Pathophysiology of Peripheral Nerve Injury During Regional Anesthesia

BACKGROUND AND OBJECTIVES: Despite attention to technical details in performance of regional anesthetics, damage to nerves continues to be a concern. Understanding of pathophysiological mechanisms may aid in decreasing the incidence and severity of such injuries. METHODS: Studies from both clinical and basic science perspective are reviewed. RESULTS: Exposure of peripheral nerves to local anesthetics may result in axonal damage, particularly if the solution is injected intrafascicularly, if the concentration is high, and if duration of exposure is prolonged. Disruption of numerous cellular functions may contribute to neuronal damage by local anesthetics, but elevated intracellular calcium levels may play a central role. Needle penetration of a nerve results in minimal lasting damage unless this is combined with local anesthetic administration within the nerve fascicle. Direct compression by a pronged tourniquet application may damage axons particularly of large myelinated fibers. Ischemia may also contribute to neuronal injury in proportion to the duration of blood flow interruption. CONCLUSIONS: The relative importance of these pathogenic factors in cases of nerve injury after regional anesthesia is not resolved.