title: Anatomical mechanism of spontaneous recovery in regions caudal to thoracic spinal cord injury lesions in rats.
abstract: BACKGROUND
  The nerve fibre circuits around a lesion play a major role in the spontaneous recovery process after spinal cord hemisection in rats. The aim of the present study was to answer the following question: in the re-control process, do all spinal cord nerves below the lesion site participate, or do the spinal cord nerves of only one vertebral segment have a role in repair?
  
  
  METHODS
  First we made a T7 spinal cord hemisection in 50 rats. Eight weeks later, they were divided into three groups based on distinct second operations at T7: ipsilateral hemisection operation, contralateral hemisection, or transection. We then tested recovery of hindlimbs for another eight weeks. The first step was to confirm the lesion had role or not in the spontaneous recovery process. Secondly, we performed T7 spinal cord hemisections in 125 rats. Eight weeks later, we performed a second single hemisection on the ipsilateral side at T8-T12 and then tested hindlimb recovery for another six weeks.
  
  
  RESULTS
  In the first part, the Basso, Beattie, Bresnahan (BBB) scores and the electrophysiology tests of both hindlimbs weren't significantly different after the second hemisection of the ipsilateral side. In the second part, the closer the second hemisection was to T12, the more substantial the resulting impairment in BBB score tests and prolonged latency periods.
  
  
  CONCLUSIONS
  The nerve regeneration from the lesion area after hemisection has no effect on spontaneous recovery of the spinal cord. Repair is carried out by all vertebrae caudal and ipsilateral to the lesion, with T12 being most important.
authors.affiliation: Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing, China; Department of Neurosurgery, Beijing Chao-yang Hospital Affiliated with Capital Medical University, China.
authors.forename: Lu-Sheng
authors.initials: LS
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University , Beijing , China.
authors.forename: Hao
authors.initials: H
authors.lastname: Yu
authors.affiliation: Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China.
authors.forename: Raynald
authors.initials: R
authors.lastname: Raynald
authors.affiliation: Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Wang
authors.affiliation: Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China.
authors.forename: Guang-Hui
authors.initials: GH
authors.lastname: Dai
authors.affiliation: Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China.
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Cheng
authors.affiliation: Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces , Beijing , China.
authors.forename: Xue-Bin
authors.initials: XB
authors.lastname: Liu
authors.affiliation: Department of Neurosurgery, Beijing Sanbo Brain Hospital, Capital Medical University, Beijing, China; Department of Functional Neurosurgery and Cytotherapy, General Hospital of Chinese People's Armed Police Forces, Beijing, China.
authors.forename: Yi-Hua
authors.initials: YH
authors.lastname: An
keywords: Electrophysiology; Function recovery; Hindlimbs; Nerve regeneration; Repair; Spinal cord injuries; Transection