title: Distinct degree of radiculopathy at different levels of peripheral nerve injury.
abstract: BACKGROUND
  Lumbar radiculopathy is a common clinical problem, characterized by dorsal root ganglion (DRG) injury and neural hyperactivity causing intense pain. However, the mechanisms involved in DRG injury have not been fully elucidated. Furthermore, little is known about the degree of radiculopathy at the various levels of nerve injury. The purpose of this study is to compare the degree of radiculopathy injury at the DRG and radiculopathy injury proximal or distal to the DRG.
  
  
  RESULTS
  The lumbar radiculopathy rat model was created by ligating the L5 nerve root 2 mm proximal to the DRG or 2 mm distal to the DRG with 6.0 silk. We examined the degree of the radiculopathy using different points of mechanical sensitivity, immunohistochemistry and in vivo patch-clamp recordings, 7 days after surgery. The rats injured distal to the DRG were more sensitive than those rats injured proximal to the DRG in the behavioral study. The number of activated microglia in laminas I-II of the L5 segmental level was significantly increased in rats injured distal to the DRG when compared with rats injured proximal to the DRG. The amplitudes and frequencies of EPSC in the rats injured distal to the DRG were higher than those injured proximal to the DRG. The results indicated that there is a different degree of radiculopathy at the distal level of nerve injury.
  
  
  CONCLUSIONS
  Our study examined the degree of radiculopathy at different levels of nerve injury. Severe radiculopathy occurred in rats injured distal to the DRG when compared with rats injured proximal to the DRG. This finding helps to correctly diagnose a radiculopathy.
authors.affiliation: Department of Orthopaedic Surgery, Wakayama Medical University, 811-1Kimiidera, Wakayama 641-8509, Japan.
authors.forename: Noboru
authors.initials: N
authors.lastname: Takiguchi
authors.forename: Munehito
authors.initials: M
authors.lastname: Yoshida
authors.forename: Wataru
authors.initials: W
authors.lastname: Taniguchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hashizume
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamada
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Miyazaki
authors.forename: Naoko
authors.initials: N
authors.lastname: Nishio
authors.forename: Terumasa
authors.initials: T
authors.lastname: Nakatsuka
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005727:Ganglia, Spinal / Q000293:injuries*; D008297:Male; D017288:Pain Threshold; D018408:Patch-Clamp Techniques; D011843:Radiculopathy / Q000503:physiopathology*; D051381:Rats; D017207:Rats, Sprague-Dawley