Regional anesthesia and pain medicine
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Reg Anesth Pain Med · Sep 2004
Comparative StudyIntrathecal mepivacaine and prilocaine are less neurotoxic than lidocaine in a rat intrathecal model.
Histologic evidence of the comparative neurotoxicity of lidocaine, mepivacaine, and prilocaine is incomplete. We compared the intrathecal neurotoxicity in rats among these 3 drugs based on morphologic and neurofunctional findings. ⋯ It is suggested that intrathecal mepivacaine and prilocaine are less neurotoxic than highly concentrated lidocaine in a rat intrathecal model.
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Reg Anesth Pain Med · Sep 2004
Neurologic and histopathologic evaluation after high-volume intrathecal amitriptyline.
Accumulating evidence indicates that amitriptyline decreases pain sensation when administered orally, intraperitoneally, or for sciatic nerve block. Previous reports of intrathecal administration of amitriptyline have yielded inconsistent results. The failure of amitriptyline to provide antinociception may partly be related to its high logP (octanol-water partition coefficient) and consequent poor spread within the cerebrospinal fluid. We evaluated spinal block after various concentrations of amitriptyline administered intrathecally in a fixed high volume. ⋯ At lower doses, intrathecal injection of high volumes of amitriptyline results in long-acting spinal block. At higher doses, intrathecal amitriptyline results in irreversible neurologic deficit. Therefore, we do not recommend the use of intrathecal amitriptyline because of a very low therapeutic index.
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Reg Anesth Pain Med · Sep 2004
Combination of intraneural injection and high injection pressure leads to fascicular injury and neurologic deficits in dogs.
Unintentional intraneural injection of local anesthetics may cause mechanical injury and pressure ischemia of the nerve fascicles. One study in small animals showed that intraneural injection may be associated with higher injection pressures. However, the pressure heralding an intraneural injection and the clinical consequences of such injections remain controversial. Our hypothesis is that an intraneural injection is associated with higher pressures and an increase in the risk of neurologic injury as compared with perineural injection. ⋯ High injection pressures at the onset of injection may indicate an intraneural needle placement and lead to severe fascicular injury and persistent neurologic deficits. If these results are applicable to clinical practice, avoiding excessive injection pressure during nerve block administration may help to reduce the risk of neurologic injury.