title: The significance of multifidus atrophy after successful radiofrequency neurotomy for low back pain.
abstract: OBJECTIVE
  To determine the presence of lumbar multifidus atrophy and pain after successful lumbar medial branch radiofrequency neurotomy for zygapophysial joint mediated pain.
  
  
  METHODS
  A prospective observational analysis of 5 patients who had undergone successful unilateral radiofrequency neurotomy (RFN) of the lumbar medial branch divisions of the lumbar dorsal rami. At 17 to 26 months after RFN, 3 blinded radiologists evaluated the relative composition and size of the multifidus muscle at different segmental levels on lumbar magnetic resonance imaging (MRI). They were asked to determine the lesioned levels by evidence of multifidus atrophy. The accuracy of predicting the correct side and level lesioned was evaluated.
  
  
  METHODS
  Private spine practice in Tyler, Texas.
  
  
  METHODS
  Five patients who had unilateral lumbar medial branch RFN for proven lumbar zygapophysial joint-mediated pain were selected.
  
  
  METHODS
  MRI of the lumbar spine at a mean of 21 months (range, 17-26) after successful lumbar RFN.
  
  
  METHODS
  Multifidus atrophy on a lumbar MRI, pain assessment and use of cointerventions.
  
  
  RESULTS
  Diffuse lumbar multifidus atrophy was detectable with MRI. However, radiologists could not reliably predict the side and segments lesioned. Despite denervation of the multifidus, at 12 months after RFN all subjects had ongoing pain relief and did not require or request additional treatment.
  
  
  CONCLUSIONS
  This preliminary study provides evidence that successful medial branch RFN for lumbar zygapophysial-mediated pain does cause initial denervation but no discernable segmental atrophy of the multifidus at long-term follow-up. Previous denervation and diffuse atrophy in these subjects was not associated with pain.
authors.affiliation: Department of Rehabilitation Medicine, University of Washington, 21108 NE 129th CT, Woodinville, WA 98077, USA. pauldreyfuss@gmail.com
authors.forename: Paul
authors.initials: P
authors.lastname: Dreyfuss
authors.forename: Alison
authors.initials: A
authors.lastname: Stout
authors.forename: Charles
authors.initials: C
authors.lastname: Aprill
authors.forename: Steve
authors.initials: S
authors.lastname: Pollei
authors.forename: Blake
authors.initials: B
authors.lastname: Johnson
authors.forename: Nikolai
authors.initials: N
authors.lastname: Bogduk
mesh_terms: D003714:Denervation; D005500:Follow-Up Studies; D006801:Humans; D017116:Low Back Pain / Q000209:etiology / Q000473:pathology* / Q000601:surgery*; D008159:Lumbar Vertebrae; D008279:Magnetic Resonance Imaging; D009134:Muscular Atrophy, Spinal / Q000209:etiology* / Q000473:pathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D016896:Treatment Outcome; D021801:Zygapophyseal Joint