Different symptoms of neuropathic pain can be induced by different degrees of compressive force on the C7 dorsal root of rats

Changsheng Huang, Wangyuan Zou, Kookhyun Lee, E. Wang, Xiaoyan Zhu, Qulian Guo

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Background context: Neuropathic pain after nerve injuries is characterized by positive and negative sensory symptoms and signs. The extent of sensory fiber loss after nerve injuries has been demonstrated to correlate with symptoms of neuropathic pain by quantitative sensory testing and confirmed by biopsies of small nerve fibers. However, the relationship between the pathologic changes of large nerves on injuries and resulting pain symptoms remains unclear. Purpose: To investigate the relationship between the extent of dorsal root injury and resulting symptoms of neuropathic pain. Study design: Nerve injury and assessment of the following pain-related behaviors and neuropathologic changes. Methods: A total of 24 adult male Sprague-Dawley rats weighing 250 to 300 g were randomly divided into three groups (n=8 each): sham group operated on but without nerve compression, 70 gf group, and 180 gf group; a compression force of 70 or 180 g was applied to the right C7 dorsal root, separately. Threshold thermal and mechanical pains were measured before surgery (baseline) and on the first, third, fifth, and seventh day after surgery. On the seventh day after surgery, all rats were killed, and the structural alterations of nerve fibers within the compressed areas were examined. Results: A compression force of 70 g resulted in hyperalgesia, whereas a compression force of 180 g induced hypoalgesia in the ipsilateral forepaw in response to both mechanical and thermal stimulations within 7 days after injury. Light microscopy and electron microscopy revealed a mild to moderate sensory fiber loss after 70-gf compression and a more severe sensory fiber loss after 180-gf compression. Conclusions: Transient injuries on sensory fibers can produce either positive or negative symptoms of neuropathic pain, and the different extent of sensory fiber loss after different degrees of injuries might account for the varied resulting symptoms of neuropathic pain.

Original languageEnglish
Pages (from-to)1154-1160
Number of pages7
JournalSpine Journal
Issue number12
Publication statusPublished - Dec 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Surgery
  • Orthopedics and Sports Medicine
  • Clinical Neurology


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