The significance of multifidus atrophy after successful radiofrequency neurotomy for low back pain.
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.
Dreyfuss
Paul
P
Department of Rehabilitation Medicine, University of Washington, 21108 NE 129th CT, Woodinville, WA 98077, USA. pauldreyfuss@gmail.com
Stout
Alison
A
Aprill
Charles
C
Pollei
Steve
S
Johnson
Blake
B
Bogduk
Nikolai
N
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