Acta Neurochir (Wien) (1997) 139:712-718

Acta N e u r o c h i r u r g i c a 9 Springer-Verlag1997 Printed in Austria

Anterior Thoracic Corpectomy without Sternotomy: A Strategy for Malignant Disease of the Upper Thoracic Spine C. H . C o m e y , M . R . M c L a u g h l i n , and J. M o o s s y Department of Neurosurgery, University of Pittsburgh, Pittsburgh, PA, U.S.A.

Summary Background: With increasing frequency, spine surgeons are being asked to provide decompression and stabilization in patients with spinal metastases. While no region of the spine is easily treated, the upper thoracic spine is perhaps the least accessible. Traditional approaches to this region involve either thoracotomy or at least limited stemotomy. The authors present an approach to anterior pathology of the upper thoracic spine that obviates the need for sternotomy. Methods: Within the past two years, two patients with cervicothoracic metastases underwent anterior decompression and fusion without stemotomy. In both patients, the bodies of C7, T1, and T2 were removed. While both patients were prepared and draped for sternotomy, each required a neck dissection only. In both patients, left-sided incisions were made along the leading edge of the sternocleidomastoid. The platysma was divided with the overlying skin. With further dissection, the strap muscles were tagged and divided approximately one centimeter above their sternal attachments. The loose areolar tissue of the superior mediastinum was then bluntly dissected. Along the entire length of the incision, the vascular plane medial to the carotid sheath was developed to facilitate exposure of the anterior spine. A Farley-Thompson retractor system was then employed to retract and protect the superior mediastinal structures. With this exposure, corpectomies were carried out using a high speed drill. Fusion was accomplished through insertion of Steinmann pins into the adjacent intact bodies above and below. This was followed by application of methyl methacrylate. Both patients had immediate postoperative stability with preservation of spinal cord function. Both patients subsequently underwent removal of dorsally located tumor with posterior fusion. Conclusions: The goal of cancer surgery is to provide for increased functional survival without undue morbidity. The authors feel that when possible, the pain of sternal and clavicular osteotomies should be avoided. The described approach works well in conjunction with a methyl methacrylate/Steinmann pin construct. Because of the intact sternum, the surgeon has a downward angle to access the superior endplate of T3. With adequate soft tissue dissection and retraction as described, however, T3 and perhaps even T4 are easily accessible. While this downward angle would likely

not permit an anterior plating procedure, it lends itself nicely to Steinmann pin/methyl methacrylate fusion and spares the patient the pain and potential morbidity of sternotomy.

Keywords: Metastatic tumor; thoracic spine; sternotomy.

Introduction T h e p r o b l e m o f m e t a s t a t i c d i s e a s e to the spine is b e c o m i n g i n c r e a s i n g l y p r e v a l e n t with b e t t e r s y s t e m i c t r e a t m e n t and l o n g e r p a t i e n t survival. It is e s t i m a t e d that b e t w e e n 5 and 33% o f all patients w i t h s y s t e m i c m a l i g n a n c y will h a v e spinal i n v o l v e m e n t . T h i s a m o u n t s to a p p r o x i m a t e l y 18,000 n e w cases p e r y e a r in the U n i t e d States [1]. T h e p r i m a r y c o n c e r n s w h e n treating spinal m e t a s t a s e s are: p r e s e r v a t i o n o f n e u r a l function, m a i n t e n a n c e o f m e c h a n i c a l stability, and minimization of overall morbidity. Treatment should be d e s i g n e d to m a x i m i z e m e a n i n g f u l s u r v i v a l o u t s i d e o f the acute care setting. W h i l e no a r e a o f the spine is e a s i l y treated, the u p p e r t h o r a c i c s p i n e is p e r h a p s the m o s t difficult. T h e s u r r o u n d i n g rib c a g e p r o v i d e s support, but also acts as an o b s t a c l e to p l a i n r a d i o g r a p h y and s u r g i c a l access. M o s t d e s c r i b e d a p p r o a c h e s to this r e g i o n inv o l v e e i t h e r a h i g h t h o r a c o t o m y or at least a l i m i t e d s t e r n o t o m y [3, 8, 9, 1 4 - 1 9 ] . F r o m the c a r d i o t h o r a c i c literature, it is c l e a r that s t e r n o t o m y can be a s s o c i a t e d with s i g n i f i c a n t m o r b i d i t y [4, 5, 7, 10, 11, 15]. F o r t r e a t m e n t o f m e t a s t a t i c l e s i o n s o f the u p p e r t h o r a c i c spine, the authors f a v o r an a n t e r i o r a p p r o a c h p e r f o r m e d w i t h o u t s t e r n o t o m y . O v e r the p a s t two years, two p a t i e n t s with m e t a s t a t i c i n v o l v e m e n t o f the c e r v i cothoracic junction were successfully decompressed and s t a b i l i z e d v i a a l o w c e r v i c a l e x p o s u r e w i t h o u t sternotomy.

