The evaluation of neuropathic components in low back pain.

Chronic low back pain is highly prevalent in Western societies. Large epidemiological studies show that 20% to 35% of patients with back pain suffer from a neuropathic pain component. Presently, chronic lumbar radicular pain is the most common neuropathic pain syndrome. The pathophysiology of back pain is complex and nociceptive, and neuropathic pain-generating mechanisms are thought to be involved, which established the term mixed pain syndrome. Neuropathic pain may be caused by lesions of nociceptive sprouts within the degenerated disc (local neuropathic), mechanical compression of the nerve root (mechanical neuropathic root pain), or by action of inflammatory mediators (inflammatory neuropathic root pain) originating from the degenerative disc even without any mechanical compression. Its diagnosis and management remain an enigma, mainly because there is no gold standard for either. Accuracy of diagnostic tests used to identify the source of back pain and their usefulness in clinical practice, particularly for guiding treatment selection, is unclear. In connection with the specific instance of back pain (one of the single most costly disorders in many industrialized nations), neuropathic pain components are a significant cost factor.