Pain
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Randomized Controlled Trial Clinical Trial
Specificity of diagnostic nerve blocks: a prospective, randomized study of sciatica due to lumbosacral spine disease.
Temporary nerve blocks using local anesthetic are employed extensively in the evaluation of pain problems, particularly lumbosacral spine disease. Their specificity and sensitivity in localizing anatomic sources of pain have never been studied formally, however, and so their diagnostic and prognostic value is questionable. There have been anecdotal reports of relief of pain by temporary blocks directed to areas of pain referral, as opposed to areas of documented underlying pathology; but there has been no study to define the frequency or magnitude of this effect. ⋯ Our findings indicate a limited role for uncontrolled local anesthetic blocks in the diagnostic evaluation of sciatica and referred pain syndromes in general. Negative blocks or a pattern of responses may have some predictive value, but isolated, positive blocks are non-specific. This lack of specificity may, however, be advantageous in therapeutic applications.
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The objectives of this study were to identify the characteristics of children who required regional anesthesia for pain associated with terminal malignancy and to identify the safety, tolerability and effectiveness of regional anesthesia as an analgesic modality in terminal pediatric malignancy. A retrospective examination was made of the medical records of children who died of malignancy following treatment at the Dana-Farber Cancer Institute and Children's Hospital, Boston, Massachusetts and who required either epidural or subarachnoid infusions, or neurolytic blockade for pain management (June, 1986--April, 1994) during the terminal phase of their illness. Eleven patients were identified, with a duration of epidural or subarachnoid infusions ranging from 3 days to 7 weeks. ⋯ Analgesia was judged to be satisfactory in all cases after regional anesthesia was instituted and remained satisfactory in all cases throughout the treatment course. Complications associated with regional anesthesia included dural puncture headache and mild respiratory depression. Five patients were nursed at home with either epidural or subarachnoid infusions.
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This study examined the responses of cultured adult human dorsal root ganglion (hDRG) neurons to protons and capsaicin, two substances known to produce pain and hyperalgesia in humans. Both substances were applied to each neuron and responses were examined under both voltage- and current-clamp recording conditions. Sensitivity to protons was tested with rapid acidification of the extracellular fluid from pH 7.35 to 6.0. ⋯ The depolarization resulted in the discharge of action potentials in 14 neurons. It is concluded that, while both protons and capsaicin exert excitatory effects on human sensory neurons, multiple membrane mechanisms lead to the depolarization of cultured hDRG neurons by low pH. Inhibition of resting membrane conductances contributes to the responses to low pH in some hDRG neurons.