Regional anesthesia can lead to postoperative nerve injury. Which mechanisms are commonly implicated?

• A. Needle trauma
• B. Compression from hematoma or tourniquet
• C. Direct neurotoxicity
• D. All of the above

Answer: (D)

Regional anesthesia can injure nerves through a combination of mechanical, ischemic, and toxic effects on the nerve. Direct needle trauma to a nerve—especially with intraneural injection or multiple needle passes—can disrupt axons or the protective myelin sheath. A hematoma around a nerve or prolonged tourniquet use around a limb can compress the nerve, reducing blood flow and causing ischemic injury. Local anesthetics themselves can be directly neurotoxic when exposed to nerve fibers at high concentrations or for extended periods, particularly if injection is intrafascicular or exposure is prolonged, and additives or vasoconstrictors can influence this risk. These mechanisms often overlap in the same patient, making all of the above plausible contributors to postoperative nerve injury after regional anesthesia. To reduce risk, use careful technique and guidance to avoid intraneural injections, minimize hematoma formation and tourniquet duration, and select the lowest effective local anesthetic concentration.