C. Comey et af.: Thoracic Corpectomy without Sternotomy

Patients and Methods Over a two-year period, two patients with cervicothoracic metastatic involvement were treated via an anterior decompression and fusion, followed by a supplemental posterior fusion. In both patients, preparation was made for sternotomy, but this was required in neither patient. The anterior approach was carried out as follows. The patients were positioned supine on a horseshoe head rest with the head turned 30 degrees to the right. Five pounds of Holter traction were applied via a chin strap to maintain alignment. A curvilinear incision was made along the leading edge of the left sternocleidomastoid muscle, extending from the angle of the mandible to several centimeters below the suprasternal notch (Fig. 1). The platysma was divided with the overlying skin. Following this, dissection was carried out medial to the sternocleidomastoid in an avascular plane. The omohyoid muscles were identified, tagged, and divided. Similarly, the superficial cervical strap muscles were identified, tagged, and approximately one centimeter above their sternal attachments. This dissection provides the exposure demonstrated in Fig. 2. In addition, the sternal attachment of the sternocleidomastoid was carefully dissected free. At this point, the aereolar tissue of the superior mediastinum was identified. To facilitate deep exposure, a Farley-Thompson retractor was used to retract and protect the superior mediastinal contents. In both cases, this degree of soft tissue dissection and retraction provided excellent visualization of the involved spinal segments. In both patients, C7, T1, and T2 corpectomies were carried out with rongeurs and a high speed drill. This was performed after removing all disk material from the C7-T1, T1-T2, and T2-T3 interspaces. Stabilization was then carried out through insertion of Steinmann pins into the intact bodies above and below, fotlowed by placement of methyl methacrylate to stabilize the construct. The methyl methacrylate was poured over a "sling" of Gelfoam| (UpJohn Company, Kalamazoo, Michigan), both to act as a mold, and to minimize contact with the dura (Fig. 3). Copious amounts of cool irrigation were used to minimize the chance of thermal injury to the spinal cord from the exothermic

713 reaction of methyl methacrylate. Since each of the patients had evidence of lateral and posterior tumor burden, each subsequently underwent supplemental posterior cervical decompression followed by stabilization using a Luque rectangle and Songer cables. Postoperatively, both patients were maintained in rigid cervical collars for a period of six weeks. Although bony fusion was not the objective of these procedures, it was felt that the collars would decrease patient discomfort by providing support as the cervical soft tissues healed.

rim.

sheath

nuscles

Fig. 2. Surgeons view of the deep surgical exposure after dissection of the longus coli muscles bilaterally. The inferior retractor blade is toed in to retract and protect the superior mediastinal contents

Steinmann pin/ Methylmethacrylate construct

Gel~n~am

1 sac

F

f

Fig. 1. Schematic of patient in position for surgery. The solid line represents the actual incision used. The dotted line represents course along which incision could be extended if sternotomy was necessary for further exposure

Fig. 3. Schematic in axial plane demonstrating the position of the sling of Gelfoam| (Upjohn, Inc., Kalamazoo, MI) sling around the methyl methacrylate, Steinmann pin construct. The posterior construct is also illustrated

