Preemptive perineural bupivacaine attenuates the maintenance of mechanical and cold allodynia in a rat spinal nerve ligation model

Abstract

BackgroundNeuropathic pain is evasive to treat once developed, however evidence suggests that local administration of anesthetics near the time of injury reduces the development of neuropathic pain. As abnormal electrical signaling in the damaged nerve contributes to the initiation and maintenance of neuropathic pain, local administration of anesthetics prior to injury may reduce its development. We hypothesized that local treatment with bupivacaine prior to nerve injury in a rat model of spinal nerve ligation (SNL) would attenuate the initiation and/or maintenance of neuropathic pain behaviors.MethodsOn the day prior to SNL, baseline measures of pre-injury mechanical, thermal, and/or cold sensitivity were recorded in adult male Sprague–Dawley rats. Immediately prior to SNL or sham treatment, the right L5 nerve was perineurally bathed in either 0.05 mL bupivacaine (0.5 %) or sterile saline (0.9 %) for 30 min. Mechanical allodynia, thermal hyperalgesia, and/or cold allodynia were then examined at 3, 7, 10, 14 and 21 days following SNL.ResultsRats exhibited both mechanical and cold allodynia, but not thermal hyperalgesia, within 3 days and up to 21 days post-SNL. No significant pain behaviors were observed in sham controls. Preemptive local bupivacaine significantly attenuated both mechanical and cold allodynia as early as 10 days following SNL compared to saline controls and were not significantly different from sham controls.ConclusionsThese data indicate that local treatment with bupivacaine prior to surgical manipulations that are known to cause nerve damage may protect against the maintenance of chronic neuropathic pain.

L5 Spinal Nerve Axotomy Induces Distinct Electrophysiological Changes in Axotomized L5- and Adjacent L4-Dorsal Root Ganglion Neurons in Rats In Vivo

“…5) in agreement with previous studies. 26 In vivo intracellular voltage recordings in normal and SNA rats…”

Effect of two-week continuous epidural administration of 2% lidocaine on mechanical allodynia induced by spinal nerve ligation in rats

“…However, an attempt at local anesthesia during or immediately following injury has been postulated as a treatment strategy [ 9 , 10 ]. Clifford et al [ 11 ] reported that preemptive local anesthetic attenuates the maintenance of mechanical allodynia in a rat SNL model. Thus suggesting that locally administering anesthetics, such as lidocaine, bupivacaine, and ropivacaine, close to the time of injury, reduces the development of neuropathic pain [ 3 , 10 ].…”

“…It was thus selected for use in this study. Previous studies have reported that if pathological activity following injury is blocked by local anesthetics, allodynia may not develop [ 9 – 11 ]. Using local anesthetics following nerve damage can be considered a treatment strategy for such pain.…”