Multimodal analgesia for chronic pain: rationale and future directions.

Chronic pain is a multifaceted disease requiring multimodal treatment. Clinicians routinely employ various combinations of pharmacologic, interventional, cognitive-behavioral, rehabilitative, and other nonmedical therapies despite the paucity of robust evidence in support of such an approach. Therapies are selected consistent with the biopsychosocial model of chronic pain, reflecting the subjective nature of the pain complaint, and the myriad stressors that shape it. Elucidating mechanisms that govern normal sensation in the periphery has provided insights into the biochemical, molecular, and neuroanatomic correlates of chronic pain, an understanding of which is leading increasingly to mechanism-specific multidrug therapies. Peripheral and central neuroplastic reorganization underlying the disease of chronic pain is influenced by patient-specific emotions, cognition, and memories, further impairing function and idiosyncratically defining the illness of chronic pain. Clinical perceptions of these and related subjective elements associated with the suffering of chronic pain drive psychosocial treatments, including, among other options, relaxation therapies, coping skills development, and cognitive-behavioral therapy. Treatment selection is thus guided by comprehensive assessment of the phenomenology and inferred pathophysiology of the pain syndrome; patient goals, preferences, and expectations; behavioral, cognitive, and physical function; and level of risk. Experiential, practice-based evidence may be necessary for improving patient care, but it is insufficient; certainly, well-designed studies are needed to support therapeutic decision making. This review will discuss the biochemical basis of pain, factors that govern its severity and chronicity, and foundational elements for current and emerging multimodal treatment strategies.