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Case report: Thymectomy-induced remission of acquired autoimmune hemolytic anemia in an adult with myasthenia gravis.

A 57-year-old woman with diabetes mellitus, hypothyroidism, idiopathic thrombocytopenic purpura, myasthenia gravis, systemic lupus erythematosus, atopy, and basal cell cancer of the skin developed a severe Coombs'-positive autoimmune hemolytic anemia which was resistant to treatment with large doses of azathioprine, cytoxan, and prednisone. One year after transcervical thymectomy the hemolytic anemia disappeared and the patient has maintained a normal hemoglobin and negative Coombs' test without immunosuppressants even since. We believe this case report to be the first recorded instance of thymectomy-induced remission of autoimmune hemolytic anemia in an adult.

Anemia, Hemolytic, Autoimmune↗

A prospective study of thymectomy and serum acetylcholine receptor antibodies in myasthenia gravis.

Forty-seven consecutively presenting myasthenia gravis (MG) patients with generalized weakness were treated according to a standardized prospective protocol. All patients underwent a sternal splitting "total" thymectomy. Medical status before surgery was optimized by plasmapheresis without immunosuppression. Medications were avoided or discontinued whenever possible. All patients were improved. At the time of latest follow-up 83% were free of generalized weakness and 61% were on no medications. There was no significant change in Acetylcholine Receptor Antibody (AChR-AB) titer. The following conclusions were made: (1) thymectomy is an effective therapy for MG, (2) additional medications are not necessary in the majority of patients, and (3) a reduction in the AChR-AB titer is not essential for clinical benefit.

Acetylcholine↗

Preoperative lumbar epidural morphine improves postoperative analgesia and ventilatory function after transsternal thymectomy in patients with myasthenia gravis.

OBJECTIVE: To test the hypothesis that preoperative lumbar epidural morphine improves postoperative pain control and ventilatory function after transsternal thymectomy in patients with myasthenia gravis. DESIGN: The study design was randomized, placebo-controlled, and double-blind. SETTING: After surgery, all patients were admitted to the Neuroscience Critical Care Unit for evaluation and treatment. PATIENTS: All patients with myasthenia gravis who presented to the hospital for thymectomy were asked to participate in the study. Twenty patients were randomized to either the placebo or epidural morphine groups. INTERVENTIONS: Patients received either epidural morphine (7 mg in 14 mL of sterile saline) or saline (14 mL) before induction of anesthesia. Supplemental iv opioids were administered intraoperatively, with need determined by the anesthesiologist. MAIN OUTCOME MEASURES: The main outcome measures were indicators of postoperative pain (e.g., Visual Analog Pain Score, requirement for supplemental opioid administration, respiratory rate) and ventilatory function (e.g., forced vital capacity, negative inspiratory pressure). RESULTS: Immediately after surgery, the Visual Analog Pain Score in the placebo group was twice as high as the score in the epidural morphine group (placebo 7.0 +/- 1.3; epidural morphine 3.5 +/- 1.2, p less than or equal to .05). During the first eight postoperative hours, the placebo group required more opioids (0.22 +/- 0.03 vs. 0.12 +/- 0.04 mg/kg morphine equivalents, p less than or equal to .06) than the epidural morphine group. Later, both groups received similar amounts of opioids. Patients receiving epidural morphine had better initial recovery of forced vital capacity (at 8 hrs: 55 +/- 6% [epidural morphine] vs. 34 +/- 5% [placebo] of preoperative value, p less than or equal to .05). Respiratory rate was lower for the first 12 postoperative hours in the epidural morphine group, without a difference in PaCO2. There was no difference between groups for the duration of postoperative intubation or ventilation. CONCLUSIONS: Preoperative lumbar epidural morphine facilitates postoperative analgesia and improves initial postoperative ventilatory performance.

Adult↗

Thymectomy delays the development of hypertension in Okamoto spontaneously hypertensive rats.

Previous studies in rats have demonstrated that immune system dysfunction contributes to the aetiology of spontaneous hypertension. Chronic immunosuppression with cyclophosphamide attenuated the level of hypertension in Okamoto spontaneously hypertensive rats (SHR) by approximately 50%. Also, neonatal thymic implants delayed the development of spontaneous hypertension and significantly attenuated its level at the age of 22 weeks in SHR. In the present study, the effect of thymectomy at the age of 4 weeks on blood pressure was investigated in SHR and Wistar-Kyoto (WKY) rats. The removal of the thymus gland in 4-week-old SHR produced a significant reduction in systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP) when rats were 16-19 weeks old, while no pressure reduction was observed in WKY rats. The decrease in arterial pressure of 16-week-old SHR was associated with a significant reduction in lymphocyte count at this age as compared with the control group. In 1-year-old SHR, thymectomized at the age of 4 weeks, there was no significant difference in arterial pressure or lymphocyte count compared with controls. These data support the hypothesis that an immune imbalance may be important in the development of spontaneous hypertension. We conclude that thymectomy at a young age (4 weeks) delays the development of hypertension in SHR.

