Assessing and Treating Chronic Pain in Patients with End-Stage Renal Disease

Neuropathic pain refers to pain that originates from pathology of the nervous system. Diabetes, infection (herpes zoster), nerve compression, nerve trauma, "channelopathies," and autoimmune disease are examples of diseases that may cause neuropathic pain. The development of both animal models and newer pharmacological strategies has led to an explosion of interest in the underlying mechanisms. Neuropathic pain reflects both peripheral and central sensitization mechanisms. Abnormal signals arise not only from injured axons but also from the intact nociceptors that share the innervation territory of the injured nerve. This review focuses on how both human studies and animal models are helping to elucidate the mechanisms underlying these surprisingly common disorders. The rapid gain in knowledge about abnormal signaling promises breakthroughs in the treatment of these often debilitating disorders.

Pain usually is the major complaint of patients with problems of the back, thus making pain evaluation a fundamental requisite in the outcome assessment in spinal surgery. Pain intensity, pain-related disability, pain duration and pain affect are the aspects that define pain and its effects. For each of these aspects, different assessment instruments exist and are discussed in terms of advantages and disadvantages. Risk factors for the development of chronic pain have been a major topic in pain research in the past two decades. Now, it has been realised that psychological and psychosocial factors may substantially influence pain perception in patients with chronic pain and thus may influence the surgical outcome. With this background, pain acceptance, pain tolerance and pain-related anxiety as factors influencing coping strategies are discussed. Finally, a recommendation for a minimum as well as for a more comprehensive pain assessment is given.

This paper reports the development of a self-report instrument designed to assess pain in cancer and other diseases. It is argued that issues of reliability and validity should be considered for every pain questionnaire. Most research on measures of pain examine reliability to the relative neglect of validity concerns. The Wisconsin Brief Pain Questionnaire (BPQ) is evaluated with regard to both reliability and validity. Data from patients with cancer at 4 primary sites and from patients with rheumatoid arthritis suggest that the BPQ is sufficiently reliable and valid for research purposes. Additional methodological and theoretical issues related to validity are discussed, and the need for continuing evaluation of the BPQ and other measures of clinical pain is stressed.