title: Use of magnetic resonance imaging to identify outcome predictors of caudal epidural steroid injections for lower lumbar radicular pain caused by a herniated disc.
abstract: OBJECTIVE
  We used lumbar magnetic resonance image (MRI) findings to determine possible outcome predictors of a caudal epidural steroid injection (CESI) for radicular pain caused by a herniated lumbar disc (HLD).
  
  
  METHODS
  Ninety-one patients with radicular pain whose MRI indicated a HLD were enrolled between September 2010 and July 2013. The CESIs were performed using ultrasound (US). A responder was defined as having complete relief or at least a 50% reduction of pain as assessed by the visual analog scale (VAS) and functional status on the Roland Morris Disability Questionnaire (RMDQ); responder (VAS n=61, RMDQ n=51), and non-responder (VAS n=30, RMDQ n=40). MRI findings were analyzed and compared between the two groups with regard to HLD level, HLD type (protrusion or exclusion), HLD zone (central, subarticular, foraminal, and extraforaminal), HLD volume (mild, moderate, or severe), relationship between HLD and nerve root (no contact, contact, displaced, or compressed), disc height loss (none, less than half, or more than half ), and disc degeneration grade (homogeneous disc structure or inhomogeneous disc structure-clear nucleus and height of intervertebral disc).
  
  
  RESULTS
  A centrally located herniated disc was more common in the responder group than that in the non-responder group. Treatment of centrally located herniated discs showed satisfactory results. (VAS p=0.025, RMDQ p=0.040). Other factors, such as HLD level, HLD type, HLD volume, relationship to nerve root, disc height loss, and disc degeneration grade, were not critical.
  
  
  CONCLUSIONS
  The HLD zone was significant for pain reduction after CESI. A centrally located herniated disc was a predictor of a good clinical outcome.
authors.affiliation: Department of Rehabilitation Medicine, Gangnam Severance Hospital, Seoul, Korea. ; Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Sung Oh
authors.initials: SO
authors.lastname: Cha
authors.affiliation: Department of Rehabilitation Medicine, Gangnam Severance Hospital, Seoul, Korea. ; Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Chul Hoon
authors.initials: CH
authors.lastname: Jang
authors.affiliation: Department of Rehabilitation Medicine, Gangnam Severance Hospital, Seoul, Korea. ; Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jin Oh
authors.initials: JO
authors.lastname: Hong
authors.affiliation: Department of Rehabilitation Medicine, Gangnam Severance Hospital, Seoul, Korea. ; Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Joon Sang
authors.initials: JS
authors.lastname: Park
authors.affiliation: Department of Rehabilitation Medicine, Gangnam Severance Hospital, Seoul, Korea. ; Rehabilitation Institute of Neuromuscular Disease, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Park
keywords: Caudal; Epidural injections; Magnetic resonance image; Radicular pain; Ultrasound