Aging↗

Effect of perinatal anti-TCR2 treatment and thymectomy on serum immunoglobulin levels in the chicken.

Treatment of chickens as embryos and in the first six days after hatching with mg amounts of anti-TCR2 (alpha beta T cell antigen receptor) antibody plus thymectomy 6 to 8 days after hatching suppressed by more than 90% the TCR2 and TCR1 (TCR gamma delta) subpopulations in the blood. Thymectomy alone resulted only in a profound reduction (greater than 90%) of the absolute number of TCR1 cells, while the absolute number of TCR2 cells was reduced only by 65%. We were interested in the regulation of the immunoglobulin synthesis in these T cell deficient chickens. We determined serum IgG, IgM and IgA levels and found a profound selective reduction (by about 90% on average) of the serum IgA level in anti-TCR2 antibody treated plus thymectomized chickens. In chickens which had been thymectomized only, the serum IgA level was reduced on average only by about 60%. Serum IgG and IgM levels were not reduced in any group. Thus, there was a positive correlation of the serum IgA level and the absolute number of TCR2 cells in all groups. These results indicate that T cells which play a role in IgA specific isotype switching or in IgA B cell differentiation belong to the TCR2 subpopulation.

Animals↗

Thymectomy in late-onset myasthenia gravis.

Two cases of late-onset myasthenia gravis were successfully treated by thymectomy using a sternal splitting technique, in spite of the fact that no thymomas could be detected preoperatively. One patient was seriously ill, the other patient responded to medical treatment. Thymolipoma and malignant thymoma, respectively, were removed from the patients. It is stressed that not all thymomas produce antibodies to striated muscles and that CT-scan of the mediastinum is of limited value in the diagnosis of thymoma. It is suggested that patients with late-onset myasthenia gravis be offered thymectomy, even in the absence of detectable thymomas.

Aged↗

The ovarian dysgenesis normally induced by neonatal thymectomy is prevented by the prior administration of estrogen.

PROBLEM: Neonatal thymectomy (Tx) and estrogen (E2) administration disrupt the reproductive and immune systems of female mice. The current experiment examined the combined effects of the two procedures on ovarian function, performed in sequence, and in reverse sequence. METHOD: Groups of (C57BL/6J x A/J)F1 (B6A) female mice were given four daily injections of 20 micrograms estradiol-17 beta, either from 0 days to 3 days, or from 3 days to 6 days postpartum. In some groups this regimen was combined with thymectomy performed either prior to steroid injection (TX-3), or after steroid treatment (TX-4). Animals were sacrificed between 100 and 110 days of age then ovaries evaluated via light microscopy for dysgenesis and follicular cysts. RESULTS: When E2 treatment followed Tx, the incidence of ovarian dysgenesis was unchanged (study 1, Tx + E2 = 60% ovarian dysgenesis; Tx = 63% ovarian dysgenesis) (study 2, Tx + E2 = 46% ovarian dysgenesis; Tx = 45% ovarian dysgenesis). In contrast, when E2 was given before Tx, ovarian dysgenesis did not occur (study 2, E2 + Tx = 0% ovarian dysgenesis; Tx = 46% ovarian dysgenesis). Ovaries from E2 + Tx animals were characteristic of ovaries from E2-injected animals without Tx. CONCLUSION: The results indicate that E2 injection prevents Tx-induced ovarian dysgenesis, suggesting E2-activation of an extrathymic pathway for thymus function.

Animals↗

Long-term prednisone followed by thymectomy in myasthenia gravis.

