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PubMed1987

Immunodeficiency following neonatal thymectomy in man.

Patients undergoing cardiac bypass operations normally have a thymectomy to facilitate cannulation of the great vessels. Laboratory indices of immune function were measured in 18 children aged 9 months to 3 years who had had a thymectomy when aged 3 months or less, and in two groups of controls individually matched for age and age at operation. Total lymphocyte numbers were similar in all three groups but thymectomized children had significantly lower numbers of T cells and T cell sub-sets than controls and showed diminished responses to phytohaemagglutinin and concanavalin A. Children who have had a thymectomy early in life represent an important group in the study of the development of the immune system in man. Although the clinical consequences of early thymectomy are unclear, evidence of impairment of parameters of immunity have been found in later infancy and routine thymectomy in paediatric cardiac surgery should be avoided.

Antigens, Surface↗

PubMedDate not supplied

[Thymectomy in myasthenia gravis].

Myasthenia gravis is an autoimmundisease characterized by muscle fatigability due to a reduction in available acetylcholinereceptors at neuromuscular junction. Although the role of the thymus in the pathophysiology remains obscure, the results of thymectomy are out of discussion. However, controversy continues concerning the indications for thymectomy. In a period of six years and a half, 24 patients underwent a thymectomy. 22 of the patients benefited from the procedure. Their was no relation with sex, age, and severity of the disease; but how sooner we operate, how greater the changes for a total remission. With this results we propose thymectomy as essential in the treatment of myasthenia gravis. We found no relationship between anatomopathological results and these of the thymectomy. But we can confirm that a reduction in the acetylcholine antibodies titer is not essential for clinical benefit.

Acetylcholine↗

PubMed1982

[Effects of adult thymectomy on the growth of 203-glioma in mice--analysis of T cell subpopulation in tumor immunology].

The effects of adult thymectomy in C 57 BL/6 mice on in vivo and in vitro responses to syngeneic methylcholanthrene-induced glioma (203-glioma) were investigated in order to analyse the role of T cell subpopulation in relation to the antitumor immunity. The tumor growth in adult mice thymectomized 3 weeks before subcutaneous inoculation of tumor cells was significantly suppressed. On the other hand, in mice thymectomized 7 or 10 weeks before tumor cell inoculation, the tumor growth was enhanced resulting in shorter mean survival time. The cytotoxic activity of the regional lymph node T cells in the former mice was increased from the beginning after tumor cell inoculation with peak observed on day 14 and maintained for about 4 weeks, while it was extremely decreased in the latter mice. The marked enhancement of cytotoxic activity in the former mice is probably due to a reduced proportion of short-lived T lymphocyte population after adult thymectomy. In contrast, the low level of cytotoxic activity in the latter mice may be due to a gradual reduction of long-lived T lymphocyte population in addition to short-lived T lymphocyte population after adult thymectomy. The cytotoxic activity was specific for 203-glioma cells and almost completely eliminated with anti-Thy-1 monoclonal antibody and complement. The surface markers of these killer T cells were checked with the results that in normal mice Lyt-1-.2.3+ and Lyt-1+.2.3+ cells participate in cytotoxic reaction. In mice thymectomized 3-10 weeks before tumor cell inoculation, however, Lyt-1+.2.3+ killer T cells were not detected suggesting strongly that the progenitors of Lyt-1+.2.3+ killer T cells are short-lived cells in contrast to those of Lyt-1-.2.3+ killer T cells which survive more than 10 weeks after adult thymectomy. The tumor growth was also significantly suppressed by the intravenous adoptive transfer of sensitized lymphocytes obtained from mice thymectomized 3 weeks before tumor cell inoculation. This effect of tumor suppression was disappeared by the pretreatment of infused lymphocytes with anti-Thy-1 monoclonal antibody and complement. These evidences may suggest that in tumor bearing mice short-lived suppressor T cells or their precursors exist and regulate the growth and differentiation of killer T cells and that adult thymectomy affects immunoregulation, possibly by altering the generation of suppressor T cells.

Animals↗

PubMed1978

Idiotype-specific transplantation resistance to MOPC-315: abrogation by post-immunization thymectomy.

