Thymectomy: its role in the management of myasthenia gravis

Myasthénie du sujet âgé: diagnostic, comorbidité et évolution

OBJECTIVE

Analyze the clinical presentation, laboratory indicators, and outcome of patients with late-onset myasthenia gravis (after 60 years).

METHOD

This retrospective cohort design with prospective follow-up included 45 patients with late-onset myasthenia gravis diagnosed in hospitals in Avignon, Montpellier, and Nimes between 1993 and 2000. Prospective data collection of their subsequent course took place in 2001.

RESULTS

Median age at onset was 72 years and median follow-up 35.5 months. Initial symptoms were ocular (38/45, 95%) and bulbar (31/45, 69%). Initial Osserman grades were distributed as follows: 10 grade I, 2 grade IIA, 25 grade IIB, 8 grade III and no grade IV. Anticholinesterase antibodies were positive in 39 patients (91%), response to anticholinesterase positive in 31/33 (94%), and electrophysiological abnormalities observed in 20/33 (61%). Thoracic computed tomography, performed in 42 patients (93%), found thymic abnormalities in 7. At least one comorbid disease was diagnosed in 41/43 patients (93%) and an autoimmune disorder in 18/43 (42%). In all, 42 patients (93%) received anticholinesterase and 36 (80%) immunosuppressive therapy. Sixteen patients (36%) died during follow-up, 8 of causes directly related to the myasthenia gravis. The relative risk of death estimated by odds ratios (OR) was highest for patients with comorbid cancer (OR 8.6 [1.8-40.6]) and those with the highest Osserman scores: grades I-II OR: 0.05 [0.01-0.29] versus grades III-IV OR: 15.5 [2.9-83.0].

CONCLUSION

Late-onset myasthenia gravis is specific in many aspects (presentation, autoimmune and other comorbid conditions, and course) that require attentive care.

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.

Thymic lesions in patients with myasthenia gravis: characterization with thallium 201 scintigraphy

PURPOSE

To assess thallium 201 ((201)Tl) single photon emission computed tomography (SPECT) for evaluation of thymic lesions associated with myasthenia gravis (MG), including lymphoid follicular hyperplasia (LFH) and thymoma.

MATERIALS AND METHODS

(201)Tl SPECT and computed tomography (CT) were performed preoperatively in 46 patients with MG who had undergone thymectomy. SPECT was conducted 15 (early image) and 180 (delayed image) minutes after (201)Tl injection. Results were visually assessed, and (201)Tl uptake ratios (thymic lesion count density/lung count density) were measured for quantitative analysis. Uptake was analyzed among the normal thymus, LFH, and thymoma patient groups.

RESULTS

Histopathologic results indicated a normal thymus, LFH, and thymoma in 19, 16, and 11 patients, respectively. Mean uptake ratios in the normal thymus, LFH, and thymoma were 0.96 (95% CI: 0.90, 1.03), 1.14 (95% CI: 1.04, 1.25), and 1.87 (95% CI: 1.56, 2.25), respectively, on early images and 1.09 (95% CI: 1.00, 1.18), 1.65 (95% CI: 1.48, 1.85), and 2.03 (95% CI: 1.65, 2.50), respectively, on delayed images. Thymoma showed more intense (201)Tl accumulation than did the normal thymus (P <.001) and LFH (P <.001) on early images. Both thymoma (P <.001) and LFH (P <.001) displayed more intense uptake than did the normal thymus on delayed images.

CONCLUSION

(201)Tl SPECT can enable differentiation between normal thymus, LFH, and thymoma in patients with MG.

Plasmapheresis in the University of Malaya Medical Centre, Malaysia

Over the past 3 decades, plasmapheresis has been used more extensively for a variety of neurological and hematological disorders. We undertook a retrospective review to ascertain its safety, efficacy, and factor(s) that predispose to poor outcome. We reviewed 117 plasma exchanges in 24 patients with a mean age of 43 +/- 15 years; half were male. A total of 79% of the patients had neurological diseases, and the most common were chronic inflammatory demyelinating polyneuropathy, Guillain-Barré syndrome, and myasthenic crisis. Plasmapheresis was effective in 79% of the patients, especially for neurological indications. Complications occurred in 23% of the exchanges affecting 58% of the patients. Most complications were mild; sepsis was the most common (9.4% of exchanges), especially catheter related sepsis (6%), rash (4.3%), and hypotension (4.3%). Only 2 (8%) patients had severe complications that required mechanical ventilation. There were 5 mortalities (21%), 3 due to sepsis and 2 due to myocardial ischemia and arrhythmia, none of which occurred within 48 h of the last exchange. Patients with poor renal function had higher mortality. Overall, our figures agree with those from other institutions and indicate that plasma exchange is an effective and safe procedure, especially for a variety of neuroimmunological conditions.

Therapeutic options in ocular myasthenia gravis

The term ocular myasthenia gravis refers to the disease clinically restricted to extrinsic ocular muscles. It can be disabling as ptosis, and to a greater extent diplopia, both interfere with daily activities. Although ocular disturbances are the most frequent initial complaints in myasthenic patients, symptoms usually progress to generalized disease and only 15% of patients complain of purely ocular weakness for the entire course of their illness. Secondary generalization occurs with the highest frequency in the first 2 years from the onset. Both the severity of symptoms and the risk of generalization should be taken into account when devising a therapeutic plan for these patients. Anticholinesterases are of limited efficacy and a considerable proportion of patients require additional therapy. Corticosteroid therapy, generally prednisone on an alternate-day schedule, is very effective, but a reason for concern is represented by the frequent need for long-term administration with increased risk of severe complications. In patients unresponsive to prednisone or requiring too high dosages, immunosuppressive drugs like azathioprine should be used with the same criteria applied in generalized myasthenia. As corticosteroids and immunosuppressants reduce the chance of generalization, their use is justified in patients with recent-onset disabling disease. In long-standing cases with low risk of generalization, treatment is aimed at the relief of symptoms and pharmacological therapy should be reduced to the minimum effective dosage. The indication for thymectomy in ocular myasthenia remains highly controversial and should be reserved for disabled patients in the early stages of the disease.

Pulmonary function after cardiac and thoracic surgery

Cardiac and thoracic surgery cause alterations in ventilatory function that can lead to significant postoperative pulmonary complications. These complications often occur among patients with pre-existing pulmonary dysfunction and cause significantly longer hospital stays. This review explores some of the recent literature concerning this issue, including the effects of lung reduction surgery.