Spinal metastases is a vague term which can be variably taken to refer to metastatic disease to any of the following:
see Vertebral metastases.
Intradural extramedullary metastases (5%)
Symptomatic spinal metastases are found in about 10% of patients with cancer. As the long-term survival of patients with carcinoma rises, the amount of patients with symptomatic spine metastases is also increasing. They usually present rapid progressive neurological disorders, which require an urgent treatment decision. Treatment options include an extensive 360° stabilization. These complex interventions are not always readily available 1).
Metastases to the spine are a common source of severe pain in cancer patients. The secondary effects of spinal metastases include pain, bone fractures, hypercalcemia, and neurological deficits. As the disease progresses, pain severity can increase until it becomes refractory to medical treatments and leads to a decreased quality of life for patients. A key obstacle in the study of pain-induced spinal cancer is the lack of reliable and reproducible spine cancer animal models 2).
The Spine Oncology Study Group Outcome Questionnaire (SOSGOQ) includes all domains relevant for measurement of function and disability and its content validity is confirmed by linkage with the International Classification of Function and Disability ICF. This questionnaire has superior content capacity to measure disease burden of patients with spine metastases 3).
A study proposes a scoring methodology -after reversing 4 inversely scored items- for the SOSGOQ and demonstrates that the questionnaire is a valid tool for the assessment of quality of life in patients with metastatic spine disease. The SOSG-OQ is superior to the EQ-5D in terms of coverage and internal consistency, but consists of more questions 4).
Choi et al. recommend the use of the EQ-5D measure in research for assessment of patient-centered outcomes and calculation of cost effectiveness of surgery for spinal metastases. Routine use of the measure in clinical practice is also encouraged, because it is a simple and quick method to assess overall clinical outcome 5).
There are three ways in which metastatic tumors can reach the epidural space. The most common way in approximately 85% of patients, the tumor reaches the spinal cord by the indirect route of an initial hematogenous metastasis to the vertebral body and the metastasis grows in the bone and then spreads into the epidural space, eventually causing secondary compression of the spinal cord 6).
The less common way is invasion of a paravertebral tumor directly into the spinal canal through an intervertebral foramen, which compresses the spinal cord. This process causes about 15% of MESCC and is commonly associated with lymphomas, Ewing's sarcoma, and neuroblastomas. However, least common mode of metastasis described is the direct hematogenous spread to spinal epidural space, dura, or spinal cord 7).
Spinal metastases may present in a myriad of ways, most commonly back pain with or without neurology.
Apart from chronic and increasing pain, spinal metastases lead to neurological deficits due to destruction of the vertebral body and subsequent epidural growth expansion.
Back pain is the earliest and most common symptom of spinal epidural metastasis. Back pain is present in more than 95% of patients at diagnosis 9).
Spinal epidural metastasis associated back pain can takes several forms. Localized pain to the region of the spine affected by the metastases is usually the first symptom; typically, the pain progressively increases in intensity over time. This pain is caused when the bone marrow metastasis extends to stretch the periosteum or invades soft tissues. Radicular pain due to compression or invasion of the nerve roots is commonly present in patients who develop MESCC. The pain is frequently unilateral with cervical or lumbosacral spine involvement or bilateral with thoracic spine involvement. Mechanical back pain is associated with spinal instability caused by vertebral body collapse and is relatively uncommon; it is made worse by movement and partially relieved by rest 10).
An unusual presentation of isolated atypical chest pain preceding metastatic cord compression, secondary to penile carcinoma. Spinal metastasis from penile carcinoma is rare with few cases reported. This unusual presentation highlights the need for a heightened level of clinical suspicion for spinal metastases as a possible cause for chest pain in any patients with a history of carcinoma. The case is discussed with reference to the literature 11).