If a sternal disruption with underlying mediastinitis is detected early, the wound may be débrided and drained with primary sternal closure. For lateral weakness or fractures in the sternum, a lateral longitudinal wire support as described by Robicsek⁸ may be used. Muscle transposition flaps are generally the preferred option, however, especially in the setting of extensive mediastinitis or sternal disruption.⁹

Injury to these veins results in bleeding with uncontrolled transection, which can be significant if the brachiocephalic vein is injured. If a transcervical approach is used, a median sternotomy may be necessary to provide exposure to control hemorrhage. Ligation of the brachiocephalic vein may result in edema of the left upper extremity, although reports indicate that the edema will eventually resolve.¹⁰ If the pleural spaces are open, blood may drain into a hemothorax. Thrombosis of the subclavian vein has also been reported.¹¹

Visualization of this thymic vessel is essential to prevent injury. As one dissects under the thymus from an inferior-to-superior direction, one must anticipate the position of the brachiocephalic vein and look for the thymic vein entering, typically, the inferior surface of this vessel (Figs. 69-1 and 69-2). Typically, there are two veins. The dissection should not stray from the surface of the pericardium. When using a transcervical approach, the thymus is dissected off the anterior surface of the brachiocephalic vein and the thymic veins are visualized and controlled posteriorly. Ventilatory volume and rate may be reduced to facilitate exposure of the mediastinum. Occasionally, the upper poles of the thymus are located posterior to the innominate vein, and this variant should be recognized.

Injury to the phrenic nerve can result in paralysis of the ipsilateral diaphragm, which may be transient in the setting of a neurapraxia or permanent if the nerve has been transected. This may result in respiratory insufficiency with prolonged mechanical ventilation, increased intensive care unit stay and development of respiratory infections.¹⁴ Forced vital capacity has been shown to be reduced after phrenic nerve injury.¹⁵ Spontaneous recovery of phrenic nerve function may be anticipated in about two thirds of patients in whom the injury is identified postoperatively.¹⁵ Most patients, however, are asymptomatic.

The surgeon must visualize both phrenic nerves during dissection of the thymic lobes off of the pleura and pericardium. The phrenic nerves are less obvious in the superior part of the mediastinum and thymus, and adipose tissue must be dissected carefully without excessive traction in this area to avoid injury. Dissection of the left side may be more challenging because the phrenic nerve may follow a more intimate course with the lateral portion of the thymus. The pleura may be incised to facilitate visualization of the phrenic nerves from within the thoracic cavities (Fig. 69-3). The pleura may be incorporated into the thymic specimen if dense adhesions are present. Dissection with cautery at low power in a patient who is free of muscle relaxants should allow one to see or feel the diaphragm move, indicating proximity to the phrenic nerve. The artery accompanying the phrenic nerve provides some blood supply to the thymus, and these small vessels should be divided with hemoclips not cautery to avoid thermal injury to the nerve. Thymomas occasionally extend into the aortopulmonary window, and this is the most frequent site of phrenic nerve involvement (Fig. 69-4). A hemiclamshell incision or left thoracoscopy may improve exposure in these instances.

The incidence of damage to the recurrent laryngeal nerve is reported to be between 0% and 4.5%.^6,7,12 Injury to the recurrent laryngeal nerve results in ipsilateral vocal cord paralysis with the cord generally in an abducted paramedian position preventing adequate airway sealing. Recurrent laryngeal nerve palsy may be devastating in the early postoperative period owing to an inability to cough and clear secretions. Aspiration is also a risk, especially in older patients. Long-term disabilities may include hoarseness, shortness of breath, swallowing difficulties, and chronic aspiration. Older patients and those with lung disease are less tolerant of vocal cord paralysis. Patients with bilateral injuries can potentially have compromise of their airway. Spontaneous recovery of nerve function is expected in the majority of patients.

Surgeons should be aware of the intrathoracic anatomy of the recurrent laryngeal nerves. The recurrent nerves should never be handled directly or encircled for retraction purposes. A common site of injury during thymectomy is in the subaortic region near the ligamentum arteriosum. When thymic or mediastinal tumors are present in the aortopulmonary window, a hemiclamshell incision or left thoracoscopy may be incorporated to improve exposure, as previously mentioned. In addition, accessory thymic lobules may be present posterior to the superior lobe of the thyroid, and the recurrent laryngeal nerves must be identified and preserved when dissecting in this area⁶ (Fig. 69-5).