The bony spine is overall the third most common site for distant cancer metastasis, with the cervical spine involved in approximately 8 to 20% of metastatic spine disease cases. Diagnosis and management of metastatic spine disease requires disease categorization into the compartment involved, pathology of the lesion, and anatomic region involved. The diagnostic approach should commence with careful physical examination, and the workup should include plain radiographs, magnetic resonance imaging, computed tomography, and bone scintigraphy. Management ranges from palliative nonoperative to aggressive surgical treatment. Optimal management requires proper patient selection to individualize the most appropriate treatment modality.
The skeletal system is the third most common site after the lungs and liver for distant cancer metastasis regardless of primary tumor pathology. Within the skeletal system, the bony spine is the most commonly affected site, with approximately 33% of cancer patients developing metastatic spine lesions. However, despite the bony spine being the most common site of osseous involvement for patients with metastatic cancer, the cervical spine is only involved in 8% to 20% of metastatic spine disease cases. Nonetheless, given the 1.5 million newly diagnosed cases of cancer annually, encountering metastatic lesions within the cervical spine is not of rare occurrence.
The initial approach to diagnosis and management of cervical spine tumors requires an organizational framework that categorizes a presentation according to the compartment involved, the pathology of the lesion, and the anatomic region involved. The compartment involved refers to whether the lesion is located in the epidural, intradural-extramedullary, or intramedullary compartment, and is essential in not only formulating an initial differential diagnosis but also in understanding the pathophysiology of the lesion as it pertains to patient presenting signs and symptoms. The pathology of the lesion is of utmost importance, as it has the largest role in dictating management. For example, if a lesion is of primary rather than metastatic origin, then a curative surgical intervention (ie, en bloc resection) is a possibility, whereas surgical intervention in the setting of a metastatic lesion may only serve a palliative role given that the patient is most likely also concomitantly afflicted with numerous systemic lesions. The anatomic region involved is divided into 3 component regions: the craniovertebral junction (CVJ; C0–C1), subaxial spine (C3–C7), and the cervicothoracic junction (C7–T1). Each of these component regions has unique biomechanical properties, thereby influencing management decisions. For example, the surgical approach to achieving en bloc resection of a tumor affecting the CVJ is very different from the approach if the same lesion is located within the subaxial spine. This article describes the diagnosis and management of metastatic epidural cervical spine tumors based on the latter considerations.
Although the thoracic spine is most commonly occupied by metastatic lesions, the cervical spine harbors metastatic lesions in 8% to 20% of cases. It is thought that the wide range in the reported incidence of cervical spine affliction is attributable to whether asymptomatic or symptomatic involvement is reported. The most common primary tumor pathologies are breast, prostate, and non–small cell lung carcinoma. The highest incidence of spinal metastases occurs among individuals in the fourth and sixth decade, and men are more likely to be afflicted than women. There are several mechanisms by which a primary neoplasm can metastasize to the spine, with the mechanism depending on primary tumor pathology. Tumor pathology dictates primary tumor location and biological behavior, both of which are factors that influence spread mechanisms. Specifically, the 3 main mechanisms by which a lesion can metastasize to the spine are direct extension or invasion, hematogenous metastasis, and cerebrospinal fluid (CSF) seeding. Direct invasion or extension occurs through primary lesions becoming locally aggressive and extending to involve the bony spine. Hematogenous seeding is facilitated by the vast arterial supply of the vertebrae and via the valveless venous drainage plexi such as Batson’s plexus. Seeding of a primary lesion through the CSF occurs much less frequently and is most often caused by surgical manipulation of primary or metastatic cerebral lesions. A retrospective study by Chaichana and colleagues found that among lesions originating from breast, kidney, lung, gastrointestinal, and prostate cancers; breast metastatic lesions were the only ones found to have a statistically significant predisposition to metastasize to the cervical spine.