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Image-guided surgery in resection of benign cervicothoracic spinal tumors: a report of two cases
The Spine Journal 5 (2005) 109–114
Image-guided surgery in resection of benign cervicothoracic spinal tumors: a report of two cases Timothy Moore, MDa, Robert F. McLain, MDb,* a
Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA b Surgical Staff, Department of Orthopaedic Surgery and The Cleveland Clinic Spine Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA Received 12 November 2003; accepted 24 June 2004
Abstract
BACKGROUND CONTEXT: Osseous spinal tumors are an uncommon cause of persistent axial pain and muscle spasm, but even benign lesions may grow to cause deformity or neurological signs. Traditional treatment approaches to resection can be debilitating even when the tumor is benign. PURPOSE: Emerging technologies allow surgeons to diagnose and treat osseous neoplasms while minimizing the collateral damage caused by surgical exposure and tumor excision. STUDY DESIGN: Technical considerations are presented through two cases of benign osseous neoplasm occurring in the cervicothoracic spine of competitive athletes, demonstrating the methods used to provide effective treatment while maintaining maximal functional capacity. METHODS: Stereotactic imaging and intraoperative guidance was used as an adjunct to tumor care in these patients. Used in combination with minimally invasive, microsurgical techniques, stereotactic guidance localized and verified excision margins of benign vertebral lesions, minimizing soft tissue trauma and collateral damage. RESULTS: Computer-assisted stereotactic localization allowed us to successfully ablate these lesions from their anatomically challenging locations, without disrupting the shoulder girdle or neck musculature, and without extensive bony resection. CONCLUSIONS: Image guidance can accurately localize and guide excision of benign vertebral lesions while minimizing soft tissue trauma and collateral damage, allowing patients a rapid and complete return to high-demand function. 쑖 2005 Elsevier Inc. All rights reserved.
Keywords:
Spine; Tumor; Stereotactic guidance; Sports; Osteoblastoma; Osteoid osteoma
Introduction Although focal, persistent pain might be treated expectantly in a normally active teen or young adult, serious spinal pathology can occasionally be overlooked. Osseous spinal tumors are an uncommon cause of neck and back pain, but they do occur in young, healthy individuals [1]. When a spinal column tumor is identified, the primary goal is to determine its nature, benign or malignant, and the second is to provide effective treatment to control or cure the lesion. If the lesion is benign, treatment should be carried FDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. Robert F. McLain, MD, Orthopaedic Spine Research, The Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA. Tel.: (216) 444-2744; fax: (216) 444-3328. E-mail address: [email protected] (R.F. McLain) 1529-9430/05/$ – see front matter doi:10.1016/j.spinee.2004.06.020
쑖 2005 Elsevier Inc. All rights reserved.
out without unnecessarily disrupting subsequent function. Traditional surgical approaches can be damaging to surrounding tissues, resulting in long-term impairment that would preclude return to high-demand activities. In athletes who throw, disruption of the shoulder girdle and cervicothoracic junction can be career ending. When operative treatment is necessitated by persistent pain and/or neurological symptoms, traditional surgical approaches reliably control these tumors, but at a significant cost in muscular injury and functional impairment [2–4]. Benign, locally invasive lesions may require extensive dissection for definitive control. Beyond reliably extirpating the lesion, the surgeon should consider the effect the surgical approach will have on function. While advances have been made in minimally invasive treatment of some tumors, percutaneous techniques cannot be safely applied immediately adjacent to the spinal cord [5,6]. Open techniques are still necessary in these circumstances.
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Stereotactic image guidance (SG), combined with microsurgical techniques, allows surgeons to use a minimally invasive approach to accurately localize and excise these benign tumors, minimizing surgical morbidity and optimizing rapid return to unrestricted function. Application of these principles is illustrated by two cases of competitive athletes presenting with benign neoplasms of the cervicothoracic junction.
Case reports Case 1 A 16-year-old soccer player presented with left-sided neck and shoulder pain of 5 month’s duration, first noticed while playing soccer. The pain began insidiously but was sharply exacerbated when heading the ball. Initial X-rays showed no shoulder or neck abnormality, but bone scan revealed focal uptake at the C7 level. Initially relieved with aspirin, the pain became less responsive over time. It was often present at night and on waking in the morning, without inciting events. The pain localized to the low cervical region just left of the midline, with radiation to the left shoulder, but it did not radiate distally into the arm. There were no right-sided symptoms. Despite full range of motion, the patient experienced pain with extremes of flexion, extension and rotation, and while tilting his head to the right. He had no atrophy, but had mild weakness in his left-hand intrinsics. Deep tendon reflexes were equal bilaterally in the upper extremities, and his lower extremity examination was normal. A computed tomography (CT) scan revealed a lesion in the left pedicle of C7, suggestive of osteoid osteoma (Fig. 1, top). Based on his progressive symptoms and the failure of conservative measures to maintain adequate function, surgical excision was indicated. A fine-cut CT was obtained and downloaded into the stereotactic workstation. Through a 2.5-cm dorsal incision, a microsurgical approach was made to the C7 lamina. The SG system was registered to the C7 vertebra, using the spinous process and the adjacent facet margins for triangulation. The SG wand was then used to select the proper entry point, through the laminar surface, based on the position and depth of the intraosseous lesion (Fig. 1, middle). A 1.2-cm window was made through 䉴 Fig. 1. (Top) Axial computed tomography image demonstrating well-circumscribed lytic lesion in cervical pedicle, with erosion of medial cortex into the neural canal. (Middle) Intraoperative stereotactic image after registration, showing probe tip over cortical entry point providing optimal access to osteoid osteoma. (Bottom) Intraoperative stereotactic image demonstrating probe tip at base of void created during excision of tumor nidus. Stereotactic image guidance permitted complete ablation of tumor without risk of entry into the canal.
