title: The effects of locally injected triamcinolone on entrapment neuropathy in a rat chronic constriction injury model.
abstract: OBJECTIVE
  Patients with idiopathic carpal tunnel syndrome are commonly treated by steroid injections into the carpal tunnel. We administered triamcinolone (Tr) to chronic constriction injury model rats. We hypothesized that Tr administration would have both favorable behavioral effects and quantifiable immunohistological effects on compressed nerves.
  
  
  METHODS
  Thirty-six male Wister rats were used. For rats to be treated with Tr, we loosely ligated their right sciatic nerves at 4 sites. Sham rats had their nerves exposed without ligation. On postoperative day 7, we reexposed their ligated nerves, after which we delivered either 0.1 mg of Tr (0.1-mg group), 0.5 mg of Tr (0.5-mg group), or normal saline (saline group) around the nerve fibers at the injured sites. Gait was analyzed, and allodynia was assessed with von Frey hairs, before surgery and on postoperative days 3, 7, 10, 14, and 21. The right sciatic nerve was resected and stained using hematoxylin-eosin, and the fourth and fifth lumbar dorsal root ganglia (DRG) were removed and assessed by immunohistochemistry for calcitonin gene-related peptide (CGRP) and activating transcription factor 3 (ATF3) on postoperative day 21. In addition, interleukin-1β (IL-1β) in sciatic nerve was quantified using enzyme-linked immunosorbent assays.
  
  
  RESULTS
  Mechanical allodynia was significantly decreased in the 0.5-mg group compared with the saline group. In hematoxylin-eosin sections, the extent of inflammation-induced edema between the nerve fibers and infiltration of inflammatory cells was significantly reduced in the 0.5-mg group compared with the saline group. IL-1β levels at the sciatic nerve in the 0.5-mg group were significantly lower than those in the saline group.
  
  
  CONCLUSIONS
  Tr-treated chronic constriction injury rats exhibited significant alleviation of sensory disturbance, edema, inflammation, and pain-related peptide upregulation. These phenomena suggest the validity of Tr administration as a treatment affecting the nerve itself.
  
  
  METHODS
  Therapeutic I.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan. Electronic address: aohigesensei@yahoo.co.jp.
authors.forename: Masataka
authors.initials: M
authors.lastname: Shibayama
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Kuniyoshi
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Takane
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuyo
authors.initials: K
authors.lastname: Yamauchi
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Ohtori
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medicine, Chiba University, Chiba, Japan.
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D002908:Chronic Disease; D004195:Disease Models, Animal; D004487:Edema / Q000188:drug therapy; D004797:Enzyme-Linked Immunosorbent Assay; D007249:Inflammation / Q000188:drug therapy; D007267:Injections; D053583:Interleukin-1beta / Q000378:metabolism; D008026:Ligation; D008297:Male; D009408:Nerve Compression Syndromes / Q000188:drug therapy*; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000293:injuries / Q000378:metabolism; D014221:Triamcinolone / Q000008:administration & dosage* / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D053583:Interleukin-1beta; D014221:Triamcinolone
keywords: Carpal tunnel syndrome; chronic constriction injury model; interleukin 1-beta; pain; triamcinolone