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PubMed1983

Thymectomy-induced decrease in T gamma cells and OKT8+ cells in multiple sclerosis.

Studies were performed on lymphocytes from patients with multiple sclerosis before and after thymectomy (group I) and before and after thymectomy and azathioprine therapy (group II), and from matched control patients with multiple sclerosis, control patients with other neurological diseases, and healthy control subjects. Following treatment the percentage of T gamma cells in both group I and group II patients decreased from above the mean normal control levels to below this level; OKT8+ cell numbers in group I became lower than in any of the control groups; the percentage of concanavalin A-induced suppressor activity, which was initially normal, fell in group II and suggestively but not significantly in group I; and total blood lymphocytes in group I decreased from normal to below control levels. Other tests showed no significant changes with therapy. No significant difference in changes in clinical status were observed after one year in the treated patients compared with matched controls.

Adult↗
PubMed2005

Subtotal parathyroidectomy with thymectomy for autonomous hyperparathyroidism after renal transplantation.

BACKGROUND: There is currently no consensus on the operation that should be performed in patients with tertiary hyperparathyroidism (HPT) after renal transplantation. METHODS: : A retrospective analysis of 70 patients with tertiary HPT who underwent subtotal parathyroidectomy with transcervical thymectomy was performed. RESULTS: Mean (s.d.) follow-up was 5.6(5.0) years. Mean (s.d.) glomerular filtration rate (GFR) at follow-up was 42(29) ml/min and was less than 30 ml/min in 26 patients (37 per cent), 30-60 ml/min in 25 (36 per cent) and more than 60 ml/min in 19 (27 per cent). One patient had persistent disease and was cured after reoperation. No patient was hypercalcaemic. Four patients (6 per cent) with a GFR below 30 ml/min had a parathyroid hormone (PTH) level more than four times the normal value without any signs or symptoms of secondary HPT. One patient (1 per cent) was hypocalcaemic and two (3 per cent) were normocalcaemic, with undetectable or below-normal PTH levels while receiving oral vitamin D and calcium medication. CONCLUSION: Systematic subtotal parathyroidectomy associated with thymectomy is effective in treating most renal transplant recipients with tertiary HPT and also minimizes the recurrence of HPT in patients with declining renal function.

Adult↗
PubMed1975

Influence on allograft rejection of thymectomy at different stages of larval development in urodele amphibian Pleurodeles waltlii Michah. (Salamandridae).

Thymectomy was performed on the urodele amphibian Pleurodeles waltlii Michah. from the 5th to the 20th week of larval development. Thymectomized animals were allografted at 7 months of age. The results obtained are as follows: (1) Pleurodeles thymectomized before 10 weeks always tolerated allografts: (2) Pleurodeles thymectomized within 11 to 13 weeks generally rejected allografts in a chronic manner, but sometimes tolerated them; (3) normal rejections occurred in Pleurodeles thymectomized at 14 weeks, or later. Stage 52 of the developmental table (10 weeks of age) is a critical "end stage" for the efficiency of thymectomy. The results are confirmed by the fate of second set allografts performed in all these animals.

Age Factors↗
PubMed1976

Lack of effect of thymectomy on spontaneous recovery from tolerance to levan.

Adult CBA mice were made tolerant with 1 mg levan and tested subsequently for sponteneous recovery by plaque-forming cell assay in response to immunizing challenge. Weakening of tolerance was first detectable only after 100 days, while return to full normal responsiveness required 400 days. Thymectomy 2 weeks prior to tolerization neither retarded nor diminished the recovery process. Loss of tolerance which had been induced by 1 mg dextran B512 was much slower in onset (greater than 250 days), yet not delayed by thymectomy (full recovery was not followed). These findings in relation to other considerations imply that associative recognition by T cells is not required for B cell responses to these "thymus-independent" antigens.

Animals↗
PubMed2005

Impact of thymectomy on the peripheral T cell pool in rhesus macaques before and after infection with simian immunodeficiency virus.