The present series of thirty patients has led us to certain conclusions concerning the management and treatment of patients with myasthenia gravis. The use of cholinesterase inhibitors alone is reserved for those patients with purely ocular myasthenia whose deficits can be satisfactorily corrected with those agents. Some of those with ocular involvement may be disabled; and in light of our excellent results with that small group, as well as similar findings presented by Fischer et al., patients with disabling or refractory ocular myasthenia should be considered for treatment with prednisone. All other patients with myasthenia are given a course of oral corticosteroids (prednisone) initially at high doses, with subsequent tapering to maintenance, alternate-day low-dose therapy. Cholinesterase inhibitors are used as needed while the patient is receiving corticosteroids. We now anticipate that patients will exhibit sustained improvement within the first two weeks, reaching maximal improvement at about three months. Exacerbations of myasthenic weakness may occur in the early phases of treatment. Such exacerbations have been commonly mild and occur with a mean onset at 5 days, and have a mean duration of 6 days. Most patients have been able to tolerate an alternate-day schedule of prednisone therapy when maintenance levels were achieved. The effective maintenance dose has been determined as the smallest dose of prednisone which allows the patient to maintain maximal improvement. Following the establishment of maximal improvement, patients have been considered for thymectomy. In our experience, the sternum-splitting procedure has been tolerated extremely well by patients exhibiting marked imporvement or remission while on corticosteroids. In those patients where thymectomy is contraindicated, irradiation of the thymus might be considered. Patients are continued on maintenance steroid therapy following surgery for a period of time that has been arbitrary. Currently, we consider an attempt to discontinue steroids at approximately one year reasonable. Should the patient relapse after discontinuation of the medication, oral corticosteroid treatment is reinitiated. Consideration is given to the possibility of recurrent thymus in patients who repeatedly fail to maintain a remission when steroids have been stopped. Our experience has not permitted us to draw firm conclusions concerning how long a time high-dose daily steroid treatment should be continued in patients who show no favorable response to that therapy. Other modes of treatment, such as courses of parenteral ACTH, methyl prednisolone, dexamethazone, or antimetabolites might be considered if there is no response after 12 weeks of high-dose, daily corticosteroid therapy.

Adolescent↗

Neonatal thymectomy prevents spontaneous diabetes mellitus in the BB/W rat.

Complete neonatal thymectomy reduced the frequency of spontaneous diabetes mellitus in BioBreeding/Worcester rats from 27 to 3 percent. Incomplete thymectomy also significantly reduced the frequency of diabetes (to 9 percent). These findings strengthen the hypothesis that thymus-dependent, cell-mediated autoimmune destruction of pancreatic B cells is responsible for the pathogenesis of diabetes in this experimental animal.

Animals↗

Postoperative management after thymectomy.

This paper reports a retrospective study of the preoperative and postoperative management of 28 patients who underwent thymectomy between 1956 and 1973. Patients who received postoperative artificial ventilation were compared with the group who did not with respect to sex, age, severity of disease, preoperative vital capacity, and thymic histology. Evidence is presented that postoperative artificial ventilation is required when the preoperative vital capacity with the patient on optimum anticholinesterase treatment is less than 2 litres. Additional features associated with a probable need for artificial ventilation were the presence of a thymoma, bulbar symptoms, especially dysphagia, and age over 50 years. These should be taken into account in any patient whose vital capacity is close to the critical level of 2 litres. When postoperative ventilation was required it was usually necessary for 12 days or more, and tracheostomy should therefore be done at or before thymectomy. Most patients in this series received the same dose of anticholinesterases after operation as before it and no evidence was found of a sudden decrease in requirements for anticholinesterase therapy. Two patients did not, and in them a myasthenic crisis was precipitated. We propose that the preoperative drug regimen can be continued in the immediate postthymectomy period, allowing selection of patients for tracheostomy and artificial ventilation primarily on the basis of the preoperative vital capacity.

Adolescent↗

Anti-acetylcholine-receptor antibody concentrations after thymectomy in patients with myasthenia gravis.

Serum concentrations of anti-acetylcholine-receptor (anti-AChR) antibody were measured in patients with myasthenia gravis. In those patients undergoing thymectomy concentrations were measured before and after the operation to see whether there might be a connection between the thymus and antibody production. We found no correlation between antibody concentration and either thymectomy or duration and severity of the disease before the operation. Our results suggest that if anti-AChR antibodies are the principal pathogenic factor in myasthenia gravis then immunological and neurophysical variables other than the total serum anti-AChR antibody concentration contribute to the severity of the disease.

Acetylcholine↗

Comparison of thymic histology with response to thymectomy in myasthenia gravis.

Fifty-four thymus glands removed surgically from patients with myasthenia gravis were examined using an accurate morphometric technique and the data compared with the response to thymectomy. There is a tendency for patients with relatively unreactive thymus glands to obtain a better result from thymectomy but this is not statistically significant.

Adolescent↗

Circulating immune complexes in myasthenia gravis: a study in relation to thymectomy, clinical severity and thymus histology.

