Pain physician
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Hydrogen sulfide (H2S) is a malodorous gas which functions as an endogenous gasotransmitter in humans. It is becoming appreciated that H2S may be involved in a wide variety of processes including nociceptive processes. The molecular mechanisms responsible for many of the activities of H2S remain uncertain, however, H2S increases cAMP levels in neuronal and glial cell lines and primary neuron cultures with hyperpolarization. ⋯ A secondary contribution to the facilitation of pronociceptive processes may come from H2S-induced activation. It would appear that much like other gasotransmitters (e.g. nitric oxide), endogenous H2S may be involved in multiple physiologic processes and its effects remain complex, difficult to predict, and may vary depending on the specific environment/circumstances/location where it is generated. A greater understanding of the clinically significant human physiology of H2S and hydrogen sulfide's effects on modulating nociceptive processes may potentially lead to novel targets for improving analgesia.
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We recently reported a novel concept for combining radioactive isotope technology with polymethylmethacrylate (PMMA) cement used for vertebral augmentation and have advocated that pain physicians become aware of this new concept when treating malignant compression fractures. The use of vertebral augmentation for malignant compression fractures is steadily increasing, and the goal of this novel approach would be to stabilize the fractured vertebral body while also controlling proliferation of the tumor cells in the vertebral body that caused the vertebral fracture. This approach would therefore provide mechanical stabilization of the fractured vertebral body at the same time as direct targeting of the cancer cells causing the fracture. ⋯ We also review the potential complications when using radioactive sources in a clinical setting. Understanding the methodologies employed in determining isotope selection empowers the practitioner by fostering understanding of this presently theoretical treatment option. We believe that embedding radioisotopes in PMMA is merely a first step in the road of local treatment for symptomatic local lesions in the setting of systemic disease.
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Case Reports
Successful treatment of meralgia paresthetica with pulsed radiofrequency of the lateral femoral cutaneous nerve.
Meralgia paresthetica is a rarely encountered sensory mononeuropathy characterized by paresthesia, pain or sensory impairment along the distribution of the lateral femoral cutaneous nerve caused by entrapment or compression of the nerve as it crosses the anterior superior iliac spine and runs beneath the inguinal ligament. ⋯ The patient had experienced long-standing pain that was recalcitrant to conservative/pharmacologic therapy and multiple nerve blocks with local steroid instillations. A single treatment with pulsed radiofrequency resulted in complete and sustained cessation of pain. No side effects were evident. Pulsed radiofrequency of the LFCN may offer an effective, low risk treatment in patients with meralgia paresthetica who are refractory to conservative medical management or are unwilling or unfit to undergo surgery.
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Lumbar facet joint pain is diagnosed by controlled diagnostic blocks. The accuracy of controlled diagnostic blocks has been demonstrated in multiple studies and confirmed in systematic reviews. Controlled diagnostic studies have shown an overall prevalence of lumbar facet joint pain in 31% of the patients with chronic low back pain without disc displacement or radiculitis, with an overall false-positive rate of 30% using a single diagnostic block. ⋯ Controlled diagnostic lumbar facet joint nerve blocks are valid utilizing the criteria of 80% pain relief and the ability to perform previously painful movements, with sustained diagnosis of lumbar facet joint pain in at least 89.5% of the patients at the end of a 2-year follow-up period.
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For many headache types, occipital peripheral nerve stimulation (ONS) provides significant relief of chronic, frequent, and severe headaches. Though rarely reported, ONS may cause painful muscle spasms that make stimulator use impractical. The classic description of the technique advocates placement of the leads transversely at the level of the arch of C1 or at C1-2. At that level, the greater occipital nerve (GON) infrequently pierces the superficial fascia of the neck muscles to become superficial. However, important anatomic variability exists. ⋯ Stimulation parameters vary, thus posting parameters may be misleading as muscle spasms occurred despite multiple reprogramming attempts and were a function of lead position, not program settings.