Different Characteristics of Nonthymomatous Generalized Myasthenia Gravis With and Without Oropharyngeal Involvement

Comprehensive evaluation of velopharyngeal function in myasthenia gravis patients

PURPOSE

Hypernasality, which is a symptom of dysarthria, may be seen in patients with Myasthenia Gravis with bulbar symptoms. However, there is not enough evidence to show that these patients may have velopharyngeal dysfunction. This study investigates the features of velopharyngeal function in myasthenia gravis patients using objective and subjective measurement tools.

METHODS

Ten adult myasthenia gravis patients with bulbar symptoms and ten adult myasthenia gravis patients without bulbar symptoms were recruited for this study. Ten healthy subjects were also included as the control group. The nasalance scores of the participants were determined using a nasometer. The degree and pattern of velopharyngeal closure were scored using flexible nasoendoscopy during speech, blowing, dry swallowing, and food swallowing. Perceptual hypernasality was assessed.

RESULTS

Velopharyngeal dysfunction was detected in 50% of the myasthenia gravis patients with bulbar symptoms. Velopharyngeal dysfunction was not seen in myasthenia gravis patients without bulbar symptoms. The degree of velopharyngeal closure in patients with bulbar symptoms differed depending on the tasks being performed. No significant difference in velopharyngeal closure patterns was observed between the groups (p < 0.05).

CONCLUSION

Myasthenia gravis patients with bulbar involvement may have velopharyngeal dysfunction. It is important to conduct a comprehensive evaluation to assess all aspects of the velopharyngeal function.

Value of Adjuvant Radiotherapy for Thymoma with Myasthenia Gravis after Extended Thymectomy

Background:

The co-existence of myasthenia gravis (MG) and thymoma makes the surgical treatment more complicated and adjuvant radiation more controversial. The aim of this study was to investigate adjuvant radiotherapy for thymoma with MG after extended thymectomy.

Methods:

A total of 181 patients with both MG and thymoma were recruited between 2003 and 2014 at Tongren Hospital, China. Among all the patients, 157 patients received radiation therapy after surgery (Group A); whereas the other 24 patients did not receive radiation therapy (Group B). According to the time that patients started mediastinal radiation therapy, we subdivided the 157 patients in Group A into subgroups (1-month subgroup, n = 98; 2-month subgroup, n = 7; and 3-month subgroup, n = 52). We then compared the effect of the mediastinal radiation therapy across these different groups using the survival rate, the rate of postoperative myasthenic crisis, and the complete stable remission (CSR) rate as the primary endpoints.

Results:

There was a significant difference in the occurrence of postoperative myasthenic crisis between 1-month subgroup and Group B (χ² = 4.631, P = 0.031). The rates of reaching CSR were 32.6% in 1-month subgroup, 25% in 3-month subgroup, and 22.7% in Group B, respectively. The overall survival rates of 1-month subgroup, 3-month subgroup, and Group B were 88.8%, 83.3%, and 77.3%, respectively. Analysis on the Kaplan-Meier survival curves demonstrated that within 8 years after surgery, there was no significant difference in aspects of overall survival and disease-free survival between 1-month subgroup and Group B, and between 3-month subgroup and Group B; over 8 years after surgery, the disease-free survival rates in 1-month subgroup, 3-month subgroup and Group B were 79.4%, 70.6%, and 55.3%, respectively.

Conclusions:

Adjuvant radiation within 1 month after extended thymectomy may be helpful in controlling postoperative MG, such as decreasing the possibility of postoperative myasthenic crisis, and raising cumulative probabilities of reaching CSR.

Combined unilateral-thoracoscopic and mediastinoscopic thymectomy

To achieve maximal benefit, after thymic tissue and mediastinal fat were removed by thoracoscopic thymectomy, a transverse cervical incision allowed access to remove fat in the neck. A mediastinoscopy was then performed for removal of the fat in the retrosternal area superior to the innominate vein. In 15 cases, ectopic thymic tissue was found. There were three cases in which the residual superior horns of thymus were found in the neck and three in the retrosternal area. The combined use of a mediastinoscope and a thoracoscope can remove almost all the thymus, including ectopic tissues. Long-term results are still being awaited.

Extended videothoracoscopic thymectomy in nonthymomatous myasthenia gravis

Myasthenia gravis (MG) is an uncommon, organ-specific, autoimmune chronic neuromuscular disorder involving the production of autoantibodies directed against the nicotinic acetylcholine receptors (anti-AchRab). It is characterized by weakness and rapid fatigability of voluntary muscles. Thymectomy is performed early in the course of the disease and is indicated for adults less than 70 years old. For many years, the clinical efficacy of thymectomy has been questioned and so far, its benefits in nonthymomatous MG have not been firmly established. Furthermore, the precise mechanisms of action of thymectomy are unknown although possible explanations include removal of the source of continued antigen stimulation and of the AchRab-recruiting B-lymphocytes as well as immunomodulation. However, thymectomy remains indicated in patients with MG and is widely applied to increase the probability of improvement or remission. This article presents the evolution of technical and surgical advances achieved within the authors' program of extended endoscopically assisted thymectomy since 1995. The use of video-assisted thoracic surgery and its variants for performing thymectomy in MG patients is now well established and will continue to evolve for further improvement in the results.