Thoracoscopic thymectomy for juvenile myasthenia gravis

Abstract

Purpose: A randomized controlled trial of thymectomy in myasthenia gravis demonstrated improved clinical outcomes in adults, but data surrounding juvenile cases, especially those treated with minimally invasive approaches, are limited. Here, we review our experience with thoracoscopic thymectomy for juvenile myasthenia gravis (JMG) in the largest cohort to date.

Methods: All cases of thymectomy for JMG in a single tertiary referral center between 2007 and 2018 were reviewed (N = 50). Patients underwent left thoracoscopic approach with extended dissection and without use of monopolar energy. Demographics, diagnostic criteria, and clinical classification, as well as surgical data were collected. Clinical status and medications were reviewed in follow-up.

Results: The mean age at surgery was 10.5 ± 0.8 years. Ocular disease and generalized disease each comprised half of the cohort. No patients suffered complications or increased risk of morbidity or mortality with thymectomy. At any interval of follow-up through 3.5 years, 49.8% of patients were improved compared to their pre-operative presentation, and there was a significant trend towards decreased steroid use.

Conclusion: Thoracoscopic thymectomy is a safe treatment for juvenile myasthenia gravis in pediatric patients over a wide range of ages, body masses, and symptoms. Our experience adds evidence that pediatric patients likely benefit from thymectomy with improved clinical status and reduced medications.

Keywords: Juvenile myasthenia gravis; Minimally invasive surgery; Thoracoscopy; Thymectomy.

Fig. 1

a Patient positioned with bump under the left chest and left arm gently abducted. b Diagram depicting port placement and operative approach. c Laparoscopic view of the thymus (dashed line) and the course of the phrenic nerve (dotted line)

Fig. 2

An average of 79.3% of patients in whom pre- and post-operative data were available presented for follow-up at any given 6-month interval between 0.5 and 3.5 years after thymectomy; the gray bars depict the number of patients due for follow-up (excluding those who relocated or transitioned to adult care at ≥ 18 years of age), the black bars depict the number of those that presented for follow-up

Fig. 3

At any given half-year follow-up between 6 and 42 months after surgery, a mean of 49.8% of patients were “improved” compared to their pre-operative status, as defined by the MGFA-PIS classification with substantial decrease in clinical symptoms or 50% reduction in medications

Fig. 4

Kaplan–Meier event curve for “Improved” clinical status by MGFA-PIS classification at last follow-up visit with the number of patients “at risk” at each time-point depicts increasing cumulative probability of “improved” clinical status after thymectomy

Fig. 5

Weight-adjusted total daily steroid intake (mg/kg/day) decreased significantly over 3.5 years of follow-up on linear regression analysis