Articles: nerve-block.
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Regional anesthesia · Sep 1994
Case ReportsSubdural anesthesia as a complication of an interscalene brachial plexus block. Case report.
Interscalene brachial plexus block is performed in the groove between the anterior and middle scalene muscles at the level of C6, just over the transverse process. Injection occurs within 1-2 cm of the dural sleeve and could be misdirected into the epidural, subdural, or subarachnoid spaces. ⋯ The case represents a partial injection of local anesthetic intended for the interscalene brachial plexus into the subdural space. The diagnosis is based on the normal evolution of the block into full motor and sensory anesthesia of the ipsilateral brachial plexus that evolved into a patchy, sensory, and motor block involving many dermatomes outside the brachial plexus, with minimal sympathetic block, and evidence of a normal interscalene block on emergence from general anesthesia. Subdural injection must be considered when unusual motor and sensory block occurs after interscalene block, especially after a time interval too long for epidural or subarachnoid injection, or with minimal evidence of sympathetic block, after suspected high central block injection.
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J Pharmacol Toxicol Methods · Aug 1994
A surgically implantable nerve irrigation system for intermittent delivery of dissolved drugs: evaluation of long-term performance and histocompatibility in rats.
A surgically implantable system designed to facilitate intermittent delivery of solutions of local anesthetic or other pharmacologically active substances to a segment of peripheral nerve was developed and its long-term performance and histocompatibility were tested in rats. Twenty-two systems, each comprising a subcutaneous injection port, a silicone conduit, and a membranous perineural sheath, were implanted in 20 animals. Of the systems, 12 could be used to perform repeated local anesthetic nerve blocks for periods lasting from several weeks to as long as 13 months. The system is suitable for use in studies of peripheral nerve pharmacology and, with improvements, could find clinical use in the management of peripheral neuralgia.
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Clinical Trial
The false-positive rate of uncontrolled diagnostic blocks of the lumbar zygapophysial joints.
One hundred and seventy-six consecutive patients with chronic low back pain and no history of previous lumbar surgery were studied to determine the false-positive rate of single diagnostic blocks of the lumbar zygapophysial joints. All patients underwent diagnostic blocks using lignocaine. Those patients who obtained definite or complete relief from these blocks subsequently underwent confirmatory blocks using bupivacaine. ⋯ Using the response to confirmatory blocks as the criterion standard, the false-positive rate of uncontrolled diagnostic blocks was 38% and the positive predictive value of these blocks was only 31%. Because the positive predictive value of a test is lower when the pre-test probability (prevalence) is low, and because the prevalence of lumbar zygapophysial joint pain is likely to be less than 50%, uncontrolled diagnostic blocks will always be associated with an unacceptably low positive predictive value. These features render uncontrolled diagnostic blocks unreliable for the diagnosis of lumbar zygapophysial joint pain not only in epidemiologic studies but also in any given patient.