The idiotype-specific myeloma transplantation resistance induced in BALB/c mice by immunization with the DNP-binding IgAlambda2 protein produced by plasmacytoma MOPC-315 is ablated by post-immunization thymectomy. Sham-thymectomy has no effect. The ablative effect of thymectomy is observed is observed in mice challenged subcutaneously with MOPC-315 cells either 3 days after thymectomy, or after a rest period of 44 days after thymectomy. These observations suggest that short-lived, thymic-dependent suppressive factors may play a role in the idiotype-specific myeloma graft resistance.

Aging↗

PubMed1995

[The long-term results of thymectomy for myasthenia gravis].

Eighty-three patients with myasthenia gravis underwent thymectomy were reviewed to evaluate the long term effects of thymectomy and analyse the factors influencing outcome. Follow up times were from 3 months to 120 months (mean: 77.6 months) after operation. The effects of thymectomy were as follows: 1) Remission rate was 26.5%, improvement rate was 56.5% and palliation rate was 83.1% at the last observed time in all cases. 2) Remission rates showed increasing (7.3% at 1 year, 22.2% at 5 years, 35.3% at 10 years) according to the time courses. Improvement rates and palliation rates showed respectively maximum (78.3%, 94.4%) at 4 years and 5 years. 3) Analysis of factors influencing outcome showed that the cases of IIA in Osserman's classification, less than 40 years old in age, less than 12 months in duration of illness, no complication of thymoma were expected the better effectiveness of thymectomy. We concluded that thymectomy for myasthenia gravis expected the delayed remission according to the time courses, and so, we must carefully follow the patients for long time.

Adolescent↗

PubMed1993

Thymectomy for myasthenia gravis: predictive factors and long term evolution. A retrospective study on 46 patients.

Forty-six patients with myasthenia gravis (MG) underwent transternal thymectomy between 1975 and 1991 and were observed over a long term follow up period (mean 6 years). Surgery was well tolerated and was followed in 32.6% of patients by remission of symptomatology. The severity of symptoms according to the Osserman scale was significantly reduced: slight forms of myasthenia increased soon after thymectomy more frequently than moderate and severe forms. Response to thymectomy at 3 months, according to the Hankins scale, was found to be positive (remission or amelioration of symptoms) in 31/41 patients, and worse in patients with thymoma. Probability of clinical remission and death were both significantly correlated with clinical response at three months after thymectomy. No other preoperatory clinical factor (onset age, sex, initial severity of MG, interval from symptom onset to thymectomy) was found to predict the response to treatment. Preoperatory mediastinic CT had a good reliability (> 85%) in diagnosing thymona, but was rarely able to distinguish between thymic hyperplasia and atrophy.

Adolescent↗

PubMed1977

Effects of neonatal thymectomy and splenectomy on survival and regulation of autoantibody formation in NZB/NZW F1 mice.

NZW F1 (B/W) mice were subjected to sham surgery or neonatal thymectomy and/or splenectomy and studied for immunoglobulin class of antibodies to double-stranded DNA and polyadenylic acid (Poly A) at 4 to 13 months of age. These antibodies occur spontaneously during the course of autoimmune disease in B/W mice. Sera were fractionated by sucrose density gradient ultracentrifugation and assayed for antibodies by a filter radioimmunoassay method. IgM was recovered in the 19S region and IgG in the 7S region as demonstrated by immunodiffusion. In sham-operated controls, at all ages studied, anti-DNA antibodies were both IgM and IgG, with the former predominating in males, and the latter in females. In both sexes, anti-Poly A antibodies were primarily IgM in young mice. There was a sequential switch from IgM to either enhanced or new IgG production in the following sequence: female anti-DNA and anti-Poly A (6 months), male anti-DNA (9 months), and male anti-Poly A (11 months). Both thymectomy and splenectomy caused earlier death in male mice, whereas females lived significantly longer after thymectomy. Neonatal thymectomy in males caused a premature switch from IgM to IgG antibodies to DNA, but it had a transient effect in females. Thymectomy almost completely prevented the late switch to IgG antibodies to Poly A in both sexes. By contrast, splenectomy promoted the formation of IgG antibodies to Poly A in male mice. These results suggest that the newborn B/W thymus and spleen contain regulatory cells and/or factors exerting different controlling influences on spontaneous antibodies to DNA and Poly A. Male B/W mice appear to be under the regulatory influence of suppressor cells, whereas the predominant regulation in female B/W mice appears to be a helper effect.

