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Ann Thorac Surg 1995;59:469-472
© 1995 The Society of Thoracic Surgeons

Combined Microneurosurgical and Thoracoscopic Removal of Neurogenic Dumbbell Tumors

Divisions of Cardiothoracic Surgery and Neurosurgery, Department of Surgery, University of Alberta, Edmonton, Alberta, Canada

Accepted for publication October 22, 1994.

	Abstract

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
The resection of posterior mediastinal dumbbell tumors has until now required laminectomy and some form of open access to the thoracic cavity. Over a 1-year period, a novel surgical approach combining posterior microneurosurgical and anterior video-assisted thoracoscopy techniques was used in 4 patients. In 3 patients, the tumor was removed successfully with minimal postoperative discomfort and rapid recovery. In the fourth patient, limited thoracotomy became necessary to control bleeding. This new approach, which combines modern-day neurosurgical and general thoracic surgical techniques, appears safe and could become the preferred method for removing most benign posterior mediastinal dumbbell tumors.

	Introduction

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
See also page 472.

Approximately 10% of posterior mediastinal neurogenic tumors include a spinal canal component, the two portions connected by a narrow foraminal segment, and, because of their resulting shape, they have commonly been called hourglass or dumbbell tumors [1, 2]. Most (about 90%) of these dumbbell tumors are benign and are of nerve sheath origin [3]. Safe removal of these tumors requires a one-stage combined neurosurgical and thoracic operation [3–8]. Various types of incisions and different patient positions in which either the laminectomy or thoracotomy is done first have been advocated. We describe here a novel operation combining microneurosurgical and video-assisted thoracoscopic techniques for the excision of dumbbell thoracic tumors.

	Operative Procedure

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
First Phase: Posterior Microneurosurgical Removal of Spinal Component of Tumor
The vertebral level of the tumor is marked preoperatively on the skin of the patient's back under radiologic guidance. After the induction of anesthesia, the patient is positioned prone and a laminectomy is carried out at the level of the tumor. In our method, a prone, rather than a lateral or decubitus, position is mandatory to permit the use of the neurosurgical operating microscope during subsequent tumor removal. Enough bone is removed to uncover the entire length of the intraspinal tumor, and the laminectomy is widened on the side of the tumor to include a generous intervertebral foraminotomy where the tumor narrows to pass into the chest cavity (Fig 1). This important step, which includes removal of part of the adjacent intervertebral facet and transverse process, facilitates removal of the entire intraspinal and foraminal tumor and enables circumferential cauterization to be performed, as well as mobilization of the tumor capsule where it enters the thorax. Once it is adequately exposed, the intraspinal tumor is removed, using the neurosurgical operating microscope for guidance, and the nerve root from which the tumor arises is transected. The dural covering of the spinal nerve root is closed either with a large metal clip or with a nonabsorbable suture to prevent a cerebrospinal fluid leak from occurring postoperatively. If necessary, the tumor is first decompressed internally to allow it to be safely excised without the need to retract the spinal cord. Frozen section examination of the tumor is carried out before the incision is closed.

View larger version (40K): [in this window] [in a new window]   Fig 1. . Single-level thoracic laminectomy, with extensive foraminotomy, enables performance of microsurgical excision of the intracanalicular and intraforaminal component of the tumor, as well as circumferential cauterization and mobilization of the proximal intrathoracic component (dotted line). The proximal nerve root of origin is sacrificed.

	Clinical Material

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
The pertinent clinical information, tumor characteristics, operation performed, and outcome in the 4 patients who underwent this procedure are summarized in Table 1, and the radiologic characteristics are shown in Figures 2 to 4.

View larger version (131K): [in this window] [in a new window]   Fig 2. . (Patient 1.) Coronal magnetic resonance image study of upper thorax demonstrating a left T2 dumbbell-shaped schwannoma. The thoracic component of the tumor contains a hypointense cyst.

View larger version (140K): [in this window] [in a new window]   Fig 3. . (Patient 2.) Computed tomographic myelogram demonstrating a right T7 dumbbell-shaped schwannoma that is markedly deviating the thecal sac and spinal cord.

View larger version (108K): [in this window] [in a new window]   Fig 4. . (Patient 3.) Coronal magnetic resonance image demonstrating a large left T9 schwannoma causing marked cord compression.

	Comment

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

In 1983, Grillo and colleagues [5] described another one-incision, one-position approach in which a modified posterolateral thoracotomy incision is extended vertically over the spinous processes of the involved vertebrae. The intrathoracic component of the tumor is mobilized and resected first. This incision is said to provide excellent exposure for both the thoracic and neurosurgical aspects of the procedure.

