specific treatments. Another 8.5% were in complete remission, meaning they showed no symptoms and did not require further treatment for at least a year.
The mean time until remission was more than two years after thymectomy. Remission rates and changes in MGFA scores didn’t differ significantly between patients with or without a thymoma.
The proportion of patients treated with the corticosteroid prednisone decreased markedly after thymectomy for patients who didn’t have a thymoma — from 44% before surgery to 28.6% at five years of follow-up. Prednisone use increased slightly after surgery for those with a thymoma — from 47.8% before the procedure to 55.2% five years later.
Similar trends were seen with the immunosuppressant azathioprine. The use of immune-suppressing therapies tended to increase after surgery in both groups, with researchers noting it’s likely many patients were simply switching to other medicines.
The researchers said their study is limited by its retrospective nature, as well as the lack of follow-up data for a sizable number of patients. More prospective research “is required to analyze clinical improvement and (drug) treatment strategies more specifically,” they said.