the laminar cortex with the bur, and a vertical shaft was developed down to the tumor nidus. The lesion was removed with a microcurette, and the SG system confirmed the resection margins (Fig. 1, bottom). The nidus of the osteoid osteoma was confirmed histologically. Recovery was uneventful, and the patient was discharged on the first postoperative day. Symptoms resolved, and at 6 weeks he had only mild incisional pain. At 4 months he was fully active. X-rays of the cervicothoracic junction showed normal alignment. After reconditioning and physical therapy, he was released to return to athletic competition. Follow-up 26 months after excision revealed no clinical evidence of disease and no neck symptoms. Radiographs were unremarkable. Case 2 A 22-year-old right-hand-dominant professional baseball pitcher presented for treatment of an upper thoracic spine tumor. He first experienced pain in his left shoulder 6 months before evaluation, but the pain had worsened over the last 2 months. He had night pain, which was not relieved by anti-inflammatory medications. He felt weak in grip strength bilaterally, but denied bowel and bladder dysfunction, numbness or tingling. He had pain in his upper back and shoulder with neck range of motion. Rotation and lateral bending were normal with pain at the extremes. Upper extremity strength was intact except that bilateral wrist flexion and extension were 5-/5. Deep tendon reflexes were bilaterally symmetrical. Neurologic examination of the lower extremities was normal, and there were no pathologic reflexes. X-rays of the cervical and thoracic spine were normal, but magnetic resonance imaging (MRI) revealed a neoplasm of the T1 and T2 vertebral body (Fig. 2, top). There was a mass occupying the left T1–T2 neural foramina. A CTguided biopsy suggested osteoblastoma, but reactive bone could not be excluded. The patient underwent open biopsy and excision of the thoracic lesion through a posterior minimally invasive approach. The SG system was registered to the T1 and T2 vertebrae, selecting the two spinous processes and the facet margin as points of reference. A left-sided hemilaminotomy was performed, and the SG system was used to localize the tumor (Fig. 2, middle). The bone over the neural formina was removed with curettes and a Kerrison rongeur. With the nerve root exposed, a blunt elevator was used to separate the mass from the nerve root. Frozen section confirmed 䉴 Fig. 2. (Top) Axial image of osteoblastoma emanating from body of T1 vertebra. Foraminal stenosis is the result of soft tissue mass. (Middle) Intraoperative stereotactic image demonstrates tumor localization and access during primary excision. (Bottom) Intraoperative stereotactic image demonstrating approach to T2 recurrent lesion, allowing excision and removal of rib head to obtain clear margins. Follow-up magnetic resonance imaging was clear for tumor at 2-year follow-up.
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the diagnosis of osteoblastoma. The remaining tumor was removed with curettes and a nerve hook. The resection margin was verified with the stereotactic wand and confirmed histopathologically. The patient went home on the first postoperative day. Six weeks after surgery he began a graded rehabilitation program. At 6 months he was throwing full speed and was ready to return to competition. Follow-up MRI at 9 months revealed a focal recurrence of the neoplasm at the adjacent vertebra (Fig. 2, bottom). Because of the lesion’s proximity to the spinal cord, adjuvant therapy was not a consideration, and a repeat excision was necessary. The microsurgical approach was repeated, and SG was used to carry out a more extensive bony excision at the T2 level, without extending the soft tissue dissection. The patient’s recovery was again rapid, and he returned to progressive rehabilitation without further difficulties. At 6 months after surgery, he was released to return to competition. MRI showed the patient to be free of recurrence at 2year follow-up, at which point he had returned to competition at the Major-League level. Surgical technique The best approach to surgical excision of any spinal column tumor is dictated by the tumor type, level, location within the vertebra and size [7]. When benign neoplasms are encountered within the spinal column, an attempt can be made to eradicate the lesion without disrupting the surrounding uninvolved tissues, but locating the tumor and determining its margins often requires a more extensive dissection and exposure [8]. The surgical exposure disrupts muscle, ligamentous tissues and bony elements important to stability. The soft tissue dissection can severely impair functional recovery, even assuming tumor removal is completely successful. For athletes involved in throwing activities or “heading,” disruption of the cervicothoracic junction, shoulder girdle musculature or chest wall can be career ending. Minimally invasive techniques have significantly improved recovery and return to activity among spine surgery patients but have had limited application in cases of spinal column tumor. SG has proven helpful in localizing intracranial lesions that traditionally required more extensive surgical exposure. SG uses a number of different image correlation technologies to provide localizing feedback to the surgeon based on recognizable surface or cortical landmarks. Threedimensional data are provided once the actual anatomy is registered and are correlated to previously acquired CT data. In the spine, SG has proven reliable in guiding placement of transpedicular and cervical transarticular screws [9]. In tumor care, SG allows the surgeon to localize subcortical pathology without wide operative exposure, then excise it and confirm proper margins, all through the smallest incision possible. Preoperative CT data, acquired by spiral CT in finecut sections, are downloaded into the image analysis workstation (Viewpoint Stereotactic Navigation System; Z-Kat
