Pathophysiology of Peripheral Nerve Injury During Regional Anesthesia

Abstract

Background-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.

Pathophysiology and Etiology of Nerve Injury Following Peripheral Nerve Blockade

“…Because such research is not possible in humans, all mechanisms of PNI are not fully understood. 8 Animal studies significantly vary in species and methodologies, making it difficult to readily extrapolate such data to actual clinical practice.…”

Local Anesthetic Sciatic Nerve Block and Nerve Fiber Damage in Diabetic Rats

“…Because lidocaine alone can also reduce rat sciatic nerve blood flow, 27,28 epinephrine-induced vasoconstriction along with the likely compromised blood flow in a diabetic nerve may all combine to induce the development of nerve pathology. 1,3,29 The addition of 7.5 Kg/mL clonidine to 1% lidocaine (which extended the duration of nerve blockade in nondiabetic rats and prolonged it even more in diabetic rats) increased the total amount of axon and myelin degeneration in diabetic rats compared with lidocaine/clonidine in nondiabetic rats, indicating that the diabetic condition increased the toxicity of that drug combination. The increased duration of lidocaine nerve block with clonidine in nondiabetic rats can be explained by inhibition of the hyperpolarization-activated cation current (I h ).…”

Local Anesthetic Schwann Cell Toxicity Is Time and Concentration Dependent

“…14,15 Such injuries may be multifactorial, although LA cytotoxicity is likely a major contributing factor. 16 An improved understanding of the effects of LAs on nerve cells may lead to strategies to decrease the risk of nerve injury following PNBs.…”