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Steinmann Di Methylmethac late construc

C. Comey et al.: Thoracic Corpectomy without Sternotomy A left-sided approach was chosen with the rationale that the left recurrent laryngeal nerve (compared to the right recurrent laryngeal nerve) is less likely to be injured by traction or sharp dissection. The left recurrent laryngeal nerve has a longer course, entering the tracheo-esophageal groove more caudally than the corresponding right nerve. In addition, the left nerve has never been found to be non-recurrent, because this would require in utero absence of the ductus arteriosus, a condition incompatible with fetal survival [ 13]. The left-sided approach however, does not place the thoracic duct at risk for unrecognized injury and resulting chylothorax. In both patients in these series, the thoracic duct was identified, ligated, and divided. Illustrative Cases

Fig. 4. Schematic demonstrating circumferential stabilization. Steinmann pin - methyl methacrylate construct is seen anterior to the thecal sac. Both patients underwent a supplemental posterior fusion with at a later stage

Case 1: The patient is a 50-year-old right-handed white woman with a history of infiltrating ductal carcinoma of the breast. Approximately five years after her initial diagnosis, she presented with progressive neck pain and a normal neurologic examination. Pre-operative imaging revealed bony involvement of C7-T2 with evidence of T1 collapse, subluxation, and spinal cord compression (Fig. 5). The patient underwent decompression and stabilization as described above. Postoperatively, there was no residual loss of height or subluxation (Fig. 6). The patient remained ambulatory and was discharged to home. She had no further spinal or neurologic difficulties prior to her death eighteen months postoperatively from progression of systemic disease. Case 2: The patient is a 67-year-old left-handed white man with a previously resected right superior sulcus tumor, squamous cell type. The patient presented with progressive neck pain and paraparesis. Pre-operative imaging revealed contiguous involvement of C7-T2 with obvious kyphosis and cord compression (Fig. 7). Although the patient was a poor surgical risk because of his significant chronic obstructive pulmonary disease as well as a right

Fig. 5. Patient 1. Median sagittal T 1-weighted magnetic resonance imaging (MRI) study (a) reveals abnormal signal in bodies of C7, T 1, and T2 with collapse of T1 (arrow). Profound canal compromise is also seen on T2-weigbted median sagittal MRI (b) (open arrows)

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Fig. 6. Patient one. Postoperative plain radiographs in the antero-posterior (AP) projection (a), and lateral projection (b) demonstrate Steinmann pin (open arrow) and Luque rectangle (solid arrows) construct with normalization of alignment

Fig. 7. Patient two. Pre-operative studies. (a) Axial Tl-weighted MRI following gadolinium administration reveals anterior, right lateral, and posterior involvement of spine, epidural space at the Ievel of the first thoracic vertebra (open arrows). The spinal cord is severely effaced at this level (small solid arrow). (b) Median sagittal Tl-weighted MRI after gadolinium injection reveals abnormal enhancement in C6-T2 (solid arrows) with a significant ventral and dorsal epidural tumor mass (open arrows). (c) Median sagittal T2-weighted MRI reveals collapse of the T1 body as well as abnormal signal in C6, C7, and T2 bodies. The C7-TI and T1-T2 disc spaces are closely apposed (arrows)

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Thoracic Corpectomy without Sternotomy

phrenic nerve palsy, it was felt that an attempt to salvage spinal cord function was warranted. The patient underwent decompression and stabilization as described above. Postoperatively, the patient had return of normal spinal cord function. His postoperative films demonstrate normalization of his cervicothoracic junction. On anteroposterior projection, the Steinmann pin/Luque rectangle constructs are well seen (Fig. 8). Unfortunately, because of his poor pulmonary reserve, the patient was unable to be successfully weaned from mechanical ventilation. He underwent a tracheostomy one month after his cervical procedures and was transferred to an extended care facility. He subsequently died from pulmonary complications approximately three months postoperatively. He had remained without subsequent neurologic compromise or spinal instability prior to his death.

