Behavioural pain-related disorders and contribution of the saphenous nerve in crush and chronic constriction injury of the rat sciatic nerve

Abstract

This study evaluated the pain-related behaviours induced by 2 models of peripheral sciatic nerve injuries in the rat: transient nerve crush and chronic constriction injury (CCI). Various lesions of the saphenous nerve were performed in order to investigate the role of saphenous innervation in behavioural disorders induced by these nerve injuries. Behavioural testing included assessment of responses to phasic stimulation (mechanical and thermal) and observation of 'spontaneous' pain-related behaviour. Results confirmed that the model of CCI induces marked and prolonged phasic and spontaneous pain-related disorders (up to week 7). Rats with crush injury exhibited moderate and transient hyperalgesia and allodynia to mechanical and thermal stimulation on the lesioned side (with a maximum at day 3 and a recovery by week 1). Section plus ligation of the ipsilateral saphenous nerve on the day of surgery prevented nociceptive behaviours and induced persistent mechanical and thermal anaesthesia or hypoesthesia of the lesioned paw in both models (lasting up to 3-4 weeks). Section without ligation of the saphenous nerve induced comparable results in rats with sciatic crush, but did not significantly modify nociceptive behaviours in rats with CCI. These data emphasise the role of adjacent saphenous nerve in the mechanisms of pain-related disorders induced by these peripheral nerve lesions. On the contralateral paw, pain-related modifications were also observed in both models, suggesting that unilateral nerve lesions induce remote modifications extending beyond the site of the injured nerve.

<i>Morus alba</i> Enhanced Functional Recovery After Sciatic Nerve Crush Injury

“…The motor function recovery of sciatic nerve in this study was in agreement with the previous study which had reported that the motor function recovery in the foot showed fully recovery after sciatic nerve crush injury within 3 weeks (Vogelaar et al, 2004). It has been reported that after nerve crush injury, the neuropathic pain which manifested as allodynia has been developed within the first 3 weeks (Attal et al, 1994;Kingery et al, 1994;Przewlocki et al, 1999;Vogelaar et al, 2004). Thus, the slow recovery process of the sensory nerve observed in this study may occur partly due to the development of neuropathic pain which takes much longer to resolve.…”

Unilateral nerve injury produces bilateral loss of distal innervation

“…11 Reports of bilateral hind paw hyperalgesia after unilateral injury demonstrate that contralesional changes affect behavior. 12,13 Systemic lidocaine has different effects against the hyperalgesia that develops in the paws ipsi-lateral and contralateral to nerve ligation.…”

Behavioral Models of Pain States Evoked by Physical Injury to the Peripheral Nerve

“…sectioned nerve. Such autotomy has been observed after complete sciatic section, 14 crush, 15 or cryolesions (transient freezing). 16 Trunk lesions have been observed to produce such autotomy in several species.…”