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Case History

image You are asked to see a 60-year-old man who has widespread bone metastases from prostate cancer, which is no longer responding to hormone treatment. He lives alone and was completely independent until a few days ago. He has been admitted to hospital because he has become unable to care for himself. When you see him, he complains of pain around his trunk, which he finds difficult to describe. The ward nurse thinks he is exaggerating the pain, because he cries out even when the bed sheets touch his abdomen or legs.

What could this pain represent?

What must be done next?

What is the initial approach to his pain?

If systemic drugs have been exhausted, what other options exist for treating this pain?


What could this pain represent?

image Band-like trunk pain in patients with cancer can represent malignant spinal cord compression. Such pain is often dermatomal, roughly corresponding to the level of compression. Patients may also have pain in dermatomes below this sensory level (e.g. radiating down the legs). Bone pain at the level of spinal metastases is common in cord compression, but its absence does not exclude the diagnosis.1

Pain caused by nerve compression or injury is called neuropathic pain. This is in contrast to nociceptive pain, which is due to physiological activation of pain fibres by noxious stimuli, e.g. tissue damage. It is often difficult for patients to describe the quality of neuropathic pain. Damaged peripheral nerves may cause burning or scalding pain in a der-matomal distribution. A classic example is post-herpetic neuralgia. The distribution of pain from damaged central nerves is more likely to extend beyond the dermatomes and can be aching or stabbing in nature. In our clinical case, the leg pain is caused by compression of the central nervous system (CNS) sensory fibres in the spinal cord.2

When sensory nerves are damaged, pain fibres can be activated by non-noxious stimuli. This is called allodynia. In this patient, gently brushing the affected dermatome with bed sheets is causing pain. It occurs because the damaged nerves are hyper-excitable, and sometimes activate spontaneously. Over time, neuropathic pain causes chemical and physiological changes in the spinal cord, resulting in 'central sensitization'. Once central sensitization is established, pain becomes less responsive to opioids. Therefore, it is important to treat neuropathic pain sooner rather than later.2

What must be done next?

In this case, urgent action is required. The attending doctor must:

  • take a thorough history including any change in limb and sphincter function

  • conduct a thorough neurological examination, palpate the abdomen for evidence of urinary retention, and examine the rectum to assess anal tone

  • consider an urgent (same day) magnetic resonance scan of the whole spine as cord compression can occur at multiple levels simultaneously.3


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