title: Conjoined lumbosacral nerve roots compromised by disk herniation: sagittal shoulder sign for the preoperative diagnosis.
abstract: OBJECTIVE
  The objective was to determine the importance of the "sagittal shoulder sign" on magnetic resonance (MR) images for the diagnosis of conjoined lumbosacral nerve roots (CLNR) that are compromised by herniated disks.
  
  
  METHODS
  Magnetic resonance images of 11 patients (6 men and 5 women; age range, 25-71 years; average age, 48.7 years) with surgically proven CLNR, which was compromised by herniated disks, were retrospectively evaluated by two musculoskeletal radiologists. MR images were evaluated for the presence or absence of the sagittal shoulder sign-a vertical structure connecting two consecutive nerve roots and overlying disk on the sagittal MR images. The radiologists noted the type of accompanying disk herniation and bony spinal canal changes, as well as other characteristic MR features of CLNR, the common passage of two consecutive nerve roots through the neural foramen on axial MR images.
  
  
  RESULTS
  The sagittal shoulder sign was identified with a mean frequency of 90.9% by the two observers (in 10 of 11 patients). The common passage of two consecutive nerve roots through the neural foramen on axial MR images was identified with a mean frequency of 59.1% (in 7 and 6 out of 11 patients, by observers 1 and 2, respectively). Good interobserver agreement for the sagittal shoulder sign was present (k = 0.621, p < 0.05).
  
  
  CONCLUSIONS
  Observation of the sagittal shoulder sign may prove helpful for diagnosing CLNR in patients with disk herniation. In particular, this sign appears to be useful when there is no evidence of CLNR on axial MR images.
authors.affiliation: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-dong, Songpa-Ku, Seoul, South Korea.
authors.forename: Chang Ho
authors.initials: CH
authors.lastname: Kang
authors.forename: Myung Jin
authors.initials: MJ
authors.lastname: Shin
authors.forename: Sung Moon
authors.initials: SM
authors.lastname: Kim
authors.forename: Sang Hoon
authors.initials: SH
authors.lastname: Lee
authors.forename: Hee Kyung
authors.initials: HK
authors.lastname: Kim
authors.forename: Jeong Ah
authors.initials: JA
authors.lastname: Ryu
authors.forename: Choon-Sung
authors.initials: CS
authors.lastname: Lee
authors.forename: Sam Soo
authors.initials: SS
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000473:pathology* / Q000601:surgery; D008161:Lumbosacral Region; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D013126:Spinal Nerve Roots / Q000002:abnormalities*