title: Injectate volumes needed to reach specific landmarks in s1 transforaminal epidural injections.
abstract: OBJECTIVE
  We identify the contrast volumes needed to reach specific landmarks during S1 transforaminal epidural injections (S1-TFEIs).
  
  
  METHODS
  Prospective, nonrandomized, observational human study. Setting.  Academic/private pain management practice. Subjects.  Forty-two patients undergoing S1-TFEIs were investigated. Thirty-seven patients were included in this study. Interventions.  S1-TFEIs were performed using contrast-enhanced fluoroscopic visualization.
  
  
  METHODS
  After confirming appropriate spinal needle position, up to 5 mL of nonionic contrast was slowly injected. Under biplanar fluoroscopic guidance, contrast volumes were recorded as flow reached specific anatomic landmarks: the ipsilateral S1 pedicle, the superior aspect of the L5-S1 disc space, and across the midline of the spinous process.
  
  
  RESULTS
  After injecting 2 mL of contrast, 100% of S1-TFEIs spread to the medial aspect of the ipsilateral superior pedicle of S1. After injecting 3.0 mL of contrast, 92% of S1-TFEIs spread to the superior aspect of the L5-S1 intervertebral disc. After injecting 4 mL of contrast, 27% of S1-TFEIs spread beyond the midline of the spinous process, but by only a few millimeters.
  
  
  CONCLUSIONS
  This study demonstrates injectate volumes needed to reach specific anatomic landmarks in S1-TFEIs. A volume of 3.0 mL of contrast reaches the superior aspect of the L5-S1 intervertebral disc 92% of the time.
authors.affiliation: Pain Management, Orthopaedic and Spine Specialists, 1855 Powder Mill Road, York, PA 17403, USA. mbfurman@gmail.com.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Furman
authors.forename: Sean P
authors.initials: SP
authors.lastname: Butler
authors.forename: Ruby E
authors.initials: RE
authors.lastname: Kim
authors.forename: Ariz R
authors.initials: AR
authors.lastname: Mehta
authors.forename: Jeremy I
authors.initials: JI
authors.lastname: Simon
authors.forename: Rikin
authors.initials: R
authors.lastname: Patel
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Lee
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Reeves
mesh_terms: D003287:Contrast Media / Q000008:administration & dosage*; D004824:Epidural Space / Q000000981:diagnostic imaging; D005260:Female; D005471:Fluoroscopy; D006801:Humans; D007268:Injections, Epidural / Q000379:methods*; D007405:Intervertebral Disc Displacement / Q000000981:diagnostic imaging / Q000188:drug therapy; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000379:methods*; D011843:Radiculopathy / Q000000981:diagnostic imaging / Q000188:drug therapy; D013130:Spinal Stenosis / Q000000981:diagnostic imaging / Q000188:drug therapy
chemical_list: D003287:Contrast Media