Systems, Cleveland, OH) and converted to a three-dimensional display that can be manipulated in real time in the operating room. In the system used here, a light-emitting diode (LED) sensor array is tracked by a binocular sensing system positioned at the foot of the surgical station. Specific instruments are designed and calibrated within the system to provide precise localization of the instrument tip in space, based on the LED alignment. Surgical treatment requires exposure of just enough bony architecture to allow the surgeon to identify three distinct nonlinear points on the bony surface. These registry points must be prominent enough to show on the CT image and at the surgical site. In unilateral spinal exposures these may be the spinous process, the transverse processes, the apex of a facet or any distinct osteophyte or prominence. After registering the selected points with the LED wand, the SG system reconciles the area described by the three points to the anticipated area described by the target points and provides an estimate of error. If an acceptable error is calculated, the system can correlate the position and orientation of the wand tip with respect to the vertebral elements (Fig. 3). Using the system as described, accuracy has been shown to range from 1.1⫾0.8 mm in early pedicle screw studies [9] to the submillimeter range in more recent studies with current image guidance tools [10]. Using this system, no outrigger assembly is needed, because the existing anatomy provides an absolute reference. The surgical excision can then be carried out without dissecting normal, uninvolved anatomy to acquire visualization, locate landmarks or apply an outrigger. The neoplastic lesion can be approached directly through the least destructive corridor and excised to the margins without disrupting the adjacent facets or surrounding bony architecture. Discussion Even though the tumor may be benign, surgery is indicated in many cases of spinal column tumor, either by pain
Fig. 3. Registry points selected for three-dimensional correlation to stored computed tomography (CT) data. Three nonlinear points are selected and correlated with well-defined CT landmarks. Accuracy of correlation is calculated by the software based on spatial resolution of the known CT landmarks and those selected in real time.
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or progressive instability or threat of local extension. There is a risk of surgery causing more long-term dysfunction than it prevents, however. The need to minimize the morbidity of surgery, while maintaining effectiveness, is something the surgeon should consider. Osteoid osteoma and osteoblastoma are primary bone tumors with a benign nature [11–19]. Osteoid osteomas account for about 10% to 11% of all primary bone tumors. Between 10% and 20% of osteoid osteomas occur in the posterior elements of the spine. Osteoblastomas are uncommon tumors accounting for only 1% of tumors, but they have an affinity for the spine [11]. About 40% occur in the vertebral column [11,14]. Large lesions can produce instability or encroach on nervous tissue [15]. Surgical treatment of spinal osteoid osteomas is complicated by the inaccessibility of the lesion. Even with a standard open surgical approach, care must be taken to accurately localize the nidus of the lesion [20]. There have been many techniques described to aid in localizing the tumor nidus [21–23]. The goal is to remove the nidus entirely without causing pathologic fracture or instability. The classic surgical procedure involves saucerizing a wide section of the overlying cortex to expose the lesion at the base. Less invasive techniques have been developed to treat osteoid osteoma in the extremities. Percutaneous ablation, removing the nidus by drilling percutaneously through the bone to the lesion [24], has been used to treat osteoid osteomas within the lumbar vertebral body, but not in proximity to the spinal cord [25]. Radiofrequency ablation has also been used to percutaneously ablate extremity and lumbar osteoid osteomas. Thin optical fibers emitting low-power laser light energy, introduced percutaneously, destroy tumor by direct heating [6,26]. The technique has been used sparingly in treating lumbar osteoid osteomas, but never in direct proximity to the spinal canal [5,27,28]. Vertebral osteoblastomas are best treated with direct excision or aggressive curettage [29]. Percutaneous treatment modalities have no role in treating these tumors. The larger size of the tumor usually dictates a more extensive dissection and greater tissue disruption, and an intralesional margin is often the best that can be obtained. Tumor recurrence has been common, therefore, unless adjuvant therapy such as cryotherapy or phenol is added after surgery. These adjuvants cannot be used around the spinal cord, so an extensive debridement is often substituted to limit the likelihood of recurrence. In cervical and cervicothoracic lesions, extensive resection can be debilitating. The minimally invasive, image-guided approach described here removes less bone and requires less soft tissue dissection than the classic open techniques, yet still allowed a full resection of the tumor in our cases [8,29]. The use of computer-assisted stereotactic localization refined intraoperative localization of the tissue to be excised. This technique allowed successful ablation of benign, painful lesions in an anatomically challenging location, without disrupting the shoulder girdle or neck musculature, and without
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extensive bony resection. To our knowledge, this approach has been reported in only one case of spine tumor [30]. The traditional en-bloc excision of a cervicothoracic tumor requires a more extensive dissection and exposure of additional vertebral levels, often requiring laminectomies and subsequent instrumentation. The more extensive soft tissue injury and potential for instability can greatly affect the return to function, particularly in high-demand activities and athletic participation. The use of the stereotactic imaging system allowed us to localize the tumor margins with great accuracy. Used more commonly for guidance during pedicle screw and atlantoaxial screw placement [9], this system allowed for safe and complete excision in immediate proximity of vital neurovascular structures. In both of these cases, contralateral spinal musculature was undisturbed. Localization was accomplished by exposing the lamina and spinous process of only a single motion segment. The end result was direct access and complete surgical excision of the lesion with soft tissue injury comparable to a trochar biopsy. Local recurrence of the osteoblastoma occurred after our initial excision (a 10% risk following traditional approaches), but even here, wider resection of the recurrent lesion was still accomplished through a minimally invasive approach. Although any patient should warrant the benefits of functionpreserving treatment offered by this approach, the extraordinary physical demands upon the throwing athlete illustrate the potential for excellent functional outcome after image-guided resection of a spinal tumor.