The goal of this study was to define, by surgical removal of the thymus in juvenile rhesus macaques, the role of the thymus in peripheral T cell homeostasis and to assess the significance of thymic output in SIV infection. By monitoring the changes in phenotypic T cell markers as well as in the numbers of TCR excisional circles--a recently described marker for recent thymic emigrants--following thymectomy, we present evidence that surgical thymectomy in juvenile macaques results in a faster decay of peripheral CD4(+) cells, but does not cause a substantial shift in CD45RA(+) and CD45RA(-) populations. We were able to measure a thymic output of 0.32% and 0.21% per day of CD4(+) and CD8(+) cells, respectively. No compensatory extra-thymic source was detected in lymphoid tissues, although there was a small compensatory increase in T cell proliferation in the peripheral T cell pool. After SIV infection, thymectomized animals did not have higher viral loads, greater T cell decay, or faster disease progression. We therefore conclude that peripheral destructive processes, rather than a loss of thymic output, appear to be the main causes of T cell depletion in SIV infection.

Animals↗
PubMed1977

Follow-up study of myasthenic children after thymectomy.

The results of thymectomy of 28 myasthenic children observed from 1 to 9 years after operation are discussed. Improvement was obtained in 19 cases (67.8%), with full remission in 12 cases (42.8%). Six children died. No correlation was found between the results of thymectomy and the duration of the disease, sex or histological findings in the thymus. No increase of incidence or severity of infections were observed in thymectomized children. Caution is recommended regarding vaccination of myasthenic children.

Adolescent↗
PubMed1976

Leucocyte migration inhibition in myasthenia gravis. The effect of thymectomy.

Cellular hypersensitivity in myasthenia gravis (MG) to the thymus, muscles and peripheral nerves was examined by the method of the leucocyte migration inhibition test. The group of MG patients without thymoma had inhibition of leucocyte migration by thymus antigens. After thymectomy, they had a normal value of leucocyte migration. However, in the group of MG patients with thymoma, the inhibition of leucocyte migration by thymus antigens was observed after thymectomy. No significant inhibition of leucocyte migration was observed using muscle and peripheral nerve antigens. Cellular immunity in myasthenia gravis and the pathogenesis of the disease was discussed.

Adult↗
PubMed1986

Chronic relapsing experimental allergic neuritis in Lewis rats: effects of thymectomy and splenectomy.

Experimental allergic neuritis (EAN) was induced in Lewis rats aged 4 months by the inoculation of whole bovine dorsal root with Freund's complete adjuvant. Prolonged follow-up demonstrated that a relapsing course is a regular feature of the disorder in animals at this age. Although the initial disease episode was the most severe, clinical recovery from subsequent relapses was less satisfactory, this probably being related to persistent morphological abnormalities in the peripheral nervous system. Antecedent thymectomy, splenectomy, or the two combined, had little effect on the clinical course of the disorder, apart from reducing the duration of relapses. This was only statistically significant following combined thymectomy/splenectomy. Histological abnormalities, however, tended to be less severe in the operated as compared with normal control or sham-operated animals with EAN. The animals must have attained an immunocompetent state at the time of thymectomy and/or splenectomy. The capacity to develop EAN presumably resides in the draining lymph nodes and the occurrence of relapses is due to the continuing presence of antigen at the injection sites.

Animals↗
PubMed1986

[Indications for thymectomy].

An absolute indication for thymectomy exists in all cases with tumors of the thymus gland, however, preoperative differentiation between benign and malignant lesions is not always possible even with modern imaging methods. In extensive tumors of questionable operability preoperative transthoracic needle biopsy (guided by CAT-scan) is recommended. After establishing the histological diagnosis, preoperative radio- and/or chemotherapy can be considered. Certain immunological diseases are a relative indication for thymectomy. Its value is proven in myasthenia gravis, questionable however in ulcerative colitis and erythroblastopenia. Systemic lupus erythematosus is a contraindication.

Autoimmune Diseases↗
PubMed1983

Thymectomy in myasthenia gravis. A review.

The role of thymectomy in the management of myasthenia gravis is reviewed in the light of the published data and of a personal series. The patients in whom the operation is most successful are non thymomatous patients aged between 10 and 40 years with an MG history of less than 3 years. There is no sex prevalence. Lasting improvement may be expected. There are no proven correlations between biological indices like the germinal centers in the thymus and/or AChR antibody titers and the postoperative course of the disease. Complete removal of the thymus seems to be crucial and hence the transsternal approach is preferred. The operation, less effective in patients with thymoma than in those with an active thymus, is nonetheless necessary to in these patients prevent putative damage to surrounding organs from thymoma infiltration. Why thymectomy should be effective in patients with an active thymus and not in those with a thymoma may be revealed by in vitro studies of the interactions between thymic cells and peripheral B cells, now in progress.

