Patients with chronic pain usually require multimodal (pharmacologic, behavioral, physical modalities, and procedural) therapies for pain that are chosen based on the underlying mechanism and the impact of the pain on function and suffering.
Fear of reinjury, catastrophizing, and poor coping skills may undermine the success of any mode of therapy. Secondary gain (litigation, ongoing workers' compensation) may also undermine successful treatment.
The success of opioid therapies in acute pain must be tempered by the realization that for chronic pain treatment, opioid-induced hyperalgesia, pharmacologic tolerance, drug diversion, patient outcomes, and legal issues must be balanced appropriately for optimal care. Continuous monitoring and attention to the physician-patient relationship is vital.
Multiple new agents targeting ion channels and neurotransmitters are being developed, with improving efficacy. Optimal use of these agents requires a thorough understanding of their pharmacology as well as the ability to compare their effects through standardized study (allowing meta-analysis) and measures such as "number needed to treat" analysis.
New studies examining combination therapy (eg, an opioid plus anticonvulsant agent) are likely to represent future practice because of the complexity of pain treatment and the realization that one agent is rarely sufficient.
Several studies suggesting that physical modalities plus cognitive-behavioral interventions are equivalent to large surgical procedures are interesting. These studies point to a future blending of traditionally separate pain clinic and pain rehabilitative programs to include even more comprehensive approaches.
The approach to the patient with chronic pain shares some similarities with the treatment of acute pain, with several notable differences. Whereas acute pain involves a specific tissue injury and an often easily identifiable initiating event, chronic pain may not have a definable source, tissue injury may not always be apparent, and treatment may be ineffective (Fig. 91-1). Unlike acute pain where the course of the disease process may be self-limited and the treatment duration is generally brief, chronic pain often requires extended and multimodal treatment. Additionally, if pharmacologic therapy is the mainstay of treatment, then the long-term implications of popular drugs used for treatment of acute pain, such as opioids and nonsteroidal anti-inflammatory agents (NSAIDs), must be considered. Acute pain is caused by a short-term event (trauma, surgery, burn, etc) and has the chance of improvement or cure with treatment or elimination of the inciting event. It is appropriately managed with opioids, regional/neuraxial local anesthetics, numerous adjuvant drugs, and corticosteroids or NSAIDS. Long-term issues of drug-induced toxicities, such as opioid-induced endocrine abnormalities or hyperalgesia and cardiovascular or gastrointestinal side effects of NSAIDs, must be considered relevant to patients with chronic medical problems. In general, there is little evidence of long-term efficacy (ie, >2 years) of medications historically used for short-term analgesia.1
Top: In acute pain, tissue damage leads to a predominantly sensory phenomenon of pain, with some superimposed cognitive, affective response. Bottom: In chronic pain, tissue damage may not be apparent, and symptom magnification, affective ...