Skip to Main Content

Case history

image A 48-year-old woman with recurrent breast cancer attended for assessment. She had undergone a right-sided mastectomy 5 years previously, followed by chemotherapy. She had no comorbidities and was a candidate for further treatment of ipsilateral supraclavicular nodal and lung involvement. She described a 1 week history of right arm pain and weakness, with constant burning along the medial aspect of the whole limb. She reported a slight reduction in pain with oral codeine phosphate 240 mg/day. She had reduced grip strength and altered sensation in the C8–T1 dermatomes.

How should the diagnosis of pain be approached in this patient?

How should her pain be managed?

How should the diagnosis of pain be approached in this patient?

Neuropathic pain should be suspected when a patient describes specific pain qualities in an area of altered sensation consistent with a neuroanatomical distribution.1 Suggestive descriptors that correlate strongly with altered sensation include ‘burning’, ‘stinging’ and ‘shooting’.2 Neuropathic pain arises as a result of a lesion or disease affecting the central or peripheral somatosensory system.3 The term encompasses heterogeneous syndromes with diverse aetiologies.4 The underlying mechanisms are incompletely understood and include peripheral and central sensitization, neuronal hyperexcitability, maintained sympathetic activity, dysfunctional central inhibition, dorsal horn rewiring and phenotypic switch.4

The prevalence of neuropathic pain in cancer patients ranges from 19% to 39%; 19–24% of all pains have a neuropathic mechanism.5,6 Cancer pain typically arises from mixed nociceptive and neuropathic mechanisms, with pain considered more or less neuropathic.7,8 Failure to identify a neuropathic component may contribute to the undertreatment of pain.5 Approximately two-thirds of neuropathic cancer pain arises from the cancer itself, through direct invasion or paraneoplastic neuropathy; 20% of reported pain results from anticancer treatment. Up to 10% reflects comorbidity.5,6 In the absence of previous radiotherapy, brachial plexopathy secondary to metastatic involvement was likely in this case.

Patients with neuropathic pain may describe or exhibit the following:1,9

  • pain occurring without a precipitating trigger (spontaneous pain) like shooting electrical attacks (paroxysmal pain);

  • numbness or reduced sensation to painful (hypoalgesia) and non-painful (hypoaesthesia) stimuli;

  • unusual and unpleasant sensations such as tingling or pins and needles (dysaesthesia/paraesthesia);

  • pain response to usually non-painful stimuli (allodynia);

  • exaggerated response to usually painful stimuli (hyperalgesia);

  • abnormal thermal sensation.

Clinical examination focuses on identifying abnormal sensation in the area of pain. Allodynia is demonstrated by eliciting pain through gentle brushing. Response to pinprick testing may be reduced (numbness) or exaggerated (hyperalgesia). Temporal summation, in which there is increasing pain sensation with repetitive application of identical stimuli, is demonstrated by repeated pinpricks at intervals of under 3 s for 30 s.1,9

Although screening and assessment tools exist, evidence does not suggest they are superior to a stepwise clinical diagnosis graded according to ...

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.