Age Factors↗

PubMed1996

[Video assisted thoracoscopic thymectomy for myasthenia gravis].

Thymectomy is now an established approach to the treatment of myasthenia gravis (MG). We used video assisted thoracoscopic surgery (VATS) in thymectomy. From June 1993 to May 1995, we performed VATS thymectomy for 10 cases (6 males, 4 females with age ranging from 9 to 76 years). Complete thymectomy was achieved in every case by examination of the thymic bed and resected specimen. There was no mortality and complications were few. Average hospital stay was 4.1 days. Compared with the conventional median sternotomy approach, VATS was associated with a shorter postoperative hospital stay and analgesic requirement. We believe that VATS thymectomy is technically feasible. However, its true role in the treatment of MG requires further study.

Adolescent↗

PubMed1987

Prognosis in occult thymomas in myasthenia gravis following transcervical thymectomy.

Thymomas were noted in 239 (11%) of 2097 myasthenic patients followed up at our institution. Among 996 patients who had undergone thymectomy, 191 patients (19%) had thymomas compared with 48 (4%) of 1101 patients treated without surgery. A definitive diagnosis of thymoma was not made until after thymectomy in 61 patients (35%); in patients not treated with thymectomy, 23% of associated tumors were diagnosed at autopsy. Patients with occult thymomas treated with the transcervical approach had a clinical course superior to those with tumors diagnosed prior to surgery and treated with the transsternal approach. Most of the advantage could be attributed to the association of occult thymomas with small tumor size and to the association of the latter with absence of invasiveness. Small tumor size was significantly associated with higher remission and lower mortality as shown in a proportional hazards analysis. Occult thymomas were accessible through the transcervical approach, with some operations necessitating a complementary mediastinotomy. Thymectomy, through the transcervical approach if technically feasible, is of benefit to all patients, has minimal morbidity, and should be performed early in the course of the disease as a diagnostic and therapeutic intervention since the risk of occult thymomas in patients with myasthenia gravis is high.

Adult↗

PubMed1998

[Thymectomy in myasthenia gravis--an analysis of current status].

Between May 1992 and June 1997, 11 patients with myasthenia gravis and 1 asymptomatic patient with thymoma underwent extensive thymectomy through a median sternotomy. Seven patients were male and 5 female. The mean age at onset of myasthenia gravis was 46.5 (13-73) years. The interval between the first symptom and diagnosis was 3.6 months (1 week-7 months), between the first symptom and thymectomy 8.3 months (2 weeks-36 months) and the mean follow-up period was 28.4 months (3-57 months). Clinical improvement after extensive thymectomy was noted in 80% of patients. Four patients became asymptomatic under decreased medication. Thymectomy was found to be beneficial even in older patients or patients with the purely ocular type of myasthenia gravis. There was no perioperative mortality or long-term morbidity.

Adolescent↗

PubMed2004

Comparison between the right side and subxiphoid bilateral approaches in performing video-assisted thoracoscopic extended thymectomy for myasthenia gravis.