Summary Although osseous spinal tumors are uncommon, they do occur in young, active individuals and can present in the competitive athlete. Once the benign nature of the osseous neoplasm has been established, one of the primary difficulties in treating an athlete with a spinal tumor is minimizing the collateral damage caused by the surgical exposure and tumor excision. Stereotactic imaging can be a useful adjunct to tumor care in properly selected patients. Image guidance, in combination with evolving minimally invasive surgical techniques, can accurately localize and guide excision of benign vertebral lesions while minimizing soft tissue trauma and collateral damage, allowing patients a rapid and complete return to preoperative function. It must be noted, however, that experience with this approach is limited and that the results obtained in these patients may not be typical. It should also be noted that the intralesional approach used in these cases would not be appropriate for primary malignant lesions arising from the spinal column.
References [1] Weinstein JN, McLain RF. Primary tumors of the spine. Spine 1988; 12(9):843–51.
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[2] Fielding JW, Keim HA, Hawkins RJ, et al. Osteoid osteoma of the cervical spine. Clin Orthop Rel Res 1977;128:163–4. [3] Kirwan EO, Hutton PA, Pozo JL, et al. Osteoid osteoma and benign osteoblastoma of the spine. Clinical presentation and treatment. J Bone Joint Surg 1984;66B(1):21–6. [4] Pettine KA, Klassen RA. Osteoid-osteoma and osteoblastoma of the spine. J Bone Joint Surg 1986;68B(3):354–61. [5] Osti OL, Sebben R. High-frequency radio-wave ablation of osteoid osteoma in the lumbar spine. Eur Spine J 1998;7(5):422–5. [6] Rosenthal DI, Hornicek FJ, Wolfe MW, et al. Percutaneous radiofrequency coagulation of osteoid osteoma compared with operative treatment. J Bone Joint Surg 1998;80A(6):815–21. [7] McLain RF, Weinstein JN. Tumors of the spine. In: Herkowitz H, Garfin S, Balderston R, Eismont F, Bell G, Weisel S, editors. Rothman and Simeone: the spine, 4th ed. Philadelphia: W.B. Saunders Company, 1999:1171–206. [8] Ward WG, Echardt JJ, Shatestehfar S, et al. Osteoid osteoma diagnosis and management with low morbidity. Clin Orthop Rel Res 1993;291: 229–35. [9] Kalfas IH, Kormos DW, Murphy MA, et al. Application of frameless stereotaxy to pedicle screw fixation of the spine. J Neurosurg 1995; 83(4):641–7. [10] Choi WW, Green BA, Levi ADO. Computer-assisted fluoroscopic targeting system for pedicle screw insertion. Neurosurgery 2000;47: 872–8. [11] Marsh BW, Bonfiglio M, Brady LP, Enneking WF. Benign osteoblastoma: range of manifestations. J Bone Joint Surg 1975;57A(1): 1–9. [12] Ciabattoni G, Tamburrelli F, Greco F. Increased prostacyclin biosynthesis in patients with osteoid osteoma. Eicosanoids 1991;4(3):165–7. [13] Bottner F, Roedl R, Wortler K, et al. Cyclooxygenase-2 inhibitor for pain management in osteoid osteomas. Clin Orthop Rel Res 2001; 393:258–63. [14] Griffin JB. Benign osteoblastoma of the thoracic spine. J Bone Joint Surg 1978;60A(6):833–5. [15] Schneider M, Sabo D, Gerner HJ, et al. Destructive osteoblastoma of the cervical spine with complete neurologic recovery. Spinal Cord 2002;40(5):248–52.
