title: Changes in excursion and strain in the rat sciatic nerve under cauda equina compression induced by epidural balloon inflation.
abstract: BACKGROUND
  Healthy nerves are able to stretch and glide as responses to normal physiological movement. Injury to the nerve may alter the nerve's mechanical properties and result in neuropathy. Whether cauda equina compression alters the mechanical properties of the sciatic nerve is still unclear.
  
  
  OBJECTIVE
  The purpose of this study was to demonstrate the changes in excursions and strains of the sciatic nerve in vivo after acute cauda equina compression was induced by epidural balloon compression.
  
  
  METHODS
  An animal comparative study with induced cauda equina compression was designed for in situ measurements of nerve properties.
  
  
  METHODS
  Twenty-six adult Sprague-Dawley rats were divided into three groups. The balloon group (n=10) underwent epidural compression induced by inflation of an embolectomy balloon catheter that was inserted through an L6 laminotomy. The control group (n=10) underwent laminotomy but without compression. The normal group (n=6) received no back surgery. This model of neuropathy was confirmed with electrophysiological examination. The excursions and strains of the sciatic nerve in response to the modified straight leg-raising (SLR) test were measured in situ and analyzed.
  
  
  RESULTS
  The scales of the excursions were lower in the balloon group than in the other two groups, in both 90° flexion and extension of the knee. The balloon group was more sensitive to positional changes. The strain was significantly higher under the condition of epidural balloon compression.
  
  
  CONCLUSIONS
  We concluded that cauda equina compression decreased the excursion and increased the strain of the sciatic nerve in response to a modified SLR test. These findings might indicate one of the mechanisms of the pain provoked by the SLR test and also possibly contribute to an understanding of the pathogenesis of the neuropathy in the lower limbs of patients with cauda equina compression.
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, 1 Daxue Rd., Tainan 70428, Taiwan; Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan.
authors.forename: Ta-Wei
authors.initials: TW
authors.lastname: Tai
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, 1 Daxue Rd., Tainan 70428, Taiwan.
authors.forename: Fong-Chin
authors.initials: FC
authors.lastname: Su
authors.affiliation: Department of Orthopaedics, Buddhist Dalin Tzuchi General Hospital, 2, Minsheng Rd., Dalin Township, Chiayi, Taiwan.
authors.forename: Jui-Teng
authors.initials: JT
authors.lastname: Chien
authors.affiliation: Department of Neurosurgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan.
authors.forename: Jung-Shun
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Orthopedics, Chia Yi Christian Hospital, 539, Zhongxiao Rd., East Dist., Chiayi City 600, Taiwan; Department of Sports Management, Chia Nan University of Pharmacy & Science, 60, Sec. 1, Erren Rd., Rende Dist., Tainan City 717, Taiwan.
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Huang
authors.affiliation: Institute of Biomedical Engineering, National Cheng Kung University, 1 Daxue Rd., Tainan 70428, Taiwan; Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan.
authors.forename: Cheng-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Department of Orthopaedics, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, 138 Sheng-Li Rd, Tainan 70428, Taiwan. Electronic address: jming@mail.ncku.edu.tw.
authors.forename: I-Ming
authors.initials: IM
authors.lastname: Jou
mesh_terms: D000818:Animals; D002420:Cauda Equina / Q000503:physiopathology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology; D007796:Laminectomy; D008297:Male; D009408:Nerve Compression Syndromes / Q000209:etiology / Q000503:physiopathology*; D010523:Peripheral Nervous System Diseases / Q000209:etiology / Q000503:physiopathology*; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000503:physiopathology*; D013117:Spinal Cord Compression / Q000150:complications / Q000503:physiopathology*
keywords: Cauda equina compression; Excursion; Neurodynamics; Sciatic nerve; Strain; neuropathy