Mechanisms of Neurologic Complications with Peripheral Nerve Blocks.

Although there are relatively few published reports of anesthesia-related nerve injury associated with the use of peripheral nerve blocks (PNBs), it is likely that the commonly cited incidence (0.4%) of severe injury is underestimated because of underreporting.1-3 The less frequent clinical application of lower-extremity nerve blocks may be the main reason that there are even fewer reports of anesthesia-related nerve injury associated with lower-extremity PNBs as compared with upper-extremity PNBs. Although neurologic complications after PNBs can be related to a variety of factors related to the block (e.g., needle trauma, intraneuronal injection, neuronal ischemia, and toxicity of local anesthetics), a search for other common causes should also include surgical factors (e.g., positioning, stretching, retractor injury, ischemia, and hematoma formation). In some instances, the neurologic injury may be a result of a combination of these factors. [ABSTRACT FROM AUTHOR]