Stretch-induced nerve injury: a proposed technique for the study of nerve regeneration and evaluation of the influence of gabapentin on this model

Abstract

The rat models currently employed for studies of nerve regeneration present distinct disadvantages. We propose a new technique of stretch-induced nerve injury, used here to evaluate the influence of gabapentin (GBP) on nerve regeneration. Male Wistar rats (300 g; n=36) underwent surgery and exposure of the median nerve in the right forelimbs, either with or without nerve injury. The technique was performed using distal and proximal clamps separated by a distance of 2 cm and a sliding distance of 3 mm. The nerve was compressed and stretched for 5 s until the bands of Fontana disappeared. The animals were evaluated in relation to functional, biochemical and histological parameters. Stretching of the median nerve led to complete loss of motor function up to 12 days after the lesion (P<0.001), compared to non-injured nerves, as assessed in the grasping test. Grasping force in the nerve-injured animals did not return to control values up to 30 days after surgery (P<0.05). Nerve injury also caused an increase in the time of sensory recovery, as well as in the electrical and mechanical stimulation tests. Treatment of the animals with GBP promoted an improvement in the morphometric analysis of median nerve cross-sections compared with the operated vehicle group, as observed in the area of myelinated fibers or connective tissue (P<0.001), in the density of myelinated fibers/mm2 (P<0.05) and in the degeneration fragments (P<0.01). Stretch-induced nerve injury seems to be a simple and relevant model for evaluating nerve regeneration.

Concept of acute neuropathic pain. The role of nervi nervorum in the distinction between acute nociceptive and neuropathic pain

“…Painful stimuli which activate nociceptors around nerves include inflammation and injury of tumor or trauma tissues. Anatomic particularities of nervi nervorum and of epineural blood vessels make them vulnerable to certain situations, such as when there is nervous tissue stretching 50,51 .…”

Editorial: Radial nerve

“…4 However, when the crush injury is accompanied by a segmental stretch injury, recovery begins on Day 12. 16 When radial nerve palsy is associated with high-energy trauma (e.g., a motorcycle accident), an extended lesion of the radial nerve is to be expected, so that the delay before spontaneous recovery should be longer. Based on the fact that spontaneous recovery of a stretched radial nerve may take longer, and that viable alternatives for reconstruction via later surgery are available, we now wait at least 6 months before operating on a closed injury of the radial nerve.…”