Regional anesthesia and pain medicine
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Reg Anesth Pain Med · May 2004
Comparative StudyElectrophysiologic effect of injectates on peripheral nerve stimulation.
A small volume of local anesthetic or normal saline abolishes the muscle twitch induced by a 1ow current (0.5 mA) during electrolocation. This study examines the hypothesis that the mechanism of this phenomenon is primarily the electrophysiologic effect of the injectate on the electrical current density at the needle tip. ⋯ The injection of a conducting solution (i.e., NS) rendered the current that was previously sufficient to elicit a motor response (0.5 mA) ineffective. The most likely reason for this change is that the conductive area surrounding the stimulating needle expanded after the injection and dispersion of the conducting solution (i.e., NS), thereby reducing the current density at the target nerve. This effect can be reversed by injecting a nonconducting solution (i.e., D5W) via the stimulating needle.
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Reg Anesth Pain Med · May 2004
Percutaneous electrode guidance using the insulated needle for prelocation of peripheral nerves during axillary plexus blocks.
Short reports have noted that percutaneous prelocation is helpful in determining the anatomic course of a peripheral nerve, and, thereby, may serve as a guide for block needle insertion. We prospectively studied percutaneous electrode guidance to assist axillary brachial plexus blocks. ⋯ Percutaneous electrode guidance using the insulated needle enabled clinicians to locate the terminal branches of the plexus in the axilla and appreciate their depth. This method could, therefore, minimize patient discomfort and perhaps the risk of nerve trauma.
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Reg Anesth Pain Med · May 2004
Comparative StudyLocating the target nerve and injectate spread in rabbit sciatic nerve block.
The purpose of this study is to determine how close the needle tip is placed to the target nerve using a nerve stimulator and to determine how far the injectate spreads in percutaneous nerve blocks. ⋯ The target nerve was located within 5 mm from the needle with less than 0.5-mA stimulation current. The injectate spread to more than 20 mm on average even when a small volume (100 microL) of the injectate was injected in rabbit sciatic nerves.
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Reg Anesth Pain Med · May 2004
Case ReportsSynovial cysts and the lithotomy position causing cauda equina syndrome.
We describe a case of cauda equina syndrome caused by synovial cysts and the lithotomy position. A transurethral resection of the prostate was performed under spinal anesthesia in the lithotomy position. ⋯ We believe that positioning the patient in the lithotomy position narrowed the cross-sectional area of the spinal canal in a patient with a coexisting critically stenosed lumbar spinal canal. The resultant mechanical pressure caused an ischemic compression injury to the cauda equina.