Discussion

Fig. 8. Patient two. Postoperative plain radiograph obtained in the anterior-posterior projection demonstrates Steinmann pin (small arrows) and Luque rectangle constructs (large arrows)

of a p p r o a c h est exposure

Fig. 9. Schematic of cervical and thoracic skeleton showing relationship between sternum and upper thoracic vertebrae. The "axis of approach" illustrates the working angle for Steinmann pin insertion

Spinal and epidural involvement are frequent sequelae of systemic cancer [1]. Surgical treatment should attempt to achieve bony stability, preserve neurologic function and minimize patient morbidity. The goal is to maximize independent life outside of the hospital in these patients with limited life expectancies. Most described anterior approaches to the upper thoracic spine involve at least limited sternotomy or thoracotomy [3, 9, 12, 16-19]. It is the impression of the authors that sternotomy may unnecessarily increase the morbidity of surgery in this region. Sternotomy m a y be associated with altered respiratory mechanics [11], rib fractures [4, 7], pain syndromes [5], and brachial plexus injuries [15]. The anatomy of the superior mediastinum and thoracic spine facilities stabilization with Steinmann pins and methyl methacrylate. With adequate suprasternal soft tissue dissection and retraction, excellent Visualization can be obtained from the mid cervical spine down to T4. It should be noted that body habitus plays a role in the relative ease of caudal visualization. In asthenic individuals with long necks, T3 and even T4 m a y be visualized without difficulty. In individuals with short necks, more dissection and deep retraction are required to obtain similar exposure. In addition, while T4 may be visualized with this exposure, lesions at this level are at the limit of the suprasternal exposure and are likely best treated in conjunction with a sternotomy [2]. The Steinmann pins are then inserted using a downward working angle (Fig. 9), thus obviating the need for even limited sternotomy. One must use great care when inserting the Steinmann pins in order to avoid inadvertent spinal canal penetration with resultant spinal cord injury. This approach does not lend itself to anterior plate fixation because the intact ster-

C. Comey et aI.: Thoracic Corpectomy without Sternotomy

hum may prevent proper caudal screw trajectory. Therefore, it should be reserved for patients with a limited life expectancy in whom immediate stability without bony fusion is the goal. In patients with more indolent or even benign tumors, a manubrial window or formal sternotomy may be required to provide an adequate exposure and working angle for an anterior plating procedure. Other alternatives to sternotomy have been described for approach to pathology of the cervicothoracic spine. A similar suprasternal approach to an aneurysmal bone cyst of the cervicothoracic junction was performed by Stillwell and Fielding [6, 14]. In these reports, the authors describe excellent visualization down to as low as T4. In addition, they were able to successfully insert a fibular strut from C6 to T3 using only a suprasternal exposure. To explain their choice of approach, the authors site the high mortality associated with transsternal approaches to the cervicothoracic spine. However, they do not discuss the advantages and shortcomings of the suprasternal route. In addition, the report by Fielding and Stillwell does not state whether the surgeons were prepared for sternotomy if this became necessary. In both patients in our report, preparation was made for sternotomy if a suprasternal exposure was deemed inadequate to safely achieve decompression and stabilization. In the present report, we have chosen the suprasternal route for malignant disease of the spine because it is less invasive while still providing excellent access for stabilization. Recently, Hernigou and Duparc reported on a lateral approach to the cervicothoracic junction [8]. Their approach involves extensive muscle dissection, thoracotomy and rib resection. In addition, it places the lower brachial plexus at risk for surgical injury. Finally, it provides only a lateral perspective, through which both decompression and fusion must be performed. While this may be a useful alternative approach to lesions involving T3 and T4, the degree of soft tissue dissection and potential morbidity seem unwarranted for pathology solely involving C7 to T2. The fact that one of our patients was unable to be weaned from mechanical ventilation underscores the degree of pulmonary and systemic compromise often present in this group of patients. Even in the absence sternotomy or an extensive transthoracic approach, he tolerated decompression and stabilization poorly. It is clear that not all cancer patients do well following cervicothoracic decompression and stabilization. Pa-

