• Matthew Smuck, Joshua Levin, Eric Zemper, Adil Ali, and David J Kennedy.
• PM&R Section, Department of Orthopaedic Surgery, Stanford University, Redwood City, California, USA.
• Pain Med. 2014 Oct 1;15(10):1695-703.

ObjectiveTo quantitatively evaluate interval magnetic resonance imaging (MRI) changes in disc morphology following plasma-mediated percutaneous discectomy.Design/SettingA retrospective comparison of pretreatment and posttreatment MRIs at a single university spine clinic.SubjectsFrom a group of 60 consecutively treated patients, 15 met the study inclusion and exclusion criteria. All had either failed treatment or had other clinical reasons for a posttreatment MRI.MethodsTwo independent physicians electronically measured disc protrusion size and disc height at the treatment discs and adjacent discs on pre- and posttreatment MRI scans. Additionally, images were compared for gross anatomic changes including disc degeneration by Pfirrman classification, new disc herniations, high intensity zone (HIZ), vertebral endplate changes, post-contrast enhancement, and changes in segmental alignment. Pearson r correlation was used to determine interobserver reliability between the two physicians' MRI measurements. Paired t-tests were calculated for comparisons of pre- and posttreatment MRI measurements, and an ANOVA was performed for comparison of pre- to posttreatment changes in disc height measurements at treatment levels relative to adjacent levels.ResultsCorrelation was high for measurement of disc height change (r = 0.89; P < 0.0001) and good for anteroposterior protrusion size change (r = 0.51; P = 0.0512). Disc height at treated discs demonstrated a small but statistically significant mean interval reduction of 0.48 mm (P = 0.0018). This remained significant when compared with the adjacent control discs (P < 0.0001). Pretreatment mean disc protrusion size (4.74 mm; range 3.75-6.55 mm) did not differ significantly (P = 0.1145) from posttreatment protrusion size (4.42 mm; range 2.55-7.95 mm). Gross anatomic changes at treatment levels included reduced disc protrusion size (N = 6), enlarged protrusion (N = 3), resolution of HIZ (N = 3), and improvement in endplate signal changes (N = 1). Also, 11/15 posttreatment MRIs included post-contrast images that showed epidural fibrosis (N = 1), rim enhancement (N = 2), and enhancement of the posterior annulus (N = 4).ConclusionsBased on MRI examinations, subtle anatomic changes may occur following plasma-mediated percutaneous discectomy. Further study is required to determine the clinical relevance of these changes.Wiley Periodicals, Inc.

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