title: Anatomical study of superior cluneal nerve entrapment.
abstract: OBJECTIVE
  Entrapment of the superior cluneal nerve (SCN) in an osteofibrous tunnel in the space surrounded by the iliac crest and the thoracolumbar fascia is a cause of low-back pain (LBP). Several anatomical and surgical reports describe SCN entrapment as a cause of LBP, and a recent clinical study reported that patients with suspected SCN disorder constitute approximately 10% of the patients suffering from LBP and/or leg symptoms. However, a detailed anatomical study of SCN entrapment is rare. The purpose of this study was to investigate the courses of SCN branches and to ascertain the frequency of SCN entrapment.
  
  
  METHODS
  Branches of the SCN were dissected in 109 usable specimens (54 on the right side and 55 on the left side) obtained in 59 formalin-preserved cadavers (average age at death 84.8 years old). All branches were exposed at the points where they perforated the thoracolumbar fascia. The presence or absence of an osteofibrous tunnel was ascertained and, if present, the entrapment of the branches in the tunnel was determined.
  
  
  RESULTS
  Of 109 specimens, 61 (56%) had at least 1 branch running through an osteofibrous tunnel. Forty-two medial (39%), 30 intermediate (28%), and 14 lateral (13%) SCN branches passed through such a tunnel. Of these, only 2 medial branches had obvious entrapment in an osteofibrous tunnel. There were several patterns for the SCN course through the tunnel: medial branch only (n = 25), intermediate branch only (n = 11), lateral branch only (n = 4), medial and intermediate branches (n = 11), medial and lateral branches (n = 2), intermediate and lateral branches (n = 4), and all branches (n = 4).
  
  
  CONCLUSIONS
  Several anatomical variations of the running patterns of SCN branches were detected. Entrapment was seen only in the medial branches. Although obvious entrapment of the SCN is rare, it may cause LBP.
authors: Department of Orthopaedic Surgery, Yokohama City University Graduate School of Medicine, Yokohama, Kanagawa, Japan. kuniyayo@live.jp
authors: Hiroshi
authors: H
authors: Kuniya
authors: Yoichi
authors: Y
authors: Aota
authors: Tomoyuki
authors: T
authors: Saito
authors: Yoshinori
authors: Y
authors: Kamiya
authors: Kengo
authors: K
authors: Funakoshi
authors: Hayato
authors: H
authors: Terayama
authors: Masahiro
authors: M
authors: Itoh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D017116:Low Back Pain / Q000209:etiology; D008160:Lumbosacral Plexus / Q000473:pathology*; D008297:Male; D009408:Nerve Compression Syndromes / Q000150:complications / Q000473:pathology*