Thymectomy for myasthenia gravis: evaluation requires controlled prospective studies

Feasible and promising modified trans-subxiphoid thoracoscopic extended thymectomy for patients with myasthenia gravis

Background

We have used a promising, minimally invasive thoracoscopic technique of extended thymectomy for patients with myasthenia gravis (MG). The aim of this study was to report our promising technique, a modified single-port trans-subxiphoid approach (MTXA) and to compare perioperative outcomes and effects on MG between our approach and sternotomy.

Methods

We retrospectively reviewed records of all patients undergoing extended thymectomy for MG and/or thymoma between January 1, 2010 and December 31, 2016. The patients were divided into the MTXA group and Sternotomy group.

Results

Of the 50 consecutive patients undergoing extended thymectomy for MG, finally, 13 patients undergoing our MTXA extended thymectomy technique were compared with 20 patients undergoing extended thymectomy via sternotomy. Intraoperative blood loss, postoperative length of stay, and C-reactive protein value on postoperative day 1 were significantly more favorable in the MTXA group than the Sternotomy group (P<0.0001, P=0.0040 and P=0.0073, respectively). Furthermore, no significant differences in the frequency of patients with improvement of their Quantitative Myasthenia Gravis score and/or MG-Activities of Daily Living scale, decrease in the serum level of acetylcholine receptor antibody, and dose reduction of oral prednisone were seen between the two groups.

Conclusions

Our approach to extended thymectomy might be more favorable than sternotomy in patients with MG.

Could thymomectomy be a reasonable option for non-myasthenic thymoma patients?

Background

Complete resection is the mainstay of treatment for thymoma, but few studies have investigated the extent of resection on normal thymus. Extended thymectomy is considered the treatment of choice for myasthenic patients with thymoma, while the optimal therapy for non-myasthenic patients is still a matter of debate. The aim of this retrospective study was to compare extended thymectomy vs. thymomectomy in non-myasthenic thymoma patients for (I) oncological outcome, (II) multicentric thymoma occurrence and (III) postoperative myasthenia gravis (MG) development.

Methods

A retrospective comparative study was conducted on 92 non-myasthenic patients with completely resected thymoma, according to the extent of resection: extended thymectomy (70 patients) vs. R0-mediastinal thymomectomy (22 patients). Clinical and pathological characteristics, oncological outcome and postoperative MG occurrence were compared between the two study groups.

Results

We did not observe any significant differences in gender, age, symptomology, preoperative chemotherapy, histology, tumour size, adjuvant therapy or complications. There were no recorded postoperative mortalities. Stage distribution was different between the two groups: similar percentages of early stage thymoma for both groups were present, but there was a prevalence of stage III for extended thymectomy and stage IV for thymomectomy (P<0.01). At a median follow-up of 77.4 months (range 1-255 months), no statistically significant differences were recorded in local recurrence (P=0.396), thymoma related deaths (P=0.504), multicentric thymoma occurrence (P=0.742) and postoperative MG development (P=0.343). A high preoperative anti-acetylcholine receptor antibodies (ARAb) serum titer assay was statistically correlated with postoperative MG occurrence (r=0.49, P<0.05).

Conclusions

Thymomectomy appears to be a valid treatment option for non-myasthenic thymoma patients, as this procedure was associated to the same 5-year oncological results, compared to extended thymectomy, for both stage I-II small thymomas and patients with giant unilateral masses, as well as advanced diseases. Moreover, thymomectomy was not associated to an increased rate of postoperative MG.

Outcomes after 151 extended transcervical thymectomies for myasthenia gravis

BACKGROUND

The ideal operative technique for thymectomy in myasthenia gravis (MG) remains controversial. We present the largest series of extended transcervical thymectomy to provide outcomes data to compare with transsternal procedures.

METHODS

A retrospective chart review/interview was made of 164 patients operated upon from 1992 to 2004. Complete remission (CR) was defined as asymptomatic off medication for 6 months or asymptomatic on low-dose single-drug therapy (< or = 10 mg/d prednisone or < or = 150 mg/d azathioprine). A modified Osserman classification based upon the Myasthenia Gravis Foundation of America quantitative disease severity score was employed.

RESULTS

The overall complication rate was 7.3%, and nearly all procedures were outpatient. Mean age at surgery was 43 years, and mean preoperative Osserman class was 2.3 (21% class 1; 39% class 2; 28% class 3; 12% class 4). Mean length of follow-up was 53 months. Mean postoperative Osserman class was 1.0. Nineteen percent of patients failed to improve. The crude cumulative CR rate was 37% (n = 58). Kaplan-Meier estimates of CR were 43% and 45% at 3 and 6 years, respectively. On multivariate analysis, only preoperative disease severity was significantly (inversely) associated with Kaplan-Meier CR rates. Longer-term follow-up (83 months) of only the earlier patients shows preserved CR rates (46%).

