J Am Acad Orthop Sur
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Methods of treatment are different for acute and chronic pain. For acute pain, analgesics such as nonsteroidal anti-inflammatory drugs and opiates are commonly used, sometimes combined with regional anesthesia, such as peripheral nerve block or peridural local anesthesia. The mechanism of transition from an acute to a chronic pain state is poorly understood. ⋯ Opiates may be used chronically, but tolerance and lack of efficacy may then develop. In selected patients with refractory chronic pain, centrally administered analgesics may be considered, including opiates, dilute local anesthetic, NMDA receptor antagonists, clonidine, midazolam, baclofen, or calcium channel blockers. For both acute and chronic pain, a single agent may be less effective than combinations of analgesics with different mechanisms of action.
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The transmission of a pain signal from the periphery to the central nervous system is complex and only partially understood. Tissue damage results in peripheral release of endogenous chemicals that can directly activate nociceptive afferent fibers, sensitize nociceptors, or cause increased local extravasation and vasodilatation. These algesiogenic substances may be found in local tissues, plasma, and nerve terminals. ⋯ Modulation of the pain signal in the dorsal horn involves local inhibitory and facilitatory interneurons as well as diverse excitatory and inhibitory neurotransmitters. The neuronal circuitry in the dorsal horn can change and modulate with time so that pain signals sometimes long outlast the original peripheral tissue injury. This central sensitization is thought to be mediated largely through the NMDA receptor complex.
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Spinal epidural abscess is a potentially life-threatening disease that can cause paralysis by the accumulation of purulent material in the epidural space. Although modern diagnostic and management methods have improved the prognosis, morbidity and mortality remain significant. Outcome usually is determined by the rapidity of the diagnosis and initiation of appropriate treatment. ⋯ Gadolinium-enhanced magnetic resonance imaging should be done in suspected cases to localize and define the abscess. For spinal epidural abscess associated with neurologic compromise, the treatment of choice is emergent surgical decompression and débridement (with or without spinal stabilization), followed by long-term antimicrobial therapy. In the absence of a neurologic deficit, medical management is an alternative to surgery when the risk of neurologic complications is low based on the location and morphology of the abscess, immune status of the patient, and virulence of the organism.
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Basic research is advancing the understanding of the pathogenesis and management of low back pain at the molecular and genetic levels. Frequently, low back pain is caused by disorders of the intervertebral disk. ⋯ Recent research using growth factors to promote chondrocyte regeneration appears to be promising. Advances in gene therapy to both prevent disk degeneration and regenerate the disk eventually may have clinical application.
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Coccygodynia is pain in the region of the coccyx. In most cases, abnormal mobility is seen on dynamic standing and seated radiographs, although the cause of pain is unknown in other patients. Bone scans and magnetic resonance imaging may show inflammation and edema, but neither technique is as accurate as dynamic radiography. ⋯ Coccygeal massage and stretching of the levator ani muscle can help. Coccygectomy is done only when nonsurgical treatment fails, which is infrequent. Coccygectomy usually is successful in carefully selected patients, with the best results in those with radiographically demonstrated abnormalities of coccygeal mobility.