[16] Bucci MN, Feldenzer JA, Phillips WA, et al. Atlanto-axial rotational limitation secondary to osteoid osteoma of the axis. J Neurosurg 1989; 70(1):129–31. [17] Goldstein GS, Dawson EG, Batzdorf U. Cervical osteoid osteoma: a cause of chronic upper back pain. Clin Orthop Rel Res 1977;129: 177–80. [18] Hershman E, Bjorkengren AJ, Fielding JW, et al. Osteoid osteoma in a cervical pedicle. Resection via transpillar approach. Clin Orthop Rel Res 1986;213:115–7. [19] Jones DA. Osteoid osteoma of the atlas. J Bone Joint Surg 1987; 69B(1):149. [20] Sim FH, Dahlin CD, Beabout JW. Osteoid-osteoma: diagnostic problems. J Bone Joint Surg 1975;57(20):154–9. [21] Ayala AG, Murray JA, Erling MA, et al. Osteoid-osteoma: intraoperative tetracycline-fluorescence demonstration of the nidus. J Bone Joint Surg 1986;68A(5):747–51. [22] Ghelman B, Thompson FM, Arnold WD. Intraoperative radioactive localization of an osteoid-osteoma. J Bone Joint Surg 1981;63A(5): 826–7. [23] Szypryt EP, Hardy JG, Colton CL. An improved technique of intraoperative bone scanning. J Bone Joint Surg 1986;68B(4):643–6. [24] Donahue F, Ahmad A, Mnaymneh W, et al. Osteoid osteoma. Computed tomography guided percutaneous excision. Clin Orthop Rel Res 1999;366:191–6. [25] Labbe JL, Clement JL, Duparc B, et al. Percutaneous extraction of vertebral osteoid osteoma under computed tomography guidance. Eur Spine J 1995;4(6):368–71. [26] Dupuy DE, Hong R, Oliver B, et al. Radiofrequency ablation of spinal tumors: temperature distribution in the spinal canal. Am J Roentgenol 2000;175(5):1263–6. [27] Lindner NJ, Ozaki T, Roedl R, et al. Percutaneous radiofrequency ablation in osteoid osteoma. J Bone Joint Surg 2001;83B(3):391–6. [28] Woertler K, Vestring T, Boettner F, et al. Osteoid osteoma: CT-guided radiofrequency ablation and follow-up in 47 patients. J Vascular Intervent Radiol 2001;12(6):717–22. [29] Levine AM, Boriani S, Donati D, et al. Benign tumors of the cervical spine. Spine 1992;17:S399–406. [30] Patel N, Sandeman DR, Cobby M, et al. Interactive image-guided surgery of the spine. J Neurosurg 1997;11(1):60–4.
Image-guided surgery in resection of benign cervicothoracic spinal tumors: a report of two cases Timothy Moore, MDa, Robert F. McLain, MDb,* a
Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA b Surgical Staff, Department of Orthopaedic Surgery and The Cleveland Clinic Spine Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA Received 12 November 2003; accepted 24 June 2004
Abstract
BACKGROUND CONTEXT: Osseous spinal tumors are an uncommon cause of persistent axial pain and muscle spasm, but even benign lesions may grow to cause deformity or neurological signs. Traditional treatment approaches to resection can be debilitating even when the tumor is benign. PURPOSE: Emerging technologies allow surgeons to diagnose and treat osseous neoplasms while minimizing the collateral damage caused by surgical exposure and tumor excision. STUDY DESIGN: Technical considerations are presented through two cases of benign osseous neoplasm occurring in the cervicothoracic spine of competitive athletes, demonstrating the methods used to provide effective treatment while maintaining maximal functional capacity. METHODS: Stereotactic imaging and intraoperative guidance was used as an adjunct to tumor care in these patients. Used in combination with minimally invasive, microsurgical techniques, stereotactic guidance localized and verified excision margins of benign vertebral lesions, minimizing soft tissue trauma and collateral damage. RESULTS: Computer-assisted stereotactic localization allowed us to successfully ablate these lesions from their anatomically challenging locations, without disrupting the shoulder girdle or neck musculature, and without extensive bony resection. CONCLUSIONS: Image guidance can accurately localize and guide excision of benign vertebral lesions while minimizing soft tissue trauma and collateral damage, allowing patients a rapid and complete return to high-demand function. 쑖 2005 Elsevier Inc. All rights reserved.
