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Positive Results After Transcervical Thymectomy Procedure: Presented at STS

By Mike Fillon

CHICAGO, IL -- February 3, 2006 -- A study with the largest number of patients to date confirms that extended transcervical thymectomy (TCT) for treatment of myasthenia gravis (MG) offers results equivalent to more radical, transsternal procedures.

"With nearly double the number of patients than in our previous analysis, the complete MG response rates at 5 years remain approximately the same," said lead researcher Joseph B. Shrager, MD, Assistant Professor of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, United States.

He presented the results of the study in a scientific poster here on January 31^st at the Society of Thoracic Surgeons (STS) 42^nd Annual Meeting

Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles. The relationship between the thymus gland and myasthenia gravis has led to the medical recommendation that the gland be removed (thymectomy). The transcervical approach to thymectomy is the least invasive method, with only a small horizontal incision across the lower part of the neck.

In this retrospective study, the researchers reviewed charts and interviewed 134 patients undergoing TCT for myasthenia gravis between 1992 and 2004. Complete remission (CR) was defined as 6 months with no symptoms off medication. They used a modified Osserman classification based upon the Myasthenia Gravis Foundation of America quantitative disease severity score.

Mean age at surgery was 42 years and mean preoperative Osserman class was 2.3 (22% class 1; 40% class 2; 28% class 3; 10% class 4). Mean length of follow-up was 54 months. Mean postoperative Osserman class was 0.95.

The researchers found that 11% of clearly failed to improve. The uncorrected crude CR rate was 31%. Kaplan-Meier estimates of CR were 37% and 40% at 5 and 8 years respectively.

Histology impacted CR rate (CR for thymoma>hyperplasia>normal/involuted thymus (P = .02), but preoperative disease severity had no significant effect (P = .36).

"We cannot rule out the possibility that the fact that we perform TCT on patients with less severe disease [mean Osserman 2.3] is in part responsible for our remission rates being equivalent to those from more extensive operations," Dr. Shrager said.

"When we look at only the more remotely operated patient group who have longer follow-up times, the response rates remain stable over time," he said. "This, and the fact that we identified no patients who worsened after an initial CR, suggests that there is no increased tendency to relapse following TCT that might be seen if residual thymic tissue was a major problem. We also found that surgical complications and length of [hospital] stay are extremely low."

"We believe that extended TCT is an excellent technique of thymectomy for myasthenia gravis," Dr. Shrager concluded. "The challenge now is educating thoracic surgeons in how to perform the procedure."


[Presentation title: Response Rates Following 134 Transcervical Thymectomies for Myasthenia Gravis.]

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