Pain

Pain is the first symptom in 90% of the patients with spinal metastases. The pain may be local or radicular in nature (radiating or having a girdle-like nature) (Bach, 1990; Helweg-Larsen, 2000; Wewel, 2020). The location of the pain is not always an indication of the exact location of the spinal metastasis, which may, e.g., be due to a phenomenon called ‘referred pain' (see also module Differential diagnosis) (Kellgren, 1949; Cook, 1998; Husband, 2001; Levack, 2002). When analysing back pain or radicular pain in cancer patients, imaging may demonstrate the presence of metastatic epidural spinal cord compression (MESCC). Dutch research has shown a median delay of over three months from initial symptoms to definitive treatment in patients with spinal metastases, with such delays significantly impairing functional status, quality of life, and survival outcomes (Kienstra, 2000; van Tol, 2019; van Tol, 2020; van Tol, 2022; van Tol, 2023). It is therefore of major importance to immediately perform imaging in patients with a history of cancer or symptoms indicating presence of a malignancy and suspected back pain (see alarm symptoms in next paragraph and module Imaging research - Timelines for suggested diagnostic intervals). Furthermore, not only the treating medical specialist, but also the patient and general practitioner (GP) should be familiar with the early signs of spinal metastases and their possible consequences (see Appendix I). The diagnosis of spinal metastases has to be considered in all patients with back pain and (a history of / symptoms indicating presence of) cancer. It is not necessary to perform imaging for every patient with a history of back pain and malignancy. However, the presence of certain red flag symptoms warrants imaging, even when the neurological examination appears normal (Kienstra, Terwee et al. 2000).

Alarm symptoms for back pain that may indicate spinal metastases are:

• Nocturnal back pain
• Progressive back pain
• New local back pain
• Pain on palpation along the spinal column
• Back pain in a patient with an oncological medical history
• Back pain in a patient with symptoms indicating presence of a malignancy

Severe pain in all positions and pain between the shoulder blades is suspicious.

Pain resulting from malignancy typically develops gradually and intensifies over time. This contrasts with lumbago, which is often chronic and characterized by fluctuating pain levels. Pain triggered by changes in position or when standing up may suggest spinal instability. A sudden escalation in pain could indicate a spontaneous spinal fracture.

Radiculopathy

Radiculopathy refers to pain or neurological deficits caused by spinal epidural metastases (SEM)-related compression of a nerve root. When both pain and neurological deficits are present, the condition is termed a radicular syndrome. In such cases, radiating pain and sensory disturbances are confined to the dermatome of the affected nerve root (see Figure 1). Motor deficits are limited to the muscle group innervated by that nerve root, known as the myotome (see Figure 2).

A bilateral radicular syndrome is characterized by pain and/or neurological deficits occurring in the same dermatome and myotome on both sides of the body, without any deficits present further down the neurological pathway. In contrast, compression of the spinal cord or cauda equina results in neurological deficits that extend below the level of the lesion.

The likelihood of SEM and MESCC increases as the signs and symptoms become more evident. The likelihood of cancer patients with just back pain having MESCC is approximately 3-10%, with radiating radicular pain 20-30% and with (motor and/or sensory) radicular deficit 40-50% (Ruff and Lanska, 1989; Byrne, 1992; Kienstra, 1996; van der Linden Dijkstra et al. 2005). Double-sided radicular pain and/or deficit suggest extensive epidural spread with an increased probability of MESCC. Approximately 50% of the patients with spinal metastases develop radicular pain. The difference with non-radicular pain is not always easy to distinguish (see module Differential diagnosis).

_{Figure 1. Nerve roots and corresponding dermatomes}

_{Figure 2. Myotomes: Spinal innervation of major muscle (groups)}

_{The dark red fields represent the most important innervating nerve roots for that particular muscle (group). The light red nerve roots generally contribute less to the innervation of that muscle (group)}

Metastatic Epidural Spinal Cord or cauda equina Compression (MESCC)

The primary complication of spinal metastases is spinal cord injury or cauda equina syndrome resulting from MESCC. Among patients with malignancy who exhibit clinical signs of myelopathy or cauda equina syndrome, the likelihood of MESCC is approximately 65–70% (Ruff and Lanska, 1989; Boogerd and van der Sande, 1993; Kienstra, 1996). Motor deficit is usually most prominent in this case, though sensory deficit is also present in the majority of cases (Gilbert, Kim and Posner, 1978). Sometimes vague complaints of gait and balance disturbances (e.g. the patient complains about rubbery or shaky legs) form the first symptoms of spinal cord or cauda equina compression and pain is not evident. Therefore, during the neurological examination, particular attention has to be paid to the patient's standing and gait, pain on palpation along the spine and a sensory level of neurological deficit.

During foetal development the vertebral column grows faster than the spinal cord resulting in a mismatch between their lengths (ascensus medullae). This frequently causes the level of spinal cord compression to be located higher than the sensory level identified during physical examination. In case of an incomplete spinal cord injury the sensory level may also be lower than the affected level, but never higher (Cook, 1998; Husband, Grant and Romaniuk, 2001; Levack, Graham et al. 2002). Micturition and defecation disturbances are observed in approximately 50% of the patients with MESCC, but are rarely the only symptom of MESCC. Cervical spinal cord compression may also cause hooting pain and tingling sensations down the back into the legs, that occur on flexion of the neck (Lhermitte's sign). Incidentally, Lhermitte's sign may also develop following radiotherapy of cervical spine or neck (Lewanski, Sinclair and Stewart, 2000). Cisplatin may also cause a transient Lhermitte's sign, but in this situation the electrical and tingling sensations are solely registered in the lower legs/feet on flexion of the neck (weeks to months after treatment) as a result of abnormal dorsal root and dorsal ganglion sensitivity (Walther, 1987).