title: In vivo discography in degenerate porcine spines revealed pressure transfer to adjacent discs.
abstract: METHODS
  In vivo experimental porcine study.
  
  
  OBJECTIVE
  To investigate if discography induced pressure increase in adjacent degenerate discs.
  
  
  BACKGROUND
  Despite refinements in the past 2 decades, the validity of discography is debated. Discography in healthy pigs has shown that the pressure increase during disc injection transmits to adjacent discs, a potential source for false positive responses.
  
  
  METHODS
  Degeneration in 1 lumbar disc was induced in 10 pigs by drilling a hole through the endplate. Intradiscal pressure was recorded using a 0.36-mm fiber-optic pressure transducer inserted into nucleus pulposus through a 22-gauge needle. The pressure was measured simultaneously in 2 adjacent discs during slow (0.03 mL/s) automated contrast injection into 1 of the discs up to 8 bar (116 psi). Ten adjacent discs were prefilled with contrast from previous discogram. A pressure increase 2 psi or more above baseline was defined as increased pressure in adjacent discs. Pressure was recorded until 15 minutes after injection.
  
  
  RESULTS
  A total of 28 discograms were successfully performed. A pressure increase during injection was detected in 57% (16) of the 28 adjacent discs with mean 3.2 psi (1.7-8.2; standard deviation, 1.8), corresponding to a mean increase above baseline of 11%. Of those 16 adjacent discs, 4 were nondegenerate and 12 degenerate, of which 7 were prefilled. Fifteen minutes after injection, 89% of adjacent discs displayed increase in pressure of mean 14% above baseline.
  
  
  CONCLUSIONS
  Discography induced pressure increase in adjacent discs in a degenerate disc model, something not reported earlier. If present, also in human spine pressure transmission, may be a potential cause for false positive discography responses.
authors.affiliation: *Department of Radiology, Sahlgrenska University Hospital, SU/M, Gothenburg, Sweden; and †Department of Orthopaedics, Sahlgrenska University Hospital, SU/S, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Hebelka
authors.forename: Andreas
authors.initials: A
authors.lastname: Nilsson
authors.forename: Lars
authors.initials: L
authors.lastname: Ekström
authors.forename: Tommy
authors.initials: T
authors.lastname: Hansson
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D007403:Intervertebral Disc / Q000473:pathology / Q000503:physiopathology*; D017116:Low Back Pain / Q000473:pathology / Q000503:physiopathology*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology*; D009192:Myelography; D010147:Pain Measurement; D013552:Swine; D014160:Transducers, Pressure