Other groups have voiced a preference for working through two different incisions, first doing either the thoracotomy or the laminectomy, then repositioning the patient and completing the second part of the operation under the same anesthetic [4, 8]. Finally, Ricci and associates [7] recently reported using Akwari's and Grillo's approaches selectively, reserving the latter for smaller tumors.

In recent years, major advances have been made in video-assisted thoracic surgical techniques [11]. Safe resection of uncomplicated posterior mediastinal lesions has been described [9, 10, 12]. We have furthered the application of this technique by using it to resect dumbbell-type tumors. The use of video-assisted thoracic surgical techniques makes it possible for the patient to recover rapidly with less pain, and consequently to return earlier to his or her preoperative activities [13]. This was evident in our first patient, who had a T2 left-sided lesion and was discharged home 3 days after a combined surgical procedure; she was able to resume her normal activities within the same week. In this case, any one of the alternative open techniques would have required a high fourth space, standard thoracotomy, and this would have entailed a much longer hospital stay and convalescence.

In our experience with the use of video-assisted thoracic surgical techniques in the removal of dumbbell tumors, a limited open thoracotomy became necessary in 1 patient to control bleeding from an intercostal artery. Fortunately, the bleeding was not serious and had ceased by the time the chest was opened.

We must emphasize some key points with regard to this novel technique. Because the neurosurgeon dissects the intraforaminal and often intrathoracic perivertebral aspects of the tumor first, the thoracoscopic dissection is minimal and usually confined to the division of the parietal pleura, its adjacent connective tissue, and the peripheral aspect of the involved nerve and its associated vessels. When the spinal bed is closed, pledgets of absorbable gelatin may be left on the spinal aspect of the tumor. These are easily identified at thoracoscopy, as it is being used to guide the depth of the dissection. In addition, we have found it helpful in our dissections to leave a rim of loose pleura (0.5 to 1 cm) around the base of the tumor. This edge can be easily grasped, and the pleura usually adheres enough to the tumor to allow it to be mobilized without the need for direct tumor handling and breakage.

The role of computed tomographic myelography or magnetic resonance imaging in confirming the dumbbell nature of these lesions is well recognized [7]. These techniques allow each lesion to be precisely localized and its extension identified. However, neither computed tomography nor magnetic resonance imaging has always proved able to differentiate between benign and malignant neoplasms of the mediastinum [14]. Evidence of local destruction caused by invasion of the ribs or adjacent vertebrae suggests malignancy, as does the presence of an associated pleural effusion or pleural studding [15]. The former changes must be differentiated from pressure atrophy seen in association with expanding benign tumors. If any invasive changes are shown by radiologic studies, we do not recommend that the thoracoscopic component of our combined approach be used.

In summary, posterior mediastinal neurogenic dumbbell tumors can be resected using combined modern-day microsurgical and thoracoscopic techniques. The approach described is safe, and, in this small series, appeared to produce much less morbidity than do the conventional open techniques that have been used in the past.

	Acknowledgments

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
We thank Mrs Peggy Small for typing the manuscript.

	Footnotes

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 
Address reprint requests to Dr Vallières, Division of Thoracic Surgery, Ottawa Civic Hospital, 1053 Carling Ave, Ottawa, Ont, K1Y 4E9, Canada.

	References

Top Footnotes Abstract Introduction Operative Procedure Clinical Material Comment Acknowledgments References

 

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3. Akwari OE, Payne WS, Onofrio BM, Dines DE, Muhm JR. Dumbbell neurogenic tumors of the mediastinum. Mayo Clin Proc 1978;53:353–8.[Medline]
4. Irger IM, Perelman MI, Koroleva NS, Stolypin SV. Combined method for removing a neurogenic mediastinal intravertebral hourglass tumor. Zh Vopr Neirokhir (Moscow) 1975;6:3–10.
5. Grillo HC, Ojemann RG, Scannell JG, Zervas NT. Combined approach to ``dumbbell'' intrathoracic and intraspinal neurogenic tumors. Ann Thorac Surg 1983;36:402–7.[Abstract]
6. Lesoin F, Bouasakao N, Autricque A, Villette L, Jomin M. Exérère complète en un temps des tumeurs intrarachidiennes dorsales en sablier à développement thoracique par transversoarthropédiculocostectomie. J Chir (Paris) 1986;123:504–7.
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13. Landreneau RJ, Hazelrigg SR, Mack MJ, et al. Postoperative pain-related morbidity: video-assisted thoracic surgery versus thoracotomy. Ann Thorac Surg 1993;56:1285–9.[Abstract]
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This Article Abstract Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vallières, E. Articles by Fraser, R. E. Search for Related Content PubMed PubMed Citation Articles by Vallières, E. Articles by Fraser, R. E. Related Collections Related Article