Keywords:
Spine; Tumor; Stereotactic guidance; Sports; Osteoblastoma; Osteoid osteoma
Introduction Although focal, persistent pain might be treated expectantly in a normally active teen or young adult, serious spinal pathology can occasionally be overlooked. Osseous spinal tumors are an uncommon cause of neck and back pain, but they do occur in young, healthy individuals [1]. When a spinal column tumor is identified, the primary goal is to determine its nature, benign or malignant, and the second is to provide effective treatment to control or cure the lesion. If the lesion is benign, treatment should be carried FDA device/drug status: not applicable. Nothing of value received from a commercial entity related to this research. * Corresponding author. Robert F. McLain, MD, Orthopaedic Spine Research, The Department of Orthopaedic Surgery, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Desk A 41, Cleveland, OH 44195, USA. Tel.: (216) 444-2744; fax: (216) 444-3328. E-mail address: [email protected] (R.F. McLain) 1529-9430/05/$ – see front matter doi:10.1016/j.spinee.2004.06.020
쑖 2005 Elsevier Inc. All rights reserved.
out without unnecessarily disrupting subsequent function. Traditional surgical approaches can be damaging to surrounding tissues, resulting in long-term impairment that would preclude return to high-demand activities. In athletes who throw, disruption of the shoulder girdle and cervicothoracic junction can be career ending. When operative treatment is necessitated by persistent pain and/or neurological symptoms, traditional surgical approaches reliably control these tumors, but at a significant cost in muscular injury and functional impairment [2–4]. Benign, locally invasive lesions may require extensive dissection for definitive control. Beyond reliably extirpating the lesion, the surgeon should consider the effect the surgical approach will have on function. While advances have been made in minimally invasive treatment of some tumors, percutaneous techniques cannot be safely applied immediately adjacent to the spinal cord [5,6]. Open techniques are still necessary in these circumstances.
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Stereotactic image guidance (SG), combined with microsurgical techniques, allows surgeons to use a minimally invasive approach to accurately localize and excise these benign tumors, minimizing surgical morbidity and optimizing rapid return to unrestricted function. Application of these principles is illustrated by two cases of competitive athletes presenting with benign neoplasms of the cervicothoracic junction.
Case reports Case 1 A 16-year-old soccer player presented with left-sided neck and shoulder pain of 5 month’s duration, first noticed while playing soccer. The pain began insidiously but was sharply exacerbated when heading the ball. Initial X-rays showed no shoulder or neck abnormality, but bone scan revealed focal uptake at the C7 level. Initially relieved with aspirin, the pain became less responsive over time. It was often present at night and on waking in the morning, without inciting events. The pain localized to the low cervical region just left of the midline, with radiation to the left shoulder, but it did not radiate distally into the arm. There were no right-sided symptoms. Despite full range of motion, the patient experienced pain with extremes of flexion, extension and rotation, and while tilting his head to the right. He had no atrophy, but had mild weakness in his left-hand intrinsics. Deep tendon reflexes were equal bilaterally in the upper extremities, and his lower extremity examination was normal. A computed tomography (CT) scan revealed a lesion in the left pedicle of C7, suggestive of osteoid osteoma (Fig. 1, top). Based on his progressive symptoms and the failure of conservative measures to maintain adequate function, surgical excision was indicated. A fine-cut CT was obtained and downloaded into the stereotactic workstation. Through a 2.5-cm dorsal incision, a microsurgical approach was made to the C7 lamina. The SG system was registered to the C7 vertebra, using the spinous process and the adjacent facet margins for triangulation. The SG wand was then used to select the proper entry point, through the laminar surface, based on the position and depth of the intraosseous lesion (Fig. 1, middle). A 1.2-cm window was made through 䉴 Fig. 1. (Top) Axial computed tomography image demonstrating well-circumscribed lytic lesion in cervical pedicle, with erosion of medial cortex into the neural canal. (Middle) Intraoperative stereotactic image after registration, showing probe tip over cortical entry point providing optimal access to osteoid osteoma. (Bottom) Intraoperative stereotactic image demonstrating probe tip at base of void created during excision of tumor nidus. Stereotactic image guidance permitted complete ablation of tumor without risk of entry into the canal.
the laminar cortex with the bur, and a vertical shaft was developed down to the tumor nidus. The lesion was removed with a microcurette, and the SG system confirmed the resection margins (Fig. 1, bottom). The nidus of the osteoid osteoma was confirmed histologically. Recovery was uneventful, and the patient was discharged on the first postoperative day. Symptoms resolved, and at 6 weeks he had only mild incisional pain. At 4 months he was fully active. X-rays of the cervicothoracic junction showed normal alignment. After reconditioning and physical therapy, he was released to return to athletic competition. Follow-up 26 months after excision revealed no clinical evidence of disease and no neck symptoms. Radiographs were unremarkable. Case 2 A 22-year-old right-hand-dominant professional baseball pitcher presented for treatment of an upper thoracic spine tumor. He first experienced pain in his left shoulder 6 months before evaluation, but the pain had worsened over the last 2 months. He had night pain, which was not relieved by anti-inflammatory medications. He felt weak in grip strength bilaterally, but denied bowel and bladder dysfunction, numbness or tingling. He had pain in his upper back and shoulder with neck range of motion. Rotation and lateral bending were normal with pain at the extremes. Upper extremity strength was intact except that bilateral wrist flexion and extension were 5-/5. Deep tendon reflexes were bilaterally symmetrical. Neurologic examination of the lower extremities was normal, and there were no pathologic reflexes. X-rays of the cervical and thoracic spine were normal, but magnetic resonance imaging (MRI) revealed a neoplasm of the T1 and T2 vertebral body (Fig. 2, top). There was a mass occupying the left T1–T2 neural foramina. A CTguided biopsy suggested osteoblastoma, but reactive bone could not be excluded. The patient underwent open biopsy and excision of the thoracic lesion through a posterior minimally invasive approach. The SG system was registered to the T1 and T2 vertebrae, selecting the two spinous processes and the facet margin as points of reference. A left-sided hemilaminotomy was performed, and the SG system was used to localize the tumor (Fig. 2, middle). The bone over the neural formina was removed with curettes and a Kerrison rongeur. With the nerve root exposed, a blunt elevator was used to separate the mass from the nerve root. Frozen section confirmed 䉴 Fig. 2. (Top) Axial image of osteoblastoma emanating from body of T1 vertebra. Foraminal stenosis is the result of soft tissue mass. (Middle) Intraoperative stereotactic image demonstrates tumor localization and access during primary excision. (Bottom) Intraoperative stereotactic image demonstrating approach to T2 recurrent lesion, allowing excision and removal of rib head to obtain clear margins. Follow-up magnetic resonance imaging was clear for tumor at 2-year follow-up.
