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  • Postoperative foraminal changes on magnetic resonance image after percutaneous endoscopic lumbar foraminotomy

    Final Number:

    Yong Ahn M.D., Ph.D; Ho Kim; Hyun-Kyong Oh; Sang-Ho Lee MD PhD; Wei Chiang Liu; Hyeon Seon Park

    Study Design:
    Clinical Trial

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting

    Introduction: Percutaneous endoscopic lumbar foraminotomy (PELF) is a novel minimally invasive technique. The objective of this study was to evaluate the radiographic efficacy of the technique. We measured the postoperative changes of lumbar foraminal parameters on MRI in both quantitative and qualitative way.

    Methods: Posterolateral PELFs using working channel endoscope were performed for the patients with foraminal or extraforaminal lumbar stenosis. Pre- and immediate postoperative MRIs were performed. The images of total 34 patients were blindly measured by 2 observers for foraminal stenosis grade and foraminal dimensions such as foraminal height (FH), superior foraminal width (SFW), middle foraminal width (MFW), posterior disc height (PDH) and foraminal area (FA). The inter-observer correlation coefficient (ICC) and the k statistic were calculated to determine the inter-observer reliability.

    Results: The mean age of 34 patients was 58.5 years and 39 foramens were evaluated. There were significant increases in mean FH from 11.36 to 13.47 mm, in mean SFW from 6.43 to 9.27 mm, in mean MFW from 1.47 to 78 mm, and in mean FA from 50.05 to 92.03 mm2 respectively (p = 0.000). In contrast, the disc heights (PDHs) were not changed. The mean foraminal stenosis grade was significantly improved from 2.66 to 0.74. The mean VAS improved from 8.44 at baseline to 3.28 at 6 weeks and 2.50 at 6 months and 1.94 at 1 year. There were no significant correlation between foraminal dimensions and pain scores. The inter-observer reliabilities for preoperative and postoperative measurements were excellent to moderate (ICCs ranging between 0.516 and 0.898, 95% CI).

    Conclusions: Foraminal dimensions and foraminal stenosis grade were significantly improved after PELF. These data indicate that the endoscopic foraminotomy technique used is efficient for decompressing the exiting nerve root in the lumbar neuroforamen.

    Patient Care: Percutaneous endoscopic lumbar foraminotomy may be useful, especially for elderly patients or medically compromised patients.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) describe the technique of minimally invasive lumbar foraminotomy, 2) discuss about the qualitative way to access the foraminal stenosis grade, 3) discuss about the quantitative way to access the foraminal dimensions.


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