A new and less invasive surgical approach to the mouse spared nerve injury model of peripheral neuropathic pain.

Spared nerve injury (SNI) is a widely used rodent model in the study of peripheral neuropathic pain. The injury, that involves ligation and resection of the common peroneal and tibial branches of the sciatic nerve, results in a robust and prolonged nociceptive response. The model is characterised by measurable mechanical and thermal hypersensitivity in the innervation area of the spared sural nerve of the lateral hind paw, that persists for several months. Since its description, the model has been used to further the understanding of a diverse range of mechanisms contributing to the development and maintenance of neuropathic pain. However, due to damage to the biceps femoris muscle during surgery, experimental results may not reflect the mechanisms of neuropathic pain alone. Here we describe an alternative protocol for SNI in the mouse, which involves manipulation of the sciatic nerve via a medial thigh incision. Mice which have undergone the medial thigh SNI procedure exhibit molecular and behavioural changes as observed in the lateral thigh SNI procedure, including glial activation and persistent mechanical, cold and heat hypersensitivity of the affected limb. The medial thigh approach promotes ease of the surgical procedure and benefits animal welfare through improved wound healing and preservation of the biceps femoris muscle, when compared to the lateral thigh SNI model of peripheral neuropathic pain. We present an alternative protocol for the SNI procedure which offers several advantages when compared to the previously described lateral thigh procedure. • Development of a less invasive mouse model of spared nerve injury for the study of neuropathic pain. • The protocol promotes ease of the surgical procedure and improved wound healing. • Nociceptive behaviour and molecular changes are consistent with the standard lateral thigh SNI model.