CONCLUSIONS

This largest series of extended transcervical thymectomy for MG confirms that the 5-year Kaplan-Meier CR rate is comparable with that obtained after transsternal procedures. Patients with less severe disease have higher CR rates. Complete responses are durable, as the CR rate remains stable with extended follow-up.

Thoracoscopic Thymectomy Mid-Term Results

BACKGROUND

Results of thymectomy in patients with myasthenia gravis need to be reported in a standardized way to allow accurate comparison.

METHODS

A retrospective study was conducted of 107 patients with myasthenia gravis without thymoma. Patients were followed-up for more than 12 months after thoracoscopic thymectomy and analyzed according to Myasthenia Gravis Foundation of America Recommendations for Clinical Research Standards.

RESULTS

The study population was aged 8 to 60 years old and included 15 men (14%) and 92 women (86%). A right-side approach was used in 36 patients, and the remaining 71 patients had a left-side approach. Mortality was 0% and morbidity was 9.34%. The mean operative time was 90 +/- 45 minutes. The histologic diagnosis of the resected thymus was hyperplasia (78.5%), atrophy (15%), and normal status (6.5%). The mean length of hospitalization was 2.3 days (range, 2 to 6 days). The mean follow-up was 36.4 months (range, 12 to 74 months). The rate of complete stable remission was 59.5% by the end of postoperative year 6. An earlier onset age and early operation were significantly associated with complete stable remission and pharmacologic remission. A comparison of right side versus left side approach showed similarities in mean operative time, mean length of hospitalization, histopathologic results, and remission rates.

CONCLUSIONS

Outcomes of the thoracoscopic approach in myasthenia gravis without thymoma were similar to those provided by open surgery, with the acknowledged benefits of minimally invasive surgery and good patient acceptance.

Paraneoplastic syndromes affecting the nervous system

The paraneoplastic neurologic disorders (PND) are a diverse group of diseases characterized by the presence of neurologic dysfunction in the setting of a remote cancer. PND can affect almost any part of the nervous system, and are most commonly associated with lung cancer (small cell) and gynecologic tumors. Laboratory studies have demonstrated that an autoimmune response links the neurologic disorder and the cancer, and established a model whereby the cancer is believed to initiate the syndrome by expressing a protein antigen normally expressed in the nervous system, leading to anti-tumor immune response followed by autoimmune neurologic symptoms. We review the currently known PND and their pathogenesis.

Treatment review and update for myasthenia gravis

Myasthenia gravis (MG) is the best understood autoimmune disease, with well-characterized humoral and cellular effector mechanisms. It is not surprising, therefore, that immunotherapies play a key role in the management of MG. Significant progress has been made over the last few decades in the treatment of patients with MG, and the number of effective avenues of therapy continue to increase. In this review, we provide an update on management options in MG, highlighting recent literature on both traditional and more novel approaches.

Is thymus redundant after adulthood?

Thymus is considered to involute with age with a decline in thymic function. However, this generality is not universally and incontrovertibly true. Many studies performed in animals and men have proved to the contrary that thymic activity and function appear to be well maintained in the old age and may be indispensable for T cell reconstitution in different immunological settings. During some clinical situations where T cell pool needs to be regenerated, renewal of thymic activity and mass has been observed in an otherwise dormant thymic remnant. New studies have revealed a dynamic interplay between postnatal thymus output and peripheral T cell pool. Moreover, age-related loss of thymic function appears to be only quantitative and not qualitative. This review, thus, focuses on the different conditions that lead to thymic involution and attempts to bring about the emerging notion and the clinical relevance of continuous thymic activity well beyond the adulthood to optimise the function of the immune system in the context of cancer and infectious diseases.

Clinical evaluation and management of myasthenia gravis

Myasthenia gravis (MG) is a syndrome of fluctuating skeletal muscle weakness that worsens with use and improves with rest. Eye, facial, oropharyngeal, axial, and limb muscles may be involved in varying combinations and degrees of severity. Its etiology is heterogeneous, divided initially between those rare congenital myasthenic syndromes, which are genetic, and the bulk of MG, which is acquired and autoimmune. The autoimmune conditions are divided in turn between those that possess measurable serum acetylcholine receptor (AChR) antibodies and a smaller group that does not. The latter group includes those MG patients who have serum antibodies to muscle-specific tyrosine kinase (MuSK). Therapeutic considerations differ for early-onset MG, late-onset MG, and MG associated with the presence of a thymoma. Most MG patients can be treated effectively, but there is still a need for more specific immunological approaches.