If you don't remember your password, you can reset it by entering your email address and clicking the Reset Password button. You will then receive an email that contains a secure link for resetting your password
If the address matches a valid account an email will be sent to __email__ with instructions for resetting your password
Address reprint requests to Michael F. Reed, MD, Penn State Milton S. Hershey Medical Center, Penn State College of Medicine, Heart and Vascular Institute, 500 University Drive, H165, Hershey, PA 17033
Tumors of the posterior mediastinum, located in the paravertebral sulcus, account for about 25% of all mediastinal tumors. They are typically related to the sympathetic chain or the rami of intercostal nerves. Mediastinal neurogenic tumors are among the more frequent mediastinal masses seen in adults. Although they are often malignant in children, over 90% are benign in the adult population. Surgical resection is usually indicated.
Posterior mediastinal tumors are frequently nerve-related neoplasms. Neurogenic tumors originate from embryonal neural crest cells, which constitute the ganglia, paraganglionic, and parasympathetic systems. Nerve sheath tumors are the most common posterior, paravertebral tumors, accounting for 40 to 60% of all neurogenic tumors. Approximately 10% have spinal canal involvement (“dumbbell” or “hourglass” tumors), thus impacting the approach to resection. Nerve sheath tumors commonly originate from Schwann cells of intercostal nerves. Although almost always benign, malignant degeneration may rarely occur. Neurofibromas also arise from peripheral nerves, with 30 to 40% of neurofibromas occurring in the setting of neurofibromatosis. Multiple tumors may occur in these individuals. The patients with von Recklinghausen's disease frequently present at a younger age and have a higher risk of malignancy.
Ganglioneuromas and ganglioneuroblastomas arise from sympathetic ganglion nerve cells. Although ganglioneuromas are benign, they tend to adhere to adjacent structures, making resection more challenging than with schwannomas. This is the most frequent benign neurogenic tumor in children. In contradistinction to ganglioneuromas, neuroblastomas frequently metastasize.
Most posterior mediastinal neurogenic tumors are benign, slow growing, and asymptomatic. They may be present for a long period of time before diagnosis. However, with growth, they can produce symptoms by local compression of adjacent tissue, bone erosion, and spinal canal involvement. Large intrathoracic tumors may produce dyspnea, pain, and cough. Neurologic deficits may also occur. Spinal cord compression from dumbbell tumors may cause abnormal gait, urinary and fecal incontinence, and loss of sensation below the lesion. Radicular pain at the level of the tumor may present with a dermatomal distribution. Occasionally a high thoracic tumor may result in Horner's syndrome.
Currently, most posterior mediastinal tumors are identified incidentally, often on plain chest radiography obtained for other, unrelated indications. Chest computed tomography is indicated to effectively demonstrate size, location, and relationship to adjacent structures. Tumors of nerve sheath origin are typically smooth, spherical, solitary, and discrete. They usually abut vertebral bodies. In the setting of neurofibromatosis, they may be multifocal and appear lobulated. In contrast, tumors of autonomic ganglion (nerve cell) origin may be less circumscribed and often are oblong. Bony changes related to pressure or erosion may be present. Occasionally magnetic resonance imaging (MRI) may be useful for evaluating proximity to the neural foramen (Fig. 1) and for determining spinal cord involvement with dumbbell tumors. Percutaneous biopsy is not required for most posterior mediastinal neurogenic tumors because radiographic diagnosis is sufficient to mandate resection. Observation of posterior mediastinal tumors is rarely appropriate, unless the patient is at prohibitively high risk for thoracoscopic surgery due to significant medical comorbidities. Surgical resection simultaneously provides both diagnosis and therapy. Moreover, permitting growth may result in expansion of the tumor into the neural foramen, requiring a more complex multistage operation involving both posterior and anterior approaches.
Dumbbell tumors possess both an intrathoracic and an intraspinal component. Surgery requires exposure of the pleural space and the spinal canal. A number of open approaches are feasible, including a lateral extracavitary approach as well as a combined anterior and posterior approach using thoracotomy for pleural exposure. However, video-assisted thoracoscopic surgery (VATS) offers equivalent pleural exposure, avoiding the side effects of thoracotomy. For these patients, a collaborative strategy involving neurosurgical or orthopedic spine surgeons with thoracic surgeons will optimize safe preoperative planning.
Due to their frequently benign nature and relatively small size, posterior mediastinal neurogenic tumors are particularly amenable to resection using a minimally invasive, thoracoscopic technique. Indeed, as VATS was gaining wider acceptance in the early 1990s, one of its earlier applications was removal of posterior mediastinal tumors.
Thoracoscopic resection remains ideal for all but the very large tumors. Compared with thoracotomy, VATS allows an equivalent intrathoracic operation with the same resection margin. As with other VATS procedures, this minimally invasive approach results in diminished postoperative pain, fewer complications, shorter length of stay, and more rapid return to normal functional status.
Surgical resection is the ideal treatment for posterior mediastinal neurogenic tumors. Benign neurogenic tumors rarely recur and no adjuvant therapy is required. Minimally invasive resection with thoracoscopic techniques is safe. Standard risks of thoracic surgery, including bleeding, infection, and pulmonary complications, are rare. The risks specific to resection of neurogenic tumors are related to nerve injury. Deficits such as Horner's syndrome, partial sympathectomy, recurrent laryngeal nerve injury, and phrenic nerve injury are possible when the tumors originate from these specific nerves. Many of these complications can be avoided by precise identification of the specific neurologic structures and avoidance of electrocautery when dissecting in close proximity to them.
For benign posterior mediastinal lesions, complete resection is typically achieved with a thoracoscopic strategy. Minimally invasive resection is not usually indicated when an invasive malignant tumor is identified preoperatively. In this setting, resection of adjacent bony structures is often required, typically negating the benefits of VATS.
Dumbbell tumors are amenable to VATS resection. When an intraspinal component is clearly compressing the cord, a combined posterior and anterior approach is indicated to achieve negative margins. Even when slight intraforaminal involvement is present, based on computed tomography and MRI, a combined thoracic surgery and spinal surgery approach is safest. Resection of the posterior mediastinal neurogenic tumor with intraforaminal involvement, while relying only on VATS exposure, or even thoracotomy alone, may require excessive retraction of the mass. Potential undetected hemorrhage in the spinal canal can result in devastating neurologic sequelae.
Thoracoscopic resection of posterior mediastinal tumors results in shorter duration of the operation, compared with the open approach. This is primarily due to avoidance of the time required to open and close a thoracotomy. As with numerous other thoracic procedures, the adoption of VATS techniques for resection of posterior mediastinal neurogenic tumors is associated with diminished postoperative morbidity, including shorter length of stay, less pain, better shoulder function, fewer pulmonary complications, and more rapid return to normal functional status.
It is the preferred approach for the resection of benign posterior mediastinal tumors, including dumbbell tumors. Thoracotomy is reserved for very large tumors, in which rib spreading would be required for removal through the chest wall, as well as for patients with significant adhesions from prior ipsilateral thoracic surgery or pleural intervention.
Thoracoscopic resection of a posterior mediastinal neurogenic tumor.