Pain physician
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Constriction of the sciatic nerve by loose ligation produces an inflammatory neuropathic injury. This represents an animal model for peripheral mononeuropathy. Oxygen-derived free radicals are suspected to play an important role in the pathogenesis of ischemia/reperfusion injury, leading to neurogenic inflammation. Hyperbaric oxygen (HBO) has been used anecdotally to treat clinically similar conditions in humans, but specific effects on the animal model have not been well studied. ⋯ This study evaluated tissue changes after nerve injury caused by loose ligation of the sciatic nerve in rats. Hyperbaric oxygen treatment following sciatic nerve injury reduced tissue edema, improved skin blood flow, and preserved muscle and neuronal ultrastructural integrity.
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Discography has been widely used in the lumbar and cervical spine as a diagnostic tool to identify sources of discogenic pain that may be amenable to surgical treatment. Discography in the cervical spine is currently performed without the benefit of pressure monitoring, and corresponding pressure parameters have not been determined. ⋯ In the cervical spine, iatrogenic disc injury may be caused at significantly lower pressures and volumes infused than in the lumbar spine. There was no measurable pressure change in any of the adjacent disc levels evaluated at maximum intradiscal pressurization. Further cadaveric testing will be necessary to develop parameters for intradiscal pressure monitoring in the cervical spine.
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Chronic refractory spinal pain poses a peculiar diagnostic challenge because of multiple putative pain sources, overlapping clinical features, and nonspecific radiologic findings. Diagnostic injection techniques are employed to isolate the source(s) of pain. Facet or zygapophysial joint pain is an example of spinal pain diagnosed by local anesthetic injections of the facet joint or its nerve supply. Diagnostic facet joint injections are expected to meet the cardinal features of a diagnostic test (i.e., accuracy, safety and reproducibility). Accuracy must be compared with a "gold" or criterion standard that can confirm presence or absence of a disease. There is, however, no available gold standard, such as biopsy, to measure presence or absence of pain. Hence, there is a degree of uncertainty concerning the accuracy of diagnostic facet joint injections. ⋯ The evidence obtained from literature review suggests that controlled comparative local anesthetic blocks of facet joint nerves (medial branch or dorsal ramus) are reproducible, reasonably accurate, and safe. The sensitivity, specificity, false-positive rates, and predictive values of these diagnostic tests for neck and low back pain have been validated and reproduced in multiple studies.
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Enthesopathies are a common cause of axial pain that is amenable to "minimally invasive" therapy. ⋯ Injection therapy of painful enthesopathies can provide significant relief of axial pain and tenderness combined with functional improvement, even in "failed back syndrome" patients. Phenol-glycerol prolotherapy provides better and longer lasting relief than injection with anesthetics alone. Prolotherapy provides over six months of relief for some patients but generally provides relief for only a few months. However, most patients described good to excellent relief, felt that the injections had been beneficial, and requested additional injections for recurrent or residual focal pain.
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The intervertebral disc has been implicated as an etiology of chronic spine pain based on clinical, basic science, and epidemiological research. Unfortunately, there is no way to determine with absolute certainty whether or not the disc is a spinal pain generator. Recent advances in the neurobiology of pain processing further underscore the possibility that we may never know the source of a patient's pain. At our current level of understanding, from an empirical standpoint, discography is thought of as the best tool to evaluate disc-related pain. ⋯ Discography is a useful imaging and pain evaluation tool in identifying a subset of patients with chronic spinal pain secondary to intervertebral disc disorders.