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the diagnosis of osteoblastoma. The remaining tumor was removed with curettes and a nerve hook. The resection margin was verified with the stereotactic wand and confirmed histopathologically. The patient went home on the first postoperative day. Six weeks after surgery he began a graded rehabilitation program. At 6 months he was throwing full speed and was ready to return to competition. Follow-up MRI at 9 months revealed a focal recurrence of the neoplasm at the adjacent vertebra (Fig. 2, bottom). Because of the lesion’s proximity to the spinal cord, adjuvant therapy was not a consideration, and a repeat excision was necessary. The microsurgical approach was repeated, and SG was used to carry out a more extensive bony excision at the T2 level, without extending the soft tissue dissection. The patient’s recovery was again rapid, and he returned to progressive rehabilitation without further difficulties. At 6 months after surgery, he was released to return to competition. MRI showed the patient to be free of recurrence at 2year follow-up, at which point he had returned to competition at the Major-League level. Surgical technique The best approach to surgical excision of any spinal column tumor is dictated by the tumor type, level, location within the vertebra and size [7]. When benign neoplasms are encountered within the spinal column, an attempt can be made to eradicate the lesion without disrupting the surrounding uninvolved tissues, but locating the tumor and determining its margins often requires a more extensive dissection and exposure [8]. The surgical exposure disrupts muscle, ligamentous tissues and bony elements important to stability. The soft tissue dissection can severely impair functional recovery, even assuming tumor removal is completely successful. For athletes involved in throwing activities or “heading,” disruption of the cervicothoracic junction, shoulder girdle musculature or chest wall can be career ending. Minimally invasive techniques have significantly improved recovery and return to activity among spine surgery patients but have had limited application in cases of spinal column tumor. SG has proven helpful in localizing intracranial lesions that traditionally required more extensive surgical exposure. SG uses a number of different image correlation technologies to provide localizing feedback to the surgeon based on recognizable surface or cortical landmarks. Threedimensional data are provided once the actual anatomy is registered and are correlated to previously acquired CT data. In the spine, SG has proven reliable in guiding placement of transpedicular and cervical transarticular screws [9]. In tumor care, SG allows the surgeon to localize subcortical pathology without wide operative exposure, then excise it and confirm proper margins, all through the smallest incision possible. Preoperative CT data, acquired by spiral CT in finecut sections, are downloaded into the image analysis workstation (Viewpoint Stereotactic Navigation System; Z-Kat
Systems, Cleveland, OH) and converted to a three-dimensional display that can be manipulated in real time in the operating room. In the system used here, a light-emitting diode (LED) sensor array is tracked by a binocular sensing system positioned at the foot of the surgical station. Specific instruments are designed and calibrated within the system to provide precise localization of the instrument tip in space, based on the LED alignment. Surgical treatment requires exposure of just enough bony architecture to allow the surgeon to identify three distinct nonlinear points on the bony surface. These registry points must be prominent enough to show on the CT image and at the surgical site. In unilateral spinal exposures these may be the spinous process, the transverse processes, the apex of a facet or any distinct osteophyte or prominence. After registering the selected points with the LED wand, the SG system reconciles the area described by the three points to the anticipated area described by the target points and provides an estimate of error. If an acceptable error is calculated, the system can correlate the position and orientation of the wand tip with respect to the vertebral elements (Fig. 3). Using the system as described, accuracy has been shown to range from 1.1⫾0.8 mm in early pedicle screw studies [9] to the submillimeter range in more recent studies with current image guidance tools [10]. Using this system, no outrigger assembly is needed, because the existing anatomy provides an absolute reference. The surgical excision can then be carried out without dissecting normal, uninvolved anatomy to acquire visualization, locate landmarks or apply an outrigger. The neoplastic lesion can be approached directly through the least destructive corridor and excised to the margins without disrupting the adjacent facets or surrounding bony architecture. Discussion Even though the tumor may be benign, surgery is indicated in many cases of spinal column tumor, either by pain
Fig. 3. Registry points selected for three-dimensional correlation to stored computed tomography (CT) data. Three nonlinear points are selected and correlated with well-defined CT landmarks. Accuracy of correlation is calculated by the software based on spatial resolution of the known CT landmarks and those selected in real time.
