Thymectomy



Thymectomy


Jason Leonard Muesse

Shanda Haley Blackmon







PATIENT HISTORY AND PHYSICAL FINDINGS



  • One-third of patients with thymoma are asymptomatic.


  • Among patients symptomatic from thymoma, about 40% present with local symptoms directly related to the mass itself, including chest pain, cough, and dyspnea, but can include superior vena cava syndrome.2


  • The parathymic syndrome most commonly associated with thymoma is myasthenia gravis, which occurs in approximately 45% of patients with thymoma (reported ranges from 10% to 67%). Other associated autoimmune conditions include pure red cell aplasia and hypogammaglobulinemia, which can occur in up to 5% of people with thymoma.2


  • Approximately 10% to 15% of patients with myasthenia gravis have a thymoma.


  • Fevers, night sweats, and other constitutional symptoms may indicate lymphoma rather than thymoma.


IMAGING AND OTHER DIAGNOSTIC STUDIES



  • Computerized tomography is the most useful imaging modality for thymoma. Thin-slice cuts will improve preoperative planning.


  • Thymomas can have variable uptake on positron emission tomography, so it is not routinely recommended. Magnetic resonance imaging can also provide helpful information about invasion into vessels or adjacent structures (FIG 1).4


  • Masses larger than 5 cm (not including thymus gland itself) in maximal diameter or those invading mediastinal structures either warrant specialized surgical planning or possibly enrollment into a neoadjuvant treatment protocol.5


  • Fine needle aspiration or core biopsy of the anterior mediastinal mass is recommended preoperatively in most cases to rule out lymphoma or germ cell tumor. If the biopsy is constituent with thymoma, resection of the entire thymic gland is indicated.4


  • Myasthenia gravis can be diagnosed with serum testing for the acetylcholine receptor antibody or through clinical improvement in symptoms with administration of edrophonium chloride.






FIG 1 • Positron emission tomography (PET) scan. Standard uptake value (SUV) of 6.5 in biopsy-proven thymoma measuring 14 cm × 8.3 cm in 38-year-old male.



SURGICAL MANAGEMENT


Preoperative Planning



  • The decision to perform thymectomy for treatment of myasthenia gravis must involve the patient, the treating neurologist, the anesthesiologist, and the thoracic surgeon. Preoperative optimization of the patient’s myasthenia gravis symptoms with pyridostigmine, steroids, and in some cases, plasmapheresis is critical.


  • Special anesthetic requirements may be necessary for patients with myasthenia gravis, taking care to avoid anticholinergics. The anesthetic team should be notified preoperatively of the patient’s medical condition and the severity of their symptoms in appropriate time to make accommodations.6


  • All patients who will undergo single-lung ventilation (VATS or RATS) should have preoperative pulmonary function testing to ensure they will be able to tolerate single-lung ventilation during resection. If the patient is deemed unable to tolerate single-lung ventilation, resection via sternotomy or transcervical approach is indicated. All patients with myasthenia gravis need pulmonary function testing preoperatively.


  • Central venous access should be obtained prior to beginning procedure.


  • A sternal saw should always be present in the operating suite and readily available in the event emergent conversion to sternotomy for bleeding is necessary.


Positioning



  • For median sternotomy or transcervical approach, a single lumen endotracheal tube is adequate.


  • For VATS or robotic-assisted thoracoscopic approach, we strongly prefer the use of double lumen endotracheal tube placement to single lumen endotracheal tube with bronchial blockers. If the patient needs to be repositioned intraoperatively, we feel that the double lumen endotracheal tube is much less likely to be dislodged than a bronchial blocker and provides more reliable lung isolation.


  • We confirm the placement of the double lumen endotracheal tube with bronchoscopy before positioning the patient.


  • Each time the patient is repositioned, proper placement of the double lumen endotracheal tube is confirmed with bronchoscopy.

Jul 24, 2016 | Posted by in GENERAL SURGERY | Comments Off on Thymectomy

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