Can pain can be more or less neuropathic? Comparison of symptom assessment tools with ratings of certainty by clinicians.

Chronic pain is generally regarded as being divided into two mutually exclusive pain mechanisms: nociceptive and neuropathic. Recently, this dichotomous approach has been questioned and a model of chronic pain being 'more or less neuropathic' has been suggested. To test whether such a spectrum exists, we examined responses by patients with chronic pain to validated neuropathic pain assessment tools and compared these with ratings of certainty about the neuropathic origin of pain by their specialist pain physicians. We examined 200 patients (100 each with nociceptive and neuropathic pain) and administered the self-complete Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS score) and the Neuropathic Pain Scale (NPS). Clinicians were asked to rate their certainty of the presence of neuropathic pain mechanisms on a 100 mm visual analogue scale (VAS) (0='not at all neuropathic in origin' to 100='completely neuropathic in origin'). The whole sample was divided into tertiles based on ascending ratings of diagnostic certainty by clinicians using the VAS and labelled 'unlikely', 'possible' and 'definite' neuropathic pain. There were significant differences in median S-LANSS and NPS composite scores between all tertile groups. There were also significant differences between many S-LANSS and NPS item scores between groups. We have shown that higher scores on both the S-LANSS and the NPS are indicative of greater clinician certainty of neuropathic pain mechanisms being present. These data support the theoretical construct that pain can be more or less neuropathic and that pain of predominantly neuropathic origin may be a useful clinical concept.