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or progressive instability or threat of local extension. There is a risk of surgery causing more long-term dysfunction than it prevents, however. The need to minimize the morbidity of surgery, while maintaining effectiveness, is something the surgeon should consider. Osteoid osteoma and osteoblastoma are primary bone tumors with a benign nature [11–19]. Osteoid osteomas account for about 10% to 11% of all primary bone tumors. Between 10% and 20% of osteoid osteomas occur in the posterior elements of the spine. Osteoblastomas are uncommon tumors accounting for only 1% of tumors, but they have an affinity for the spine [11]. About 40% occur in the vertebral column [11,14]. Large lesions can produce instability or encroach on nervous tissue [15]. Surgical treatment of spinal osteoid osteomas is complicated by the inaccessibility of the lesion. Even with a standard open surgical approach, care must be taken to accurately localize the nidus of the lesion [20]. There have been many techniques described to aid in localizing the tumor nidus [21–23]. The goal is to remove the nidus entirely without causing pathologic fracture or instability. The classic surgical procedure involves saucerizing a wide section of the overlying cortex to expose the lesion at the base. Less invasive techniques have been developed to treat osteoid osteoma in the extremities. Percutaneous ablation, removing the nidus by drilling percutaneously through the bone to the lesion [24], has been used to treat osteoid osteomas within the lumbar vertebral body, but not in proximity to the spinal cord [25]. Radiofrequency ablation has also been used to percutaneously ablate extremity and lumbar osteoid osteomas. Thin optical fibers emitting low-power laser light energy, introduced percutaneously, destroy tumor by direct heating [6,26]. The technique has been used sparingly in treating lumbar osteoid osteomas, but never in direct proximity to the spinal canal [5,27,28]. Vertebral osteoblastomas are best treated with direct excision or aggressive curettage [29]. Percutaneous treatment modalities have no role in treating these tumors. The larger size of the tumor usually dictates a more extensive dissection and greater tissue disruption, and an intralesional margin is often the best that can be obtained. Tumor recurrence has been common, therefore, unless adjuvant therapy such as cryotherapy or phenol is added after surgery. These adjuvants cannot be used around the spinal cord, so an extensive debridement is often substituted to limit the likelihood of recurrence. In cervical and cervicothoracic lesions, extensive resection can be debilitating. The minimally invasive, image-guided approach described here removes less bone and requires less soft tissue dissection than the classic open techniques, yet still allowed a full resection of the tumor in our cases [8,29]. The use of computer-assisted stereotactic localization refined intraoperative localization of the tissue to be excised. This technique allowed successful ablation of benign, painful lesions in an anatomically challenging location, without disrupting the shoulder girdle or neck musculature, and without
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extensive bony resection. To our knowledge, this approach has been reported in only one case of spine tumor [30]. The traditional en-bloc excision of a cervicothoracic tumor requires a more extensive dissection and exposure of additional vertebral levels, often requiring laminectomies and subsequent instrumentation. The more extensive soft tissue injury and potential for instability can greatly affect the return to function, particularly in high-demand activities and athletic participation. The use of the stereotactic imaging system allowed us to localize the tumor margins with great accuracy. Used more commonly for guidance during pedicle screw and atlantoaxial screw placement [9], this system allowed for safe and complete excision in immediate proximity of vital neurovascular structures. In both of these cases, contralateral spinal musculature was undisturbed. Localization was accomplished by exposing the lamina and spinous process of only a single motion segment. The end result was direct access and complete surgical excision of the lesion with soft tissue injury comparable to a trochar biopsy. Local recurrence of the osteoblastoma occurred after our initial excision (a 10% risk following traditional approaches), but even here, wider resection of the recurrent lesion was still accomplished through a minimally invasive approach. Although any patient should warrant the benefits of functionpreserving treatment offered by this approach, the extraordinary physical demands upon the throwing athlete illustrate the potential for excellent functional outcome after image-guided resection of a spinal tumor.
Summary Although osseous spinal tumors are uncommon, they do occur in young, active individuals and can present in the competitive athlete. Once the benign nature of the osseous neoplasm has been established, one of the primary difficulties in treating an athlete with a spinal tumor is minimizing the collateral damage caused by the surgical exposure and tumor excision. Stereotactic imaging can be a useful adjunct to tumor care in properly selected patients. Image guidance, in combination with evolving minimally invasive surgical techniques, can accurately localize and guide excision of benign vertebral lesions while minimizing soft tissue trauma and collateral damage, allowing patients a rapid and complete return to preoperative function. It must be noted, however, that experience with this approach is limited and that the results obtained in these patients may not be typical. It should also be noted that the intralesional approach used in these cases would not be appropriate for primary malignant lesions arising from the spinal column.
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