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tient selection for decompression and stabilization must be performed in conjunction with procedure selection. The authors feel strongly that although several different approaches may provide access to the cervicothoracic spine, it is incumbent upon the surgeon to choose a procedure with the least expected and potential morbidity. The cervical approach to the cervicothoracic region is technically straightforward, and serves to minimize surgical morbidity for this difficult group of patients. References 1. Black P (1979) Spinal metastases: current status and guidelines for management. Neurosurgery 5:726-746 2. Calliauw L, Dallenga A, Caemaert J (1994) Transsternal approach to intraspinal tumours in the upper thoracic region. Acta Neurochir (Wien) 127:227-231 3. Cauchoix J, Binet J (1957) Anterior surgical approaches to the spine. Ann R Coll Surg Engl 27:237-243 4. Dalton ML, Connally SR (1993) Median sternotomy. Surg GynecoI Obstet 176:615-624 5. Eastridge CE, Mahfood SS, Walker WA, Cole FH Jr (1991) Delayed chest wall pain due to sternal wire sutures. Ann Thorac Surg 51:56-59 6. Fielding JW, Stillwell WT (1976) Anterior cervical approach to the upper thoracic spine: a case report. Spine 1:158-161 7. Gumbs RV, Peniston RL, Nabhani HA, Henry LJ (1991) Rib fractures complicating median sternotomy. Ann Thorac Surg 5 !: 952-955 8. Hernigou P, Duparc F (1994) Lateral exposure of the cervicothoracic spine for anterior decompression and osteosynthesis. Neurosurgery 35:1121-1125 9. Hodgson AR, Stock FE, Fang HSY, Ong GB (1960) Anterior spinal fusion: the operative approach and pathologic findings in 4i2 patients with Port's disease of the spine. Br J Surg 48: 172-178 10. Hugo NE, Sultan MR, Ascherman JA, Patsis MC, Smith CR, Rose EA (1994) Single-stage management of 74 consecutive sternal wound complications with pectoralis major myocutaneous advancement flaps. Plast Reconstr Surg 93:1433-1441 11. Locke TJ, Griffiths TL, Mould H, Gibson GJ (1990) Rib cage mechanics after median sternotomy. Thorax 45:465-468 12. McDonald P, Letts M, Sutherland G, Unruh H (1992) Aneurysreal bone cyst of the upper thoracic spine. An operative approach through a manubrial sternotomy. Clin Orthop 279: 127-132 13. Sanders G, Uyeda RY, Karlan MS (1983) Nonrecurrent inferior laryngeal nerves and their association with a recurrent branch. Am J Surg 146:501-503 14. Stillwell WT, Fielding JW (1984) Aneurysmal bone cyst of the cervicodorsal spine. Clin Orthop 187:144-146 15. Stoelting RK (1994) Brachial plexus injury after median sternotomy: an unexpected liability for anesthesiologists. J Cardiothorac Anesth 8 : 2 4 16. Sundaresan N, Bains M, McCormack P (1985) Surgical treatment of spinal cord compression in patients with lung cancer. Neurosurgery 16:350-356

718 17. Sundaresan N, Hilaris B, Martini N (1987) The combined neurosurgical thoracic management of superior sulcus tumors. J Clin OncoI 5:1739-I745 18. Sundaresan N, Shah J, Feghali JG (1984) A transsternal approach to the upper thoracic vertebrae. Am J Surg 148: 473477 19. Sundaresan N, Shah J, Foley KM, Rosen G (1984) An anterior

C. Comey et al.: Thoracic Corpectomy without Sternotomy surgical approach to the upper thoracic vertebrae. J Neurosurg 61 : 686-690

Correspondence: Christopher H. Comey, M.D., Department of Neurosurgery, University of Pittsburgh, UPMC Suite B400, 200 Lothrop Street, Pittsburgh, PA 15213, U.S.A.