Adolescent↗
PubMed1987

Favorable results of thymectomy combined with prednisolone alternate-day administration in myasthenia gravis.

Administration of anti-cholinesterase before operation and high doses of prednisolone after the operation are commonly prescribed in cases of thymectomy for the treatment of myasthenia gravis. Our policy is to carry out an extended thymectomy combined with pre- and post-operative administration of prednisolone on alternate days. Our method was used in the treatment of 50 patients with generalized myasthenia gravis, from January 1979 to December 1984. The results were examined in conjunction with the necessity for preoperative administration of an anti-cholinesterase preparation and also with factors influencing the follow-up result and postoperative process. This method made it feasible to perform surgery under conditions of stabilization of clinical symptoms and satisfactory postoperative management. A postoperative period of unstable symptoms could thus be avoided. The palliation rate at one year after the operation was 96 per cent, while the remission rate at 5 years after the operation was 70 per cent. The preoperative supplement of anti-cholinesterase and preoperative per cent forced vital capacity were considered to be predictive factors concerning the necessity of artificial respiration.

Adult↗
PubMed1997

Effects of postnatal age and of thymectomy on hamster pulmonary neuroendocrine system and aspects of programmed cell death.

Effects of postnatal age and neonatal thymectomy on the numbers and characteristics of pulmonary neuroepithelial bodies (NEB) were investigated in 14-day- compared with 2.5-month-old hamsters. Left lung sections were stained for the marker PGP 9.5 and used for light-microscopic quantification, while the right lungs were processed for an electron-microscopic survey of the NEB ultrastructural features. For the first time, it is clearly demonstrated that, depending on the sampling method, the number of NEB may rise or fall with age; when considering the entire lung volume, the actual number of NEB doubles, whereas when studying a constant surface area, their number apparently decreases. Also, the proportion of alveolar NEB as well as luminal contact increase on normal development. In neonates, in contrast to older animals, apoptosis is clearly present in NEB, and approximately 10% of the NEB are associated with inflammatory cells. In some cases, the dead cells have properties of both apoptosis, disintegration and cytoplasmic degeneration. The presence of intracorpuscular neutrophilic granulocytes correlates with cellular death and innervation of the NEB. Thymectomy causes only minor effects on the pulmonary neuroendocrine system. It is argued that development of the NEB and of their innervation continue during the postnatal period.

Animals↗
PubMed2004

Endoscopic robot-assisted extended thymectomy by subxiphoid approach with sternal lifting: feasibility in the pig.

BACKGROUND: In the search for novel approaches to thoracoscopic thymectomy we assessed the feasibility of a subxiphoid approach using computer-enhanced instruments and sternal lifting. METHODS: In 12 pigs, after lifting of the sternum, ports were placed subxiphoid (stereoscope) and in the left and right fourth intercostal space (instruments). Using computer-enhanced instruments, dissection of the thymus and anterior mediastinal fat pads was started at the diaphragm and continued cephalad. RESULTS: After setup of the robot system (23 +/- 6 min, mean +/- SD), the thymus, including both superior horns, and fat pads in the anterior mediastinum and cardiophrenic angles were dissected (109 +/- 23 min), with excellent view of the phrenic nerves. Visual inspection after sternotomy after the procedure showed all thymic and fatty tissue was removed. CONCLUSIONS: In the pig, endoscopic extended thymectomy can be safely performed by subxiphoid access using computer-enhanced instruments, sternal lifting, and three ports total.

Animals↗
PubMed2004

Video-assisted transcervical thymectomy.

