title: Paramedian access to the epidural space: the optimum window for ultrasound imaging.
abstract: OBJECTIVE
  To establish a useful ultrasonic approach to the epidural space so as to optimize pre-puncture diagnostics.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  University clinic.
  
  
  METHODS
  60 participants (19 to 34 years of age), 40 healthy volunteers (20 male, 20 female) and 20 parturients.
  
  
  METHODS
  Ultrasound scanning of the lumbar spine was performed at the L(3)-L(4) vertebral interspace. Three ultrasound planes were employed: the transverse, median, and paramedian longitudinal approaches.
  
  
  METHODS
  We compared the width of the ultrasound-permeable area in the median and paramedian planes and assessed the visibility of the epidural space and its surrounding structures.
  
  
  RESULTS
  In the paramedian plane, the permeable window was larger (p < 0.001) than in the median approach. The visibility of the ligamentum flavum (p < 0.0001), dura mater (p < 0.0001), and cauda equina (p < 0.0001) was significantly higher. Pulsation of epidural vessels could be observed more frequently (p < 0.0001) in the paramedian plane.
  
  
  CONCLUSIONS
  The longitudinal paramedian plane provided information about the epidural space depth in excellent imaging quality. The additional information might be beneficial in epidural anesthesia and in other clinical specialties (e.g., neurosurgery, trauma care).
authors.affiliation: Department of Anaesthesiology, University of Heidelberg, Heidelberg, Germany. thomas_grau@med.uni-heidelberg.de
authors.forename: T
authors.initials: T
authors.lastname: Grau
authors.forename: R W
authors.initials: RW
authors.lastname: Leipold
authors.forename: J
authors.initials: J
authors.lastname: Horter
authors.forename: R
authors.initials: R
authors.lastname: Conradi
authors.forename: E O
authors.initials: EO
authors.lastname: Martin
authors.forename: J
authors.initials: J
authors.lastname: Motsch
mesh_terms: D000328:Adult; D000767:Anesthesia, Epidural / Q000379:methods*; D000773:Anesthesia, Obstetrical; D004824:Epidural Space / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011446:Prospective Studies; D013131:Spine / Q000000981:diagnostic imaging; D014463:Ultrasonography