An animal model of neuropathic pain employing injury to the sciatic nerve branches.

The present study was conducted to develop a new animal model of neuropathic pain employing injury to the distal sciatic nerve branches. Under halothane anesthesia, the tibial, sural, and/or common peroneal nerves were injured and neuropathic pain behaviors were compared among different groups of rats. Different types of injury produced different levels of neuropathic pain. Rats with injury to the tibial and sural nerves showed the most vigorous mechanical allodynia, cold allodynia, and spontaneous pain. These neuropathic pain behaviors were not relieved by functional sympathectomy using guanethidine. The results suggested that injury to the tibial and sural nerves, while leaving the common peroneal nerve intact, can be used as a new animal model of neuropathic pain and that this model represents sympathetically independent pain (SIP). The present animal model is very simple to produce injury and can produce profound and reliable pain behaviors. These features enable the new animal model to be a useful tool in elucidating the mechanisms of neuropathic pain, especially SIP.