BACKGROUND: This study aimed to compare the efficacy of the right thoracoscopic (RtT) approach and the subxiphoid bilateral thoracoscopic (SxBiT) approach in performing thymectomy for myasthenia gravis. METHODS: Between March 2001 and April 2003, 27 myasthenic patients were enrolled in this prospective study. The operations were conducted by two surgical teams in a single institute. The surgical procedures included RtT for 12 patients and SxBiT for 15 patients. The operation time, resected thymus weights, and thoracic drainage periods were compared. RESULTS: Subxiphoid video-assisted thoracoscopic extended thymectomy (SxVATET) and right-side thoracoscopic extended thymectomy (RtVATET) were performed for 27 consecutive myasthenic patients. The mean operation time, weights of resected specimens, and duration of hospital stay for the SxVATET and RtVATET groups were, respectively, 151.3 min (range, 120-200 min) versus 191.5 min (range, 120-225 min) (p = 0.0012), 73.3 g (range, 40-90 g) versus 50.8 g (range, 5-90 g) (p = 0.0029), and 3.1 days (range, 2-4 days) versus 3.8 days (range, 2-4 days) (p = 0.914). Ten patients (37%) had complete remission, observed during a mean follow-up period of 18.5 months (range, 6-30 months). CONCLUSIONS: During this consecutive experience, both the RtT and SxBiT approaches showed satisfactory results for nonthymomatous myasthenic patients. However, a better view of the bilateral pleural cavities and more radical thymectomy could be achieved only by the SxBiT approach.

Adult↗

PubMed2006

Safer video-assisted thoracoscopic thymectomy after location of thymic veins with multidetector computed tomography.

BACKGROUND: Video-assisted thoracoscopic (VATS) thymectomy has been applied as a surgical option for autoimmune myasthenia gravis. Prior identification and fine division of the thymic veins are critical to the prevention of unexpected severe bleeding that may require conversion to open surgery. Until recently, such bleeding could be avoided only by meticulous dissection of thymic fat tissue away from the left brachiocephalic vein (LBV). With recent advances in computed tomography (CT), multidetector-row computed tomography (MDCT) can readily be obtained and provides three-dimensional (3D) images. This study explored its value for preoperative identification of the thymic veins draining into the LBV, and thus for prevention of injury to these veins during endoscopic thymectomy. METHODS: Five patients with myasthenia gravis, thymoma, or both underwent enhanced MDCT preoperatively. The thymic veins draining into the LBV were visualized using both horizontal and sagittal/coronal CT images. Then 3D images were reconstructed to enable operators to simulate endoscopic views. During each VATS extended thymectomy, the numbers and branching patterns of the thymic veins were compared with the preoperative MDCT images. RESULTS: The thymic veins draining into the LBV were clearly identified with MDCT in all five patients examined. Reconstructed 3D images clearly located their courses in the thymic/fat tissue and their entry routes into the LBV, thus simulating the actual intraoperative endoscopic views. All tributaries divided during surgery were identified preoperatively with MDCT. CONCLUSIONS: Location of thymic veins with MDCT can provide precise preoperative information about thymic venous anatomy. This easy and less invasive examination has the potential to make VATS thymectomy easier and safer.

Adult↗

PubMed2006

A case of systemic lupus erythematosus complicated by pure red cell aplasia and idiopathic portal hypertension after thymectomy.

We describe a 49-year-old woman who presented in 2002 with pure red cell aplasia (PRCA), systemic lupus erythematosus (SLE), and idiopathic portal hypertension (IPH) that developed following a thymectomy. She underwent a thymectomy at 40 years of age to treat myasthenia gravis. PRCA developed 3 years after the thymectomy and she was successfully treated with cyclosporin. Systemic lupus erythematosus and IPH were diagnosed 6 years later. We conclude that immunological dysfunction resulting from the thymectomy contributed significantly to the subsequent development of PRCA, SLE, and IPH in this patient. This is the first report to describe this extremely rare occurrence.

Adult↗

PubMed1989

Transsternal radical thymectomy for myasthenia gravis: a 15-year review.

Thymectomy is an accepted therapeutic modality for patients with myasthenia gravis. The selection of patients for operation and the surgical approach are controversial. We reviewed 52 patients (aged 18 months to 82 years; mean age, 34 years) treated with transsternal radical thymectomy between 1972 and 1987. Patients were symptomatically staged according to the modified Osserman classification. There was one hospital death and postoperative follow-up was obtained on 51 patients. Improvement after thymectomy was observed in 3 of 11 patients (27%) in Osserman stage I, 16 of 25 patients (64%) in Osserman stage IIA, and 13 of 15 patients (86%) in combined Osserman stages IIB, III, and IV. Preoperative Osserman stage, patient sex, and thymic histology correlated with postoperative clinical response. Transsternal radical thymectomy is effective therapy for myasthenia gravis. Sustained improvement is obtained in patients with moderate and advanced disease. The majority of patients with ocular disease do not benefit from operation.

