Neuropathic pain is defined as ‘pain that is caused by a lesion or disease of the somatosensory nervous system.’ The International Association for the Study of Pain (IASP) pain grading system is a simple way of determining the likelihood of a neuropathic component. If the history suggests a relevant neurological lesion or disease and the patient describes pain in an anatomically plausible distribution of a nerve, neuropathic pain is ‘possible’; it is ‘probable’ if there are corresponding examination findings in that same distribution and ‘definite’ if there is a confirmatory diagnostic test.