The neuropathic pain scales.

N europathic pain is defined as pain initiated or caused by a primary lesion or dysfunction of the nervous system. Syndromes such as postherpetic neural-gia, complex regional pain syndrome, peripheral neuropathy, and phantom pain typify neuropathic pain. Advances in the diagnosis and treatment of neuropathic pain have been hampered by the absence of consensus on its diagnostic criteria, 1 the lack of scales to assess the intensity of the neuropathic pain symptoms and follow the response of the patient to treatments, and the lack of questionnaires to determine whether the patient's pain is neuropathic or not. Whereas the McGill Pain Questionnaire has been transformed into a short form to make it more clinically applicable, 2 the neuropathic pain questionnaires lack bedside applicability. This situation may be changing. Recently, several publications have appeared on scales to determine the intensity of the neuropathic pain and questionnaires to distinguish neuropathic from nonneuropathic pain. The newer scales have also been shortened to be applicable to a busy clinical practice. The Neuropathic Pain Scale (NPS) was designed to assess the distinct pain qualities associated with neuropathic pain. 3 The NPS consists of 10 items. Seven of the 10 items contain the words intense, sharp, hot, dull, cold, and itchy to characterize the patient's pain and the word sensitive to describe the patient's pain reaction to light touch or clothing. One item describes the time quality of the pain (all the time or some of the time). The ninth item describes the overall unpleasantness of the pain, whereas the last item indicates the intensity of the deep and surface pain. All the items are rated on a 0 to 10 scale. The authors noted that 4 items (sharp, sensitive, cold, itchy) distinguished postherpetic neuralgia from diabetic neuropathy and complex regional pain syndrome. Because the characteristics of the pain sensation may indicate the underlying pathophysiologic mechanisms, their findings suggested that the different neuropathic pain syndromes may have different pathophysiologic mechanisms. Postherpetic neuralgia may be secondary to neuronal damage to the central and peripheral nervous systems, and the acute inflammatory response results in injury to the cutaneous sensory nerves. 3 The investigators also noted that almost all of the NPS items were sensitive to the effects of treatment. The authors recommended that the NPS be used to examine the effects of treatment on the specific dimensions of pain experience of patients with neuropathic pain. In a subsequent publication, …