Circulating immune complexes were assayed employing the method recently described by Barnett and Chia in a group of patients with myasthenia gravis. The subjects were classified according to clinical severity and immune complexes were sought before and after thymectomy. The operated subjects were further divided into those with thymoma or thymic hyperplasia. Antigen-antibody complexes were higher before thymectomy than after, in hyperplasias than in thymomas, and in severe myasthenia gravis than in mild disease. Circulating immune complexes and anti-acetylcholine receptor antibodies did not correlate.

Antigen-Antibody Complex↗

Thymectomy in myasthenia with pure ocular symptoms.

Eighteen patients with exclusively ocular symptoms of myasthenia were thymectomised. Suspected thymoma, resistance to pyridostigmine therapy or relapse following immunosuppressive therapy were taken as indications for surgery. The mean preoperative observation period before operation was 40 months, and after operation was 26 months. There was no operative or postoperative morbidity or mortality. Histological thymic abnormalities were found in all patients (in one case, thymoma; in four, persistent thymus; in 13, thymic hyperplasia). The histological abnormalities were identical to those found in generalised myasthenia. This included the distribution of T-cell subtypes as identified by use of monoclonal antibodies. The severity of ocular symptoms was rated using a score developed for this purpose. The score progressively declined after surgery to an average of 70% of its initial amount in 80% of patients. Full remission occurred in three cases. No patient developed generalized myasthenia. Antibody titres against acetylcholine receptors if elevated preoperatively also dropped following surgery, with one exception. Clear criteria for the expected therapeutic success of thymectomy could not be identified. Based on our results, and on the assumed significance of the thymus gland for pathogenesis, thymectomy should be considered in patients with pure ocular symptoms.

Adult↗

The long term experience of thymectomy for myasthenia gravis.

A retrospective survey of the records of 287 patients with generalised myasthenia gravis treated at New End Hospital and later at the Royal Free Hospital by anticholinesterase drugs, with or without thymectomy, between the years 1942 and 1976, shows that 62% of patients were improved. The timing of the operation, the grading of disease and the age and sex of the patient did not greatly influence overall results. The poor diagnosis of thymic tumours was confirmed in this series. A decrease occurred in the number of patients achieving complete remission after 1961, although the proportion of patients improving did not fall. It is possible that anticholinesterase therapy may alter the response to thymectomy.

Age Factors↗

An improved method in rabbit intubation and thymectomy.

A procedure is developed for endotracheal intubation followed by positive pressure ventilation anaesthesia, allowing major thoracic surgery, including thymectomy, to be performed in the young and adult rabbit. A method is described to bring the animal in a position favourable for thymectomy. A detailed description is given of a thymus ablation technique in which the thoracic wall is left intact.

Animals↗

Effect of thymectomy on lymphocyte subpopulations in the pig. Demonstration of a thymus-dependent 'null' cell.

Thymectomy in neonatal pigs results in marked lymphopenia. Surface Ig immunofluorescence, Fc rosettes and SRBC rosettes have been used to identify blood lymphocyte subpopulations. There was no marked reduction in numbers of cells in these subpopulations after thymectomy, although their proportion increased. This change was explained by a 90% reduction in 'null' lymphocytes, defined as those lacking sIg and Dextran SRBC receptor, which comprised 30-45% of blood lymphocytes.

Animals↗

Effect of adult thymectomy on the development of 1-chloro-2,4-dinitrobenzene contact sensitivity and other T lymphocyte functions in patients with myasthenia gravis.

1-Chloro-2,4-dinitrobenzene (DNCB) contact sensitivity and other T lymphocyte functions were studied in thymectomized and non-thymectomized patients with myasthenia gravis. The ability to develop contact sensitivity was reduced in patients with myasthenia gravis and was further reduced after thymectomy. Memory lymphocyte function, as measured by skin tests with common microbial antigens, was intact. A positive phytohemagglutinin (PHA) skin test was found mainly in those patients who also developed contact sensitivity to DNCB. The number of rosette-forming T cells in the peripheral blood as well as mitogen stimulation with PHA was found to be normal in thymectomized as well as non-thymectomized patients. In the thymectomized group, mitogen stimulation with concanavalin A and staphylococcal protein A was also within the normal range, while increased stimulation was obtained with pokeweed mitogen (PWM) and purified protein derivative (PPD). No alteration in mixed lymphocyte culture reactivity or immunoglobulin levels was obtained compared with healthy blood donors. On the basis of these results, it is concluded that non-thymectomized as well as thymectomized patients with myasthenia gravis may have a defective subpopulation of T cells possibly residing in the TH1-positive population. Furthermore, the increased lymphocyte stimulation obtained with PPD and PWM may indicate a reduction of suppressor cell activity after thymectomy.

Adolescent↗