Screening tools for neuropathic pain

Neuropathic pain (NP) is a special type of pain which arises as a direct consequence of a lesion or disease affecting the somatosensory system. It comprises a large group of neurological conditions, including diabetic neuropathy, other polyneuropathies, trigeminal neuralgia, postherpetic neuralgia, post-stroke pain, multiple sclerosis, and spinal cord injury, as well as common conditions, such as radiculopathies, traumatic nerve injuries and cancer related pain. NP is a common debilitating problem in clinical practice. Compared to nociceptive pain, NP is often refractory to common analgesics and treatment, and patients with NP suffer from more pain severity, greater costs, and relatively impaired quality of life. In western countries, the prevalence of NP in the general population is estimated to be between 6.9% and 10%. Lack of gold standard of diagnostic tests increase the potential for unrecognized cases. Hence, the International Association for the Study of Pain (IASP) has set out a grading system to guide clinical assessment and diagnosis. This approach involves multiple steps: identifying negative or positive sensory symptoms, assessing the neuroanatomical plausibility of pain, using clinical sensory examination to evaluate nervous system involvement, and running diagnostic test confirming nervous system lesions or disease (e.g., neuroimaging or neurophysiological tests). Such grading relies mainly on clinical experience, skills, and resources available for assessment. In clinical practice in many countries as well as in Taiwan, due to time constraints and the expertise required, the IASP grading system may not be applicable in the initial assessment. Therefore, screening tools with less resource intensity have been developed in primary care setting. It is considered that the special painful and non-painful sensations in NP are resulting from particular mechanisms. Besides, certain pain descriptors are indicative, but not pathognomonic for NP, such as burning, electric shocks or shooting, pricking or pins and needles, pain evoked by light touch or cold, and associated sensations such as numbness and tingling. Hence, screening questionnaires consist of several characteristic pain descriptors and, in some cases, the addition of a brief sensory examination. The most commonly used tools include the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS), the neuropathic pain questionnaire (NPQ),