Adult↗

PubMed1994

Transcervical thymectomy for myasthenia gravis.

The use of transcervical thymectomy in the treatment of myasthenia gravis remains controversial. We retrospectively reviewed our experience with this procedure to determine its usefulness in the management of myasthenia gravis. Fifty-three selected myasthenic patients without thymoma underwent transcervical thymectomy between 1977 and 1991. The mean age (27.5 +/- 1.5 years), duration of symptoms (2 +/- 1.0 years), and preoperative Osserman classification (13% class I, 53% class IIA, 28% class IIB, 6% class III) were consistent with previous reports. The average hospitalization was 3.0 +/- 0.3 days, but has been 1.6 +/- 0.2 days since 1987 (n = 14). There were no deaths, and no patients required mechanical ventilation for more than 24 hours. Average follow-up was 4.3 +/- 0.4 years with a range of 0 to 13 years. Eighty-one percent of patients are symptom free, and 9 of 21 (43%) are in complete remission at least 5 years postoperatively. One patient required a transsternal exploration for worsening symptoms. Clinical improvement continued over an extended period of time, and a statistically significant decrease in symptoms was evident comparing the first and sixth postoperative years. Patients were more likely to be improved or in remission if thymectomy was performed within the first year of the onset of symptoms (p < 0.05). Osserman classification, thymus histology, and patient age were not prognostic indicators. Transcervical thymectomy is effective surgical therapy for myasthenia gravis in selected patients without thymoma.

Adolescent↗

PubMed1994

A technique for complete thymectomy in adult rats.

50 open thymectomies were performed in adult rodents using intubation combined with a fibrin glue able to prevent hemorrhage and pulmonary air leakage. This method had a 100% success rate and lower mortality than the ordinal suction procedure. Although the conventional suction thymectomy has been widely used, the open thymectomy method would permit more complete thymectomies for immunological studies.

Animals↗

PubMed1991

Thymectomy at weaning. An accelerated aging model for the mouse immune system.

Mouse thymectomy at weaning induces a long lasting immunodepression which can be measured by in vivo and in vitro experiments. Lymphocyte proliferation and IL2 production in response to a T cell mitogen are greatly diminished during the whole life of the animals, on the contrary B cell proliferation in the presence of lipopolysaccharide is not modified. The lack of effect of surgery on the in vitro T cytotoxic activity compared to the total abolition of in vivo graft versus host reaction shows that these two phenomena are under the control of different immunocompetent cell subsets. Thymectomy induces a stabilization of natural killer cell activity, while during normal aging, this parameter decreases regularly. Surprisingly, the thy 1+ cell level is normal 8-10 months after thymectomy compared to sham operated animals showing that phenotypically normal cells can be dysfunctional. Macrophage activity is not modified either by aging or by thymectomy. So, thymectomized mice can be used after less than 1 year to study immunopharmacology of aging.

Aging↗

PubMed1992

Follow-up of soluble interleukin-2 receptor levels after thymectomy in patients with myasthenia gravis.

Soluble interleukin-2 receptor (sIL-2R) levels were followed up after thymectomy by a quantitative immunoradiometric assay in 59 patients with myasthenia gravis (MG). Increased levels of sIL-2R were found in 30.5% of the patients before thymectomy. Serum levels were significantly higher in severely affected patients. Sequential sampling after thymectomy indicated a significant and progressive decline of sIL-2R levels within 2 years after surgery, which was well associated with clinical improvement or remission. The sIL-2R purified from sera of patients with MG had a molecular mass of 45 kDa as the normal sIL-2R. The decline after thymectomy of sIL-2R titers suggests a possible role of the thymus in the occurrence of sIL-2R in the periphery. Soluble IL-2R levels may represent a marker of disease severity in MG, which might be useful in the follow-up of individual patients.

Adolescent↗