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Journal of Clinical Oncology, Vol 23, No 30 (October 20), 2005: pp. 7750-7751 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.02.7029
Systematic Review of the Diagnosis and Management of Malignant Extradural Spine Cord Compression: The Cancer Care Ontario Practice Guidelines Initiative's Neuro-Oncology Disease Site GroupH. Lee Moffitt Cancer Center & Research Institute Department of Interdisciplinary Oncology Division of Neuro-Oncology, Tampa, FL To the Editor: Loblaw et al are to be commended for their systematic review of metastatic epidural spinal cord compression (ESCC).1 We have several comments and points of elaboration we believe are relevant and warrant discussion regarding clinical presentation, spine imaging, spine-directed surgery, and dexamethasone usage. The clinical manifestations of ESCC overwhelmingly comprise a progressive pain syndrome that may be local, referred, radicular, funicular, or mechanical in character.2-4 The pain evolves over 6+ weeks before neurologic signs appear and when neurologic signs appear, most often they are manifested as a thoracic sensory radiculopathy, myelopathy, or cauda equina syndrome.2-4 The clinical presentation of patients with ESCC is therefore dependent on time of discovery and consideration of the diagnosis particularly when patients present with pain only signs and symptoms. For clinicians managing patients with cancer and new evolving back pain, early spine directed radiographic studies are imperative. Another consideration is the choice of spinal neuroimaging. The complexities and limitations of computed-tomography–myelography (invasive procedure, long duration of study, patient discomfort, risk of spinal herniation, inability to image the spinal subarachnoid space above a myelographic cerebral spinal fluid block) are such that spine magnetic resonance imaging (MRI) is the preferred and overwhelmingly utilized neuroradiographic study of choice. Not emphasized in the Loblaw review is the fact that the entire spine should be screened, as approximately one third of patients have asymptomatic but radiographically evident ESCC disease distant from the symptomatic site.3,5,6 These distant sites warrant treatment similar to that of the symptomatic site. Furthermore, spine MRI is best performed without contrast as ESCC typically involves bony vertebral elements and appears hypointense on T1W MRIs. Addition of contrast often normalizes T1W hypointensity thereby obscuring the differentiation between involved and uninvolved bone. Our approach therefore is to perform T1W sagittal MRIs of entire spine without gadolinium contrast, and reserve axial imaging for regions of interest. The issue of recurrent ESCC in previously irradiated patients has been addressed in the literature regarding both symptomatic and asymptomatic lesions.2,5,6 Overall, approximately 80% of previously irradiated patients fail at the site of previous radiation necessitating continued vigilance for re-emergent ESCC. Not noted in the Loblaw review, is the lack of benefit of laminectomy for the majority of patients with ESCC as compared to primary radiation therapy.7,8 Six of seven patients with ESCC have the epicenter of metastatic disease in the vertebral body. In these cases, laminectomy fails to decompress the cord, while potentially exacerbating spinal instability by compromising the load-bearing posterior bony spine elements.2,8 In such patients, vertebrectomy may be the preferred approach and should be considered.9 Furthermore, in patients with vertebral body collapse (spinal instability extrusion of bony elements into the spinal canal, significant kyphosis, subluxation) radiotherapy is unlikely to decompress the spinal cord. As a result, these patients are best considered for vertebral body resection and spinal reconstruction.2,7 Furthermore, patients clinically failing radiotherapy either during initial treatment or subsequently may be considered for surgery. Lastly, a recent retrospective review of patients with ESCC treated at Johns Hopkins suggests only 25% of all patients would be eligible for vertebral body resection based on Patchell's randomized clinical trial inclusion criteria (ie, single site of ESCC, adult age, histology not lymphoma or myeloma, absence of paraplegia, primary tumor not posterior spine element-based, and expected survival < 3 months.)7,8 Consequently, the majority of patients with ESCC are best treated with radiotherapy to all sites identified radiographically. With regard to the use of dexamethasone as an adjuvant therapy, two issues are pertinent. First, for patients with ESCC and neuropathic pain, dexamethasone is an effective analgesic often obviating the need for opioids.3,4 Consequently, early initiation of dexamethasone results in better pain control simplifying performance of diagnostic spine imaging and application of radiotherapy. Second, dexamethasone-related toxicity is both a function of dose and duration of treatment.10 The incidence of steroid toxicity is minimized if duration of therapy is less than three weeks, suggesting that rapid tapering of dexamethasone will mitigate steroid toxicity. Nonetheless, approximately 25% of all patients with ESCC require maintenance dexamethasone for preservation of neurological function.2-5 We concur with Loblaw et al that early diagnosis of ESCC before appearance of neurological signs results in best treatment outcomes (ie, maintenance of unassisted ambulation). In addition, the role of vertebrectomy in patients with ESCC is best offered to patients with intracanalicular bony elements and those meeting the inclusion of Patchell's criteria.7 Authors' Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest. REFERENCES
1. Loblaw DA, Perry J, Chambers A, et al: Systematic review of the diagnosis and management of malignant extradural spine cord compression: The Cancer Care Ontario Practice Guidelines Initiative's Neuro-Oncology Disease Site Group. J Clin Oncol 23:2028-2037, 2005 2. Chamberlain MC, Abitol JJ, Garfin SR: Epidural spinal cord compression: Treatment seminar. Spine Surg 2:203-209, 1990
3. Chamberlain MC, Kormanik PA: Epidural spinal cord compression: A single institution's retrospective experience. Neuro-Oncology 1:120-123, 1999 4. Zaidat OO, Ruff RL: Treatment of spinal epidural metastasis improves patient survival and functional state. Neurology 14:1360-1366, 2002
5. Kaminski HJ, Diwan VG, Ruff RL: Second occurrence of spinal epidural metastases. Neurology 41:744-746, 1991 6. van der Sande JJ, Kroger R, Boogerd W: Multiple spinal eqidural metastases: An unexpectedly frequent finding. J Neurol Neurosurg Psychiatry 53:1001-1003, 1990 7. Batara JF, Grossman SA, Gokaslan Z: TA-02 Role for surgery in epidural cord compressions. Neuro-Oncology 6:370, 2004 8. Patchell R, Tibbs PA, Regine F, et al: A randomized trial of direct decompressive surgical resection in the treatment of spinal cord compression caused by metastasis. Lancet 366:643-648, 2005 9. Gokaslan ZL, York JE, Walsh GL, et al: Transthoracic vertebrectomy for metastatic spinal tumors. J Neurosurg 89:599-609, 1998 10. Weissman DE: Glucocorticoid treatment for brain metastases and epidural spinal cord compression: A review. J Clin Oncol 6:543-551, 1988[Medline]
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Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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