BACKGROUND: The optimal surgical approach for complete removal of the thymus gland has long been debated. In this report, the excision of the entire gland through a transcervical incision using video-assisted techniques is described. METHODS: Ten patients, including one with thymoma and myasthenia gravis, underwent surgery via the transcervical approach. After standard dissection up to the level of the innominate vein and ligation of the thymic vessels, a laparoscope was inserted into the mediastinum. In the patient with thymoma, the operation was completed by a small incision in the third intercostal space. RESULTS: No perioperative mortality or long-term morbitity was observed. The mean hospital stay was 69.6 h. After a mean follow-up period of 63.8 months, eight patients displayed complete remission, whereas one continued to receive minimal medication. The patient with thymoma showed considerable improvement, but remained on same medical regimen No complications were seen throughout the study. CONCLUSION: Video-assisted thymectomy improves effectiveness of the transcervical approach for thymectomy with a minimum of trauma and excellent results.

Adult↗
PubMed2006

Inclusion of the transcervical approach in video-assisted thoracoscopic extended thymectomy (VATET) for myasthenia gravis: a prospective trial.

BACKGROUND: Because evidence-based data regarding the quality of video-assisted thoracoscopic thymectomy for the treatment of myasthenia gravis are lacking, a prospective trial comparing three different operative approaches was conducted to evaluate their efficacy. METHODS: This prospective study enrolled 20 consecutive patients with nonthymomatous myasthenia gravis. A series of three approaches for bilateral video-assisted thoracoscopic extended thymectomy (VATET) using the anterior chest wall-lifting method (original), the original method with a flexed-neck position (modified), and the original method with a transcervical approach (final) were prospectively performed in each patient for quantitative and pathologic evaluation of the residual thymus after each approach. RESULTS: Complete VATET required 242 +/- 48 min, with the transcervical procedure requiring 23 +/- 12 min. After the modified method, the residual thymus in the cervical region was 1.5 cm in size and weighed 0.8 g (0.8% of the entire thymus), as compared with a size of 2.2 cm and a weight of 1.3 g (3.2%) after the original method. Each value is the result of comparison with the final method. Histopathologic studies showed residual tissue in the germinal center as well as Hassall's corpuscles in more than 70% of cases. CONCLUSION: The findings show that VATET without the transcervical approach could be an immunologically incomplete treatment for myasthenia gravis. Therefore, the transcervical approach should be included in VATET procedures to ensure radicality.

Adult↗
PubMed1983

Recurrence of thymic hyperplasia after thymectomy in myasthenia gravis. Its importance as a cause of failure of surgical treatment.

Persistence of symptoms in patients with myasthenia gravis who have undergone previous thymectomy has been attributed to thymus remnants. Patients with partial or no recovery were studied 40 +/- 31 months (mean +/- SD) after surgery, which had been carried out by the transcervical approach in 20 and trans-sternal approach in four. Lateral x-ray tomography of the mediastinum after injection of air showed images compatible with residual thymus gland in 18 patients (75 percent). Thirteen of these underwent reoperation by the trans-sternal approach, and thymic tissue was found in 11 (85 percent). After repeated thymectomy, 67 percent of the patients improved clinically. Therefore, it is quite reasonable to infer that incomplete removal of the thymus was responsible, at least partly, for failure of the first procedure.

Adult↗
PubMed1983

Thymectomy for myasthenia gravis.

Thymectomy was performed on 249 patients with myasthenia gravis between 1957 and 1981. During a follow-up period that ranged from 2 months to 24 years (mean 7.5 years), the remission rate for the entire group was 51 percent, and an additional 36 percent had improvement (87 percent benefited). In those 51 patients with thymoma, the remission rate was 37 percent, with 68 percent of the patients benefiting from operations. The remaining 198 patients fared better after the operation: 54 percent had remission and a total of 91 percent benefited. The female patients within this group had a 94 percent probability of benefit from operation. We conclude that most patients with myasthenia gravis will benefit from thymectomy, and that the improvement persists over an extended period of time in a high percentage of patients.

Adolescent↗
PubMed1996

Adjuvant pneumomediastinum in thoracoscopic thymectomy for myasthenia gravis.

To facilitate initial visualization and subsequent mobilization of the thymus, adjuvant pneumomediastinum was preoperatively induced in 4 patients who underwent video-assisted thoracoscopic thymectomy. Neither mortality nor technique-related morbidity was observed. This experience shows video-assisted thoracoscopic thymectomy to be a safe and reliable procedure. In addition, we believe that adjuvant pneumomediastinum seems to facilitate the dissection maneuvers and could shorten operative time.

Endoscopy↗